const { z } = require("zod");
const { AppError } = require("../utils/AppError");
const { sendData } = require("../utils/reply");
const { resolvePermissionsForRoles, hasPermission, ROLE_PERMISSIONS } = require("../constants/permissions");
const { getWorkflowStepsSnapshot, resolveActionableStep, toMoneyString } = require("../utils/workflow");
const {
  findActiveDelegationForDelegate,
  listActiveDelegationPrincipals,
} = require("../utils/delegation");

const TASK_ID_SCHEMA = z.string().uuid();
const REQUIRED_COMMENT_SCHEMA = z.object({
  comment: z.string().trim().min(1).max(500),
});
const TRANSFER_BODY_SCHEMA = z.object({
  toApproverId: z.string().uuid(),
  reason: z.string().max(500),
});

const TASK_LIST_QUERY_SCHEMA = z.object({
  status: z.enum(["pending", "completed", "rejected", "cancelled", "skipped"]).optional(),
  page: z.coerce.number().int().min(1).optional(),
  pageSize: z.coerce.number().int().min(1).max(100).optional(),
});

const APPROVER_LIST_QUERY_SCHEMA = z.object({
  keyword: z.string().trim().max(100).optional(),
  page: z.coerce.number().int().min(1).optional(),
  pageSize: z.coerce.number().int().min(1).max(100).optional(),
});

const APPROVER_ROLE_CODES = Object.keys(ROLE_PERMISSIONS).filter((roleCode) =>
  hasPermission(ROLE_PERMISSIONS[roleCode], "expense.approve"),
);

function parseRequiredComment(body) {
  const parsed = REQUIRED_COMMENT_SCHEMA.safeParse(body ?? {});
  if (!parsed.success) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: parsed.error.flatten(),
    });
  }

  return parsed.data.comment;
}

function parseTransferBody(body) {
  const parsed = TRANSFER_BODY_SCHEMA.safeParse(body ?? {});
  if (!parsed.success) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: parsed.error.flatten(),
    });
  }

  const reason = parsed.data.reason.trim();
  if (reason.length < 10) {
    throw new AppError({
      code: "VALID_002",
      message: "转审原因不足 10 字",
      statusCode: 400,
      details: { reason: "too_short" },
    });
  }

  return {
    toApproverId: parsed.data.toApproverId,
    reason,
  };
}

function parseTaskId(taskId) {
  const parsed = TASK_ID_SCHEMA.safeParse(taskId);
  if (!parsed.success) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: { taskId: "invalid_uuid" },
    });
  }

  return parsed.data;
}

function parseTaskListQuery(query) {
  const parsed = TASK_LIST_QUERY_SCHEMA.safeParse(query ?? {});
  if (!parsed.success) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: parsed.error.flatten(),
    });
  }

  return {
    status: parsed.data.status ?? "pending",
    page: parsed.data.page ?? 1,
    pageSize: parsed.data.pageSize ?? 20,
  };
}

function parseApproverListQuery(query) {
  const parsed = APPROVER_LIST_QUERY_SCHEMA.safeParse(query ?? {});
  if (!parsed.success) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: parsed.error.flatten(),
    });
  }

  return {
    keyword: parsed.data.keyword ?? "",
    page: parsed.data.page ?? 1,
    pageSize: parsed.data.pageSize ?? 20,
  };
}

function isoOrNull(value) {
  if (!value) {
    return null;
  }

  return value.toISOString();
}

function mapTaskSummary(task) {
  const workflowInstance = task.workflow_instance
    ? {
        entity_type: task.workflow_instance.entity_type,
        entity_id: task.workflow_instance.entity_id,
        current_status: task.workflow_instance.current_status,
      }
    : null;

  return {
    id: task.id,
    instance_id: task.instance_id,
    step_id: task.step_id,
    step_name: task.step_name,
    assignee_id: task.assignee_id,
    assignee_role: task.assignee_role,
    status: task.status,
    outcome: task.outcome,
    created_at: isoOrNull(task.created_at),
    completed_at: isoOrNull(task.completed_at),
    workflow_instance: workflowInstance,

    instanceId: task.instance_id,
    stepId: task.step_id,
    stepName: task.step_name,
    assigneeId: task.assignee_id,
    assigneeRole: task.assignee_role,
    createdAt: isoOrNull(task.created_at),
    completedAt: isoOrNull(task.completed_at),
    workflowInstance: workflowInstance
      ? {
          entityType: workflowInstance.entity_type,
          entityId: workflowInstance.entity_id,
          currentStatus: workflowInstance.current_status,
        }
      : null,
  };
}

async function buildTaskVisibilityFilters(tx, request) {
  const roleFilters = request.employee.roleCodes.length
    ? [{ assignee_role: { in: request.employee.roleCodes } }]
    : [];
  const delegatedPrincipalIds = await listActiveDelegationPrincipals(tx, {
    delegateEmployeeId: request.employee.id,
    allowedScopes: ["all"],
  });

  const assigneeFilters = [{ assignee_id: request.employee.id }, ...roleFilters];
  if (delegatedPrincipalIds.length) {
    assigneeFilters.push({ assignee_id: { in: delegatedPrincipalIds } });
  }

  return assigneeFilters;
}

function listAllowedActionsForTask(request, task, actionable) {
  if (task.status !== "pending" || !actionable) {
    return [];
  }

  const actions = [];
  if (hasPermission(request.employee.permissionCodes, "expense.approve")) {
    actions.push("approve", "reject", "return");
  }

  if (hasPermission(request.employee.permissionCodes, "expense.transfer")) {
    actions.push("transfer");
  }

  return actions;
}

async function lockWorkflowTask(tx, taskId) {
  const taskRows = await tx.$queryRaw`
    SELECT id, instance_id, step_id, step_name, assignee_id, assignee_role, status
    FROM "workflow_tasks"
    WHERE id = ${taskId}::uuid
    FOR UPDATE
  `;

  if (!Array.isArray(taskRows) || taskRows.length === 0) {
    throw new AppError({
      code: "SYS_404",
      message: "Not Found",
      statusCode: 404,
    });
  }

  return taskRows[0];
}

function ensurePendingTask(task) {
  if (task.status !== "pending") {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 409,
      details: { task: "already_processed" },
    });
  }
}

async function ensureTaskAssignableToCurrentEmployee(tx, task, request) {
  const matchesAssigneeId = Boolean(task.assignee_id && task.assignee_id === request.employee.id);
  const matchesAssigneeRole = Boolean(
    task.assignee_role && request.employee.roleCodes.includes(task.assignee_role),
  );
  const isUnassigned = !task.assignee_id && !task.assignee_role;

  if (matchesAssigneeId || matchesAssigneeRole || isUnassigned) {
    return {
      delegated: false,
      delegationId: null,
      principalId: null,
    };
  }

  if (task.assignee_id) {
    const delegation = await findActiveDelegationForDelegate(tx, {
      principalEmployeeId: task.assignee_id,
      delegateEmployeeId: request.employee.id,
      allowedScopes: ["all"],
    });

    if (delegation) {
      return {
        delegated: true,
        delegationId: delegation.id,
        principalId: delegation.principal_employee_id,
      };
    }
  }

  throw new AppError({
    code: "PERM_002",
    message: "不在审批范围/非当前处理人",
    statusCode: 403,
  });
}

function withDelegationPayload(payload, assignment, delegateId) {
  const nextPayload = payload ? { ...payload } : {};

  if (assignment?.delegated) {
    nextPayload.delegation_id = assignment.delegationId;
    nextPayload.principal_id = assignment.principalId;
    nextPayload.delegate_id = delegateId;
  }

  return nextPayload;
}

async function loadWorkflowInstanceForTask(tx, instanceId) {
  const workflowInstance = await tx.workflowInstance.findUnique({
    where: { id: instanceId },
    select: {
      id: true,
      entity_id: true,
      current_step_id: true,
      context_data: true,
      workflow_definition: {
        select: {
          definition_json: true,
        },
      },
    },
  });

  if (!workflowInstance) {
    throw new AppError({
      code: "SYS_404",
      message: "Not Found",
      statusCode: 404,
    });
  }

  return workflowInstance;
}

async function createSkipHistoryRecords(tx, workflowInstanceId, actorId, ownerId, skippedSteps) {
  for (const skipped of skippedSteps) {
    await tx.workflowHistory.create({
      data: {
        instance_id: workflowInstanceId,
        actor_id: actorId,
        action: "skip",
        payload: {
          step_id: skipped.step.id,
          reason: skipped.reason,
          owner_id: ownerId,
          depth_checked: skipped.depthChecked,
        },
      },
    });
  }
}

async function cancelOtherPendingTasks(tx, workflowInstanceId, taskId, actorId) {
  await tx.workflowTask.updateMany({
    where: {
      instance_id: workflowInstanceId,
      status: "pending",
      NOT: { id: taskId },
    },
    data: {
      status: "cancelled",
      completed_at: new Date(),
      completed_by: actorId,
    },
  });
}

async function ensureTransferChainNotExceeded(tx, taskId) {
  const transferCount = await tx.workflowHistory.count({
    where: {
      task_id: taskId,
      action: "transfer",
    },
  });

  if (transferCount >= 3) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 409,
      details: { transfer: "chain_limit_exceeded" },
    });
  }

  return transferCount;
}

async function ensureTransferTargetEligible(tx, toApproverId) {
  const target = await tx.employee.findUnique({
    where: { id: toApproverId },
    select: {
      id: true,
      status: true,
      roles: {
        select: {
          role_code: true,
        },
      },
    },
  });

  if (!target || target.status !== "active") {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 409,
      details: { toApproverId: "invalid_target" },
    });
  }

  const roleCodes = target.roles.map((item) => item.role_code);
  const permissionCodes = resolvePermissionsForRoles(roleCodes);
  if (!hasPermission(permissionCodes, "expense.approve")) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 409,
      details: { toApproverId: "target_not_approver" },
    });
  }
}

async function workflowRoutes(fastify) {
  fastify.get(
    "/workflow/tasks",
    {
      preHandler: fastify.authenticate,
    },
    async (request, reply) => {
      const query = parseTaskListQuery(request.query);
      const skip = (query.page - 1) * query.pageSize;

      const assigneeFilters = await buildTaskVisibilityFilters(fastify.prisma, request);

      const where = {
        status: query.status,
        OR: assigneeFilters,
      };

      const [tasks, total] = await Promise.all([
        fastify.prisma.workflowTask.findMany({
          where,
          orderBy: { created_at: "desc" },
          skip,
          take: query.pageSize,
          select: {
            id: true,
            instance_id: true,
            step_id: true,
            step_name: true,
            assignee_id: true,
            assignee_role: true,
            status: true,
            outcome: true,
            created_at: true,
            completed_at: true,
            workflow_instance: {
              select: {
                entity_type: true,
                entity_id: true,
                current_status: true,
              },
            },
          },
        }),
        fastify.prisma.workflowTask.count({ where }),
      ]);

      return sendData(reply, request, {
        page: query.page,
        pageSize: query.pageSize,
        total,
        items: tasks.map(mapTaskSummary),
      });
    },
  );

  fastify.get(
    "/workflow/tasks/:taskId",
    {
      preHandler: fastify.authenticate,
    },
    async (request, reply) => {
      const taskId = parseTaskId(request.params?.taskId);
      const assigneeFilters = await buildTaskVisibilityFilters(fastify.prisma, request);

      const task = await fastify.prisma.workflowTask.findFirst({
        where: {
          id: taskId,
          OR: assigneeFilters,
        },
        select: {
          id: true,
          instance_id: true,
          step_id: true,
          step_name: true,
          assignee_id: true,
          assignee_role: true,
          status: true,
          outcome: true,
          comment: true,
          created_at: true,
          completed_at: true,
          workflow_instance: {
            select: {
              id: true,
              current_status: true,
              current_step_id: true,
              started_at: true,
              completed_at: true,
              reimbursement_form: {
                select: {
                  id: true,
                  form_number: true,
                  status: true,
                  total_amount: true,
                  reimbursement_date: true,
                  description: true,
                  owner: {
                    select: {
                      id: true,
                      employee_no: true,
                      name: true,
                    },
                  },
                  submitter: {
                    select: {
                      id: true,
                      employee_no: true,
                      name: true,
                    },
                  },
                },
              },
            },
          },
        },
      });

      if (!task) {
        const existing = await fastify.prisma.workflowTask.findUnique({
          where: { id: taskId },
          select: { id: true },
        });

        if (existing) {
          throw new AppError({
            code: "PERM_002",
            message: "不在审批范围/非当前处理人",
            statusCode: 403,
          });
        }

        throw new AppError({
          code: "SYS_404",
          message: "Not Found",
          statusCode: 404,
        });
      }

      let actionable = false;
      if (task.status === "pending") {
        try {
          await ensureTaskAssignableToCurrentEmployee(fastify.prisma, task, request);
          actionable = true;
        } catch (error) {
          if (error instanceof AppError && error.code === "PERM_002") {
            actionable = false;
          } else {
            throw error;
          }
        }
      }

      const historyItems = await fastify.prisma.workflowHistory.findMany({
        where: { instance_id: task.instance_id },
        orderBy: { created_at: "asc" },
        select: {
          id: true,
          task_id: true,
          actor_id: true,
          action: true,
          comment: true,
          payload: true,
          created_at: true,
          actor: {
            select: {
              id: true,
              name: true,
              employee_no: true,
            },
          },
        },
      });

      return sendData(reply, request, {
        task: {
          id: task.id,
          instanceId: task.instance_id,
          stepId: task.step_id,
          stepName: task.step_name,
          assigneeId: task.assignee_id,
          assigneeRole: task.assignee_role,
          status: task.status,
          outcome: task.outcome,
          comment: task.comment,
          createdAt: isoOrNull(task.created_at),
          completedAt: isoOrNull(task.completed_at),
        },
        workflowInstance: task.workflow_instance
          ? {
              id: task.workflow_instance.id,
              currentStatus: task.workflow_instance.current_status,
              currentStepId: task.workflow_instance.current_step_id,
              startedAt: isoOrNull(task.workflow_instance.started_at),
              completedAt: isoOrNull(task.workflow_instance.completed_at),
            }
          : null,
        reimbursement: task.workflow_instance?.reimbursement_form
          ? {
              id: task.workflow_instance.reimbursement_form.id,
              formNumber: task.workflow_instance.reimbursement_form.form_number,
              status: task.workflow_instance.reimbursement_form.status,
              reimbursementDate:
                task.workflow_instance.reimbursement_form.reimbursement_date
                  ?.toISOString?.()
                  ?.slice(0, 10) ?? null,
              totalAmount: toMoneyString(task.workflow_instance.reimbursement_form.total_amount),
              description: task.workflow_instance.reimbursement_form.description,
              owner: task.workflow_instance.reimbursement_form.owner
                ? {
                    id: task.workflow_instance.reimbursement_form.owner.id,
                    employeeNo: task.workflow_instance.reimbursement_form.owner.employee_no,
                    name: task.workflow_instance.reimbursement_form.owner.name,
                  }
                : null,
              submitter: task.workflow_instance.reimbursement_form.submitter
                ? {
                    id: task.workflow_instance.reimbursement_form.submitter.id,
                    employeeNo: task.workflow_instance.reimbursement_form.submitter.employee_no,
                    name: task.workflow_instance.reimbursement_form.submitter.name,
                  }
                : null,
            }
          : null,
        allowedActions: listAllowedActionsForTask(request, task, actionable),
        history: historyItems.map((item) => ({
          id: item.id,
          taskId: item.task_id,
          actorId: item.actor_id,
          actorName: item.actor?.name ?? "",
          actorEmployeeNo: item.actor?.employee_no ?? "",
          action: item.action,
          comment: item.comment,
          payload: item.payload,
          createdAt: isoOrNull(item.created_at),
        })),
      });
    },
  );

  fastify.get(
    "/workflow/approvers",
    {
      preHandler: fastify.requirePermission("expense.transfer"),
    },
    async (request, reply) => {
      const query = parseApproverListQuery(request.query);
      const skip = (query.page - 1) * query.pageSize;

      const where = {
        status: "active",
        id: { not: request.employee.id },
        roles: {
          some: {
            role_code: { in: APPROVER_ROLE_CODES },
          },
        },
        ...(query.keyword
          ? {
              OR: [
                { name: { contains: query.keyword, mode: "insensitive" } },
                { email: { contains: query.keyword, mode: "insensitive" } },
                { employee_no: { contains: query.keyword, mode: "insensitive" } },
              ],
            }
          : {}),
      };

      const [items, total] = await Promise.all([
        fastify.prisma.employee.findMany({
          where,
          orderBy: { name: "asc" },
          skip,
          take: query.pageSize,
          select: {
            id: true,
            employee_no: true,
            name: true,
            email: true,
            roles: {
              select: {
                role_code: true,
              },
            },
          },
        }),
        fastify.prisma.employee.count({ where }),
      ]);

      return sendData(reply, request, {
        page: query.page,
        pageSize: query.pageSize,
        total,
        items: items.map((item) => ({
          id: item.id,
          employeeNo: item.employee_no,
          name: item.name,
          email: item.email,
          roleCodes: item.roles.map((role) => role.role_code),
        })),
      });
    },
  );

  fastify.post(
    "/workflow/tasks/:taskId/approve",
    {
      preHandler: fastify.requirePermission("expense.approve"),
    },
    async (request, reply) => {
      const taskId = parseTaskId(request.params?.taskId);
      let result = null;

      await fastify.prisma.$transaction(async (tx) => {
        const task = await lockWorkflowTask(tx, taskId);
        ensurePendingTask(task);
        const assignment = await ensureTaskAssignableToCurrentEmployee(tx, task, request);

        const workflowInstance = await loadWorkflowInstanceForTask(tx, task.instance_id);
        const steps = getWorkflowStepsSnapshot(workflowInstance);
        const currentStepIndex = steps.findIndex((step) => step.id === workflowInstance.current_step_id);
        if (currentStepIndex < 0) {
          throw new AppError({
            code: "VALID_001",
            message: "参数校验失败",
            statusCode: 409,
            details: { workflow: "current_step_not_found" },
          });
        }

        const now = new Date();
        await tx.workflowTask.update({
          where: { id: taskId },
          data: {
            status: "completed",
            outcome: "approved",
            completed_at: now,
            completed_by: request.employee.id,
          },
        });

        const { actionable, skipped } = await resolveActionableStep({
          tx,
          steps,
          startIndex: currentStepIndex + 1,
          ownerId: workflowInstance.context_data?.owner_id,
          logger: fastify.log,
        });

        await createSkipHistoryRecords(
          tx,
          workflowInstance.id,
          request.employee.id,
          workflowInstance.context_data?.owner_id,
          skipped,
        );

        if (actionable) {
          const nextTask = await tx.workflowTask.create({
            data: {
              instance_id: workflowInstance.id,
              step_id: actionable.step.id,
              step_name: actionable.step.name ?? actionable.step.id,
              assignee_id: actionable.assigneeId,
              assignee_role: actionable.assigneeRole,
            },
            select: { id: true },
          });

          await tx.workflowInstance.update({
            where: { id: workflowInstance.id },
            data: {
              current_step_id: actionable.step.id,
              current_status: "pending",
              updated_by: request.employee.id,
            },
          });

          await tx.workflowHistory.create({
            data: {
              instance_id: workflowInstance.id,
              task_id: taskId,
              actor_id: request.employee.id,
              action: "approve",
              payload: withDelegationPayload(
                {
                  from_step_id: task.step_id,
                  to_step_id: actionable.step.id,
                },
                assignment,
                request.employee.id,
              ),
            },
          });

          result = {
            taskId,
            outcome: "approved",
            workflowInstanceId: workflowInstance.id,
            nextTaskId: nextTask.id,
            reimbursementStatus: "reviewing",
          };
          return;
        }

        await tx.workflowInstance.update({
          where: { id: workflowInstance.id },
          data: {
            current_status: "approved",
            completed_at: now,
            updated_by: request.employee.id,
          },
        });

        await tx.reimbursementForm.update({
          where: { id: workflowInstance.entity_id },
          data: {
            status: "approved",
            updated_by: request.employee.id,
          },
        });

        await tx.workflowHistory.create({
          data: {
            instance_id: workflowInstance.id,
            task_id: taskId,
            actor_id: request.employee.id,
            action: "approve",
            payload: withDelegationPayload(
              {
                from_step_id: task.step_id,
                terminal: true,
              },
              assignment,
              request.employee.id,
            ),
          },
        });

        result = {
          taskId,
          outcome: "approved",
          workflowInstanceId: workflowInstance.id,
          nextTaskId: null,
          reimbursementStatus: "approved",
        };
      });

      return sendData(reply, request, result);
    },
  );

  fastify.post(
    "/workflow/tasks/:taskId/reject",
    {
      preHandler: fastify.requirePermission("expense.approve"),
    },
    async (request, reply) => {
      const taskId = parseTaskId(request.params?.taskId);
      const comment = parseRequiredComment(request.body);
      let result = null;

      await fastify.prisma.$transaction(async (tx) => {
        const task = await lockWorkflowTask(tx, taskId);
        ensurePendingTask(task);
        const assignment = await ensureTaskAssignableToCurrentEmployee(tx, task, request);

        const workflowInstance = await loadWorkflowInstanceForTask(tx, task.instance_id);
        const now = new Date();

        await tx.workflowTask.update({
          where: { id: taskId },
          data: {
            status: "rejected",
            outcome: "rejected",
            comment,
            completed_at: now,
            completed_by: request.employee.id,
          },
        });

        await cancelOtherPendingTasks(tx, workflowInstance.id, taskId, request.employee.id);

        await tx.workflowInstance.update({
          where: { id: workflowInstance.id },
          data: {
            current_status: "rejected",
            completed_at: now,
            updated_by: request.employee.id,
          },
        });

        await tx.reimbursementForm.update({
          where: { id: workflowInstance.entity_id },
          data: {
            status: "rejected",
            updated_by: request.employee.id,
          },
        });

        await tx.workflowHistory.create({
          data: {
            instance_id: workflowInstance.id,
            task_id: taskId,
            actor_id: request.employee.id,
            action: "reject",
            comment,
            payload: withDelegationPayload(
              {
                from_step_id: task.step_id,
              },
              assignment,
              request.employee.id,
            ),
          },
        });

        result = {
          taskId,
          outcome: "rejected",
          workflowInstanceId: workflowInstance.id,
          reimbursementStatus: "rejected",
        };
      });

      return sendData(reply, request, result);
    },
  );

  fastify.post(
    "/workflow/tasks/:taskId/return",
    {
      preHandler: fastify.requirePermission("expense.approve"),
    },
    async (request, reply) => {
      const taskId = parseTaskId(request.params?.taskId);
      const comment = parseRequiredComment(request.body);
      let result = null;

      await fastify.prisma.$transaction(async (tx) => {
        const task = await lockWorkflowTask(tx, taskId);
        ensurePendingTask(task);
        const assignment = await ensureTaskAssignableToCurrentEmployee(tx, task, request);

        const workflowInstance = await loadWorkflowInstanceForTask(tx, task.instance_id);
        const now = new Date();

        await tx.workflowTask.update({
          where: { id: taskId },
          data: {
            status: "completed",
            outcome: "returned",
            comment,
            completed_at: now,
            completed_by: request.employee.id,
          },
        });

        await cancelOtherPendingTasks(tx, workflowInstance.id, taskId, request.employee.id);

        await tx.workflowInstance.update({
          where: { id: workflowInstance.id },
          data: {
            current_status: "terminated",
            completed_at: now,
            updated_by: request.employee.id,
          },
        });

        await tx.reimbursementForm.update({
          where: { id: workflowInstance.entity_id },
          data: {
            status: "draft",
            updated_by: request.employee.id,
          },
        });

        await tx.workflowHistory.create({
          data: {
            instance_id: workflowInstance.id,
            task_id: taskId,
            actor_id: request.employee.id,
            action: "return",
            comment,
            payload: withDelegationPayload(
              {
                from_step_id: task.step_id,
              },
              assignment,
              request.employee.id,
            ),
          },
        });

        result = {
          taskId,
          outcome: "returned",
          workflowInstanceId: workflowInstance.id,
          reimbursementStatus: "draft",
        };
      });

      return sendData(reply, request, result);
    },
  );

  fastify.post(
    "/workflow/tasks/:taskId/transfer",
    {
      preHandler: fastify.requirePermission("expense.transfer"),
    },
    async (request, reply) => {
      const taskId = parseTaskId(request.params?.taskId);
      const { toApproverId, reason } = parseTransferBody(request.body);
      let result = null;

      await fastify.prisma.$transaction(async (tx) => {
        const task = await lockWorkflowTask(tx, taskId);
        ensurePendingTask(task);
        const assignment = await ensureTaskAssignableToCurrentEmployee(tx, task, request);

        const workflowInstance = await loadWorkflowInstanceForTask(tx, task.instance_id);
        const transferCount = await ensureTransferChainNotExceeded(tx, taskId);
        await ensureTransferTargetEligible(tx, toApproverId);

        if (toApproverId === request.employee.id) {
          throw new AppError({
            code: "VALID_001",
            message: "参数校验失败",
            statusCode: 409,
            details: { transfer: "same_assignee_not_allowed" },
          });
        }

        await tx.workflowTask.update({
          where: { id: taskId },
          data: {
            assignee_id: toApproverId,
            assignee_role: null,
          },
        });

        const transfer = await tx.approvalTransfer.create({
          data: {
            reimbursement_id: workflowInstance.entity_id,
            from_approver_id: request.employee.id,
            to_approver_id: toApproverId,
            reason,
            status: "active",
            created_by: request.employee.id,
          },
          select: {
            id: true,
          },
        });

        await tx.workflowHistory.create({
          data: {
            instance_id: workflowInstance.id,
            task_id: taskId,
            actor_id: request.employee.id,
            action: "transfer",
            comment: reason,
            payload: withDelegationPayload(
              {
                from_approver_id: request.employee.id,
                to_approver_id: toApproverId,
                reason,
                transfer_count: transferCount + 1,
              },
              assignment,
              request.employee.id,
            ),
          },
        });

        result = {
          taskId,
          outcome: "transferred",
          workflowInstanceId: workflowInstance.id,
          reimbursementStatus: "reviewing",
          transferId: transfer.id,
          fromApproverId: request.employee.id,
          toApproverId,
          transferCount: transferCount + 1,
        };
      });

      return sendData(reply, request, result);
    },
  );
}

module.exports = workflowRoutes;