const childProcess = require('child_process')
const fsPromises = require('fs/promises')
const fse = require('fs-extra')
const os = require('os')
const Path = require('path')
const { callbackify, promisify } = require('util')

const Settings = require('@overleaf/settings')
const logger = require('@overleaf/logger')
const OError = require('@overleaf/o-error')

const ResourceWriter = require('./ResourceWriter')
const LatexRunner = require('./LatexRunner')
const OutputFileFinder = require('./OutputFileFinder')
const OutputCacheManager = require('./OutputCacheManager')
const Metrics = require('./Metrics')
const DraftModeManager = require('./DraftModeManager')
const TikzManager = require('./TikzManager')
const LockManager = require('./LockManager')
const Errors = require('./Errors')
const CommandRunner = require('./CommandRunner')
const { emitPdfStats } = require('./ContentCacheMetrics')
const SynctexOutputParser = require('./SynctexOutputParser')

const execFile = promisify(childProcess.execFile)

const COMPILE_TIME_BUCKETS = [
  // NOTE: These buckets are locked in per metric name.
  //       If you want to change them, you will need to rename metrics.
  0, 1, 2, 3, 4, 6, 8, 11, 15, 22, 31, 43, 61, 86, 121, 170, 240,
].map(seconds => seconds * 1000)

function getCompileName(projectId, userId) {
  if (userId != null) {
    return `${projectId}-${userId}`
  } else {
    return projectId
  }
}

function getCompileDir(projectId, userId) {
  return Path.join(Settings.path.compilesDir, getCompileName(projectId, userId))
}

function getOutputDir(projectId, userId) {
  return Path.join(Settings.path.outputDir, getCompileName(projectId, userId))
}

async function doCompileWithLock(request) {
  const compileDir = getCompileDir(request.project_id, request.user_id)
  // use a .project-lock file in the compile directory to prevent
  // simultaneous compiles
  const lockFile = Path.join(compileDir, '.project-lock')
  await fse.ensureDir(compileDir)
  const lock = await LockManager.acquire(lockFile)
  try {
    return await doCompile(request)
  } finally {
    await lock.release()
  }
}

async function doCompile(request) {
  const compileDir = getCompileDir(request.project_id, request.user_id)
  const outputDir = getOutputDir(request.project_id, request.user_id)

  const timerE2E = new Metrics.Timer(
    'compile-e2e-v2',
    1,
    request.metricsOpts,
    COMPILE_TIME_BUCKETS
  )
  const writeToDiskTimer = new Metrics.Timer(
    'write-to-disk',
    1,
    request.metricsOpts
  )
  logger.debug(
    { projectId: request.project_id, userId: request.user_id },
    'syncing resources to disk'
  )

  let resourceList
  try {
    // NOTE: resourceList is insecure, it should only be used to exclude files from the output list
    resourceList = await ResourceWriter.promises.syncResourcesToDisk(
      request,
      compileDir
    )
  } catch (error) {
    if (error instanceof Errors.FilesOutOfSyncError) {
      OError.tag(error, 'files out of sync, please retry', {
        projectId: request.project_id,
        userId: request.user_id,
      })
    } else {
      OError.tag(error, 'error writing resources to disk', {
        projectId: request.project_id,
        userId: request.user_id,
      })
    }
    throw error
  }
  logger.debug(
    {
      projectId: request.project_id,
      userId: request.user_id,
      time_taken: Date.now() - writeToDiskTimer.start,
    },
    'written files to disk'
  )
  const syncStage = writeToDiskTimer.done()

  // set up environment variables for chktex
  const env = {}
  if (Settings.texliveOpenoutAny && Settings.texliveOpenoutAny !== '') {
    // override default texlive openout_any environment variable
    env.openout_any = Settings.texliveOpenoutAny
  }
  if (Settings.texliveMaxPrintLine && Settings.texliveMaxPrintLine !== '') {
    // override default texlive max_print_line environment variable
    env.max_print_line = Settings.texliveMaxPrintLine
  }
  // only run chktex on LaTeX files (not knitr .Rtex files or any others)
  const isLaTeXFile = request.rootResourcePath?.match(/\.tex$/i)
  if (request.check != null && isLaTeXFile) {
    env.CHKTEX_OPTIONS = '-nall -e9 -e10 -w15 -w16'
    env.CHKTEX_ULIMIT_OPTIONS = '-t 5 -v 64000'
    if (request.check === 'error') {
      env.CHKTEX_EXIT_ON_ERROR = 1
    }
    if (request.check === 'validate') {
      env.CHKTEX_VALIDATE = 1
    }
  }

  // apply a series of file modifications/creations for draft mode and tikz
  if (request.draft) {
    await DraftModeManager.promises.injectDraftMode(
      Path.join(compileDir, request.rootResourcePath)
    )
  }

  const needsMainFile = await TikzManager.promises.checkMainFile(
    compileDir,
    request.rootResourcePath,
    resourceList
  )
  if (needsMainFile) {
    await TikzManager.promises.injectOutputFile(
      compileDir,
      request.rootResourcePath
    )
  }

  const compileTimer = new Metrics.Timer('run-compile', 1, request.metricsOpts)
  // find the image tag to log it as a metric, e.g. 2015.1 (convert . to - for graphite)
  let tag = 'default'
  if (request.imageName != null) {
    const match = request.imageName.match(/:(.*)/)
    if (match != null) {
      tag = match[1].replace(/\./g, '-')
    }
  }
  // exclude smoke test
  if (!request.project_id.match(/^[0-9a-f]{24}$/)) {
    tag = 'other'
  }
  Metrics.inc('compiles', 1, request.metricsOpts)
  Metrics.inc(`compiles-with-image.${tag}`, 1, request.metricsOpts)
  const compileName = getCompileName(request.project_id, request.user_id)

  let compileResult
  try {
    compileResult = await LatexRunner.promises.runLatex(compileName, {
      directory: compileDir,
      mainFile: request.rootResourcePath,
      compiler: request.compiler,
      timeout: request.timeout,
      image: request.imageName,
      flags: request.flags,
      environment: env,
      compileGroup: request.compileGroup,
      stopOnFirstError: request.stopOnFirstError,
    })

    // We use errors to return the validation state. It would be nice to use a
    // more appropriate mechanism.
    if (request.check === 'validate') {
      const validationError = new Error('validation')
      validationError.validate = 'pass'
      throw validationError
    }
  } catch (originalError) {
    let error = originalError
    // request was for validation only
    if (request.check === 'validate' && !error.validate) {
      error = new Error('validation')
      error.validate = originalError.code ? 'fail' : 'pass'
    }

    // request was for compile, and failed on validation
    if (request.check === 'error' && originalError.message === 'exited') {
      error = new Error('compilation')
      error.validate = 'fail'
    }

    // compile was killed by user, was a validation, or a compile which failed validation
    if (error.terminated || error.validate || error.timedout) {
      // record timeout errors as a separate counter, success is recorded later
      if (error.timedout) {
        Metrics.inc('compiles-timeout', 1, request.metricsOpts)
      }

      const { outputFiles } = await OutputFileFinder.promises.findOutputFiles(
        resourceList,
        compileDir
      )
      error.outputFiles = outputFiles // return output files so user can check logs
    }
    throw error
  }

  // compile completed normally
  let { stats, timings } = compileResult
  stats = stats || {}
  timings = timings || {}
  Metrics.inc('compiles-succeeded', 1, request.metricsOpts)
  for (const metricKey in stats) {
    const metricValue = stats[metricKey]
    Metrics.count(metricKey, metricValue, 1, request.metricsOpts)
  }
  for (const metricKey in timings) {
    const metricValue = timings[metricKey]
    Metrics.timing(metricKey, metricValue, 1, request.metricsOpts)
  }
  const loadavg = typeof os.loadavg === 'function' ? os.loadavg() : undefined
  if (loadavg != null) {
    Metrics.gauge('load-avg', loadavg[0])
  }
  const ts = compileTimer.done()
  logger.debug(
    {
      projectId: request.project_id,
      userId: request.user_id,
      time_taken: ts,
      stats,
      timings,
      loadavg,
    },
    'done compile'
  )
  if (stats['latex-runs'] > 0) {
    Metrics.histogram(
      'avg-compile-per-pass-v2',
      ts / stats['latex-runs'],
      COMPILE_TIME_BUCKETS,
      request.metricsOpts
    )
    Metrics.timing(
      'avg-compile-per-pass-v2',
      ts / stats['latex-runs'],
      1,
      request.metricsOpts
    )
  }
  if (stats['latex-runs'] > 0 && timings['cpu-time'] > 0) {
    Metrics.timing(
      'run-compile-cpu-time-per-pass',
      timings['cpu-time'] / stats['latex-runs'],
      1,
      request.metricsOpts
    )
  }
  // Emit compile time.
  timings.compile = ts

  const outputStageTimer = new Metrics.Timer(
    'process-output-files',
    1,
    request.metricsOpts
  )

  let { outputFiles } = await OutputFileFinder.promises.findOutputFiles(
    resourceList,
    compileDir
  )

  try {
    outputFiles = await OutputCacheManager.promises.saveOutputFiles(
      { request, stats, timings },
      outputFiles,
      compileDir,
      outputDir
    )
  } catch (err) {
    const { project_id: projectId, user_id: userId } = request
    logger.err({ projectId, userId, err }, 'failed to save output files')
  }

  const outputStage = outputStageTimer.done()
  timings.sync = syncStage
  timings.output = outputStage

  // Emit e2e compile time.
  timings.compileE2E = timerE2E.done()
  Metrics.timing('compile-e2e-v2', timings.compileE2E, 1, request.metricsOpts)

  if (stats['pdf-size']) {
    emitPdfStats(stats, timings, request)
  }

  return { outputFiles, stats, timings }
}

async function stopCompile(projectId, userId) {
  const compileName = getCompileName(projectId, userId)
  await LatexRunner.promises.killLatex(compileName)
}

async function clearProject(projectId, userId) {
  const compileDir = getCompileDir(projectId, userId)

  const exists = await _checkDirectory(compileDir)
  if (!exists) {
    // skip removal if no directory present
    return
  }

  try {
    await execFile('rm', ['-r', '-f', '--', compileDir])
  } catch (err) {
    OError.tag(err, `rm -r failed`, { compileDir, stderr: err.stderr })
    throw err
  }
}

async function _findAllDirs() {
  const root = Settings.path.compilesDir
  const files = await fsPromises.readdir(root)
  const allDirs = files.map(file => Path.join(root, file))
  return allDirs
}

async function clearExpiredProjects(maxCacheAgeMs) {
  const now = Date.now()
  const dirs = await _findAllDirs()
  for (const dir of dirs) {
    let stats
    try {
      stats = await fsPromises.stat(dir)
    } catch (err) {
      // ignore errors checking directory
      continue
    }

    const age = now - stats.mtime
    const hasExpired = age > maxCacheAgeMs
    if (hasExpired) {
      await fse.remove(dir)
    }
  }
}

async function _checkDirectory(compileDir) {
  let stats
  try {
    stats = await fsPromises.lstat(compileDir)
  } catch (err) {
    if (err.code === 'ENOENT') {
      //  directory does not exist
      return false
    }
    OError.tag(err, 'error on stat of project directory for removal', {
      dir: compileDir,
    })
    throw err
  }
  if (!stats.isDirectory()) {
    throw new OError('project directory is not directory', {
      dir: compileDir,
      stats,
    })
  }
  return true
}

async function syncFromCode(
  projectId,
  userId,
  filename,
  line,
  column,
  imageName
) {
  // If LaTeX was run in a virtual environment, the file path that synctex expects
  // might not match the file path on the host. The .synctex.gz file however, will be accessed
  // wherever it is on the host.
  const compileName = getCompileName(projectId, userId)
  const baseDir = Settings.path.synctexBaseDir(compileName)
  const inputFilePath = Path.join(baseDir, filename)
  const outputFilePath = Path.join(baseDir, 'output.pdf')
  const command = [
    'synctex',
    'view',
    '-i',
    `${line}:${column}:${inputFilePath}`,
    '-o',
    outputFilePath,
  ]
  const stdout = await _runSynctex(projectId, userId, command, imageName)
  logger.debug(
    { projectId, userId, filename, line, column, command, stdout },
    'synctex code output'
  )
  return SynctexOutputParser.parseViewOutput(stdout)
}

async function syncFromPdf(projectId, userId, page, h, v, imageName) {
  const compileName = getCompileName(projectId, userId)
  const baseDir = Settings.path.synctexBaseDir(compileName)
  const outputFilePath = `${baseDir}/output.pdf`
  const command = [
    'synctex',
    'edit',
    '-o',
    `${page}:${h}:${v}:${outputFilePath}`,
  ]
  const stdout = await _runSynctex(projectId, userId, command, imageName)
  logger.debug({ projectId, userId, page, h, v, stdout }, 'synctex pdf output')
  return SynctexOutputParser.parseEditOutput(stdout, baseDir)
}

async function _checkFileExists(dir, filename) {
  try {
    await fsPromises.stat(dir)
  } catch (error) {
    if (error.code === 'ENOENT') {
      throw new Errors.NotFoundError('no output directory')
    }
    throw error
  }

  const file = Path.join(dir, filename)
  let stats
  try {
    stats = await fsPromises.stat(file)
  } catch (error) {
    if (error.code === 'ENOENT') {
      throw new Errors.NotFoundError('no output file')
    }
  }
  if (!stats.isFile()) {
    throw new Error('not a file')
  }
}

async function _runSynctex(projectId, userId, command, imageName) {
  const directory = getCompileDir(projectId, userId)
  const timeout = 60 * 1000 // increased to allow for large projects
  const compileName = getCompileName(projectId, userId)
  const compileGroup = 'synctex'
  const defaultImageName =
    Settings.clsi && Settings.clsi.docker && Settings.clsi.docker.image
  await _checkFileExists(directory, 'output.synctex.gz')
  try {
    const output = await CommandRunner.promises.run(
      compileName,
      command,
      directory,
      imageName || defaultImageName,
      timeout,
      {},
      compileGroup
    )
    return output.stdout
  } catch (error) {
    throw OError.tag(error, 'error running synctex', {
      command,
      projectId,
      userId,
    })
  }
}

async function wordcount(projectId, userId, filename, image) {
  logger.debug({ projectId, userId, filename, image }, 'running wordcount')
  const filePath = `$COMPILE_DIR/${filename}`
  const command = [
    'texcount',
    '-nocol',
    '-inc',
    filePath,
    `-out=${filePath}.wc`,
  ]
  const compileDir = getCompileDir(projectId, userId)
  const timeout = 60 * 1000
  const compileName = getCompileName(projectId, userId)
  const compileGroup = 'wordcount'
  try {
    await fse.ensureDir(compileDir)
  } catch (err) {
    throw OError.tag(err, 'error ensuring dir for wordcount', {
      projectId,
      userId,
      filename,
    })
  }
  await CommandRunner.promises.run(
    compileName,
    command,
    compileDir,
    image,
    timeout,
    {},
    compileGroup
  )

  let stdout
  try {
    stdout = await fsPromises.readFile(
      compileDir + '/' + filename + '.wc',
      'utf-8'
    )
  } catch (err) {
    throw OError.tag(err, 'error reading word count output', {
      command,
      compileDir,
      projectId,
      userId,
    })
  }

  const results = _parseWordcountFromOutput(stdout)
  logger.debug({ projectId, userId, wordcount: results }, 'word count results')
  return results
}

function _parseWordcountFromOutput(output) {
  const results = {
    encode: '',
    textWords: 0,
    headWords: 0,
    outside: 0,
    headers: 0,
    elements: 0,
    mathInline: 0,
    mathDisplay: 0,
    errors: 0,
    messages: '',
  }
  for (const line of output.split('\n')) {
    const [data, info] = line.split(':')
    if (data.indexOf('Encoding') > -1) {
      results.encode = info.trim()
    }
    if (data.indexOf('in text') > -1) {
      results.textWords = parseInt(info, 10)
    }
    if (data.indexOf('in head') > -1) {
      results.headWords = parseInt(info, 10)
    }
    if (data.indexOf('outside') > -1) {
      results.outside = parseInt(info, 10)
    }
    if (data.indexOf('of head') > -1) {
      results.headers = parseInt(info, 10)
    }
    if (data.indexOf('Number of floats/tables/figures') > -1) {
      results.elements = parseInt(info, 10)
    }
    if (data.indexOf('Number of math inlines') > -1) {
      results.mathInline = parseInt(info, 10)
    }
    if (data.indexOf('Number of math displayed') > -1) {
      results.mathDisplay = parseInt(info, 10)
    }
    if (data === '(errors') {
      // errors reported as (errors:123)
      results.errors = parseInt(info, 10)
    }
    if (line.indexOf('!!! ') > -1) {
      // errors logged as !!! message !!!
      results.messages += line + '\n'
    }
  }
  return results
}

module.exports = {
  doCompileWithLock: callbackify(doCompileWithLock),
  stopCompile: callbackify(stopCompile),
  clearProject: callbackify(clearProject),
  clearExpiredProjects: callbackify(clearExpiredProjects),
  syncFromCode: callbackify(syncFromCode),
  syncFromPdf: callbackify(syncFromPdf),
  wordcount: callbackify(wordcount),
  promises: {
    doCompileWithLock,
    stopCompile,
    clearProject,
    clearExpiredProjects,
    syncFromCode,
    syncFromPdf,
    wordcount,
  },
}