var Cast = require('../util/cast');

var Scratch3DataBlocks = function (runtime) {
    /**
     * The runtime instantiating this block package.
     * @type {Runtime}
     */
    this.runtime = runtime;
};

/**
 * Retrieve the block primitives implemented by this package.
 * @return {object.<string, Function>} Mapping of opcode to Function.
 */
Scratch3DataBlocks.prototype.getPrimitives = function () {
    return {
        data_variable: this.getVariable,
        data_setvariableto: this.setVariableTo,
        data_changevariableby: this.changeVariableBy,
        data_listcontents: this.getListContents,
        data_addtolist: this.addToList,
        data_deleteoflist: this.deleteOfList,
        data_insertatlist: this.insertAtList,
        data_replaceitemoflist: this.replaceItemOfList,
        data_itemoflist: this.getItemOfList,
        data_lengthoflist: this.lengthOfList,
        data_listcontainsitem: this.listContainsItem
    };
};

Scratch3DataBlocks.prototype.getVariable = function (args, util) {
    var variable = util.target.lookupOrCreateVariable(args.VARIABLE);
    return variable.value;
};

Scratch3DataBlocks.prototype.setVariableTo = function (args, util) {
    var variable = util.target.lookupOrCreateVariable(args.VARIABLE);
    variable.value = args.VALUE;
};

Scratch3DataBlocks.prototype.changeVariableBy = function (args, util) {
    var variable = util.target.lookupOrCreateVariable(args.VARIABLE);
    var castedValue = Cast.toNumber(variable.value);
    var dValue = Cast.toNumber(args.VALUE);
    variable.value = castedValue + dValue;
};

Scratch3DataBlocks.prototype.getListContents = function (args, util) {
    var list = util.target.lookupOrCreateList(args.LIST);
    // Determine if the list is all single letters.
    // If it is, report contents joined together with no separator.
    // If it's not, report contents joined together with a space.
    var allSingleLetters = true;
    for (var i = 0; i < list.contents.length; i++) {
        var listItem = list.contents[i];
        if (!((typeof listItem === 'string') &&
              (listItem.length === 1))) {
            allSingleLetters = false;
            break;
        }
    }
    if (allSingleLetters) {
        return list.contents.join('');
    } else {
        return list.contents.join(' ');
    }
};

Scratch3DataBlocks.prototype.addToList = function (args, util) {
    var list = util.target.lookupOrCreateList(args.LIST);
    list.contents.push(args.ITEM);
};

Scratch3DataBlocks.prototype.deleteOfList = function (args, util) {
    var list = util.target.lookupOrCreateList(args.LIST);
    var index = Cast.toListIndex(args.INDEX, list.contents.length);
    if (index === Cast.LIST_INVALID) {
        return;
    } else if (index === Cast.LIST_ALL) {
        list.contents = [];
        return;
    }
    list.contents.splice(index - 1, 1);
};

Scratch3DataBlocks.prototype.insertAtList = function (args, util) {
    var item = args.ITEM;
    var list = util.target.lookupOrCreateList(args.LIST);
    var index = Cast.toListIndex(args.INDEX, list.contents.length + 1);
    if (index === Cast.LIST_INVALID) {
        return;
    }
    list.contents.splice(index - 1, 0, item);
};

Scratch3DataBlocks.prototype.replaceItemOfList = function (args, util) {
    var item = args.ITEM;
    var list = util.target.lookupOrCreateList(args.LIST);
    var index = Cast.toListIndex(args.INDEX, list.contents.length);
    if (index === Cast.LIST_INVALID) {
        return;
    }
    list.contents.splice(index - 1, 1, item);
};

Scratch3DataBlocks.prototype.getItemOfList = function (args, util) {
    var list = util.target.lookupOrCreateList(args.LIST);
    var index = Cast.toListIndex(args.INDEX, list.contents.length);
    if (index === Cast.LIST_INVALID) {
        return '';
    }
    return list.contents[index - 1];
};

Scratch3DataBlocks.prototype.lengthOfList = function (args, util) {
    var list = util.target.lookupOrCreateList(args.LIST);
    return list.contents.length;
};

Scratch3DataBlocks.prototype.listContainsItem = function (args, util) {
    var item = args.ITEM;
    var list = util.target.lookupOrCreateList(args.LIST);
    if (list.contents.indexOf(item) >= 0) {
        return true;
    }
    // Try using Scratch comparison operator on each item.
    // (Scratch considers the string '123' equal to the number 123).
    for (var i = 0; i < list.contents.length; i++) {
        if (Cast.compare(list.contents[i], item) === 0) {
            return true;
        }
    }
    return false;
};

module.exports = Scratch3DataBlocks;