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

function getFirstIssueMessage(error: z.ZodError): string {
  const issue = error.issues[0]
  return issue?.message ?? 'Validation failed'
}

export function validateBody<T extends z.ZodTypeAny>(schema: T) {
  return (req: Request, res: Response, next: NextFunction): void => {
    const result = schema.safeParse(req.body)
    if (!result.success) {
      res.status(400).json({ error: getFirstIssueMessage(result.error) })
      return
    }
    req.body = result.data as z.infer<T>
    next()
  }
}

export function validateQuery<T extends z.ZodTypeAny>(schema: T) {
  return (req: Request, res: Response, next: NextFunction): void => {
    const result = schema.safeParse(req.query)
    if (!result.success) {
      res.status(400).json({ error: getFirstIssueMessage(result.error) })
      return
    }
    ;(req as unknown as Record<string, unknown>).parsedQuery = result.data
    next()
  }
}

export function validateParams<T extends z.ZodTypeAny>(schema: T) {
  return (req: Request, res: Response, next: NextFunction): void => {
    const result = schema.safeParse(req.params)
    if (!result.success) {
      res.status(400).json({ error: getFirstIssueMessage(result.error) })
      return
    }
    Object.assign(req.params, result.data)
    next()
  }
}