// TODO: Refactor this action

const {execSync} = require('child_process');

/**
 * Gets the value of an input.  The value is also trimmed.
 *
 * @param     name     name of the input to get
 * @param     options  optional. See InputOptions.
 * @returns   string
 */
function getInput(name, options) {
  const val = process.env[`INPUT_${name.replace(/ /g, '_').toUpperCase()}`] || '';
  if (options && options.required && !val) {
    throw new Error(`Input required and not supplied: ${name}`);
  }

  return val.trim();
}

const START_FROM = getInput('from');
const END_TO = getInput('to');
const INCLUDE_COMMIT_BODY = getInput('include-commit-body') === 'true';
const INCLUDE_ABBREVIATED_COMMIT = getInput('include-abbreviated-commit') === 'true';

/**
 * @typedef {Object} ICommit
 * @property {string | undefined} abbreviated_commit
 * @property {string | undefined} subject
 * @property {string | undefined} body
 */

/**
 * @typedef {ICommit & {type: string | undefined, scope: string | undefined}} ICommitExtended
 */


/**
 * Any unique string that is guaranteed not to be used in committee text.
 * Used to split data in the commit line
 * @type {string}
 */
const commitInnerSeparator = '~~~~';


/**
 * Any unique string that is guaranteed not to be used in committee text.
 * Used to split each commit line
 * @type {string}
 */
const commitOuterSeparator = '₴₴₴₴';


/**
 * Commit data to be obtained.
 * @type {Map<string, string>}
 *
 * @see https://git-scm.com/docs/git-log#Documentation/git-log.txt-emnem
 */
const commitDataMap = new Map([
  ['subject', '%s'], // Required
]);

if (INCLUDE_COMMIT_BODY) {
  commitDataMap.set('body', '%b');
}

if (INCLUDE_ABBREVIATED_COMMIT) {
  commitDataMap.set('abbreviated_commit', '%h');
}

/**
 * The type used to group commits that do not comply with the convention
 * @type {string}
 */
const fallbackType = 'other';


/**
 * List of all desired commit groups and in what order to display them.
 * @type {string[]}
 */
const supportedTypes = [
  'feat',
  'fix',
  'perf',
  'refactor',
  'style',
  'docs',
  'test',
  'build',
  'ci',
  'chore',
  'revert',
  'deps',
  fallbackType,
];

/**
 * @param {string} commitString
 * @returns {ICommit}
 */
function parseCommit(commitString) {
  /** @type {ICommit} */
  const commitDataObj = {};
  const commitDataArray =
    commitString
      .split(commitInnerSeparator)
      .map(s => s.trim());

  for (const [key] of commitDataMap) {
    commitDataObj[key] = commitDataArray.shift();
  }

  return commitDataObj;
}

/**
 * Returns an array of commits since the last git tag
 * @return {ICommit[]}
 */
function getCommits() {

  const format = Array.from(commitDataMap.values()).join(commitInnerSeparator) + commitOuterSeparator;

  const logs = String(execSync(`git --no-pager log ${START_FROM}..${END_TO} --pretty=format:"${format}" --reverse`));

  return logs
    .trim()
    .split(commitOuterSeparator)
    .filter(r => !!r.trim()) // Skip empty lines
    .map(parseCommit);
}


/**
 *
 * @param {ICommit} commit
 * @return {ICommitExtended}
 */
function setCommitTypeAndScope(commit) {

  const matchRE = new RegExp(`^(?:(${supportedTypes.join('|')})(?:\\((\\S+)\\))?:)?(.*)`, 'i');

  let [, type, scope, clearSubject] = commit.subject.match(matchRE);

  /**
   * Additional rules for checking committees that do not comply with the convention, but for which it is possible to determine the type.
   */
  // Commits like `revert something`
  if (type === undefined && commit.subject.startsWith('revert')) {
    type = 'revert';
  }

  return {
    ...commit,
    type: (type || fallbackType).toLowerCase().trim(),
    scope: (scope || '').toLowerCase().trim(),
    subject: (clearSubject || commit.subject).trim(),
  };
}

class CommitGroup {
  constructor() {
    this.scopes = new Map;
    this.commits = [];
  }

  /**
   *
   * @param {ICommitExtended[]} array
   * @param {ICommitExtended} commit
   */
  static _pushOrMerge(array, commit) {
    const similarCommit = array.find(c => c.subject === commit.subject);
    if (similarCommit) {
      if (commit.abbreviated_commit !== undefined) {
        similarCommit.abbreviated_commit += `, ${commit.abbreviated_commit}`;
      }
    } else {
      array.push(commit);
    }
  }

  /**
   * @param {ICommitExtended} commit
   */
  push(commit) {
    if (!commit.scope) {
      CommitGroup._pushOrMerge(this.commits, commit);
      return;
    }

    const scope = this.scopes.get(commit.scope) || {commits: []};
    CommitGroup._pushOrMerge(scope.commits, commit);
    this.scopes.set(commit.scope, scope);
  }

  get isEmpty() {
    return this.commits.length === 0 && this.scopes.size === 0;
  }
}


/**
 * Groups all commits by type and scopes
 * @param {ICommit[]} commits
 * @returns {Map<string, CommitGroup>}
 */
function getGroupedCommits(commits) {
  const parsedCommits = commits.map(setCommitTypeAndScope);

  const types = new Map(
    supportedTypes.map(id => ([id, new CommitGroup()])),
  );

  for (const parsedCommit of parsedCommits) {
    const typeId = parsedCommit.type;
    const type = types.get(typeId);
    type.push(parsedCommit);
  }

  return types;
}

/**
 * Return markdown list with commits
 * @param {ICommitExtended[]} commits
 * @param {string} pad
 * @returns {string}
 */
function getCommitsList(commits, pad = '') {
  let changelog = '';
  for (const commit of commits) {
    changelog += `${pad}- ${commit.subject}.`;

    if (commit.abbreviated_commit !== undefined) {
      changelog += ` (${commit.abbreviated_commit})`;
    }

    changelog += '\r\n';

    if (commit.body === undefined) {
      continue;
    }

    const body = commit.body.replace('[skip ci]', '').trim();
    if (body !== '') {
      changelog += `${
        body
          .split(/\r*\n+/)
          .filter(s => !!s.trim())
          .map(s => `${pad}  ${s}`)
          .join('\r\n')
      }${'\r\n'}`;
    }
  }

  return changelog;
}


function replaceHeader(str) {
  switch (str) {
    case 'feat':
      return 'New Features';
    case 'fix':
      return 'Bug Fixes';
    case 'docs':
      return 'Documentation Changes';
    case 'build':
      return 'Build System';
    case 'chore':
      return 'Chores';
    case 'ci':
      return 'Continuous Integration';
    case 'refactor':
      return 'Refactors';
    case 'style':
      return 'Code Style Changes';
    case 'test':
      return 'Tests';
    case 'perf':
      return 'Performance improvements';
    case 'revert':
      return 'Reverts';
    case 'deps':
      return 'Dependency updates';
    case 'other':
      return 'Other Changes';
    default:
      return str;
  }
}


/**
 * Return markdown string with changelog
 * @param {Map<string, CommitGroup>} groups
 */
function getChangeLog(groups) {

  let changelog = '';

  for (const [typeId, group] of groups) {
    if (group.isEmpty) {
      continue;
    }

    changelog += `### ${replaceHeader(typeId)}${'\r\n'}`;

    for (const [scopeId, scope] of group.scopes) {
      if (scope.commits.length) {
        changelog += `- #### ${replaceHeader(scopeId)}${'\r\n'}`;
        changelog += getCommitsList(scope.commits, '  ');
      }
    }

    if (group.commits.length) {
      changelog += getCommitsList(group.commits);
    }

    changelog += ('\r\n' + '\r\n');
  }

  return changelog.trim();
}


function escapeData(s) {
  return String(s)
    .replace(/%/g, '%25')
    .replace(/\r/g, '%0D')
    .replace(/\n/g, '%0A');
}

try {
  const commits = getCommits();
  const grouped = getGroupedCommits(commits);
  const changelog = getChangeLog(grouped);
  process.stdout.write('::set-output name=release-note::' + escapeData(changelog) + '\r\n');
// require('fs').writeFileSync('../CHANGELOG.md', changelog, {encoding: 'utf-8'})
} catch (e) {
  console.error(e);
  process.exit(1);
}