const { ValidationError, UniqueConstraintError } = require("sequelize");
const { ZodError } = require("zod");

class AppError extends Error {
  constructor(status, code, message, details) {
    super(message);
    this.status = status;
    this.code = code;
    this.details = details;
  }
}

const notFound = (req, _res, next) => next(new AppError(404, "NOT_FOUND", "Route not found"));

const errorHandler = (error, req, res, _next) => {
  let status = error.status || error.statusCode || 500;
  let code = error.code || "INTERNAL_ERROR";
  let message = error.message || "An unexpected error occurred";
  let details = error.details;

  if (error instanceof ZodError) {
    status = 400; code = "VALIDATION_ERROR"; message = "Invalid request data";
    details = error.issues.map(({ path, message: detailMessage }) => ({ field: path.join("."), message: detailMessage }));
  } else if (error instanceof UniqueConstraintError) {
    status = 409; code = "CONFLICT"; message = "A record with these values already exists";
    details = error.errors?.map(({ path, message: detailMessage }) => ({ field: path, message: detailMessage }));
  } else if (error instanceof ValidationError) {
    status = 400; code = "VALIDATION_ERROR"; message = "Invalid request data";
    details = error.errors?.map(({ path, message: detailMessage }) => ({ field: path, message: detailMessage }));
  } else if (error.type === "entity.too.large") {
    status = 413; code = "PAYLOAD_TOO_LARGE"; message = "Request body is too large";
  } else if (error.name === "UnauthorizedError" || error.name === "JsonWebTokenError") {
    status = 401; code = "UNAUTHORIZED"; message = "Authentication failed";
  }

  if (status >= 500) {
    console.error(`[${req.id || "no-request-id"}] Request failed`, { name: error.name, message: error.message });
    if (process.env.NODE_ENV === "production") message = "An unexpected error occurred";
  }

  const payload = { success: false, error: { code, message }, requestId: req.id };
  if (details && status < 500) payload.error.details = details;
  res.status(status).json(payload);
};

module.exports = { AppError, notFound, errorHandler };