/**
 * @license Licensed under the Apache License, Version 2.0 (the "License"):
 *          http://www.apache.org/licenses/LICENSE-2.0
 */

/**
 * @fileOverview Generating Arduino code for the loop blocks.
 *
 * TODO: 'For each' block needs to have lists implemented.
 */
'use strict';

goog.provide('Blockly.Arduino.loops');

goog.require('Blockly.Arduino');


/**
 * Generator for the repeat block (number in a drop down) using a For loop
 * statement.
 * Arduino code: loop { for (int count = 0; count < X; count++) { Y } }
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_repeat'] = function (block) {
    var repeats = Number(block.getFieldValue('TIMES'));
    var branch = Blockly.Arduino.statementToCode(block, 'DO');
    branch = Blockly.Arduino.addLoopTrap(branch, block.id);
    var loopVar = Blockly.Arduino.variableDB_.getDistinctName(
        'count', Blockly.Variables.NAME_TYPE);
    var code = 'for (int ' + loopVar + ' = 0; ' +
        loopVar + ' < ' + repeats + '; ' +
        loopVar + '++) {\n' +
        branch + '}\n';
    return code;
};

/**
 * Generator for the repeat block (using external number block) using a
 * For loop statement.
 * Arduino code: loop { for (int count = 0; count < X; count++) { Y } }
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_repeat_ext'] = function (block) {
    var repeats = Blockly.Arduino.valueToCode(block, 'TIMES',
        Blockly.Arduino.ORDER_ADDITIVE) || '0';
    var branch = Blockly.Arduino.statementToCode(block, 'DO');
    branch = Blockly.Arduino.addLoopTrap(branch, block.id);
    var code = '';
    var loopVar = Blockly.Arduino.variableDB_.getDistinctName(
        'count', Blockly.Variables.NAME_TYPE);
    var endVar = repeats;
    if (!repeats.match(/^\w+$/) && !Blockly.isNumber(repeats)) {
        var endVar = Blockly.Arduino.variableDB_.getDistinctName(
            'repeat_end', Blockly.Variables.NAME_TYPE);
        code += 'int ' + endVar + ' = ' + repeats + ';\n';
    }
    code += 'for (int ' + loopVar + ' = 0; ' +
        loopVar + ' < ' + endVar + '; ' +
        loopVar + '++) {\n' +
        branch + '}\n';
    return code;
};

/**
 * Generator for the repeat while block using a While statement.
 * Arduino code: loop { while (X) { Y } }
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_whileUntil'] = function (block) {
    // Do while/until loop.
    var until = block.getFieldValue('MODE') == 'UNTIL';
    var argument0 = Blockly.Arduino.valueToCode(block, 'BOOL',
        until ? Blockly.Arduino.ORDER_LOGICAL_OR :
            Blockly.Arduino.ORDER_NONE) || 'false';
    var branch = Blockly.Arduino.statementToCode(block, 'DO');
    branch = Blockly.Arduino.addLoopTrap(branch, block.id);
    if (until) {
        if (!argument0.match(/^\w+$/)) {
            argument0 = '(' + argument0 + ')';
        }
        argument0 = '!' + argument0;
    }
    return 'while (' + argument0 + ') {\n' + branch + '}\n';
};

/**
 * Generator for the repeat while block using a While statement.
 * Arduino code: loop { while (X) { Y } }
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_time_loop'] = function (block) {
    var time = Blockly.Arduino.valueToCode(block, 'LOOP_SEC', Blockly.Arduino.ORDER_ATOMIC) || '10';
    var dec = 'unsigned long duration_time_diff;';
    Blockly.Arduino.addVariable('var_ctloop', dec, true);
    var argument0 = '!(millis() - duration_time_diff >= (' + time + ' * 1000))';
    var branch = Blockly.Arduino.statementToCode(block, 'DO');
    branch = Blockly.Arduino.addLoopTrap(branch, block.id);
    var code = 'duration_time_diff = millis();\n';

    return code + 'while (' + argument0 + ') {\n' + branch + '}\n';
};

/**
 * Generator for the For loop statements.
 * Arduino code: loop { for (i = X; i <= Y; i+=Z) { } }
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_for'] = function (block) {
    var variable0 = Blockly.Arduino.variableDB_.getName(
        block.getFieldValue('VAR'), Blockly.Variables.NAME_TYPE);
    var argument0 = Blockly.Arduino.valueToCode(block, 'FROM',
        Blockly.Arduino.ORDER_ASSIGNMENT) || '0';
    var argument1 = Blockly.Arduino.valueToCode(block, 'TO',
        Blockly.Arduino.ORDER_ASSIGNMENT) || '0';
    var increment = Blockly.Arduino.valueToCode(block, 'BY',
        Blockly.Arduino.ORDER_ASSIGNMENT) || '1';
    var branch = Blockly.Arduino.statementToCode(block, 'DO');
    branch = Blockly.Arduino.addLoopTrap(branch, block.id);
    var code;
    if (Blockly.isNumber(argument0) && Blockly.isNumber(argument1) &&
        Blockly.isNumber(increment)) {
        // All arguments are simple numbers.
        var up = parseFloat(argument0) <= parseFloat(argument1);
        code = 'for (' + variable0 + ' = ' + argument0 + '; ' +
            variable0 + (up ? ' <= ' : ' >= ') + argument1 + '; ' +
            variable0;
        var step = Math.abs(parseFloat(increment));
        if (step == 1) {
            code += up ? '++' : '--';
        } else {
            code += (up ? ' += ' : ' -= ') + step;
        }
        code += ') {\n' + branch + '}\n';
    } else {
        code = '';
        // Cache non-trivial values to variables to prevent repeated look-ups.
        var startVar = argument0;
        if (!argument0.match(/^\w+$/) && !Blockly.isNumber(argument0)) {
            var startVar = Blockly.Arduino.variableDB_.getDistinctName(
                variable0 + '_start', Blockly.Variables.NAME_TYPE);
            code += 'int ' + startVar + ' = ' + argument0 + ';\n';
        }
        var endVar = argument1;
        if (!argument1.match(/^\w+$/) && !Blockly.isNumber(argument1)) {
            var endVar = Blockly.Arduino.variableDB_.getDistinctName(
                variable0 + '_end', Blockly.Variables.NAME_TYPE);
            code += 'int ' + endVar + ' = ' + argument1 + ';\n';
        }
        // Determine loop direction at start, in case one of the bounds
        // changes during loop execution.
        var incVar = Blockly.Arduino.variableDB_.getDistinctName(
            variable0 + '_inc', Blockly.Variables.NAME_TYPE);
        code += 'int ' + incVar + ' = ';
        if (Blockly.isNumber(increment)) {
            code += Math.abs(increment) + ';\n';
        } else {
            code += 'abs(' + increment + ');\n';
        }
        code += 'if (' + startVar + ' > ' + endVar + ') {\n';
        code += Blockly.Arduino.INDENT + incVar + ' = -' + incVar + ';\n';
        code += '}\n';
        code += 'for (' + variable0 + ' = ' + startVar + ';\n' +
            '     ' + incVar + ' >= 0 ? ' +
            variable0 + ' <= ' + endVar + ' : ' +
            variable0 + ' >= ' + endVar + ';\n' +
            '     ' + variable0 + ' += ' + incVar + ') {\n' +
            branch + '}\n';
    }
    return code;
};

/**
 * A "for each" block.
 * TODO: Removed for now from toolbox as lists are not yet implemented.
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_forEach'] = Blockly.Arduino.noGeneratorCodeLine;

/**
 * Generator for the loop flow control statements.
 * Arduino code: loop { break;/continue; }
 * @param {!Blockly.Block} block Block to generate the code from.
 * @return {string} Completed code.
 */
Blockly.Arduino['controls_flow_statements'] = function (block) {
    switch (block.getFieldValue('FLOW')) {
        case 'BREAK':
            return 'break;\n';
        case 'CONTINUE':
            return 'continue;\n';
    }
    throw 'Unknown flow statement.';
};
