/*
 * Meta Extension
 *
 * Sets default metadata on a load record (load.metadata) from
 * loader.metadata via SystemJS.meta function.
 *
 *
 * Also provides an inline meta syntax for module meta in source.
 *
 * Eg:
 *
 * loader.meta({
 *   'my/module': { deps: ['jquery'] }
 *   'my/*': { format: 'amd' }
 * });
 *
 * Which in turn populates loader.metadata.
 *
 * load.metadata.deps and load.metadata.format will then be set
 * for 'my/module'
 *
 * The same meta could be set with a my/module.js file containing:
 *
 * my/module.js
 *   "format amd";
 *   "deps[] jquery";
 *   "globals.some value"
 *   console.log('this is my/module');
 *
 * Configuration meta always takes preference to inline meta.
 *
 * Multiple matches in wildcards are supported and ammend the meta.
 *
 *
 * The benefits of the function form is that paths are URL-normalized
 * supporting say
 *
 * loader.meta({ './app': { format: 'cjs' } });
 *
 * Instead of needing to set against the absolute URL (https://site.com/app.js)
 *
 */

(function() {

  hookConstructor(function(constructor) {
    return function() {
      this.meta = {};
      constructor.call(this);
    };
  });

  hook('locate', function(locate) {
    return function(load) {
      var meta = this.meta;
      var name = load.name;

      // NB for perf, maybe introduce a fast-path wildcard lookup cache here
      // which is checked first

      // apply wildcard metas
      var bestDepth = 0;
      var wildcardIndex;
      for (var module in meta) {
        wildcardIndex = module.indexOf('*');
        if (wildcardIndex === -1)
          continue;
        if (module.substr(0, wildcardIndex) === name.substr(0, wildcardIndex)
            && module.substr(wildcardIndex + 1) === name.substr(name.length - module.length + wildcardIndex + 1)) {
          var depth = module.split('/').length;
          if (depth > bestDepth)
            bestDepth = depth;
          extendMeta(load.metadata, meta[module], bestDepth != depth);
        }
      }

      // apply exact meta
      if (meta[name])
        extendMeta(load.metadata, meta[name]);

      return locate.call(this, load);
    };
  });

  // detect any meta header syntax
  // only set if not already set
  var metaRegEx = /^(\s*\/\*[^\*]*(\*(?!\/)[^\*]*)*\*\/|\s*\/\/[^\n]*|\s*"[^"]+"\s*;?|\s*'[^']+'\s*;?)+/;
  var metaPartRegEx = /\/\*[^\*]*(\*(?!\/)[^\*]*)*\*\/|\/\/[^\n]*|"[^"]+"\s*;?|'[^']+'\s*;?/g;

  function setMetaProperty(target, p, value) {
    var pParts = p.split('.');
    var curPart;
    while (pParts.length > 1) {
      curPart = pParts.shift();
      target = target[curPart] = target[curPart] || {};
    }
    curPart = pParts.shift();
    if (!(curPart in target))
      target[curPart] = value;
  }

  hook('translate', function(translate) {
    return function(load) {
      // NB meta will be post-translate pending transpiler conversion to plugins
      var meta = load.source.match(metaRegEx);
      if (meta) {
        var metaParts = meta[0].match(metaPartRegEx);

        for (var i = 0; i < metaParts.length; i++) {
          var curPart = metaParts[i];
          var len = curPart.length;

          var firstChar = curPart.substr(0, 1);
          if (curPart.substr(len - 1, 1) == ';')
            len--;

          if (firstChar != '"' && firstChar != "'")
            continue;

          var metaString = curPart.substr(1, curPart.length - 3);
          var metaName = metaString.substr(0, metaString.indexOf(' '));

          if (metaName) {
            var metaValue = metaString.substr(metaName.length + 1, metaString.length - metaName.length - 1);

            if (metaName.substr(metaName.length - 2, 2) == '[]') {
              metaName = metaName.substr(0, metaName.length - 2);
              load.metadata[metaName] = load.metadata[metaName] || [];
              load.metadata[metaName].push(metaValue);
            }
            else if (load.metadata[metaName] instanceof Array) {
              // temporary backwards compat for previous "deps" syntax
              warn.call(this, 'Module ' + load.name + ' contains deprecated "deps ' + metaValue + '" meta syntax.\nThis should be updated to "deps[] ' + metaValue + '" for pushing to array meta.');
              load.metadata[metaName].push(metaValue);
            }
            else {
              setMetaProperty(load.metadata, metaName, metaValue);
            }
          }
          else {
            load.metadata[metaString] = true;
          }
        }
      }

      return translate.call(this, load);
    };
  });
})();