package-cache.ts

import Package from './package';
import { realpathSync } from 'fs';
import { getOrCreate } from './get-or-create';
import resolvePackagePath from 'resolve-package-path';
import { dirname } from 'path';
import { sync as pkgUpSync }  from 'pkg-up';

export default class PackageCache {
  resolve(packageName: string, fromPackage: Package): Package {
    let cache = getOrCreate(this.resolutionCache, fromPackage, () => new Map());
    return getOrCreate(cache, packageName, () => {
      let root = dirname(resolvePackagePath(packageName, this.basedir(fromPackage)));
      return this.getAddon(root);
    });
  }

  getApp(packageRoot: string) {
    return this.getPackage(packageRoot, false);
  }

  overridePackage(pkg: Package) {
    this.rootCache.set(pkg.root, pkg);
  }

  overrideResolution(packageName: string, fromPackage: Package, answer: Package) {
    this.rootCache.set(answer.root, answer);
    let cache = getOrCreate(this.resolutionCache, fromPackage, () => new Map());
    cache.set(packageName, answer);
  }

  protected rootCache: Map<string, Package> = new Map();
  protected resolutionCache: Map<Package, Map<string, Package>> = new Map();

  protected basedir(pkg: Package): string {
    return pkg.root;
  }

  private getPackage(packageRoot: string, isAddon: boolean): Package {
    let root = realpathSync(packageRoot);
    let p = getOrCreate(this.rootCache, root, () => {
      return new Package(root, !isAddon, this);
    });
    return p;
  }

  getAddon(packageRoot: string) {
    return this.getPackage(packageRoot, true);
  }

  ownerOfFile(filename: string): Package | undefined {
    let segments = filename.split('/');

    // first we look through our cached packages for any that are rooted right
    // at or above the file.
    for (let length = segments.length - 1; length >= 0; length--) {
      if (segments[length-1] === 'node_modules') {
        // once we hit a node_modules, we're leaving the package we were in, so
        // any higher caches don't apply to us
        break;
      }
      let candidate = segments.slice(0, length).join('/');
      if (this.rootCache.has(candidate)) {
        return this.rootCache.get(candidate);
      }
    }

    let packageJSONPath = pkgUpSync(filename);
    if (packageJSONPath) {
      return this.getAddon(dirname(packageJSONPath));
    }
  }

  // register to be shared as the per-process package cache with the given name
  shareAs(identifier: string) {
    shared.set(identifier, this);
  }

  static shared(identifier: string) {
    let p = shared.get(identifier);
    if (p) {
      return p;
    }
    p =  new PackageCache();
    shared.set(identifier,p);
    return p;
  }

}

const shared: Map<string, PackageCache> = new Map();