import {red} from 'chalk';
import {readdirSync, readFileSync, statSync} from 'fs';
import {task} from 'gulp';
import {IMinimatch, Minimatch} from 'minimatch';
import {join} from 'path';
import {execNodeTask} from '../util/task-helpers';

/** Glob that matches all SCSS or CSS files that should be linted. */
const styleGlob = 'src/**/*.+(css|scss)';

/** List of flags that will passed to the different TSLint tasks. */
const tsLintBaseFlags = ['-c', 'tslint.json', '--project', './tsconfig.json'];

/** Path for the Github owners file. */
const ownersFilePath = '.github/CODEOWNERS';

/** Path for the .gitignore file. */
const gitIgnorePath = '.gitignore';

task('lint', ['tslint', 'stylelint', 'ownerslint']);

/** Task to lint Angular Material's scss stylesheets. */
task('stylelint', execNodeTask(
  'stylelint', [styleGlob, '--config', 'stylelint-config.json', '--syntax', 'scss']
));

/** Task to run TSLint against the e2e/ and src/ directories. */
task('tslint', execNodeTask('tslint', tsLintBaseFlags));

/** Task that automatically fixes TSLint warnings. */
task('tslint:fix', execNodeTask('tslint', [...tsLintBaseFlags, '--fix']));

task('ownerslint', () => {
  let errors = 0;

  let ownedPaths = readFileSync(ownersFilePath, 'utf8').split('\n')
      // Trim lines.
      .map(line => line.trim())
      // Remove empty lines and comments.
      .filter(line => line && !line.startsWith('#'))
      // Split off just the path glob.
      .map(line => line.split(/\s+/)[0])
      // Turn paths into Minimatch objects.
      .map(path => new Minimatch(path, {dot: true, matchBase: true}));

  let ignoredPaths = readFileSync(gitIgnorePath, 'utf8').split('\n')
      // Trim lines.
      .map(line => line.trim())
      // Remove empty lines and comments.
      .filter(line => line && !line.startsWith('#'))
      // Turn paths into Minimatch objects.
      .map(path => new Minimatch(path, {dot: true, matchBase: true}));

  for (let paths = getChildPaths('.'); paths.length;) {
    paths = Array.prototype.concat(...paths
        // Remove ignored paths
        .filter(path => !ignoredPaths.reduce(
            (isIgnored, ignoredPath) => isIgnored || ignoredPath.match('/' + path), false))
        // Remove paths that match an owned path.
        .filter(path => !ownedPaths.reduce(
            (isOwned, ownedPath) => isOwned || isOwnedBy(path, ownedPath), false))
        // Report an error for any files that didn't match any owned paths.
        .filter(path => {
          if (statSync(path).isFile()) {
            console.log(red(`No code owner found for "${path}".`));
            errors++;
            return false;
          }
          return true;
        })
        // Get the next level of children for any directories.
        .map(path => getChildPaths(path)));
  }

  if (errors) {
    throw Error(`Found ${errors} files with no owner.`);
  }
});

/** Check if the given path is owned by the given owned path matcher. */
function isOwnedBy(path: string, ownedPath: IMinimatch) {
  // If the owned path ends with `**` its safe to eliminate whole directories.
  if (ownedPath.pattern.endsWith('**') || statSync(path).isFile()) {
    return ownedPath.match('/' + path);
  }
  return false;
}

/** Get the immediate child paths of the given path. */
function getChildPaths(path: string) {
  return readdirSync(path).map(child => join(path, child));
}