const fsPromises = require('node:fs/promises')
const os = require('node:os')
const Path = require('node:path')
const { callbackify } = require('node: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 ClsiMetrics = 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 {
  downloadLatestCompileCache,
  downloadOutputDotSynctexFromCompileCache,
} = require('./CLSICacheHandler')
const StatsManager = require('./StatsManager')
const SafeReader = require('./SafeReader')
const { enableLatexMkMetrics, addLatexFdbMetrics } = require('./LatexMetrics')
const { callbackifyMultiResult } = require('@overleaf/promise-utils')

const KNOWN_LATEXMK_RULES = new Set([
  'biber',
  'bibtex',
  'dvipdf',
  'latex',
  'lualatex',
  'makeindex',
  'pdflatex',
  'xdvipdfmx',
  'xelatex',
])

const LATEX_PASSES_RULES = new Set(['latex', 'lualatex', 'xelatex', 'pdflatex'])

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, stats, timings) {
  const compileDir = getCompileDir(request.project_id, request.user_id)
  request.isInitialCompile =
    (await fsPromises.mkdir(compileDir, { recursive: true })) === compileDir
  // prevent simultaneous compiles
  const lock = LockManager.acquire(compileDir)
  try {
    return await doCompile(request, stats, timings)
  } finally {
    lock.release()
  }
}

async function doCompile(request, stats, timings) {
  const { project_id: projectId, user_id: userId } = request
  const compileDir = getCompileDir(request.project_id, request.user_id)

  const e2eCompileStart = Date.now()

  if (request.isInitialCompile) {
    stats.isInitialCompile = 1
    request.metricsOpts.compile = 'initial'
    if (request.compileFromClsiCache) {
      try {
        if (await downloadLatestCompileCache(projectId, userId, compileDir)) {
          stats.restoredClsiCache = 1
          request.metricsOpts.compile = 'from-clsi-cache'
        }
      } catch (err) {
        logger.warn(
          { err, projectId, userId },
          'failed to populate compile dir from cache'
        )
      }
    }
  } else {
    request.metricsOpts.compile = 'recompile'
  }

  const syncStart = Date.now()
  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
  }

  timings.sync = Date.now() - syncStart
  logger.debug(
    {
      projectId: request.project_id,
      userId: request.user_id,
      timeTaken: timings.sync,
    },
    'written files to disk'
  )

  // set up environment variables for chktex
  const env = {
    OVERLEAF_PROJECT_ID: request.project_id,
  }
  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 compileStart = Date.now()

  const compileName = getCompileName(request.project_id, request.user_id)

  // Record latexmk -time stats for a subset of users
  const recordPerformanceMetrics = StatsManager.sampleRequest(
    request,
    Settings.performanceLogSamplingPercentage
  )

  // Define a `latexmk` property on the stats object
  // to collect latexmk -time stats.
  enableLatexMkMetrics(stats)

  try {
    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,
      stats,
      timings,
    })

    // 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'
    }

    const { outputFiles, allEntries, buildId } = await _saveOutputFiles({
      request,
      compileDir,
      resourceList,
      stats,
      timings,
    })
    error.outputFiles = outputFiles // return output files so user can check logs
    error.buildId = buildId
    // Clear project if this compile was abruptly terminated
    if (error.terminated || error.timedout) {
      await clearProjectWithListing(
        request.project_id,
        request.user_id,
        allEntries
      )
    }

    if (!_shouldSkipMetrics(request)) {
      const status = error.timedout
        ? 'timeout'
        : error.terminated
          ? 'terminated'
          : 'failure'
      timings.compile = Date.now() - compileStart
      _emitMetrics(request, status, stats, timings)
    }
    throw error
  }

  timings.compile = Date.now() - compileStart

  logger.debug(
    {
      projectId: request.project_id,
      userId: request.user_id,
      timeTaken: timings.compile,
      stats,
      timings,
    },
    'done compile'
  )

  const { outputFiles, buildId } = await _saveOutputFiles({
    request,
    compileDir,
    resourceList,
    stats,
    timings,
  })
  timings.compileE2E = Date.now() - e2eCompileStart

  const status = stats['latexmk-errors'] ? 'error' : 'success'
  _emitMetrics(request, status, stats, timings)

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

  // Record compile performance for a subset of users
  if (recordPerformanceMetrics) {
    // Add fdb metrics if available
    try {
      const fdbFileContent = await _readFdbFile(compileDir)
      if (fdbFileContent) {
        addLatexFdbMetrics(fdbFileContent, stats)
      }
    } catch (err) {
      // ignore errors reading fdb file
      logger.warn(
        { err, projectId, userId },
        'error reading fdb file for performance metrics'
      )
    }

    const loadavg = typeof os.loadavg === 'function' ? os.loadavg() : undefined

    logger.info(
      {
        userId: request.user_id,
        projectId: request.project_id,
        timeTaken: timings.compile,
        clsiRequest: request,
        stats,
        timings,
        // explicitly include latexmk stats to bypass the non-enumerable property
        latexmk: stats.latexmk,
        loadavg1m: loadavg?.[0],
        loadavg5m: loadavg?.[1],
        loadavg15m: loadavg?.[2],
        samplingPercentage: Settings.performanceLogSamplingPercentage,
      },
      'sampled performance log'
    )
  }

  return { outputFiles, buildId }
}

async function _saveOutputFiles({
  request,
  compileDir,
  resourceList,
  stats,
  timings,
}) {
  const start = Date.now()
  const outputDir = getOutputDir(request.project_id, request.user_id)

  const { outputFiles: rawOutputFiles, allEntries } =
    await OutputFileFinder.promises.findOutputFiles(resourceList, compileDir)

  const { buildId, outputFiles } =
    await OutputCacheManager.promises.saveOutputFiles(
      { request, stats, timings },
      rawOutputFiles,
      compileDir,
      outputDir
    )

  timings.output = Date.now() - start
  return { outputFiles, allEntries, buildId }
}

// Set a maximum size for reading output.fdb_latexmk files
// This limit is chosen to prevent excessive memory usage and ensure performance,
// as fdb files are typically much smaller and only metrics are extracted from them.
const MAX_FDB_FILE_SIZE = 1024 * 1024 // 1 MB

async function _readFdbFile(compileDir) {
  const fdbFile = Path.join(compileDir, 'output.fdb_latexmk')
  const { result } = await SafeReader.promises.readFile(
    fdbFile,
    MAX_FDB_FILE_SIZE,
    'utf8'
  )
  return result
}

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)
  await fsPromises.rm(compileDir, { force: true, recursive: true })
}

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

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

  for (const pathInProject of allEntries) {
    const path = Path.join(compileDir, pathInProject)
    if (path.endsWith('/')) {
      await fsPromises.rmdir(path)
    } else {
      await fsPromises.unlink(path)
    }
  }
  await fsPromises.rmdir(compileDir)
}

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 fsPromises.rm(dir, { force: true, recursive: true })
    }
  }
}

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, opts) {
  // 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, downloadedFromCache } = await _runSynctex(
    projectId,
    userId,
    command,
    opts
  )
  logger.debug(
    { projectId, userId, filename, line, column, command, stdout },
    'synctex code output'
  )
  return {
    codePositions: SynctexOutputParser.parseViewOutput(stdout),
    downloadedFromCache,
  }
}

async function syncFromPdf(projectId, userId, page, h, v, opts) {
  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, downloadedFromCache } = await _runSynctex(
    projectId,
    userId,
    command,
    opts
  )
  logger.debug({ projectId, userId, page, h, v, stdout }, 'synctex pdf output')
  return {
    pdfPositions: SynctexOutputParser.parseEditOutput(stdout, baseDir),
    downloadedFromCache,
  }
}

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, opts) {
  const { imageName, editorId, buildId, compileFromClsiCache } = opts

  if (imageName && !_isImageNameAllowed(imageName)) {
    throw new Errors.InvalidParameter('invalid image')
  }
  if (editorId && !/^[a-f0-9-]+$/.test(editorId)) {
    throw new Errors.InvalidParameter('invalid editorId')
  }
  if (buildId && !OutputCacheManager.BUILD_REGEX.test(buildId)) {
    throw new Errors.InvalidParameter('invalid buildId')
  }

  const outputDir = getOutputDir(projectId, userId)
  const runInOutputDir = buildId && CommandRunner.canRunSyncTeXInOutputDir()

  const directory = runInOutputDir
    ? Path.join(outputDir, OutputCacheManager.CACHE_SUBDIR, buildId)
    : getCompileDir(projectId, userId)
  const timeout = 60 * 1000 // increased to allow for large projects
  const compileName = getCompileName(projectId, userId)
  const compileGroup = runInOutputDir ? 'synctex-output' : 'synctex'
  const defaultImageName =
    Settings.clsi && Settings.clsi.docker && Settings.clsi.docker.image
  // eslint-disable-next-line @typescript-eslint/return-await
  return await OutputCacheManager.promises.queueDirOperation(
    outputDir,
    /**
     * @return {Promise<{stdout: string, downloadedFromCache: boolean}>}
     */
    async () => {
      let downloadedFromCache = false
      try {
        await _checkFileExists(directory, 'output.synctex.gz')
        if (compileFromClsiCache) {
          try {
            await _checkFileExists(directory, 'output.log')
          } catch (err) {
            if (err instanceof Errors.NotFoundError) downloadedFromCache = true
          }
        }
      } catch (err) {
        if (
          err instanceof Errors.NotFoundError &&
          compileFromClsiCache &&
          editorId &&
          buildId
        ) {
          try {
            downloadedFromCache =
              await downloadOutputDotSynctexFromCompileCache(
                projectId,
                userId,
                editorId,
                buildId,
                directory
              )
          } catch (err) {
            logger.warn(
              { err, projectId, userId, editorId, buildId },
              'failed to download output.synctex.gz from clsi-cache'
            )
          }
          await _checkFileExists(directory, 'output.synctex.gz')
        } else {
          throw err
        }
      }
      try {
        const { stdout } = await CommandRunner.promises.run(
          compileName,
          command,
          directory,
          imageName || defaultImageName,
          timeout,
          {},
          compileGroup
        )
        return {
          stdout,
          downloadedFromCache,
        }
      } 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]
  const compileDir = getCompileDir(projectId, userId)
  const timeout = 60 * 1000
  const compileName = getCompileName(projectId, userId)
  const compileGroup = 'wordcount'

  if (image && !_isImageNameAllowed(image)) {
    throw new Errors.InvalidParameter('invalid image')
  }

  try {
    await fsPromises.mkdir(compileDir, { recursive: true })
  } catch (err) {
    throw OError.tag(err, 'error ensuring dir for wordcount', {
      projectId,
      userId,
      filename,
    })
  }

  try {
    const { stdout } = await CommandRunner.promises.run(
      compileName,
      command,
      compileDir,
      image,
      timeout,
      {},
      compileGroup
    )
    const results = _parseWordcountFromOutput(stdout)
    logger.debug(
      { projectId, userId, wordcount: results },
      'word count results'
    )
    return results
  } catch (err) {
    throw OError.tag(err, 'error reading word count output', {
      command,
      compileDir,
      projectId,
      userId,
    })
  }
}

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
}

function _isImageNameAllowed(imageName) {
  const ALLOWED_IMAGES =
    Settings.clsi && Settings.clsi.docker && Settings.clsi.docker.allowedImages
  return !ALLOWED_IMAGES || ALLOWED_IMAGES.includes(imageName)
}

function _shouldSkipMetrics(request) {
  return ['clsi-perf', 'health-check'].includes(request.metricsOpts.path)
}

function _emitMetrics(request, status, stats, timings) {
  if (_shouldSkipMetrics(request)) {
    return
  }

  // find the image tag to log it as a metric, e.g. 2015.1
  let tag = 'default'
  if (request.imageName != null) {
    const match = request.imageName.match(/:(.*)/)
    if (match != null) {
      tag = match[1]
    }
  }

  const runs = stats.latexmk?.['latexmk-rule-times']
  let passes = 0
  if (runs != null) {
    let cumulativeRuleTimeMs = 0
    for (const run of runs) {
      if (LATEX_PASSES_RULES.has(run.rule)) {
        passes += 1
      }

      const rule = KNOWN_LATEXMK_RULES.has(run.rule) ? run.rule : 'other'
      ClsiMetrics.latexmkRuleDurationSeconds.observe(
        {
          group: request.compileGroup,
          rule,
        },
        run.time_ms / 1000
      )
      cumulativeRuleTimeMs += run.time_ms
    }

    const totalTimeMs = stats.latexmk?.['latexmk-time']?.total
    if (totalTimeMs != null) {
      ClsiMetrics.latexmkRuleDurationSeconds.observe(
        { group: request.compileGroup, rule: 'overhead' },
        (totalTimeMs - cumulativeRuleTimeMs) / 1000
      )
    }
  }

  const imgTimings = stats.latexmk?.['latexmk-img-times']
  if (imgTimings != null) {
    for (const timing of imgTimings) {
      ClsiMetrics.imageProcessingDurationSeconds.observe(
        {
          group: request.compileGroup,
          type: timing.type,
        },
        timing.time_ms / 1000
      )
    }
  }

  ClsiMetrics.compilesTotal.inc({
    status,
    engine: request.compiler,
    image: tag,
    compile: request.metricsOpts.compile,
    group: request.compileGroup,
    draft: request.draft ? 'true' : 'false',
    stop_on_first_error: request.stopOnFirstError ? 'true' : 'false',
    passes,
  })

  if (timings.sync != null) {
    ClsiMetrics.syncResourcesDurationSeconds.observe(
      {
        type: request.syncType,
        compile: request.metricsOpts.compile,
        group: request.compileGroup,
      },
      timings.sync / 1000
    )
  }

  if (timings.compile != null) {
    ClsiMetrics.compileDurationSeconds.observe(
      {
        status,
        engine: request.compiler,
        compile: request.metricsOpts.compile,
        group: request.compileGroup,
        passes: passes === 0 ? 'none' : passes === 1 ? 'single' : 'multiple',
      },
      timings.compile / 1000
    )
  }

  if (timings.output != null) {
    ClsiMetrics.processOutputFilesDurationSeconds.observe(
      {
        compile: request.metricsOpts.compile,
        group: request.compileGroup,
      },
      timings.output / 1000
    )
  }

  if (timings.compileE2E != null) {
    ClsiMetrics.e2eCompileDurationSeconds.observe(timings.compileE2E / 1000)
  }
}

module.exports = {
  doCompileWithLock: callbackify(doCompileWithLock),
  stopCompile: callbackify(stopCompile),
  clearProject: callbackify(clearProject),
  clearExpiredProjects: callbackify(clearExpiredProjects),
  syncFromCode: callbackifyMultiResult(syncFromCode, [
    'codePositions',
    'downloadedFromCache',
  ]),
  syncFromPdf: callbackifyMultiResult(syncFromPdf, [
    'pdfPositions',
    'downloadedFromCache',
  ]),
  wordcount: callbackify(wordcount),
  promises: {
    doCompileWithLock,
    stopCompile,
    clearProject,
    clearExpiredProjects,
    syncFromCode,
    syncFromPdf,
    wordcount,
  },
}