#!/usr/bin/env node

/**
 * Git COMMIT-MSG hook for validating commit message
 * See https://docs.google.com/document/d/1rk04jEuGfk9kYzfqCuOlPTSJw3hEDZJTBN5E5f1SALo/edit
 *
 * Installation:
 * >> use ghooks, config in package.json
 */

const fs = require('fs');
const util = require('util');
const resolve = require('path').resolve;
const findup = require('findup');
const semverRegex = require('semver-regex');

const config = getConfig();
const MAX_LENGTH = config.maxSubjectLength || 100;
const IGNORED = new RegExp(
  util.format('(^WIP)|(^v)|(^%s$)', semverRegex().source)
);

// fixup! and squash! are part of Git, commits tagged with them are not intended to be merged, cf. https://git-scm.com/docs/git-commit
const PATTERN = /^((fixup! |squash! )?(\w+)(?:\(([^\)\s]+)\))?: (.+))(?:\n|$)/;
const MERGE_COMMIT_PATTERN = /^Merge /;
const error = function() {
  // gitx does not display it
  // http://gitx.lighthouseapp.com/projects/17830/tickets/294-feature-display-hook-error-message-when-hook-fails
  // https://groups.google.com/group/gitx/browse_thread/thread/a03bcab60844b812
  console[config.warnOnFail ? 'warn' : 'error'](
    `Invalid commit message: ${util.format.apply(null, arguments)}`
  );
  console.log(
    'See our specific at:',
    'https://github.com/alibaba/ice/.github/GIT_COMMIT_SPECIFIC.md'
  );
};

const validateMessage = function(raw) {
  let types = (config.types = config.types || 'conventional-commit-types');

  // resolve types from a module
  if (typeof types === 'string' && types !== '*') {
    types = Object.keys(require(types).types);
  }

  const messageWithBody = (raw || '')
    .split('\n')
    .filter((str) => {
      return str.indexOf('#') !== 0;
    })
    .join('\n');

  const message = messageWithBody.split('\n').shift();

  if (message === '') {
    console.log('Aborting commit due to empty commit message.');
    return false;
  }

  let isValid = true;

  if (MERGE_COMMIT_PATTERN.test(message)) {
    console.log('Merge commit detected.');
    return true;
  }

  if (IGNORED.test(message)) {
    console.log('Commit message validation ignored.');
    return true;
  }

  const match = PATTERN.exec(message);

  if (!match) {
    error('does not match "<type>(<scope>): <subject>" !');
    isValid = false;
  } else {
    const firstLine = match[1];
    const squashing = !!match[2];
    const type = match[3];
    const scope = match[4];
    const subject = match[5];

    const SUBJECT_PATTERN = new RegExp(config.subjectPattern || '.+');
    const SUBJECT_PATTERN_ERROR_MSG =
      config.subjectPatternErrorMsg ||
      'subject does not match subject pattern!';

    if (firstLine.length > MAX_LENGTH && !squashing) {
      error('is longer than %d characters !', MAX_LENGTH);
      isValid = false;
    }

    if (types !== '*' && types.indexOf(type) === -1) {
      error(
        '"%s" is not allowed type ! Valid types are: %s',
        type,
        types.join(', ')
      );
      isValid = false;
    }

    if (!SUBJECT_PATTERN.exec(subject)) {
      error(SUBJECT_PATTERN_ERROR_MSG);
      isValid = false;
    }
  }

  // Some more ideas, do want anything like this ?
  // - Validate the rest of the message (body, footer, BREAKING CHANGE annotations)
  // - allow only specific scopes (eg. fix(docs) should not be allowed ?
  // - auto correct the type to lower case ?
  // - auto correct first letter of the subject to lower case ?
  // - auto add empty line after subject ?
  // - auto remove empty () ?
  // - auto correct typos in type ?
  // - store incorrect messages, so that we can learn

  isValid = isValid || config.warnOnFail;

  if (isValid) {
    // exit early and skip messaging logics
    return true;
  }

  const argInHelp =
    config.helpMessage && config.helpMessage.indexOf('%s') !== -1;

  if (argInHelp) {
    console.log(config.helpMessage, messageWithBody);
  } else if (message) {
    console.log(message);
  }

  if (!argInHelp && config.helpMessage) {
    console.log(config.helpMessage);
  }

  return false;
};

// publish for testing
exports.validateMessage = validateMessage;
exports.getGitFolder = getGitFolder;
exports.config = config;

// hacky start if not run by mocha :-D
// istanbul ignore next
if (process.argv.join('').indexOf('mocha') === -1) {
  const commitMsgFile = process.argv[2] || `${getGitFolder()}/COMMIT_EDITMSG`;
  const incorrectLogFile = commitMsgFile.replace(
    'COMMIT_EDITMSG',
    'logs/incorrect-commit-msgs'
  );

  const hasToString = function hasToString(x) {
    return x && typeof x.toString === 'function';
  };

  fs.readFile(commitMsgFile, (err, buffer) => {
    const msg = getCommitMessage(buffer);

    if (!validateMessage(msg)) {
      fs.appendFile(incorrectLogFile, `${msg}\n`, () => {
        process.exit(1);
      });
    } else {
      process.exit(0);
    }

    function getCommitMessage(buffer) {
      return hasToString(buffer) && buffer.toString();
    }
  });
}

function getConfig() {
  const pkgFile = findup.sync(process.cwd(), 'package.json');
  const pkg = JSON.parse(fs.readFileSync(resolve(pkgFile, 'package.json')));
  return (pkg && pkg.config && pkg.config['validate-commit-msg']) || {};
}

function getGitFolder() {
  let gitDirLocation = './.git';
  if (!fs.existsSync(gitDirLocation)) {
    throw new Error(`Cannot find file ${gitDirLocation}`);
  }

  if (!fs.lstatSync(gitDirLocation).isDirectory()) {
    const unparsedText = `${fs.readFileSync(gitDirLocation)}`;
    gitDirLocation = unparsedText.substring('gitdir: '.length).trim();
  }

  if (!fs.existsSync(gitDirLocation)) {
    throw new Error(`Cannot find file ${gitDirLocation}`);
  }

  return gitDirLocation;
}