provider.ts

import { existsSync, promises as fs } from 'node:fs'
import _url from 'node:url'
import type { Profiler } from 'node:inspector'
import MagicString from 'magic-string'
import remapping from '@ampproject/remapping'
import { extname, resolve } from 'pathe'
import c from 'picocolors'
import { provider } from 'std-env'
import type { EncodedSourceMap } from 'vite-node'
import { coverageConfigDefaults } from 'vitest/config'
import { BaseCoverageProvider } from 'vitest/coverage'
// eslint-disable-next-line no-restricted-imports
import type { AfterSuiteRunMeta, CoverageC8Options, CoverageProvider, ReportContext, ResolvedCoverageOptions } from 'vitest'
import type { Vitest } from 'vitest/node'
import type { Report } from 'c8'
// @ts-expect-error missing types
import createReport from 'c8/lib/report.js'
// @ts-expect-error missing types
import { checkCoverages } from 'c8/lib/commands/check-coverage.js'

type Options = ResolvedCoverageOptions<'c8'>

// Note that this needs to match the line ending as well
const VITE_EXPORTS_LINE_PATTERN = /Object\.defineProperty\(__vite_ssr_exports__.*\n/g

export class C8CoverageProvider extends BaseCoverageProvider implements CoverageProvider {
  name = 'c8'

  ctx!: Vitest
  options!: Options
  coverages: Profiler.TakePreciseCoverageReturnType[] = []

  initialize(ctx: Vitest) {
    const config: CoverageC8Options = ctx.config.coverage

    this.ctx = ctx
    this.options = {
      ...coverageConfigDefaults,

      // Provider specific defaults
      excludeNodeModules: true,
      allowExternal: false,

      // User's options
      ...config,

      // Resolved fields
      provider: 'c8',
      reporter: this.resolveReporters(config.reporter || coverageConfigDefaults.reporter),
      reportsDirectory: resolve(ctx.config.root, config.reportsDirectory || coverageConfigDefaults.reportsDirectory),
      lines: config['100'] ? 100 : config.lines,
      functions: config['100'] ? 100 : config.functions,
      branches: config['100'] ? 100 : config.branches,
      statements: config['100'] ? 100 : config.statements,
    }
  }

  resolveOptions() {
    return this.options
  }

  async clean(clean = true) {
    if (clean && existsSync(this.options.reportsDirectory))
      await fs.rm(this.options.reportsDirectory, { recursive: true, force: true, maxRetries: 10 })

    this.coverages = []
  }

  onAfterSuiteRun({ coverage }: AfterSuiteRunMeta) {
    this.coverages.push(coverage as Profiler.TakePreciseCoverageReturnType)
  }

  async reportCoverage({ allTestsRun }: ReportContext = {}) {
    if (provider === 'stackblitz')
      this.ctx.logger.log(c.blue(' % ') + c.yellow('@vitest/coverage-c8 does not work on Stackblitz. Report will be empty.'))

    const options: ConstructorParameters<typeof Report>[0] = {
      ...this.options,
      all: this.options.all && allTestsRun,
      reporter: this.options.reporter.map(([reporterName]) => reporterName),
      reporterOptions: this.options.reporter.reduce((all, [name, options]) => ({
        ...all,
        [name]: {
          skipFull: this.options.skipFull,
          projectRoot: this.ctx.config.root,
          ...options,
        },
      }), {}),
    }

    const report = createReport(options)

    // Overwrite C8's loader as results are in memory instead of file system
    report._loadReports = () => this.coverages

    interface MapAndSource { map: EncodedSourceMap; source: string | undefined }
    type SourceMapMeta = { url: string; filepath: string } & MapAndSource

    // add source maps
    const sourceMapMeta: Record<SourceMapMeta['url'], MapAndSource> = {}
    const extensions = Array.isArray(this.options.extension) ? this.options.extension : [this.options.extension]

    const entries = Array
      .from(this.ctx.vitenode.fetchCache.entries())
      .filter(entry => report._shouldInstrument(entry[0]))
      .map(([file, { result }]) => {
        if (!result.map)
          return null

        const filepath = file.split('?')[0]
        const url = _url.pathToFileURL(filepath).href
        const extension = extname(file) || extname(url)

        return {
          filepath,
          url,
          extension,
          map: result.map,
          source: result.code,
        }
      })
      .filter((entry) => {
        if (!entry)
          return false

        if (!extensions.includes(entry.extension))
          return false

        // Mappings and sourcesContent are needed for C8 to work
        return (
          entry.map.mappings.length > 0
          && entry.map.sourcesContent
          && entry.map.sourcesContent.length > 0
          && entry.map.sourcesContent[0]
          && entry.map.sourcesContent[0].length > 0
        )
      }) as SourceMapMeta[]

    await Promise.all(entries.map(async ({ url, source, map, filepath }) => {
      if (url in sourceMapMeta)
        return

      let code: string | undefined
      try {
        code = (await fs.readFile(filepath)).toString()
      }
      catch { }

      // Vite does not report full path in sourcemap sources
      // so use an actual file path
      const sources = [url]

      sourceMapMeta[url] = {
        source,
        map: {
          sourcesContent: code ? [code] : undefined,
          ...map,
          sources,
        },
      }
    }))

    // This is a magic number. It corresponds to the amount of code
    // that we add in packages/vite-node/src/client.ts:114 (vm.runInThisContext)
    // TODO: Include our transformations in sourcemaps
    const offset = 185

    report._getSourceMap = (coverage: Profiler.ScriptCoverage) => {
      const path = _url.pathToFileURL(coverage.url.split('?')[0]).href
      const data = sourceMapMeta[path]

      if (!data)
        return {}

      return {
        sourceMap: {
          sourcemap: removeViteHelpersFromSourceMaps(data.source, data.map),
        },
        source: Array(offset).fill('.').join('') + data.source,
      }
    }

    await report.run()
    await checkCoverages(options, report)

    if (this.options.thresholdAutoUpdate && allTestsRun) {
      this.updateThresholds({
        coverageMap: await report.getCoverageMapFromAllCoverageFiles(),
        thresholds: {
          branches: this.options.branches,
          functions: this.options.functions,
          lines: this.options.lines,
          statements: this.options.statements,
        },
        perFile: this.options.perFile,
        configurationFile: this.ctx.server.config.configFile,
      })
    }
  }
}

/**
 * Remove generated code from the source maps:
 * - Vite's export helpers: e.g. `Object.defineProperty(__vite_ssr_exports__, "sum", { enumerable: true, configurable: true, get(){ return sum }});`
 */
function removeViteHelpersFromSourceMaps(source: string | undefined, map: EncodedSourceMap) {
  if (!source || !source.match(VITE_EXPORTS_LINE_PATTERN))
    return map

  const sourceWithoutHelpers = new MagicString(source)
  sourceWithoutHelpers.replaceAll(VITE_EXPORTS_LINE_PATTERN, '\n')

  const mapWithoutHelpers = sourceWithoutHelpers.generateMap({
    hires: true,
  })

  // A merged source map where the first one excludes helpers
  const combinedMap = remapping(
    [{ ...mapWithoutHelpers, version: 3 }, map],
    () => null,
  )

  return combinedMap
}