const { AppError } = require("./AppError");

const UUID_REGEX = /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
const MAX_MANAGER_DEPTH = 10;

function parseWorkflowSteps(definitionJson) {
  const steps = definitionJson?.steps;
  if (!Array.isArray(steps) || steps.length === 0) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: { workflow: "invalid_steps" },
    });
  }

  return steps;
}

function buildWorkflowStepsFromApprovalRule(approvalRule) {
  if (!approvalRule || typeof approvalRule !== "object") {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: { workflow: "invalid_approval_rule" },
    });
  }

  const roleCodes = [
    approvalRule.level1_role,
    approvalRule.level2_role,
    approvalRule.level3_role,
  ].filter(Boolean);

  if (roleCodes.length === 0) {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: { workflow: "empty_approval_chain" },
    });
  }

  return roleCodes.map((roleCode, index) => ({
    id: `approval_${index + 1}_${roleCode}`,
    name: `审批节点${index + 1}`,
    type: "approval",
    assignee_rule:
      roleCode === "manager"
        ? { type: "department_manager" }
        : { type: "role", value: roleCode },
  }));
}

async function resolveDepartmentManagerAssignee({ tx, ownerId, logger }) {
  let currentId = ownerId;
  const visited = new Set();

  for (let depth = 1; depth <= MAX_MANAGER_DEPTH; depth += 1) {
    if (visited.has(currentId)) {
      logger?.warn?.(
        { ownerId, currentId, reason: "cycle_detected" },
        "Circular manager reference detected",
      );
      return {
        assigneeId: null,
        reason: "cycle_detected",
        depthChecked: depth - 1,
      };
    }
    visited.add(currentId);

    const employee = await tx.employee.findUnique({
      where: { id: currentId },
      select: {
        id: true,
        direct_manager_id: true,
      },
    });

    if (!employee) {
      return {
        assigneeId: null,
        reason: "chain_broken",
        depthChecked: depth,
      };
    }

    const managerId = employee.direct_manager_id;
    if (!managerId) {
      return {
        assigneeId: null,
        reason: "no_manager_found",
        depthChecked: depth,
      };
    }

    if (managerId === currentId) {
      logger?.warn?.(
        { ownerId, currentId, reason: "self_loop" },
        "Self-loop manager reference detected",
      );
      return {
        assigneeId: null,
        reason: "self_loop",
        depthChecked: depth,
      };
    }

    if (managerId === ownerId) {
      currentId = managerId;
      continue;
    }

    if (visited.has(managerId)) {
      logger?.warn?.(
        { ownerId, currentId: managerId, reason: "cycle_detected" },
        "Circular manager reference detected",
      );
      return {
        assigneeId: null,
        reason: "cycle_detected",
        depthChecked: depth,
      };
    }

    return {
      assigneeId: managerId,
      reason: null,
      depthChecked: depth,
    };
  }

  logger?.warn?.(
    { ownerId, currentId, reason: "max_depth_exceeded" },
    "Manager resolution reached max depth",
  );
  return {
    assigneeId: null,
    reason: "max_depth_exceeded",
    depthChecked: MAX_MANAGER_DEPTH,
  };
}

async function resolveAssigneeFromRule(rule, options = {}) {
  if (!rule || typeof rule !== "object") {
    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: { workflow: "invalid_assignee_rule" },
    });
  }

  if (rule.type === "role") {
    if (typeof rule.value !== "string" || !rule.value) {
      throw new AppError({
        code: "VALID_001",
        message: "参数校验失败",
        statusCode: 400,
        details: { workflow: "invalid_role_assignee" },
      });
    }

    return {
      assigneeId: null,
      assigneeRole: rule.value,
      skipReason: null,
      depthChecked: 0,
    };
  }

  if (rule.type === "specific_user") {
    if (typeof rule.value !== "string" || !UUID_REGEX.test(rule.value)) {
      throw new AppError({
        code: "VALID_001",
        message: "参数校验失败",
        statusCode: 400,
        details: { workflow: "invalid_specific_user_assignee" },
      });
    }

    return {
      assigneeId: rule.value,
      assigneeRole: null,
      skipReason: null,
      depthChecked: 0,
    };
  }

  if (rule.type === "department_manager") {
    const ownerId = options.ownerId;
    const tx = options.tx;

    if (!ownerId || !UUID_REGEX.test(ownerId) || !tx) {
      throw new AppError({
        code: "VALID_001",
        message: "参数校验失败",
        statusCode: 400,
        details: { workflow: "invalid_department_manager_context" },
      });
    }

    const managerResult = await resolveDepartmentManagerAssignee({
      tx,
      ownerId,
      logger: options.logger,
    });

    if (!managerResult.assigneeId) {
      return {
        assigneeId: null,
        assigneeRole: null,
        skipReason: managerResult.reason,
        depthChecked: managerResult.depthChecked,
      };
    }

    return {
      assigneeId: managerResult.assigneeId,
      assigneeRole: null,
      skipReason: null,
      depthChecked: managerResult.depthChecked,
    };
  }

  throw new AppError({
    code: "VALID_001",
    message: "参数校验失败",
    statusCode: 400,
    details: { workflow: "unsupported_assignee_rule_type" },
  });
}

async function resolveActionableStep({ tx, steps, startIndex, ownerId, logger }) {
  const skipped = [];

  for (let index = startIndex; index < steps.length; index += 1) {
    const step = steps[index];
    const resolved = await resolveAssigneeFromRule(step.assignee_rule, {
      tx,
      ownerId,
      logger,
    });

    if (resolved.assigneeId || resolved.assigneeRole) {
      return {
        actionable: {
          index,
          step,
          assigneeId: resolved.assigneeId,
          assigneeRole: resolved.assigneeRole,
        },
        skipped,
      };
    }

    if (resolved.skipReason) {
      skipped.push({
        index,
        step,
        reason: resolved.skipReason,
        depthChecked: resolved.depthChecked,
      });
      continue;
    }

    throw new AppError({
      code: "VALID_001",
      message: "参数校验失败",
      statusCode: 400,
      details: { workflow: "invalid_resolved_assignee" },
    });
  }

  return {
    actionable: null,
    skipped,
  };
}

function getWorkflowStepsSnapshot(workflowInstance) {
  const snapshot = workflowInstance?.context_data?.workflow_steps_snapshot;
  if (Array.isArray(snapshot) && snapshot.length > 0) {
    return parseWorkflowSteps({ steps: snapshot });
  }

  return parseWorkflowSteps(workflowInstance?.workflow_definition?.definition_json);
}

function toMoneyString(value) {
  if (value == null) return null;
  return typeof value === "string" ? value : value.toString();
}

module.exports = {
  buildWorkflowStepsFromApprovalRule,
  getWorkflowStepsSnapshot,
  parseWorkflowSteps,
  resolveActionableStep,
  resolveAssigneeFromRule,
  resolveDepartmentManagerAssignee,
  toMoneyString,
};