/**
 * Jest transformer for uni-app `.vue` Single File Components (Vue 2.7).
 *
 * PURPOSE: cfc-frontend's default jest.config.js only transforms `.js` via
 * babel-jest, so `.vue` SFCs cannot be imported by tests. This transformer
 * compiles the SFC `<script>` block (Options API) to CommonJS and precompiles
 * the `<template>` block to a Vue 2 render function (the default `vue` entry
 * in Node is runtime-only and has no template compiler), so tests can `mount`
 * real page components with `@vue/test-utils`.
 *
 * TEST-ONLY infrastructure: this file lives under `__tests__/` and is NOT part
 * of the app runtime. It does not modify any `pages/` / `utils/` business code.
 */
const { parseComponent, compileTemplate } = require('@vue/compiler-sfc')
const babel = require('@babel/core')

module.exports = {
  process(src, filename) {
    const descriptor = parseComponent(src, { filename })
    if (descriptor.errors && descriptor.errors.length) {
      throw new Error('[vue-transform] SFC parse error in ' + filename + ':\n' + descriptor.errors.join('\n'))
    }

    let code = ''
    if (descriptor.script && descriptor.script.content) {
      // Options API: `export default {...}` -> `const __sfc_main = {...}`
      code += descriptor.script.content.replace(/export\s+default/, 'const __sfc_main =')
    } else {
      code += 'const __sfc_main = {}'
    }

    if (descriptor.template && descriptor.template.content) {
      const res = compileTemplate({
        source: descriptor.template.content,
        filename,
        id: filename.replace(/[^\w]/g, '_')
      })
      if (res.errors && res.errors.length) {
        throw new Error('[vue-transform] template compile error in ' + filename + ':\n' + res.errors.join('\n'))
      }
      code += '\n' + res.code
      code += '\n__sfc_main.render = render'
      code += '\n__sfc_main.staticRenderFns = staticRenderFns'
    }

    code += '\nmodule.exports = __sfc_main'
    // Transpile the assembled module to CommonJS (the <script> block keeps ES
    // `import` statements; Node cannot execute them in a jest CJS module).
    const out = babel.transformSync(code, {
      filename,
      presets: [['@babel/preset-env', { targets: { node: 'current' } }]],
      babelrc: false,
      configFile: false
    })
    return { code: out.code, map: null }
  }
}