import { TRPCError } from "@trpc/server";
import { randomUUID } from "crypto";
import { and, asc, count, desc, eq, inArray, sql } from "drizzle-orm";
import { z } from "zod";

import { createTRPCRouter, protectedProcedure } from "~/server/api/trpc";
import type { db } from "~/server/db";
import {
  actions,
  activityLogs,
  experiments,
  experimentStatusEnum,
  robots,
  steps,
  trials,
  stepTypeEnum,
  studyMembers,
  userSystemRoles,
} from "~/server/db/schema";
import { convertStepsToDatabase } from "~/lib/experiment-designer/block-converter";
import type {
  ExperimentStep,
  ExperimentDesign,
} from "~/lib/experiment-designer/types";
import { validateAndCompile } from "~/lib/experiment-designer/execution-compiler";
import { estimateDesignDurationSeconds } from "~/lib/experiment-designer/visual-design-guard";

// Helper function to check study access (with admin bypass)
async function checkStudyAccess(
  database: typeof db,
  userId: string,
  studyId: string,
  requiredRole?: string[],
) {
  // Check if user is system administrator (bypass study permissions)
  const adminRole = await database.query.userSystemRoles.findFirst({
    where: and(
      eq(userSystemRoles.userId, userId),
      eq(userSystemRoles.role, "administrator"),
    ),
  });

  if (adminRole) {
    return { role: "administrator", studyId, userId, joinedAt: new Date() };
  }

  // Check study membership
  const membership = await database.query.studyMembers.findFirst({
    where: and(
      eq(studyMembers.studyId, studyId),
      eq(studyMembers.userId, userId),
    ),
  });

  if (!membership) {
    throw new TRPCError({
      code: "FORBIDDEN",
      message: "You don't have access to this study",
    });
  }

  if (requiredRole && !requiredRole.includes(membership.role)) {
    throw new TRPCError({
      code: "FORBIDDEN",
      message: "You don't have permission to perform this action",
    });
  }

  return membership;
}

export const experimentsRouter = createTRPCRouter({
  list: protectedProcedure
    .input(
      z.object({
        studyId: z.string().uuid(),
        status: z.enum(experimentStatusEnum.enumValues).optional(),
      }),
    )
    .query(async ({ ctx, input }) => {
      const { studyId, status } = input;
      const userId = ctx.session.user.id;

      // Check study access
      await checkStudyAccess(ctx.db, userId, studyId);

      const conditions = [eq(experiments.studyId, studyId)];
      if (status) {
        conditions.push(eq(experiments.status, status));
      }

      const experimentsList = await ctx.db.query.experiments.findMany({
        where: and(...conditions),
        with: {
          createdBy: {
            columns: {
              id: true,
              name: true,
              email: true,
            },
          },
          robot: {
            columns: {
              id: true,
              name: true,
              manufacturer: true,
            },
          },
          steps: {
            columns: {
              id: true,
              name: true,
              type: true,
              orderIndex: true,
            },
            orderBy: [asc(steps.orderIndex)],
          },
          trials: {
            columns: {
              id: true,
              status: true,
            },
          },
        },
        orderBy: [desc(experiments.updatedAt)],
      });

      // Aggregate action counts & latest trial activity (single pass merges)
      const experimentIds = experimentsList.map((e) => e.id);

      const actionCountMap = new Map<string, number>();
      const latestTrialActivityMap = new Map<string, Date>();

      if (experimentIds.length > 0) {
        // Action counts (join actions -> steps -> experiments)
        const actionCounts = await ctx.db
          .select({
            experimentId: steps.experimentId,
            count: count(),
          })
          .from(actions)
          .innerJoin(steps, eq(actions.stepId, steps.id))
          .where(inArray(steps.experimentId, experimentIds))
          .groupBy(steps.experimentId);

        actionCounts.forEach((row) =>
          actionCountMap.set(row.experimentId, Number(row.count) || 0),
        );

        // Latest trial activity (max of trial started/completed/created timestamps)
        const trialActivity = await ctx.db
          .select({
            experimentId: trials.experimentId,
            latest: sql`max(GREATEST(
  COALESCE(${trials.completedAt}, 'epoch':: timestamptz),
  COALESCE(${trials.startedAt}, 'epoch':: timestamptz),
  COALESCE(${trials.createdAt}, 'epoch':: timestamptz)
))`.as("latest"),
          })
          .from(trials)
          .where(inArray(trials.experimentId, experimentIds))
          .groupBy(trials.experimentId);

        trialActivity.forEach((row) => {
          if (row.latest) {
            latestTrialActivityMap.set(row.experimentId, row.latest as Date);
          }
        });
      }

      return experimentsList.map((exp) => {
        const trialLatest = latestTrialActivityMap.get(exp.id);
        const latestActivityAt =
          trialLatest && trialLatest > exp.updatedAt
            ? trialLatest
            : exp.updatedAt;

        return {
          ...exp,
          stepCount: exp.steps.length,
          trialCount: exp.trials.length,
          actionCount: actionCountMap.get(exp.id) ?? 0,
          latestActivityAt,
        };
      });
    }),

  getUserExperiments: protectedProcedure
    .input(
      z.object({
        page: z.number().min(1).default(1),
        limit: z.number().min(1).max(100).default(20),
        status: z.enum(experimentStatusEnum.enumValues).optional(),
      }),
    )
    .query(async ({ ctx, input }) => {
      const { page, limit, status } = input;
      const offset = (page - 1) * limit;
      const userId = ctx.session.user.id;

      // Get all studies user is a member of
      const userStudies = await ctx.db.query.studyMembers.findMany({
        where: eq(studyMembers.userId, userId),
        columns: {
          studyId: true,
        },
      });

      const studyIds = userStudies.map((membership) => membership.studyId);

      if (studyIds.length === 0) {
        return {
          experiments: [],
          pagination: {
            page,
            limit,
            total: 0,
            pages: 0,
          },
        };
      }

      // Build where conditions
      const conditions = [inArray(experiments.studyId, studyIds)];

      if (status) {
        conditions.push(eq(experiments.status, status));
      }

      const whereClause = and(...conditions);

      // Get experiments with relations
      const userExperiments = await ctx.db.query.experiments.findMany({
        where: whereClause,
        with: {
          study: {
            columns: {
              id: true,
              name: true,
            },
          },
          createdBy: {
            columns: {
              id: true,
              name: true,
              email: true,
            },
          },
          steps: {
            columns: {
              id: true,
            },
          },
          trials: {
            columns: {
              id: true,
            },
          },
        },
        limit,
        offset,
        orderBy: [desc(experiments.updatedAt)],
      });

      // Get total count
      const totalCountResult = await ctx.db
        .select({ count: count() })
        .from(experiments)
        .where(whereClause);

      const totalCount = totalCountResult[0]?.count ?? 0;

      // Transform data to include counts
      const transformedExperiments = userExperiments.map((experiment) => ({
        ...experiment,
        _count: {
          steps: experiment.steps.length,
          trials: experiment.trials.length,
        },
      }));

      return {
        experiments: transformedExperiments,
        pagination: {
          page,
          limit,
          total: totalCount,
          pages: Math.ceil(totalCount / limit),
        },
      };
    }),

  get: protectedProcedure
    .input(z.object({ id: z.string().uuid() }))
    .query(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, input.id),
        with: {
          study: {
            columns: {
              id: true,
              name: true,
            },
          },
          createdBy: {
            columns: {
              id: true,
              name: true,
              email: true,
            },
          },
          robot: true,
          steps: {
            with: {
              actions: {
                orderBy: [asc(actions.orderIndex)],
              },
            },
            orderBy: [asc(steps.orderIndex)],
          },
        },
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access
      await checkStudyAccess(ctx.db, userId, experiment.studyId);

      // Narrow executionGraph shape defensively before summarizing with explicit typing
      interface ExecActionSummary {
        actions?: unknown[];
      }
      interface ExecStepSummary {
        id?: string;
        name?: string;
        actions?: ExecActionSummary[];
      }
      interface ExecutionGraphShape {
        steps?: ExecStepSummary[];
        generatedAt?: string;
        version?: number;
      }

      const egRaw: unknown = experiment.executionGraph;
      const eg: ExecutionGraphShape | null =
        egRaw && typeof egRaw === "object" && !Array.isArray(egRaw)
          ? (egRaw as ExecutionGraphShape)
          : null;

      const stepsArray: ExecStepSummary[] | null = Array.isArray(eg?.steps)
        ? eg.steps
        : null;

      const executionGraphSummary = stepsArray
        ? {
          steps: stepsArray.length,
          actions: stepsArray.reduce((total, step) => {
            const acts = step.actions;
            return (
              total +
              (Array.isArray(acts)
                ? acts.reduce(
                  (aTotal, a) =>
                    aTotal +
                    (Array.isArray(a?.actions) ? a.actions.length : 0),
                  0,
                )
                : 0)
            );
          }, 0),
          generatedAt: eg?.generatedAt ?? null,
          version: eg?.version ?? null,
        }
        : null;

      return {
        ...experiment,
        integrityHash: experiment.integrityHash,
        executionGraphSummary,
        pluginDependencies: experiment.pluginDependencies ?? [],
      };
    }),

  create: protectedProcedure
    .input(
      z.object({
        studyId: z.string().uuid(),
        name: z.string().min(1).max(255),
        description: z.string().optional(),
        robotId: z.string().uuid().optional(),
        estimatedDuration: z.number().int().min(1).optional(),
        metadata: z.record(z.string(), z.any()).optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, input.studyId, [
        "owner",
        "researcher",
      ]);

      // Validate robot exists if provided
      if (input.robotId) {
        const robot = await ctx.db.query.robots.findFirst({
          where: eq(robots.id, input.robotId),
        });
        if (!robot) {
          throw new TRPCError({
            code: "NOT_FOUND",
            message: "Robot not found",
          });
        }
      }

      const newExperimentResults = await ctx.db
        .insert(experiments)
        .values({
          ...input,
          createdBy: userId,
        })
        .returning();

      const newExperiment = newExperimentResults[0];
      if (!newExperiment) {
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to create experiment",
        });
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: input.studyId,
        userId,
        action: "experiment_created",
        description: `Created experiment "${newExperiment.name}"`,
        resourceType: "experiment",
        resourceId: newExperiment.id,
      });

      return newExperiment;
    }),

  validateDesign: protectedProcedure
    .input(
      z.object({
        experimentId: z.string().uuid(),
        visualDesign: z.record(z.string(), z.any()),
        compileExecution: z.boolean().default(true),
      }),
    )
    .query(async ({ ctx, input }) => {
      const { experimentId, visualDesign, compileExecution } = input;
      const userId = ctx.session.user.id;

      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, experimentId),
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      const { parseVisualDesignSteps } = await import(
        "~/lib/experiment-designer/visual-design-guard"
      );
      const { steps: guardedSteps, issues } = parseVisualDesignSteps(
        visualDesign.steps,
      );

      if (issues.length) {
        return {
          valid: false,
          issues,
          pluginDependencies: [] as string[],
          integrityHash: null as string | null,
          compiled: null as unknown,
        };
      }

      let compiledGraph: ReturnType<typeof validateAndCompile> | null = null;
      if (compileExecution) {
        try {
          const designForCompile: ExperimentDesign = {
            id: experiment.id,
            name: experiment.name,
            description: experiment.description ?? "",
            version: experiment.version,
            steps: guardedSteps,
            lastSaved: new Date(),
          };
          compiledGraph = validateAndCompile(designForCompile);
        } catch (err) {
          return {
            valid: false,
            issues: [
              `Compilation failed: ${err instanceof Error ? err.message : "Unknown error"
              }`,
            ],
            pluginDependencies: [],
            integrityHash: null,
            compiled: null,
          };
        }
      }

      const pluginDeps = new Set<string>();
      for (const step of guardedSteps) {
        for (const action of step.actions) {
          if (action.source.kind === "plugin" && action.source.pluginId) {
            const versionPart = action.source.pluginVersion
              ? `@${action.source.pluginVersion}`
              : "";
            pluginDeps.add(`${action.source.pluginId}${versionPart}`);
          }
        }
      }

      return {
        valid: true,
        issues: [] as string[],
        pluginDependencies: Array.from(pluginDeps).sort(),
        integrityHash: compiledGraph?.hash ?? null,
        compiled: compiledGraph
          ? {
            steps: compiledGraph.steps.length,
            actions: compiledGraph.steps.reduce(
              (acc, s) => acc + s.actions.length,
              0,
            ),
            transportSummary: summarizeTransports(compiledGraph.steps),
          }
          : null,
      };
    }),

  update: protectedProcedure
    .input(
      z.object({
        id: z.string().uuid(),
        name: z.string().min(1).max(255).optional(),
        description: z.string().optional(),
        status: z.enum(experimentStatusEnum.enumValues).optional(),
        estimatedDuration: z.number().int().min(1).optional(),
        metadata: z.record(z.string(), z.any()).optional(),
        visualDesign: z.record(z.string(), z.any()).optional(),
        pluginDependencies: z.array(z.string()).optional(),
        createSteps: z.boolean().default(true),
        compileExecution: z.boolean().default(true),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { id, createSteps, compileExecution, ...updateData } = input;
      const userId = ctx.session.user.id;
      console.log("[DEBUG] experiments.update called", { id, visualDesign: updateData.visualDesign, createSteps });

      // Get experiment to check study access
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, id),
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      // Handle step creation from visual design
      const pluginDependencySet = new Set<string>();
      let compiledGraph: ReturnType<typeof validateAndCompile> | null = null;
      let integrityHash: string | undefined;
      let normalizedSteps: ExperimentStep[] = [];

      if (createSteps && updateData.visualDesign?.steps) {
        try {
          // Parse & normalize steps using visual design guard
          const { parseVisualDesignSteps } = await import(
            "~/lib/experiment-designer/visual-design-guard"
          );
          const { steps: guardedSteps, issues } = parseVisualDesignSteps(
            updateData.visualDesign.steps,
          );
          if (issues.length) {
            throw new TRPCError({
              code: "BAD_REQUEST",
              message: `Visual design validation failed: \n - ${issues.join("\n- ")}`,
            });
          }
          normalizedSteps = guardedSteps;
          // Auto-estimate duration if not provided
          updateData.estimatedDuration ??= Math.max(
            1,
            Math.round(estimateDesignDurationSeconds(normalizedSteps) / 60),
          );
          const convertedSteps = convertStepsToDatabase(normalizedSteps);
          // Compile execution graph & integrity hash if requested
          if (compileExecution) {
            try {
              // Compile from normalized steps (no synthetic unsafe casting)
              const designForCompile = {
                id: experiment.id,
                name: experiment.name,
                description: experiment.description ?? "",
                version: experiment.version,
                steps: normalizedSteps,
                lastSaved: new Date(),
              } as ExperimentDesign;
              compiledGraph = validateAndCompile(designForCompile);
              integrityHash ??= compiledGraph.hash;
              for (const dep of compiledGraph.pluginDependencies) {
                pluginDependencySet.add(dep);
              }
            } catch (compileErr) {
              throw new TRPCError({
                code: "BAD_REQUEST",
                message: `Execution graph compilation failed: ${compileErr instanceof Error
                  ? compileErr.message
                  : "Unknown error"
                  }`,
              });
            }
          }
          // Collect plugin dependencies from converted actions
          for (const step of convertedSteps) {
            for (const action of step.actions) {
              if (action.pluginId) {
                const versionPart = action.pluginVersion
                  ? `@${action.pluginVersion}`
                  : "";
                pluginDependencySet.add(`${action.pluginId}${versionPart}`);
              }
            }
          }

          // Delete existing steps and actions for this experiment
          await ctx.db.delete(steps).where(eq(steps.experimentId, id));

          // Create new steps and actions
          for (const convertedStep of convertedSteps) {
            const [newStep] = await ctx.db
              .insert(steps)
              .values({
                experimentId: id,
                name: convertedStep.name,
                description: convertedStep.description,
                type: convertedStep.type,
                orderIndex: convertedStep.orderIndex,
                durationEstimate: convertedStep.durationEstimate,
                required: convertedStep.required,
                conditions: convertedStep.conditions,
              })
              .returning();

            if (!newStep) {
              throw new TRPCError({
                code: "INTERNAL_SERVER_ERROR",
                message: "Failed to create step",
              });
            }

            // Create actions for this step
            for (const convertedAction of convertedStep.actions) {
              await ctx.db.insert(actions).values({
                stepId: newStep.id,
                name: convertedAction.name,
                description: convertedAction.description,
                type: convertedAction.type,
                orderIndex: convertedAction.orderIndex,
                parameters: convertedAction.parameters,
                timeout: convertedAction.timeout,
                retryCount: 0,
                // provenance & execution
                sourceKind: convertedAction.sourceKind,
                pluginId: convertedAction.pluginId,
                pluginVersion: convertedAction.pluginVersion,
                robotId: convertedAction.robotId ?? null,
                baseActionId: convertedAction.baseActionId,
                category: convertedAction.category,
                transport: convertedAction.transport,
                ros2: convertedAction.ros2,
                rest: convertedAction.rest,
                retryable: convertedAction.retryable,
                parameterSchemaRaw: convertedAction.parameterSchemaRaw,
              });
            }
          }
        } catch (error) {
          throw new TRPCError({
            code: "INTERNAL_SERVER_ERROR",
            message: `Step conversion failed: ${error instanceof Error ? error.message : "Unknown error"}`,
          });
        }
      }

      const updatedExperimentResults = await ctx.db
        .update(experiments)
        .set({
          ...updateData,
          pluginDependencies:
            pluginDependencySet.size > 0
              ? Array.from(pluginDependencySet).sort()
              : (updateData.pluginDependencies ??
                experiment.pluginDependencies),
          executionGraph: compiledGraph ?? experiment.executionGraph,
          integrityHash: integrityHash ?? experiment.integrityHash,
          updatedAt: new Date(),
        })
        .where(eq(experiments.id, id))
        .returning();

      const updatedExperiment = updatedExperimentResults[0];
      if (!updatedExperiment) {
        console.error("[DEBUG] Failed to update experiment - no result returned");
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to update experiment",
        });
      }
      console.log("[DEBUG] Experiment updated successfully", { updatedAt: updatedExperiment.updatedAt });

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "experiment_updated",
        description: `Updated experiment "${updatedExperiment.name}"`,
        resourceType: "experiment",
        resourceId: id,
      });

      return updatedExperiment;
    }),

  duplicate: protectedProcedure
    .input(
      z.object({
        experimentId: z.string().uuid(),
        newName: z.string().min(1).max(255),
        includeSteps: z.boolean().default(true),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { experimentId, newName, includeSteps } = input;
      const userId = ctx.session.user.id;

      // Get original experiment
      const originalExperiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, experimentId),
        with: {
          steps: {
            with: {
              actions: {
                orderBy: [asc(actions.orderIndex)],
              },
            },
            orderBy: [asc(steps.orderIndex)],
          },
        },
      });

      if (!originalExperiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, originalExperiment.studyId, [
        "owner",
        "researcher",
      ]);

      // Create duplicate experiment
      const newExperimentResults = await ctx.db
        .insert(experiments)
        .values({
          studyId: originalExperiment.studyId,
          name: newName,
          description: originalExperiment.description,
          robotId: originalExperiment.robotId,
          estimatedDuration: originalExperiment.estimatedDuration,
          metadata: originalExperiment.metadata,
          createdBy: userId,
        })
        .returning();

      const newExperiment = newExperimentResults[0];
      if (!newExperiment) {
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to create duplicate experiment",
        });
      }

      // Duplicate steps and actions if requested
      if (includeSteps && originalExperiment.steps.length > 0) {
        for (const step of originalExperiment.steps) {
          const newStepResults = await ctx.db
            .insert(steps)
            .values({
              experimentId: newExperiment.id,
              name: step.name,
              description: step.description,
              type: step.type,
              orderIndex: step.orderIndex,
              durationEstimate: step.durationEstimate,
              required: step.required,
              conditions: step.conditions,
            })
            .returning();

          const newStep = newStepResults[0];
          if (!newStep) {
            throw new TRPCError({
              code: "INTERNAL_SERVER_ERROR",
              message: "Failed to duplicate step",
            });
          }

          // Duplicate actions
          if (step.actions.length > 0) {
            const actionValues = step.actions.map(
              (action: typeof actions.$inferSelect) => ({
                stepId: newStep.id,
                name: action.name,
                description: action.description,
                type: action.type,
                orderIndex: action.orderIndex,
                parameters: action.parameters,
                validationSchema: action.validationSchema,
                timeout: action.timeout,
                retryCount: action.retryCount,
              }),
            );

            await ctx.db.insert(actions).values(actionValues);
          }
        }
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: originalExperiment.studyId,
        userId,
        action: "experiment_duplicated",
        description: `Duplicated experiment "${originalExperiment.name}" as "${newName}"`,
        resourceType: "experiment",
        resourceId: newExperiment.id,
      });

      return newExperiment;
    }),

  delete: protectedProcedure
    .input(z.object({ id: z.string().uuid() }))
    .mutation(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // Get experiment to check study access
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, input.id),
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      // Soft delete experiment
      await ctx.db
        .update(experiments)
        .set({
          deletedAt: new Date(),
          updatedAt: new Date(),
        })
        .where(eq(experiments.id, input.id));

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "experiment_deleted",
        description: `Deleted experiment "${experiment.name}"`,
        resourceType: "experiment",
        resourceId: input.id,
      });

      return { success: true };
    }),

  addStep: protectedProcedure
    .input(
      z.object({
        experimentId: z.string().uuid(),
        name: z.string().min(1).max(255),
        description: z.string().optional(),
        type: z.enum(stepTypeEnum.enumValues),
        orderIndex: z.number().int().min(0),
        durationEstimate: z.number().int().min(0).optional(),
        required: z.boolean().default(true),
        conditions: z.record(z.string(), z.any()).optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { experimentId, ...stepData } = input;
      const userId = ctx.session.user.id;

      // Get experiment to check study access
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, experimentId),
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      const newStepResults = await ctx.db
        .insert(steps)
        .values({
          experimentId,
          ...stepData,
        })
        .returning();

      const newStep = newStepResults[0];
      if (!newStep) {
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to create step",
        });
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "step_added",
        description: `Added step "${newStep.name}" to experiment "${experiment.name}"`,
        resourceType: "step",
        resourceId: newStep.id,
      });

      return newStep;
    }),

  updateStep: protectedProcedure
    .input(
      z.object({
        id: z.string().uuid(),
        name: z.string().min(1).max(255).optional(),
        description: z.string().optional(),
        type: z.enum(stepTypeEnum.enumValues).optional(),
        orderIndex: z.number().int().min(0).optional(),
        durationEstimate: z.number().int().min(0).optional(),
        required: z.boolean().optional(),
        conditions: z.record(z.string(), z.any()).optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { id, ...updateData } = input;
      const userId = ctx.session.user.id;

      // Get step and experiment to check study access
      const step = await ctx.db.query.steps.findFirst({
        where: eq(steps.id, id),
        with: {
          experiment: true,
        },
      });

      if (!step) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Step not found",
        });
      }

      // Get experiment to access studyId
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, step.experimentId),
        columns: { studyId: true },
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      const updatedStepResults = await ctx.db
        .update(steps)
        .set({
          ...updateData,
          updatedAt: new Date(),
        })
        .where(eq(steps.id, id))
        .returning();

      const updatedStep = updatedStepResults[0];
      if (!updatedStep) {
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to update step",
        });
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "step_updated",
        description: `Updated step "${updatedStep.name}"`,
        resourceType: "step",
        resourceId: id,
      });

      return updatedStep;
    }),

  deleteStep: protectedProcedure
    .input(z.object({ id: z.string().uuid() }))
    .mutation(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // Get step and experiment to check study access
      const step = await ctx.db.query.steps.findFirst({
        where: eq(steps.id, input.id),
        with: {
          experiment: true,
        },
      });

      if (!step) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Step not found",
        });
      }

      // Get experiment to access studyId
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, step.experimentId),
        columns: { studyId: true },
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      // Delete step (cascades to actions)
      await ctx.db.delete(steps).where(eq(steps.id, input.id));

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "step_deleted",
        description: `Deleted step "${step.name}"`,
        resourceType: "step",
        resourceId: input.id,
      });

      return { success: true };
    }),

  reorderSteps: protectedProcedure
    .input(
      z.object({
        experimentId: z.string().uuid(),
        stepIds: z.array(z.string().uuid()),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { experimentId, stepIds } = input;
      const userId = ctx.session.user.id;

      // Get experiment to check study access
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, experimentId),
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      // Verify all steps belong to this experiment
      const existingSteps = await ctx.db.query.steps.findMany({
        where: and(
          eq(steps.experimentId, experimentId),
          inArray(steps.id, stepIds),
        ),
      });

      if (existingSteps.length !== stepIds.length) {
        throw new TRPCError({
          code: "BAD_REQUEST",
          message: "Some steps don't belong to this experiment",
        });
      }

      // Update order indexes
      for (let i = 0; i < stepIds.length; i++) {
        const stepId = stepIds[i];
        if (stepId) {
          await ctx.db
            .update(steps)
            .set({ orderIndex: i })
            .where(eq(steps.id, stepId));
        }
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "steps_reordered",
        description: `Reordered steps in experiment "${experiment.name}"`,
        resourceType: "experiment",
        resourceId: experimentId,
      });

      return { success: true };
    }),

  addAction: protectedProcedure
    .input(
      z.object({
        stepId: z.string().uuid(),
        name: z.string().min(1).max(255),
        description: z.string().optional(),
        type: z.string().min(1).max(100),
        orderIndex: z.number().int().min(0),
        parameters: z.record(z.string(), z.any()).optional(),
        validationSchema: z.record(z.string(), z.any()).optional(),
        timeout: z.number().int().min(0).optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { stepId, ...actionData } = input;
      const userId = ctx.session.user.id;

      // Get step and experiment to check study access
      const step = await ctx.db.query.steps.findFirst({
        where: eq(steps.id, stepId),
        with: {
          experiment: true,
        },
      });

      if (!step) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Step not found",
        });
      }

      // Get experiment to access studyId
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, step.experimentId),
        columns: { studyId: true },
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(ctx.db, userId, experiment.studyId, [
        "owner",
        "researcher",
      ]);

      const newActionResults = await ctx.db
        .insert(actions)
        .values({
          stepId,
          ...actionData,
        })
        .returning();

      const newAction = newActionResults[0];
      if (!newAction) {
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to create action",
        });
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: experiment.studyId,
        userId,
        action: "action_added",
        description: `Added action "${newAction.name}" to step "${step.name}"`,
        resourceType: "action",
        resourceId: newAction.id,
      });

      return newAction;
    }),

  updateAction: protectedProcedure
    .input(
      z.object({
        id: z.string().uuid(),
        name: z.string().min(1).max(255).optional(),
        description: z.string().optional(),
        type: z.string().min(1).max(100).optional(),
        orderIndex: z.number().int().min(0).optional(),
        parameters: z.record(z.string(), z.any()).optional(),
        validationSchema: z.record(z.string(), z.any()).optional(),
        timeout: z.number().int().min(0).optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const { id, ...updateData } = input;
      const userId = ctx.session.user.id;

      // Get action, step, and experiment to check study access
      const action = await ctx.db.query.actions.findFirst({
        where: eq(actions.id, id),
        with: {
          step: {
            with: {
              experiment: true,
            },
          },
        },
      });

      if (!action) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Action not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(
        ctx.db,
        userId,
        (action.step.experiment as { studyId: string }).studyId,
        ["owner", "researcher"],
      );

      const updatedActionResults = await ctx.db
        .update(actions)
        .set({
          ...updateData,
          updatedAt: new Date(),
        })
        .where(eq(actions.id, id))
        .returning();

      const updatedAction = updatedActionResults[0];
      if (!updatedAction) {
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to update action",
        });
      }

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: (action.step.experiment as { studyId: string }).studyId,
        userId,
        action: "action_updated",
        description: `Updated action "${updatedAction.name}"`,
        resourceType: "action",
        resourceId: id,
      });

      return updatedAction;
    }),

  deleteAction: protectedProcedure
    .input(z.object({ id: z.string().uuid() }))
    .mutation(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // Get action, step, and experiment to check study access
      const action = await ctx.db.query.actions.findFirst({
        where: eq(actions.id, input.id),
        with: {
          step: {
            with: {
              experiment: true,
            },
          },
        },
      });

      if (!action) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Action not found",
        });
      }

      // Check study access with researcher permission
      await checkStudyAccess(
        ctx.db,
        userId,
        (action.step.experiment as { studyId: string }).studyId,
        ["owner", "researcher"],
      );

      // Delete action
      await ctx.db.delete(actions).where(eq(actions.id, input.id));

      // Log activity
      await ctx.db.insert(activityLogs).values({
        studyId: (action.step.experiment as { studyId: string }).studyId,
        userId,
        action: "action_deleted",
        description: `Deleted action "${action.name}"`,
        resourceType: "action",
        resourceId: input.id,
      });

      return { success: true };
    }),

  validate: protectedProcedure
    .input(z.object({ experimentId: z.string().uuid() }))
    .query(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // Get experiment with steps and actions
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, input.experimentId),
        with: {
          steps: {
            with: {
              actions: {
                orderBy: [asc(actions.orderIndex)],
              },
            },
            orderBy: [asc(steps.orderIndex)],
          },
        },
      });

      if (!experiment) {
        throw new TRPCError({
          code: "NOT_FOUND",
          message: "Experiment not found",
        });
      }

      // Check study access
      await checkStudyAccess(ctx.db, userId, experiment.studyId);

      const errors: Array<{
        type: string;
        message: string;
        stepId?: string;
        actionId?: string;
      }> = [];
      const warnings: Array<{
        type: string;
        message: string;
        stepId?: string;
        actionId?: string;
      }> = [];

      // Basic validation
      if (experiment.steps.length === 0) {
        errors.push({
          type: "no_steps",
          message: "Experiment must have at least one step",
        });
      }

      // Validate steps
      for (const step of experiment.steps) {
        if (step.actions.length === 0) {
          warnings.push({
            type: "empty_step",
            message: `Step "${step.name}" has no actions`,
            stepId: step.id,
          });
        }

        // Validate actions
        for (const action of step.actions) {
          if (action.timeout && action.timeout < 1) {
            errors.push({
              type: "invalid_timeout",
              message: `Action "${action.name}" has invalid timeout`,
              stepId: step.id,
              actionId: action.id,
            });
          }

          if (
            action.type === "wait" &&
            !(action.parameters as { duration?: number })?.duration
          ) {
            errors.push({
              type: "missing_duration",
              message: `Wait action "${action.name}" missing duration parameter`,
              stepId: step.id,
              actionId: action.id,
            });
          }
        }
      }

      // Check for duplicate step order indexes
      const orderIndexes = experiment.steps.map((s) => s.orderIndex);
      const uniqueOrderIndexes = new Set(orderIndexes);
      if (orderIndexes.length !== uniqueOrderIndexes.size) {
        errors.push({
          type: "duplicate_order",
          message: "Steps have duplicate order indexes",
        });
      }

      return {
        valid: errors.length === 0,
        errors,
        warnings,
      };
    }),

  getSteps: protectedProcedure
    .input(z.object({ experimentId: z.string().uuid() }))
    .query(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // First verify user has access to this experiment
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, input.experimentId),
        with: {
          study: {
            with: {
              members: {
                where: eq(studyMembers.userId, userId),
              },
            },
          },
        },
      });

      if (!experiment || experiment.study.members.length === 0) {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Access denied to this experiment",
        });
      }

      // Get steps with their actions
      const experimentSteps = await ctx.db.query.steps.findMany({
        where: eq(steps.experimentId, input.experimentId),
        with: {
          actions: {
            orderBy: [asc(actions.orderIndex)],
          },
        },
        orderBy: [asc(steps.orderIndex)],
      });

      // Transform to designer format
      return experimentSteps.map((step) => ({
        id: step.id,
        type: step.type,
        name: step.name,
        description: step.description,
        order: step.orderIndex,
        duration: step.durationEstimate,
        parameters: step.conditions as Record<string, unknown>,
        parentId: undefined, // Not supported in current schema
        children: [], // TODO: implement hierarchical steps if needed
        actions: step.actions.map((action) => ({
          id: action.id,
          name: action.name,
          description: action.description,
          type: action.type,
          order: action.orderIndex,
          parameters: action.parameters as Record<string, unknown>,
          pluginId: action.pluginId,
        })),
      }));
    }),

  saveDesign: protectedProcedure
    .input(
      z.object({
        experimentId: z.string().uuid(),
        steps: z.array(
          z.object({
            id: z.string(),
            type: z.enum(["wizard", "robot", "parallel", "conditional"]),
            name: z.string(),
            description: z.string().optional(),
            order: z.number(),
            duration: z.number().optional(),
            parameters: z.record(z.string(), z.any()),
            actions: z
              .array(
                z.object({
                  id: z.string(),
                  type: z.enum([
                    "speak",
                    "move",
                    "gesture",
                    "look_at",
                    "wait",
                    "instruction",
                    "question",
                    "observe",
                  ]),
                  name: z.string(),
                  description: z.string().optional(),
                  parameters: z.record(z.string(), z.any()),
                  duration: z.number().optional(),
                  order: z.number(),
                }),
              )
              .optional(),
            expanded: z.boolean().optional(),
            parentId: z.string().optional(),
            children: z.array(z.string()).optional(),
          }),
        ),
        version: z.number(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // Verify user has write access to this experiment
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, input.experimentId),
        with: {
          study: {
            with: {
              members: {
                where: and(
                  eq(studyMembers.userId, userId),
                  inArray(studyMembers.role, ["owner", "researcher"] as const),
                ),
              },
            },
          },
        },
      });

      if (!experiment || experiment.study.members.length === 0) {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Access denied to modify this experiment",
        });
      }

      // Get existing steps
      const existingSteps = await ctx.db.query.steps.findMany({
        where: eq(steps.experimentId, input.experimentId),
      });

      const existingStepIds = new Set(existingSteps.map((s) => s.id));
      const newStepIds = new Set(input.steps.map((s) => s.id));

      // Steps to delete (exist in DB but not in input)
      const stepsToDelete = existingSteps.filter((s) => !newStepIds.has(s.id));

      // Steps to insert (in input but don't exist in DB or have temp IDs)
      const stepsToInsert = input.steps.filter(
        (s) => !existingStepIds.has(s.id) || s.id.startsWith("step-"),
      );

      // Steps to update (exist in both)
      const stepsToUpdate = input.steps.filter(
        (s) => existingStepIds.has(s.id) && !s.id.startsWith("step-"),
      );

      // Execute in transaction
      await ctx.db.transaction(async (tx) => {
        // Delete removed steps
        if (stepsToDelete.length > 0) {
          await tx.delete(steps).where(
            inArray(
              steps.id,
              stepsToDelete.map((s) => s.id),
            ),
          );
        }

        // Insert new steps
        for (const step of stepsToInsert) {
          const stepId = step.id.startsWith("step-") ? randomUUID() : step.id;

          await tx.insert(steps).values({
            id: stepId,
            experimentId: input.experimentId,
            name: step.name,
            description: step.description,
            type: step.type,
            orderIndex: step.order,
            durationEstimate: step.duration,
            conditions: step.parameters,
          });
        }

        // Update existing steps
        for (const step of stepsToUpdate) {
          await tx
            .update(steps)
            .set({
              name: step.name,
              description: step.description,
              type: step.type,
              orderIndex: step.order,
              durationEstimate: step.duration,
              conditions: step.parameters,
              updatedAt: new Date(),
            })
            .where(eq(steps.id, step.id));
        }

        // Update experiment's updated timestamp
        await tx
          .update(experiments)
          .set({ updatedAt: new Date() })
          .where(eq(experiments.id, input.experimentId));
      });

      return { success: true };
    }),

  getExecutionData: protectedProcedure
    .input(z.object({ experimentId: z.string().uuid() }))
    .query(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;

      // First verify user has access to this experiment
      const experiment = await ctx.db.query.experiments.findFirst({
        where: eq(experiments.id, input.experimentId),
        with: {
          study: {
            with: {
              members: {
                where: eq(studyMembers.userId, userId),
              },
            },
          },
          robot: true,
        },
      });

      if (!experiment || experiment.study.members.length === 0) {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Access denied to this experiment",
        });
      }

      // Get steps with their actions for execution
      const executionSteps = await ctx.db.query.steps.findMany({
        where: eq(steps.experimentId, input.experimentId),
        with: {
          actions: {
            orderBy: [asc(actions.orderIndex)],
          },
        },
        orderBy: [asc(steps.orderIndex)],
      });

      // Transform to execution format
      return {
        experimentId: experiment.id,
        experimentName: experiment.name,
        description: experiment.description,
        estimatedDuration: experiment.estimatedDuration,
        robot: experiment.robot,
        visualDesign: experiment.visualDesign,
        steps: executionSteps.map((step) => ({
          id: step.id,
          name: step.name,
          description: step.description,
          type: step.type,
          orderIndex: step.orderIndex,
          durationEstimate: step.durationEstimate,
          required: step.required,
          conditions: step.conditions,
          actions: step.actions.map((action) => ({
            id: action.id,
            name: action.name,
            description: action.description,
            type: action.type,
            orderIndex: action.orderIndex,
            parameters: action.parameters,
            validationSchema: action.validationSchema,
            timeout: action.timeout,
            retryCount: action.retryCount,
          })),
        })),
        totalSteps: executionSteps.length,
        totalActions: executionSteps.reduce(
          (sum, step) => sum + step.actions.length,
          0,
        ),
      };
    }),
});

// Helper (moved outside router) to summarize transports for validateDesign output
function summarizeTransports(
  stepsCompiled: ReturnType<typeof validateAndCompile>["steps"],
): Record<string, number> {
  const counts: Record<string, number> = {};
  for (const st of stepsCompiled) {
    for (const act of st.actions) {
      const t = act.execution.transport;
      counts[t] = (counts[t] ?? 0) + 1;
    }
  }
  return counts;
}