<?php

/*
 * Copyright (C) 2014, NoccyLabs
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

namespace NoccyLabs\Gpio;

use NoccyLabs\Gpio\Exception\HardwareException;

class Gpio implements \ArrayAccess
{
    // Direction
    const DIR_IN       = "in";
    const DIR_OUT      = "out";
    // Values
    const VAL_HIGH     = 1;
    const VAL_LOW      = 0;
    // Edges
    const EDGE_NONE    = "none";
    const EDGE_RISING  = "rising";
    const EDGE_FALLING = "faling";
    const EDGE_BOTH    = "both";

    protected $gpio = array();
    
    /** @var NoccyLabs\Gpio\GpioMapperInterface */
    protected $mapper;
    
    public function __construct($force=false)
    {
        if (!$force) {
            if (!file_exists("/sys/class/gpio")) {
                throw new HardwareException("gpio sysfs is not available");
            }
            if (!is_writable("/sys/class/gpio/export")) {
                throw new HardwareException("gpio sysfs is not writable");
            }
        }
    }

    public function refresh()
    {
        $read = $this->fd_gpio;
        $write = array();
        $except = $read;
        select($read, $write, $except, 0);
        foreach($except as $fd) {
            $pin = $this->getPinFromFd($fd);
            $pin->doInterrupt();
        
        }
    }
    
    public function getPinFromFd($fd)
    {
        foreach($this->fd_pins as $pinfd=>$pin) {
            if ($pinfd == $fd) { return $pin; }
        }
        return false;
    }
    
    protected $fd_gpio = array();
    protected $fd_pins = array();
    
    public function enableInterrupt(GpioPin $pin, $fd)
    {
        $this->fd_gpio[] = $fd;
        
        $this->fd_pins[$fd] = $pin;
        
    }
    
    public function disableInterrupt(GpioPin $pin)
    {
    }
    
    public function setMapper(GpioMapperInterface $mapper=null)
    {
        $this->mapper = $mapper;
        return $this;
    }
    
    public function offsetGet($index)
    {
        if ($this->mapper) { $index = $this->mapper->mapLogicalToGpioPin($index); }
        if (empty($this->gpio[$index])) {
            $this->gpio[$index] = new GpioPin($index, $this);
        }
        return $this->gpio[$index];
    }
    
    public function offsetExists($index)
    {
        return array_key_exists($index, $this->gpio);
    }
    

    public function offsetSet($index,$value)
    {   throw new \Exception(); }
    
    public function offsetUnset($index)
    {   
        unset($this->gpio[$index]);
    }
    
}