import { z } from 'zod';
import { Request, Response, NextFunction } from 'express';

/**
 * Schema for creating a new user
 * - email: required, must be valid email format
 * - password: required, minimum 8 characters
 * - name: required (first_name + last_name combined or separate)
 * - role_id: required, must be valid UUID
 * - is_active: optional, defaults to true
 */
export const createUserSchema = z.object({
  email: z
    .string({ required_error: 'Email is required' })
    .email('Invalid email format')
    .transform((val) => val.toLowerCase().trim()),
  password: z
    .string({ required_error: 'Password is required' })
    .min(8, 'Password must be at least 8 characters'),
  first_name: z
    .string({ required_error: 'First name is required' })
    .min(1, 'First name cannot be empty')
    .max(100, 'First name cannot exceed 100 characters'),
  last_name: z
    .string({ required_error: 'Last name is required' })
    .min(1, 'Last name cannot be empty')
    .max(100, 'Last name cannot exceed 100 characters'),
  role_id: z
    .number({ required_error: 'Role ID is required' })
    .int('Role ID must be an integer')
    .positive('Role ID must be a positive number'),
  is_active: z.boolean().default(true),
});

/**
 * Schema for updating a user
 * All fields are optional
 * Password has different rules (not allowed in regular update)
 */
export const updateUserSchema = z.object({
  email: z
    .string()
    .email('Invalid email format')
    .transform((val) => val.toLowerCase().trim())
    .optional(),
  first_name: z
    .string()
    .min(1, 'First name cannot be empty')
    .max(100, 'First name cannot exceed 100 characters')
    .optional(),
  last_name: z
    .string()
    .min(1, 'Last name cannot be empty')
    .max(100, 'Last name cannot exceed 100 characters')
    .optional(),
  role_id: z
    .number()
    .int('Role ID must be an integer')
    .positive('Role ID must be a positive number')
    .optional(),
  is_active: z.boolean().optional(),
});

/**
 * Schema for changing password
 * - current_password: required
 * - new_password: required, minimum 8 characters
 */
export const changePasswordSchema = z.object({
  current_password: z
    .string({ required_error: 'Current password is required' })
    .min(1, 'Current password cannot be empty'),
  new_password: z
    .string({ required_error: 'New password is required' })
    .min(8, 'New password must be at least 8 characters'),
});

/**
 * Type definitions derived from schemas
 */
export type CreateUserInput = z.infer<typeof createUserSchema>;
export type UpdateUserInput = z.infer<typeof updateUserSchema>;
export type ChangePasswordInput = z.infer<typeof changePasswordSchema>;

/**
 * Generic validation middleware factory
 * Creates a middleware that validates request body against a Zod schema
 * @param schema - Zod schema to validate against
 */
export function validate<T extends z.ZodTypeAny>(schema: T) {
  return (req: Request, res: Response, next: NextFunction): void => {
    const result = schema.safeParse(req.body);

    if (!result.success) {
      const errors = result.error.errors.map((err) => ({
        field: err.path.join('.'),
        message: err.message,
      }));

      res.status(400).json({
        success: false,
        error: 'Validation failed',
        errors,
      });
      return;
    }

    // Replace body with validated and typed data
    req.body = result.data;
    next();
  };
}

/**
 * Pre-configured validation middlewares
 */
export const validateCreateUser = validate(createUserSchema);
export const validateUpdateUser = validate(updateUserSchema);
export const validateChangePassword = validate(changePasswordSchema);