import type { Plugin } from 'vite'
import { mockRules, type MockContext } from './index'

const MOCK_PREFIX = '/api/v1'

function readBody(req: NodeJS.ReadableStream): Promise<string> {
  return new Promise((resolve) => {
    let raw = ''
    req.on('data', (chunk) => (raw += chunk))
    req.on('end', () => resolve(raw))
  })
}

/**
 * 本地 mock 中间件：始终挂载于 dev，但仅命中「全局 mock 开启」或标记 alwaysMock 的规则。
 * 这样新增页面的接口可被单独 mock，而项目其余接口仍走真实后端代理。
 * 不引入三方 mock 依赖，避免污染生产依赖树。
 */
export function mockPlugin(globalMock = false): Plugin {
  return {
    name: 'portal-mock',
    apply: 'serve',
    configureServer(server) {
      server.middlewares.use((req, res, next) => {
        if (!req.url?.startsWith(MOCK_PREFIX)) return next()

        const requestUrl = new URL(req.url, 'http://localhost')
        void (async () => {
          const raw = req.method === 'GET' ? '' : await readBody(req)
          const isJsonBody = (req.headers['content-type'] ?? '').includes('application/json')
          const rule = mockRules.find(
            (item) =>
              item.method === (req.method ?? 'GET').toUpperCase() &&
              item.pattern.test(requestUrl.pathname) &&
              (globalMock || item.alwaysMock === true),
          )

          if (!rule) return next()

          const matched = requestUrl.pathname.match(rule.pattern)
          const ctx: MockContext = {
            url: requestUrl.pathname,
            params: matched ? matched.slice(1) : [],
            query: Object.fromEntries(requestUrl.searchParams.entries()),
            body: raw && isJsonBody ? JSON.parse(raw) : {},
          }

          res.setHeader('Content-Type', 'application/json;charset=utf-8')
          res.end(
            JSON.stringify({ code: '00000', data: rule.handler(ctx) ?? null, msg: 'success' }),
          )
        })()
      })
    },
  }
}