/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import * as fs from 'fs';
import * as path from 'path';
import * as tsLint from 'tslint';  // tslint:disable-line:no-implicit-dependencies
import * as ts from 'typescript';  // tslint:disable-line:no-implicit-dependencies
import { SchematicContext, TaskExecutor } from '../../src';
import { TslintFixTaskOptions } from './options';


function _loadConfiguration(
  Configuration: typeof tsLint.Configuration,
  options: TslintFixTaskOptions,
  root: string,
  file?: string,
) {
  if (options.tslintConfig) {
    return Configuration.parseConfigFile(options.tslintConfig, root);
  } else if (options.tslintPath) {
    return Configuration.findConfiguration(path.join(root, options.tslintPath)).results;
  } else if (file) {
    return Configuration.findConfiguration(null, file).results;
  } else {
    throw new Error('Executor must specify a tslint configuration.');
  }
}


function _getFileContent(
  file: string,
  options: TslintFixTaskOptions,
  program?: ts.Program,
): string | undefined {
  // The linter retrieves the SourceFile TS node directly if a program is used
  if (program) {
    const source = program.getSourceFile(file);
    if (!source) {
      const message
        = `File '${file}' is not part of the TypeScript project '${options.tsConfigPath}'.`;
      throw new Error(message);
    }

    return source.getFullText(source);
  }

  // NOTE: The tslint CLI checks for and excludes MPEG transport streams; this does not.
  try {
    // Strip BOM from file data.
    // https://stackoverflow.com/questions/24356713
    return fs.readFileSync(file, 'utf-8').replace(/^\uFEFF/, '');
  } catch {
    throw new Error(`Could not read file '${file}'.`);
  }
}


function _listAllFiles(root: string): string[] {
  const result: string[] = [];

  function _recurse(location: string) {
    const dir = fs.readdirSync(path.join(root, location));

    dir.forEach(name => {
      const loc = path.join(location, name);
      if (fs.statSync(path.join(root, loc)).isDirectory()) {
        _recurse(loc);
      } else {
        result.push(loc);
      }
    });
  }
  _recurse('');

  return result;
}


export default function (): TaskExecutor<TslintFixTaskOptions> {
  return async (options: TslintFixTaskOptions = {}, context: SchematicContext) => {
    const root = process.cwd();
    const tslint = await import('tslint'); // tslint:disable-line:no-implicit-dependencies

    const includes = (
      Array.isArray(options.includes)
        ? options.includes
        : (options.includes ? [options.includes] : [])
    );
    const files = (
      Array.isArray(options.files)
        ? options.files
        : (options.files ? [options.files] : [])
    );

    const Linter = tslint.Linter;
    const Configuration = tslint.Configuration;
    let program: ts.Program | undefined = undefined;
    let filesToLint: string[] = files;

    if (options.tsConfigPath && files.length == 0) {
      const tsConfigPath = path.join(process.cwd(), options.tsConfigPath);

      if (!fs.existsSync(tsConfigPath)) {
        throw new Error('Could not find tsconfig.');
      }

      program = Linter.createProgram(tsConfigPath);
      filesToLint = Linter.getFileNames(program);
    }

    if (includes.length > 0) {
      const allFilesRel = _listAllFiles(root);
      const pattern = '^('
        + (includes as string[])
          .map(ex => '('
            + ex.split(/[\/\\]/g).map(f => f
              .replace(/[\-\[\]{}()+?.^$|]/g, '\\$&')
              .replace(/^\*\*/g, '(.+?)?')
              .replace(/\*/g, '[^/\\\\]*'))
              .join('[\/\\\\]')
            + ')')
          .join('|')
        + ')($|/|\\\\)';
      const re = new RegExp(pattern);

      filesToLint.push(...allFilesRel
        .filter(x => re.test(x))
        .map(x => path.join(root, x)),
      );
    }

    const lintOptions = {
      fix: true,
      formatter: options.format || 'prose',
    };

    const linter = new Linter(lintOptions, program);
    // If directory doesn't change, we
    let lastDirectory: string | null = null;
    let config;

    for (const file of filesToLint) {
      const dir = path.dirname(file);
      if (lastDirectory !== dir) {
        lastDirectory = dir;
        config = _loadConfiguration(Configuration, options, root, file);
      }
      const content = _getFileContent(file, options, program);

      if (!content) {
        continue;
      }

      linter.lint(file, content, config);
    }

    const result = linter.getResult();

    // Format and show the results.
    if (!options.silent) {
      const Formatter = tslint.findFormatter(options.format || 'prose');
      if (!Formatter) {
        throw new Error(`Invalid lint format "${options.format}".`);
      }
      const formatter = new Formatter();

      // Certain tslint formatters outputs '\n' when there are no failures.
      // This will bloat the console when having schematics running refactor tasks.
      // see https://github.com/palantir/tslint/issues/4244
      const output = (formatter.format(result.failures, result.fixes) || '').trim();
      if (output) {
        context.logger.info(output);
      }
    }

    if (!options.ignoreErrors && result.errorCount > 0) {
      throw new Error('Lint errors were found.');
    }
  };
}
