/**
 * @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
 */
// tslint:disable
// TODO: cleanup this file, it's copied as is from Angular CLI.

import { Compiler, loader } from 'webpack';
import { CachedSource, ConcatSource, OriginalSource, RawSource, Source } from 'webpack-sources';
import { interpolateName } from 'loader-utils';
import * as path from 'path';

const Chunk = require('webpack/lib/Chunk');
const EntryPoint = require('webpack/lib/Entrypoint');

export interface ScriptsWebpackPluginOptions {
  name: string;
  sourceMap: boolean;
  scripts: string[];
  filename: string;
  basePath: string;
}

interface ScriptOutput {
  filename: string;
  source: CachedSource;
}

function addDependencies(compilation: any, scripts: string[]): void {
  for (const script of scripts) {
    compilation.fileDependencies.add(script);
  }
}

function hook(compiler: any, action: (compilation: any, callback: (err?: Error) => void) => void) {
  compiler.hooks.thisCompilation.tap('scripts-webpack-plugin', (compilation: any) => {
    compilation.hooks.additionalAssets.tapAsync(
      'scripts-webpack-plugin',
      (callback: (err?: Error) => void) => action(compilation, callback),
    );
  });
}

export class ScriptsWebpackPlugin {
  private _lastBuildTime?: number;
  private _cachedOutput?: ScriptOutput;

  constructor(private options: Partial<ScriptsWebpackPluginOptions> = {}) { }

  shouldSkip(compilation: any, scripts: string[]): boolean {
    if (this._lastBuildTime == undefined) {
      this._lastBuildTime = Date.now();
      return false;
    }

    for (let i = 0; i < scripts.length; i++) {
      const scriptTime = compilation.fileTimestamps.get(scripts[i]);
      if (!scriptTime || scriptTime > this._lastBuildTime) {
        this._lastBuildTime = Date.now();
        return false;
      }
    }

    return true;
  }

  private _insertOutput(compilation: any, { filename, source }: ScriptOutput, cached = false) {
    const chunk = new Chunk(this.options.name);
    chunk.rendered = !cached;
    chunk.id = this.options.name;
    chunk.ids = [chunk.id];
    chunk.files.push(filename);

    const entrypoint = new EntryPoint(this.options.name);
    entrypoint.pushChunk(chunk);
    chunk.addGroup(entrypoint);
    compilation.entrypoints.set(this.options.name, entrypoint);
    compilation.chunks.push(chunk);
    compilation.assets[filename] = source;
  }

  apply(compiler: Compiler): void {
    if (!this.options.scripts || this.options.scripts.length === 0) {
      return;
    }

    const scripts = this.options.scripts
      .filter(script => !!script)
      .map(script => path.resolve(this.options.basePath || '', script));

    hook(compiler, (compilation, callback) => {
      if (this.shouldSkip(compilation, scripts)) {
        if (this._cachedOutput) {
          this._insertOutput(compilation, this._cachedOutput, true);
        }

        addDependencies(compilation, scripts);
        callback();

        return;
      }

      const sourceGetters = scripts.map(fullPath => {
        return new Promise<Source>((resolve, reject) => {
          compilation.inputFileSystem.readFile(fullPath, (err: Error, data: Buffer) => {
            if (err) {
              reject(err);
              return;
            }

            const content = data.toString();

            let source;
            if (this.options.sourceMap) {
              // TODO: Look for source map file (for '.min' scripts, etc.)

              let adjustedPath = fullPath;
              if (this.options.basePath) {
                adjustedPath = path.relative(this.options.basePath, fullPath);
              }
              source = new OriginalSource(content, adjustedPath);
            } else {
              source = new RawSource(content);
            }

            resolve(source);
          });
        });
      });

      Promise.all(sourceGetters)
        .then(sources => {
          const concatSource = new ConcatSource();
          sources.forEach(source => {
            concatSource.add(source);
            concatSource.add('\n;');
          });

          const combinedSource = new CachedSource(concatSource);
          const filename = interpolateName(
            { resourcePath: 'scripts.js' } as loader.LoaderContext,
            this.options.filename as string,
            { content: combinedSource.source() },
          );

          const output = { filename, source: combinedSource };
          this._insertOutput(compilation, output);
          this._cachedOutput = output;
          addDependencies(compilation, scripts);

          callback();
        })
        .catch((err: Error) => callback(err));
    });
  }
}
