import * as fs from 'fs';
import * as path from 'path';
import * as glob from 'glob';

/**
 * Simple Promiseify function that takes a Node API and return a version that supports promises.
 * We use promises instead of synchronized functions to make the process less I/O bound and
 * faster. It also simplify the code.
 */
function promiseify(fn) {
  return function (...args) {
    return new Promise((resolve, reject) => {
      fn.apply(this, args.concat([function (err, value) {
        if (err) {
          reject(err);
        } else {
          resolve(value);
        }
      }]));
    });
  };
}

const readFile = promiseify(fs.readFile);
const writeFile = promiseify(fs.writeFile);


export function copyResources(globs) {
  if (typeof globs === 'string') {
    globs = [globs];
  }

  /**
   * For every argument, inline the templates and styles under it and write the new file.
   */
  return Promise.all(globs.map(pattern => {
    if (pattern.indexOf('*') < 0) {
      // Argument is a directory target, add glob patterns to include every files.
      pattern = path.join(pattern, '**', '*');
    }

    const files = glob.sync(pattern, {})
      .filter(name => /\.js$/.test(name)); // Matches only JavaScript files.

    // Generate all files content with inlined templates.
    return Promise.all(files.map(filePath => {
      return readFile(filePath, 'utf-8')
        .then(content => inlineResourcesFromString(content, url => {
          return path.join(path.dirname(filePath), url);
        }))
        .then(content => writeFile(filePath, content))
        .catch(err => {
          console.error('An error occurred: ', err);
        });
    }));
  }));
}

/**
 * Inline resources from a string content.
 * @param content {string} The source file's content.
 * @param urlResolver {Function} A resolver that takes a URL and return a path.
 * @returns {string} The content with resources inlined.
 */
function inlineResourcesFromString(content, urlResolver) {
  // Curry through the inlining functions.
  return [
    inlineTemplate,
    inlineStyle,
    removeModuleId,
  ].reduce((с, fn) => fn(с, urlResolver), content);
}

if (require.main === module) {
  copyResources(process.argv.slice(2));
}


/**
 * Inline the templates for a source file. Simply search for instances of `templateUrl: ...` and
 * replace with `template: ...` (with the content of the file included).
 * @param content {string} The source file's content.
 * @param urlResolver {Function} A resolver that takes a URL and return a path.
 * @return {string} The content with all templates inlined.
 */
function inlineTemplate(content, urlResolver) {
  return content.replace(/templateUrl:\s*'([^']+?\.html)'/g, function (_, templateUrl) {
    const templateFile = urlResolver(templateUrl);
    const templateContent = fs.readFileSync(templateFile, 'utf-8');
    const shortenedTemplate = templateContent
      .replace(/([\n\r]\s*)+/gm, ' ')
      .replace(/"/g, '\\"');
    return `template: "${shortenedTemplate}"`;
  });
}


/**
 * Inline the styles for a source file. Simply search for instances of `styleUrls: [...]` and
 * replace with `styles: [...]` (with the content of the file included).
 * @param urlResolver {Function} A resolver that takes a URL and return a path.
 * @param content {string} The source file's content.
 * @return {string} The content with all styles inlined.
 */
function inlineStyle(content, urlResolver) {
  return content.replace(/styleUrls:\s*(\[[\s\S]*?\])/gm, function (_, styleUrls) {
    // tslint:disable-next-line
    const urls = eval(styleUrls);
    return 'styles: [' +
      urls.map(styleUrl => {
        const styleFile = urlResolver(styleUrl);
        const styleContent = fs.readFileSync(styleFile, 'utf-8');
        const shortenedStyle = styleContent
          .replace(/([\n\r]\s*)+/gm, ' ')
          .replace(/"/g, '\\"');
        return `"${shortenedStyle}"`;
      })
        .join(',\n') +
      ']';
  });
}


/**
 * Remove every mention of `moduleId: module.id`.
 * @param content {string} The source file's content.
 * @returns {string} The content with all moduleId: mentions removed.
 */
function removeModuleId(content) {
  return content.replace(/\s*moduleId:\s*module\.id\s*,?\s*/gm, '');
}