anmonteiro/chital

var constants = require( './constants' ),
  cheerio = require( 'cheerio' ),
  url = require( 'url' ),
  utils = require( './utils' );


var getParser = function( type, contextURL ) {
  var context = contextURL;

  var resolveRelativeURL = function ( path ) {
    return url.resolve( url.format( context ), path );
  };

  var parser = {};

  parser[ constants.mime.JSON ] = {
    parse : function( data, selectors, callback ) {
      var self = this,
        obj,
        items = [];

      try {
        obj = JSON.parse( data );
      }
      catch( err ) {
        return callback( new Error( 'Invalid data object' ), null );
      }

      var list = obj;

      // find the list of items specified in the configuration
      selectors.list.split( '.' )
        .forEach(function( elem ) {
          list = list[ elem ];
        });

      list.forEach(function( elem ) {
        self.parseElement( elem, selectors.article, function( err, res) {
          if( err ) {
            return console.log( err );
          }
          return items.push( res );
        });
      });

      return callback(null, items);
    },
    parseElement : function( el, selectors, callback ) {
      var result = {},
        keys = Object.keys( selectors ),
        keysLen = keys.length,
        i = 0;

      for ( ; i < keysLen; i++ ) {
        var key = keys[ i ],
        selector = selectors[ key ],
        element = el;

        selector.split( '.' ).forEach(function( elem ) {
          element = element[ elem ];
        });

        if( !element ) {
          return callback( new Error( 'Invalid element' ), null );
        }
        result[ key ] = element;
      }

      return callback( null, result );
    }
  };

  parser[ constants.mime.HTML ] = {
    parse : function( data, selectors, callback ) {
      var self = this,
        $ = cheerio.load( data ),
        items = [];

      $( selectors.list ).each(function( index, element ) {
        self.parseElement( $( element ), selectors.article, function( err, res ) {
          if( err ) {
            return console.log( err );
          }
          return items.push( res );
        });
      });

      return callback( null, items );
    },
    parseElement : function( $el, selectors, callback ) {
      var result = {},
      keys = Object.keys( selectors ),
      i = 0,
      len = keys.length;

      for ( ; i < len; i++ ) {
        var key = keys[ i ],
        sel = selectors[ key ],
        isObj = utils.isObj( sel ),
        selector = isObj ? sel.selector : sel,
        fn = isObj ? $el.attr : $el.html,
        args = isObj ? [ sel.attr ] : [];

        var element = $el.find( selector ) || {};

        if( !element.length ) {
          return callback( new Error( 'Invalid element' ), null );
        }
        result[ key ] = fn.apply( element, args );

        if( sel.attr === 'href' ) {
          result[ key ] = resolveRelativeURL( result[ key ] );
        }
      }

      return callback( null, result );
    }
  };

  return parser[ type ];
};

module.exports = function( type, contextURL ) {
  var context = url.parse(contextURL || '');
  context.pathName = null;

  var engine = getParser( type, context );

  return Object.create({
    parse : function( data, selectors, callback ) {
      return engine.parse.call( engine, data, selectors, callback );
    },
    // pending issue to solve this matter (grunt)
    __test_only__ : {
      parseElement : engine.parseElement
    }
  });
};