/**
 * @license
 * Copyright (C) 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {PackageName, PackageVersion, DirPath, FilePath} from "./base-types";
import {fail} from "./utils";
import * as path from "path";
import * as fs from "fs";

/**
 * Describe one installed package from node_modules
 */
export interface InstalledPackage {
  /** Package name (it is calculated based on path to module) */
  name: PackageName;
  /** Package version from package.json */
  version: PackageVersion;
  /**
   * Path to the top-level package directory, where package.json is placed
   * This path is relative to process working directory (because bazel pass all paths relative to it)
   */
  rootPath: DirPath;
  /** All files in package. Path is relative to rootPath */
  files: FilePath[];
}

/**
 * Calculates all installed packages from a list of files
 * It is expected, that the addPackageJson method is called first for
 * all package.json files first and then the addFile method is called for all files (including package.json)
 */
export class InstalledPackagesBuilder {
  private readonly rootPathToPackageMap: Map<DirPath, InstalledPackage> = new Map();

  public constructor(private readonly nonPackages: Set<string>) {}

  public addPackageJson(packageJsonPath: string) {
    const pack = this.createInstalledPackage(packageJsonPath);
    if (!pack) return;
    this.rootPathToPackageMap.set(pack.rootPath, pack);
  }

  public addFile(file: string) {
    const pack = file.includes("@file+")
      ? this.findLocalPackageForFile(file)
      : this.findPackageForFile(file);

    pack.files.push(path.relative(pack.rootPath, file));
  }

  /**
   * Create new InstalledPackage.
   *  The name of a package is a relative path to the closest node_modules parent.
   * For example for the packageJsonFile='/a/node_modules/b/node_modules/d/e/package.json'
   * the package name is 'd/e'
   */
  private createInstalledPackage(packageJsonFile: string): InstalledPackage | undefined {
    const nameParts: Array<string> = [];
    const rootPath = path.dirname(packageJsonFile);
    let currentDir = rootPath;
    while (currentDir !== "") {
      const partName = path.basename(currentDir);
      if (partName === "node_modules") {
        const packageName = nameParts.reverse().join("/");
        const version = JSON.parse(
          fs.readFileSync(packageJsonFile, {encoding: "utf-8"})
        )["version"];
        if (!version) {
          if (this.nonPackages.has(packageName)) {
            return undefined;
          }
          fail(`Can't get version for ${packageJsonFile}`);
        }
        return {
          name: packageName,
          rootPath: rootPath,
          version: version,
          files: [],
        };
      }
      nameParts.push(partName);
      currentDir = path.dirname(currentDir);
    }
    fail(`Can't create package info for '${packageJsonFile}'`);
  }

  private findPackageForFile(filePath: FilePath): InstalledPackage {
    let currentDir = path.dirname(filePath);

    while (true) {
      if (this.rootPathToPackageMap.has(currentDir)) {
        return this.rootPathToPackageMap.get(currentDir)!;
      }

      const nextDir = path.dirname(currentDir);
      if (nextDir === currentDir) {
        break;
      }
      currentDir = nextDir;
    }

    fail(`Can't find package for '${filePath}'`);
  }

  private findLocalPackageForFile(filePath: FilePath): InstalledPackage {
    let currentDir = path.dirname(filePath);
    currentDir = this.getPackagePathRelativeToNodeModules(currentDir);

    const parts = currentDir.split("/");
    const pack =
      parts[0].startsWith("@") && parts.length > 1
        ? `${parts[0]}/${parts[1]}`
        : parts[0];

    if (this.rootPathToPackageMap.has(pack)) {
      return this.rootPathToPackageMap.get(pack)!;
    }

    const packIndex = filePath.lastIndexOf(pack);
    if (packIndex === -1) {
      fail(`Can't determine package root for '${filePath}'`);
    }

    const installedPack: InstalledPackage = {
      name: pack,
      version: "Snapshot",
      rootPath: filePath.substring(0, packIndex + pack.length),
      files: [],
    };
    this.rootPathToPackageMap.set(pack, installedPack);
    return installedPack;
  }

  public build(): InstalledPackage[] {
    return [...this.rootPathToPackageMap.values()];
  }

  private getPackagePathRelativeToNodeModules(filePath: string): string {
    const nodeModulesPathPart = "/node_modules/";
    const index = filePath.lastIndexOf(nodeModulesPathPart);
    if (index === -1) {
      fail(`Path does not contain '${nodeModulesPathPart}': '${filePath}'`);
    }
    return filePath.substring(index + nodeModulesPathPart.length);
  }
}