// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.

import {
  getMappedModuleName,
  parseTypeDirectives
} from "./compiler_type_directives.ts";
import { assert, log } from "./util.ts";

// Warning! The values in this enum are duplicated in `cli/msg.rs`
// Update carefully!
export enum MediaType {
  JavaScript = 0,
  JSX = 1,
  TypeScript = 2,
  TSX = 3,
  Json = 4,
  Wasm = 5,
  Unknown = 6
}

/** The shape of the SourceFile that comes from the privileged side */
export interface SourceFileJson {
  url: string;
  filename: string;
  mediaType: MediaType;
  sourceCode: string;
}

/** Returns the TypeScript Extension enum for a given media type. */
function getExtension(fileName: string, mediaType: MediaType): ts.Extension {
  switch (mediaType) {
    case MediaType.JavaScript:
      return ts.Extension.Js;
    case MediaType.JSX:
      return ts.Extension.Jsx;
    case MediaType.TypeScript:
      return fileName.endsWith(".d.ts") ? ts.Extension.Dts : ts.Extension.Ts;
    case MediaType.TSX:
      return ts.Extension.Tsx;
    case MediaType.Json:
      return ts.Extension.Json;
    case MediaType.Wasm:
      // Custom marker for Wasm type.
      return ts.Extension.Js;
    case MediaType.Unknown:
    default:
      throw TypeError("Cannot resolve extension.");
  }
}

/** A self registering abstraction of source files. */
export class SourceFile {
  extension!: ts.Extension;
  filename!: string;

  /** An array of tuples which represent the imports for the source file.  The
   * first element is the one that will be requested at compile time, the
   * second is the one that should be actually resolved.  This provides the
   * feature of type directives for Deno. */
  importedFiles?: Array<[string, string]>;

  mediaType!: MediaType;
  processed = false;
  sourceCode!: string;
  tsSourceFile?: ts.SourceFile;
  url!: string;

  constructor(json: SourceFileJson) {
    if (SourceFile._moduleCache.has(json.url)) {
      throw new TypeError("SourceFile already exists");
    }
    Object.assign(this, json);
    this.extension = getExtension(this.url, this.mediaType);
    SourceFile._moduleCache.set(this.url, this);
  }

  /** Cache the source file to be able to be retrieved by `moduleSpecifier` and
   * `containingFile`. */
  cache(moduleSpecifier: string, containingFile?: string): void {
    containingFile = containingFile || "";
    let innerCache = SourceFile._specifierCache.get(containingFile);
    if (!innerCache) {
      innerCache = new Map();
      SourceFile._specifierCache.set(containingFile, innerCache);
    }
    innerCache.set(moduleSpecifier, this);
  }

  /** Process the imports for the file and return them. */
  imports(): Array<[string, string]> {
    if (this.processed) {
      throw new Error("SourceFile has already been processed.");
    }
    assert(this.sourceCode != null);
    // we shouldn't process imports for files which contain the nocheck pragma
    // (like bundles)
    if (this.sourceCode.match(/\/{2}\s+@ts-nocheck/)) {
      log(`Skipping imports for "${this.filename}"`);
      return [];
    }
    const preProcessedFileInfo = ts.preProcessFile(this.sourceCode, true, true);
    this.processed = true;
    const files = (this.importedFiles = [] as Array<[string, string]>);

    function process(references: ts.FileReference[]): void {
      for (const { fileName } of references) {
        files.push([fileName, fileName]);
      }
    }

    const {
      importedFiles,
      referencedFiles,
      libReferenceDirectives,
      typeReferenceDirectives
    } = preProcessedFileInfo;
    const typeDirectives = parseTypeDirectives(this.sourceCode);
    if (typeDirectives) {
      for (const importedFile of importedFiles) {
        files.push([
          importedFile.fileName,
          getMappedModuleName(importedFile, typeDirectives)
        ]);
      }
    } else {
      process(importedFiles);
    }
    process(referencedFiles);
    process(libReferenceDirectives);
    process(typeReferenceDirectives);
    return files;
  }

  /** A cache of all the source files which have been loaded indexed by the
   * url. */
  private static _moduleCache: Map<string, SourceFile> = new Map();

  /** A cache of source files based on module specifiers and containing files
   * which is used by the TypeScript compiler to resolve the url */
  private static _specifierCache: Map<
    string,
    Map<string, SourceFile>
  > = new Map();

  /** Retrieve a `SourceFile` based on a `moduleSpecifier` and `containingFile`
   * or return `undefined` if not preset. */
  static getUrl(
    moduleSpecifier: string,
    containingFile: string
  ): string | undefined {
    const containingCache = this._specifierCache.get(containingFile);
    if (containingCache) {
      const sourceFile = containingCache.get(moduleSpecifier);
      return sourceFile && sourceFile.url;
    }
    return undefined;
  }

  /** Retrieve a `SourceFile` based on a `url` */
  static get(url: string): SourceFile | undefined {
    return this._moduleCache.get(url);
  }

  /** Determine if a source file exists or not */
  static has(url: string): boolean {
    return this._moduleCache.has(url);
  }
}