const { GitProcess } = require('dugite');
const fs = require('fs');
const os = require('os');
const path = require('path');

const ELECTRON_DIR = path.resolve(__dirname, '..', '..');
const SRC_DIR = path.resolve(ELECTRON_DIR, '..');

const RELEASE_BRANCH_PATTERN = /(\d)+-(?:(?:[0-9]+-x$)|(?:x+-y$))/;
// TODO(main-migration): Simplify once main branch is renamed
const MAIN_BRANCH_PATTERN = /^(main|master)$/;
const ORIGIN_MAIN_BRANCH_PATTERN = /^origin\/(main|master)$/;

require('colors');
const pass = '✓'.green;
const fail = '✗'.red;

function getElectronExec () {
  const OUT_DIR = getOutDir();
  switch (process.platform) {
    case 'darwin':
      return `out/${OUT_DIR}/Electron.app/Contents/MacOS/Electron`;
    case 'win32':
      return `out/${OUT_DIR}/electron.exe`;
    case 'linux':
      return `out/${OUT_DIR}/electron`;
    default:
      throw new Error('Unknown platform');
  }
}

function getOutDir (options = {}) {
  const shouldLog = options.shouldLog || false;
  const presetDirs = ['Testing', 'Release', 'Default', 'Debug'];

  if (options.outDir || process.env.ELECTRON_OUT_DIR) {
    const outDir = options.outDir || process.env.ELECTRON_OUT_DIR;
    const outPath = path.resolve(SRC_DIR, 'out', outDir);

    // Check that user-set variable is a valid/existing directory
    if (fs.existsSync(outPath)) {
      if (shouldLog) console.log(`OUT_DIR is: ${outDir}`);
      return outDir;
    }

    // Throw error if user passed/set nonexistent directory.
    throw new Error(`${outDir} directory not configured on your machine.`);
  } else {
    for (const buildType of presetDirs) {
      const outPath = path.resolve(SRC_DIR, 'out', buildType);
      if (fs.existsSync(outPath)) {
        if (shouldLog) console.log(`OUT_DIR is: ${buildType}`);
        return buildType;
      }
    }
  }

  // If we got here, it means process.env.ELECTRON_OUT_DIR was not
  // set and none of the preset options could be found in /out, so throw
  throw new Error(`No valid out directory found; use one of ${presetDirs.join(',')} or set process.env.ELECTRON_OUT_DIR`);
}

function getAbsoluteElectronExec () {
  return path.resolve(SRC_DIR, getElectronExec());
}

async function handleGitCall (args, gitDir) {
  const details = await GitProcess.exec(args, gitDir);
  if (details.exitCode === 0) {
    return details.stdout.replace(/^\*|\s+|\s+$/, '');
  } else {
    const error = GitProcess.parseError(details.stderr);
    console.log(`${fail} couldn't parse git process call: `, error);
    process.exit(1);
  }
}

async function getCurrentBranch (gitDir) {
  let branch = await handleGitCall(['rev-parse', '--abbrev-ref', 'HEAD'], gitDir);
  if (!MAIN_BRANCH_PATTERN.test(branch) && !RELEASE_BRANCH_PATTERN.test(branch)) {
    const lastCommit = await handleGitCall(['rev-parse', 'HEAD'], gitDir);
    const branches = (await handleGitCall([
      'branch',
      '--contains',
      lastCommit,
      '--remote'
    ], gitDir)).split('\n');

    branch = branches.find(b => MAIN_BRANCH_PATTERN.test(b.trim()) || ORIGIN_MAIN_BRANCH_PATTERN.test(b.trim()) || RELEASE_BRANCH_PATTERN.test(b.trim()));
    if (!branch) {
      console.log(`${fail} no release branch exists for this ref`);
      process.exit(1);
    }
    if (branch.startsWith('origin/')) branch = branch.substr('origin/'.length);
  }
  return branch.trim();
}

function chunkFilenames (filenames, offset = 0) {
  // Windows has a max command line length of 2047 characters, so we can't
  // provide too many filenames without going over that. To work around that,
  // chunk up a list of filenames such that it won't go over that limit when
  // used as args. Other platforms may have higher limits, but 4095 might be
  // the limit on Linux systems according to `termios(3)`, so cap it there.
  const MAX_FILENAME_ARGS_LENGTH =
    (os.platform() === 'win32' ? 2047 : 4095) - offset;

  return filenames.reduce(
    (chunkedFilenames, filename) => {
      const currChunk = chunkedFilenames[chunkedFilenames.length - 1];
      const currChunkLength = currChunk.reduce(
        (totalLength, _filename) => totalLength + _filename.length + 1,
        0
      );
      if (currChunkLength + filename.length + 1 > MAX_FILENAME_ARGS_LENGTH) {
        chunkedFilenames.push([filename]);
      } else {
        currChunk.push(filename);
      }
      return chunkedFilenames;
    },
    [[]]
  );
}

module.exports = {
  chunkFilenames,
  getCurrentBranch,
  getElectronExec,
  getOutDir,
  getAbsoluteElectronExec,
  ELECTRON_DIR,
  SRC_DIR
};
