/*
 * Package Configuration Extension
 *
 * Example:
 *
 * SystemJS.packages = {
 *   jquery: {
 *     main: 'index.js', // when not set, package name is requested directly
 *     format: 'amd',
 *     defaultExtension: 'ts', // defaults to 'js', can be set to false
 *     modules: {
 *       '*.ts': {
 *         loader: 'typescript'
 *       },
 *       'vendor/sizzle.js': {
 *         format: 'global'
 *       }
 *     },
 *     map: {
 *        // map internal require('sizzle') to local require('./vendor/sizzle')
 *        sizzle: './vendor/sizzle.js',
 *        // map any internal or external require of 'jquery/vendor/another' to 'another/index.js'
 *        './vendor/another.js': './another/index.js',
 *        // test.js / test -> lib/test.js
 *        './test.js': './lib/test.js',
 *
 *        // environment-specific map configurations
 *        './index.js': {
 *          '~browser': './index-node.js'
 *        }
 *     },
 *     // allows for setting package-prefixed depCache
 *     // keys are normalized module names relative to the package itself
 *     depCache: {
 *       // import 'package/index.js' loads in parallel package/lib/test.js,package/vendor/sizzle.js
 *       './index.js': ['./test'],
 *       './test.js': ['external-dep'],
 *       'external-dep/path.js': ['./another.js']
 *     }
 *   }
 * };
 *
 * Then:
 *   import 'jquery'                       -> jquery/index.js
 *   import 'jquery/submodule'             -> jquery/submodule.js
 *   import 'jquery/submodule.ts'          -> jquery/submodule.ts loaded as typescript
 *   import 'jquery/vendor/another'        -> another/index.js
 *
 * Detailed Behaviours
 * - main can have a leading "./" can be added optionally
 * - map and defaultExtension are applied to the main
 * - defaultExtension adds the extension only if the exact extension is not present
 * - defaultJSExtensions applies after map when defaultExtension is not set
 * - if a meta value is available for a module, map and defaultExtension are skipped
 * - like global map, package map also applies to subpaths (sizzle/x, ./vendor/another/sub)
 * - condition module map is '@env' module in package or '@system-env' globally
 * - map targets support conditional interpolation ('./x': './x.#{|env}.js')
 * - internal package map targets cannot use boolean conditionals
 *
 * Package Configuration Loading
 *
 * Not all packages may already have their configuration present in the System config
 * For these cases, a list of packageConfigPaths can be provided, which when matched against
 * a request, will first request a ".json" file by the package name to derive the package
 * configuration from. This allows dynamic loading of non-predetermined code, a key use
 * case in SystemJS.
 *
 * Example:
 *
 *   SystemJS.packageConfigPaths = ['packages/test/package.json', 'packages/*.json'];
 *
 *   // will first request 'packages/new-package/package.json' for the package config
 *   // before completing the package request to 'packages/new-package/path'
 *   SystemJS.import('packages/new-package/path');
 *
 *   // will first request 'packages/test/package.json' before the main
 *   SystemJS.import('packages/test');
 *
 * When a package matches packageConfigPaths, it will always send a config request for
 * the package configuration.
 * The package name itself is taken to be the match up to and including the last wildcard
 * or trailing slash.
 * The most specific package config path will be used.
 * Any existing package configurations for the package will deeply merge with the
 * package config, with the existing package configurations taking preference.
 * To opt-out of the package configuration request for a package that matches
 * packageConfigPaths, use the { configured: true } package config option.
 *
 */
(function() {

  hookConstructor(function(constructor) {
    return function() {
      constructor.call(this);
      this.packages = {};
      this.packageConfigPaths = [];
    };
  });

  function getPackage(loader, normalized) {
    // use most specific package
    var curPkg, curPkgLen = 0, pkgLen;
    for (var p in loader.packages) {
      if (normalized.substr(0, p.length) === p && (normalized.length === p.length || normalized[p.length] === '/')) {
        pkgLen = p.split('/').length;
        if (pkgLen > curPkgLen) {
          curPkg = p;
          curPkgLen = pkgLen;
        }
      }
    }
    return curPkg;
  }

  function addDefaultExtension(loader, pkg, pkgName, subPath, skipExtensions) {
    // don't apply extensions to folders or if defaultExtension = false
    if (!subPath || subPath[subPath.length - 1] == '/' || skipExtensions || pkg.defaultExtension === false)
      return subPath;

    // NB are you sure about this?
    // skip if we have interpolation conditional syntax in subPath?
    if (subPath.match(interpolationRegEx))
      return subPath;

    var metaMatch = false;

    // exact meta or meta with any content after the last wildcard skips extension
    if (pkg.meta)
      getMetaMatches(pkg.meta, subPath, function(metaPattern, matchMeta, matchDepth) {
        if (matchDepth == 0 || metaPattern.lastIndexOf('*') != metaPattern.length - 1)
          return metaMatch = true;
      });

    // exact global meta or meta with any content after the last wildcard skips extension
    if (!metaMatch && loader.meta)
      getMetaMatches(loader.meta, pkgName + '/' + subPath, function(metaPattern, matchMeta, matchDepth) {
        if (matchDepth == 0 || metaPattern.lastIndexOf('*') != metaPattern.length - 1)
          return metaMatch = true;
      });

    if (metaMatch)
      return subPath;

    // work out what the defaultExtension is and add if not there already
    // NB reconsider if default should really be ".js"?
    var defaultExtension = '.' + (pkg.defaultExtension || 'js');
    if (subPath.substr(subPath.length - defaultExtension.length) != defaultExtension)
      return subPath + defaultExtension;
    else
      return subPath;
  }

  function applyPackageConfigSync(loader, pkg, pkgName, subPath, skipExtensions) {
    // main
    if (!subPath) {
      if (pkg.main)
        subPath = pkg.main.substr(0, 2) == './' ? pkg.main.substr(2) : pkg.main;
      // also no submap if name is package itself (import 'pkg' -> 'path/to/pkg.js')
      else
        // NB can add a default package main convention here when defaultJSExtensions is deprecated
        // if it becomes internal to the package then it would no longer be an exit path
        return pkgName + (loader.defaultJSExtensions ? '.js' : '');
    }

    // map config checking without then with extensions
    if (pkg.map) {
      var mapPath = './' + subPath;

      var mapMatch = getMapMatch(pkg.map, mapPath);

      // we then check map with the default extension adding
      if (!mapMatch) {
        mapPath = './' + addDefaultExtension(loader, pkg, pkgName, subPath, skipExtensions);
        if (mapPath != './' + subPath)
          mapMatch = getMapMatch(pkg.map, mapPath);
      }
      if (mapMatch)
        return doMapSync(loader, pkg, pkgName, mapMatch, mapPath, skipExtensions);
    }

    // normal package resolution
    return pkgName + '/' + addDefaultExtension(loader, pkg, pkgName, subPath, skipExtensions);
  }

  function validateMapping(mapMatch, mapped, pkgName) {
    // disallow internal to subpath maps
    if (mapMatch == '.')
      throw new Error('Package ' + pkgName + ' has a map entry for "." which is not permitted.');
    // disallow internal ./x -> ./x/y recursive maps
    else if (mapped.substr(0, mapMatch.length) == mapMatch && (mapMatch[mapMatch.length - 1] != '/' && mapped[mapMatch.length] == '/'))
      throw new Error('Package ' + pkgName + ' has a recursive map for "' + mapMatch + '" which is not permitted.');
  }

  function doMapSync(loader, pkg, pkgName, mapMatch, path, skipExtensions) {
    var mapped = pkg.map[mapMatch];

    if (typeof mapped == 'object')
      throw new Error('Synchronous conditional normalization not supported sync normalizing ' + mapMatch + ' in ' + pkgName);

    validateMapping(mapMatch, mapped, pkgName);

    // ignore conditionals in sync
    if (typeof mapped != 'string')
      mapped = mapMatch = path;

    validateMapping(mapMatch, mapped, pkgName);

    // package map to main / base-level
    if (mapped == '.')
      mapped = pkgName;

    // internal package map
    else if (mapped.substr(0, 2) == './')
      return pkgName + '/' + addDefaultExtension(loader, pkg, pkgName, mapped.substr(2) + path.substr(mapMatch.length), skipExtensions);
    
    // external map reference
    return loader.normalizeSync(mapped + path.substr(mapMatch.length), pkgName + '/');
  }

  function applyPackageConfig(loader, pkg, pkgName, subPath, skipExtensions) {
    // main
    if (!subPath) {
      if (pkg.main)
        subPath = pkg.main.substr(0, 2) == './' ? pkg.main.substr(2) : pkg.main;
      // also no submap if name is package itself (import 'pkg' -> 'path/to/pkg.js')
      else
        // NB can add a default package main convention here when defaultJSExtensions is deprecated
        // if it becomes internal to the package then it would no longer be an exit path
        return Promise.resolve(pkgName + (loader.defaultJSExtensions ? '.js' : ''));
    }

    // map config checking without then with extensions
    var mapPath, mapMatch;

    if (pkg.map) {
      mapPath = './' + subPath;
      mapMatch = getMapMatch(pkg.map, mapPath);

      // we then check map with the default extension adding
      if (!mapMatch) {
        mapPath = './' + addDefaultExtension(loader, pkg, pkgName, subPath, skipExtensions);
        if (mapPath != './' + subPath)
          mapMatch = getMapMatch(pkg.map, mapPath);
      }
    }

    return (mapMatch ? doMap(loader, pkg, pkgName, mapMatch, mapPath, skipExtensions) : Promise.resolve())
    .then(function(mapped) {
      if (mapped)
        return Promise.resolve(mapped);

      // normal package resolution / fallback resolution for no conditional match
      return Promise.resolve(pkgName + '/' + addDefaultExtension(loader, pkg, pkgName, subPath, skipExtensions));
    });
  }

  function doStringMap(loader, pkg, pkgName, mapMatch, mapped, path, skipExtensions) {
    // NB the interpolation cases should strictly skip subsequent interpolation

    // package map to main / base-level
    if (mapped == '.')
      mapped = pkgName;
    
    // internal package map
    else if (mapped.substr(0, 2) == './')
      return Promise.resolve(pkgName + '/' + addDefaultExtension(loader, pkg, pkgName, mapped.substr(2) + path.substr(mapMatch.length), skipExtensions))
      .then(function(name) {
        return interpolateConditional.call(loader, name, pkgName + '/');
      });
    
    // external map reference
    return loader.normalize(mapped + path.substr(mapMatch.length), pkgName + '/');
  }

  function doMap(loader, pkg, pkgName, mapMatch, path, skipExtensions) {
    var mapped = pkg.map[mapMatch];

    if (typeof mapped == 'string') {
      validateMapping(mapMatch, mapped, pkgName);
      return doStringMap(loader, pkg, pkgName, mapMatch, mapped, path, skipExtensions);
    }

    // we use a special conditional syntax to allow the builder to handle conditional branch points further
    if (loader.builder)
      return Promise.resolve(pkgName + '/#:' + path);

    // map object -> conditional map
    return loader['import'](pkg.map['@env'] || '@system-env', pkgName)
    .then(function(env) {
      // first map condition to match is used
      for (var e in mapped) {
        var negate = e[0] == '~';

        var value = readMemberExpression(negate ? e.substr(1) : e, env);

        if (!negate && value || negate && !value)
          return mapped[e];
      }
    })
    .then(function(mapped) {
      if (mapped) {
        if (typeof mapped != 'string')
          throw new Error('Unable to map a package conditional to a package conditional.');
        validateMapping(mapMatch, mapped, pkgName);
        return doStringMap(loader, pkg, pkgName, mapMatch, mapped, path, skipExtensions);
      }

      // no environment match -> fallback to original subPath by returning undefined
    });
  }

  // normalizeSync = decanonicalize + package resolution
  SystemJSLoader.prototype.normalizeSync = SystemJSLoader.prototype.decanonicalize = SystemJSLoader.prototype.normalize;

  // decanonicalize must JUST handle package defaultExtension: false case when defaultJSExtensions is set
  // to be deprecated!
  hook('decanonicalize', function(decanonicalize) {
    return function(name, parentName) {
      if (this.builder)
        return decanonicalize.call(this, name, parentName, true);

      var decanonicalized = decanonicalize.call(this, name, parentName);

      if (!this.defaultJSExtensions)
        return decanonicalized;
    
      var pkgName = getPackage(this, decanonicalized);

      var pkg = this.packages[pkgName];
      var defaultExtension = pkg && pkg.defaultExtension;

      if (defaultExtension == undefined && pkg && pkg.meta)
        getMetaMatches(pkg.meta, decanonicalized.substr(pkgName), function(metaPattern, matchMeta, matchDepth) {
          if (matchDepth == 0 || metaPattern.lastIndexOf('*') != metaPattern.length - 1) {
            defaultExtension = false;
            return true;
          }
        });
      
      if ((defaultExtension === false || defaultExtension && defaultExtension != '.js') && name.substr(name.length - 3, 3) != '.js' && decanonicalized.substr(decanonicalized.length - 3, 3) == '.js')
        decanonicalized = decanonicalized.substr(0, decanonicalized.length - 3);

      return decanonicalized;
    };
  });

  hook('normalizeSync', function(normalizeSync) {
    return function(name, parentName, isPlugin) {
      warn.call(this, 'SystemJS.normalizeSync has been deprecated for SystemJS.decanonicalize.');

      var loader = this;
      isPlugin = isPlugin === true;

      // apply contextual package map first
      // (we assume the parent package config has already been loaded)
      if (parentName)
        var parentPackageName = getPackage(loader, parentName) ||
            loader.defaultJSExtensions && parentName.substr(parentName.length - 3, 3) == '.js' &&
            getPackage(loader, parentName.substr(0, parentName.length - 3));

      var parentPackage = parentPackageName && loader.packages[parentPackageName];

      // ignore . since internal maps handled by standard package resolution
      if (parentPackage && name[0] != '.') {
        var parentMap = parentPackage.map;
        var parentMapMatch = parentMap && getMapMatch(parentMap, name);

        if (parentMapMatch && typeof parentMap[parentMapMatch] == 'string')
          return doMapSync(loader, parentPackage, parentPackageName, parentMapMatch, name, isPlugin);
      }

      var defaultJSExtension = loader.defaultJSExtensions && name.substr(name.length - 3, 3) != '.js';

      // apply map, core, paths, contextual package map
      var normalized = normalizeSync.call(loader, name, parentName);

      // undo defaultJSExtension
      if (defaultJSExtension && normalized.substr(normalized.length - 3, 3) != '.js')
        defaultJSExtension = false;
      if (defaultJSExtension)
        normalized = normalized.substr(0, normalized.length - 3);

      var pkgConfigMatch = getPackageConfigMatch(loader, normalized);
      var pkgName = pkgConfigMatch && pkgConfigMatch.packageName || getPackage(loader, normalized);

      if (!pkgName)
        return normalized + (defaultJSExtension ? '.js' : '');

      var subPath = normalized.substr(pkgName.length + 1);

      return applyPackageConfigSync(loader, loader.packages[pkgName] || {}, pkgName, subPath, isPlugin);
    };
  });

  hook('normalize', function(normalize) {
    return function(name, parentName, isPlugin) {
      var loader = this;
      isPlugin = isPlugin === true;

      return Promise.resolve()
      .then(function() {
        // apply contextual package map first
        // (we assume the parent package config has already been loaded)
        if (parentName)
          var parentPackageName = getPackage(loader, parentName) ||
              loader.defaultJSExtensions && parentName.substr(parentName.length - 3, 3) == '.js' &&
              getPackage(loader, parentName.substr(0, parentName.length - 3));

        var parentPackage = parentPackageName && loader.packages[parentPackageName];

        // ignore . since internal maps handled by standard package resolution
        if (parentPackage && name.substr(0, 2) != './') {
          var parentMap = parentPackage.map;
          var parentMapMatch = parentMap && getMapMatch(parentMap, name);

          if (parentMapMatch)
            return doMap(loader, parentPackage, parentPackageName, parentMapMatch, name, isPlugin);
        }

        return Promise.resolve();
      })
      .then(function(mapped) {
        if (mapped)
          return mapped;

        var defaultJSExtension = loader.defaultJSExtensions && name.substr(name.length - 3, 3) != '.js';

        // apply map, core, paths, contextual package map
        var normalized = normalize.call(loader, name, parentName);

        // undo defaultJSExtension
        if (defaultJSExtension && normalized.substr(normalized.length - 3, 3) != '.js')
          defaultJSExtension = false;
        if (defaultJSExtension)
          normalized = normalized.substr(0, normalized.length - 3);

        var pkgConfigMatch = getPackageConfigMatch(loader, normalized);
        var pkgName = pkgConfigMatch && pkgConfigMatch.packageName || getPackage(loader, normalized);

        if (!pkgName)
          return Promise.resolve(normalized + (defaultJSExtension ? '.js' : ''));

        var pkg = loader.packages[pkgName];

        // if package is already configured or not a dynamic config package, use existing package config
        var isConfigured = pkg && (pkg.configured || !pkgConfigMatch);
        return (isConfigured ? Promise.resolve(pkg) : loadPackageConfigPath(loader, pkgName, pkgConfigMatch.configPath))
        .then(function(pkg) {
          var subPath = normalized.substr(pkgName.length + 1);

          return applyPackageConfig(loader, pkg, pkgName, subPath, isPlugin);
        });
      });
    };
  });

  // check if the given normalized name matches a packageConfigPath
  // if so, loads the config
  var packageConfigPaths = {};

  // data object for quick checks against package paths
  function createPkgConfigPathObj(path) {
    var lastWildcard = path.lastIndexOf('*');
    var length = Math.max(lastWildcard + 1, path.lastIndexOf('/'));
    return {
      length: length,
      regEx: new RegExp('^(' + path.substr(0, length).replace(/[.+?^${}()|[\]\\]/g, '\\$&').replace(/\*/g, '[^\\/]+') + ')(\\/|$)'),
      wildcard: lastWildcard != -1
    };
  }

  // most specific match wins
  function getPackageConfigMatch(loader, normalized) {
    var pkgName, exactMatch = false, configPath;
    for (var i = 0; i < loader.packageConfigPaths.length; i++) {
      var packageConfigPath = loader.packageConfigPaths[i];
      var p = packageConfigPaths[packageConfigPath] || (packageConfigPaths[packageConfigPath] = createPkgConfigPathObj(packageConfigPath));
      if (normalized.length < p.length)
        continue;
      var match = normalized.match(p.regEx);
      if (match && (!pkgName || (!(exactMatch && p.wildcard) && pkgName.length < match[1].length))) {
        pkgName = match[1];
        exactMatch = !p.wildcard;
        configPath = pkgName + packageConfigPath.substr(p.length);
      }
    }

    if (!pkgName)
      return;

    return {
      packageName: pkgName,
      configPath: configPath
    };
  }

  function loadPackageConfigPath(loader, pkgName, pkgConfigPath) {
    var configLoader = loader.pluginLoader || loader;

    // NB remove this when json is default
    (configLoader.meta[pkgConfigPath] = configLoader.meta[pkgConfigPath] || {}).format = 'json';

    return configLoader.load(pkgConfigPath)
    .then(function() {
      var cfg = configLoader.get(pkgConfigPath)['default'];

      // support "systemjs" prefixing
      if (cfg.systemjs)
        cfg = cfg.systemjs;

      // modules backwards compatibility
      if (cfg.modules) {
        cfg.meta = cfg.modules;
        warn.call(loader, 'Package config file ' + pkgConfigPath + ' is configured with "modules", which is deprecated as it has been renamed to "meta".');
      }

      // remove any non-system properties if generic config file (eg package.json)
      for (var p in cfg) {
        if (indexOf.call(packageProperties, p) == -1)
          delete cfg[p];
      }

      // deeply-merge (to first level) config with any existing package config
      var pkg = loader.packages[pkgName] = loader.packages[pkgName] || {};
      extendMeta(pkg, cfg, true);

      // support external depCache
      if (cfg.depCache) {
        for (var d in cfg.depCache) {
          var dNormalized;

          if (d.substr(0, 2) == './')
            dNormalized = pkgName + '/' + d.substr(2);
          else
            dNormalized = coreResolve.call(loader, d);
          loader.depCache[dNormalized] = (loader.depCache[dNormalized] || []).concat(cfg.depCache[d]);
        }
        delete cfg.depCache;
      }

      // main object becomes main map
      if (typeof pkg.main == 'object') {
        pkg.map = pkg.map || {};
        pkg.map['./@main'] = pkg.main;
        pkg.main['default'] = pkg.main['default'] || './';
        pkg.main = '@main';
      }

      return pkg;
    });
  }

  function getMetaMatches(pkgMeta, subPath, matchFn) {
    // wildcard meta
    var meta = {};
    var wildcardIndex;
    for (var module in pkgMeta) {
      // allow meta to start with ./ for flexibility
      var dotRel = module.substr(0, 2) == './' ? './' : '';
      if (dotRel)
        module = module.substr(2);

      wildcardIndex = module.indexOf('*');
      if (wildcardIndex === -1)
        continue;

      if (module.substr(0, wildcardIndex) == subPath.substr(0, wildcardIndex)
          && module.substr(wildcardIndex + 1) == subPath.substr(subPath.length - module.length + wildcardIndex + 1)) {
        // alow match function to return true for an exit path
        if (matchFn(module, pkgMeta[dotRel + module], module.split('/').length))
          return;
      }
    }
    // exact meta
    var exactMeta = pkgMeta[subPath] && pkgMeta.hasOwnProperty && pkgMeta.hasOwnProperty(subPath) ? pkgMeta[subPath] : pkgMeta['./' + subPath];
    if (exactMeta)
      matchFn(exactMeta, exactMeta, 0);
  }

  hook('locate', function(locate) {
    return function(load) {
      var loader = this;
      return Promise.resolve(locate.call(this, load))
      .then(function(address) {
        var pkgName = getPackage(loader, load.name);
        if (pkgName) {
          var pkg = loader.packages[pkgName];
          var subPath = load.name.substr(pkgName.length + 1);

          // format
          if (pkg.format)
            load.metadata.format = load.metadata.format || pkg.format;

          var meta = {};
          if (pkg.meta) {
            var bestDepth = 0;

            // NB support a main shorthand in meta here?
            getMetaMatches(pkg.meta, subPath, function(metaPattern, matchMeta, matchDepth) {
              if (matchDepth > bestDepth)
                bestDepth = matchDepth;
              extendMeta(meta, matchMeta, matchDepth && bestDepth > matchDepth);
            });

            extendMeta(load.metadata, meta);
          }
        }

        return address;
      });
    };
  });

})();