<?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;

use NoccyLabs\Sansi\Charset as CS;

/**
 * GPIO pin implementation. This class wraps all interaction with a GPIO pin,
 * thus decoupling it from the main Gpio class.
 *
 */
class GpioPin
{
    protected $fd;
    
    protected $pin;
    
    protected $value = 0;
    
    protected $direction;
    
    protected $edge;
    
    protected $handler;
    
    protected $hardware;

    protected $label;
    
    protected $gpio;

    public function __construct($pin, Gpio $gpio)
    {
        $this->pin = (int)$pin;
        $this->gpio = $gpio;
    }
    
    public function getPin()
    {
        return $this->pin;
    }
    
    private function findHardware()
    {
    	$chips = glob("/sys/class/gpio/gpiochip*");
    	$pinchip = null;
    	foreach($chips as $chip) {
    		$r = null;
    		if (preg_match("/([0-9]+?)/", $chip, $r)) {
    			$base = (int)$r[1];
    			if ($base < $this->pin) { $pinchip = $chip; }
    		}
    	}
    	if ($pinchip) {
	    	$hw = trim(file_get_contents($pinchip."/label"));
    		return $hw;
   		}
   		return "unknown";
    }
    
    public function __destruct()
    {
    	if ($this->fd) {
	        fclose($this->fd);
	    }
    }
    
    public function setDirection($direction)
    {
        if (!in_array($direction, array("in", "out"))) {
            throw new \Exception;
        }
        $this->direction = $direction;
        $this->sysfsWrite($this->pin, "direction", $direction);
        return $this;
    }
    
    public function getDirection()
    {
        return $this->sysfsRead($this->pin, "direction");
    }
    
    public function setValue($value)
    {
        $this->value = (bool)$value;
        @file_put_contents("/sys/class/gpio/gpio{$this->pin}/value", (int)$this->value);
        return $this;
    }
    
    public function getValue()
    {
        return $this->sysfsRead($this->pin, "value");
    }

    /**
     * Set a descriptive label for the pin, used for debugging and troubleshooting.
     *
     * @param string $label
     * @return NoccyLabs\Gpio\GpioPin 
     */    
    public function setLabel($label)
    {
        $this->label = (string)$label;
        return $this;
    }
    
    /**
     * Get the assigned label for this pin.
     *
     * @return string The label
     */    
    public function getLabel()
    {
        return $this->label;
    }
    
    public function export()
    {
        if (file_exists("/sys/class/gpio/gpio{$this->pin}")) {
        	return $this;
        }
        $this->sysfsWrite(null, "export", $this->pin);
        if (!file_exists("/sys/class/gpio/gpio{$this->pin}")) {
            throw new HardwareException("Unable to export pin {$this->pin}");
        }
        $this->hardware = $this->findHardware();
        return $this;
    }
    
    public function unexport()
    {
    	$this->sysfsWrite(null, "unexport", $this->pin);
        return $this;
    }
    
    public function sysfsWrite($pin, $file, $value)
    {
        if ($pin!==null) {
            $path = "/sys/class/gpio/gpio{$pin}/{$file}";
        } else {
            $path = "/sys/class/gpio/{$file}";
        }
        if (!file_exists($path)) {
            throw new HardwareException("Sysfs file {$path} does not exist");
        }

        $ts = microtime(true);
        while ((!is_writable($path)) && (microtime(true) < $ts+1)) {
        	usleep(10000);
        }

        $f = @fopen($path,"c");
        if (!is_resource($f)) {
        	$err = error_get_last();
            throw new HardwareException("Unable to write to sysfs file {$path}: ".$err['message']);
        }
        fwrite($f,$value);
        fclose($f);
    }
    
    public function sysfsRead($pin, $file)
    {
        $path = "/sys/class/gpio/gpio{$pin}/{$file}";
        $f = fopen($path,"r");
        if (!is_resource($f)) {
            throw new HardwareException("Unable to read from sysfs file {$path}");
        }
        $ret = fgets($f);
        fclose($f);
        return trim($ret);
    }
    
    public function setEdge($edge)
    {
        if (!in_array($edge, array("rising", "falling", "both", "none"))) {
            throw new \Exception;
        }
        $this->edge = $edge;
        $this->sysfsWrite($this->pin, "edge", $edge);
        return $this;
    }
    
    public function getEdge()
    {
        return $this->sysfsRead($this->pin, "edge");
    }
    
    public function setHandler(callable $handler=null)
    {
        $this->gpio->setInterruptHandler($this->pin, $this->fd);
        return $this;
    }

    public function doInterrupt()
    {
        fseek($this->fd,0,SEEK_SET);
        $val = fgets($this->fd);
    }
    
    public function dumpStatus($ansi=false)
    {
        if ($ansi) {
            $status = "\e[44;37;1m          GPIO{$this->pin}          \e[0m\n";
            $direction = 
                ($this->direction=="input"?(CS::chr(0x2190)):(CS::chr(0x2192))).
                " ".$this->direction;
            $edge = $this->edge; //"";
            /*if ($this->edge == "rising") {
                $edge.= CS::chr(0x21A5)." rising";
            } elseif ($this->edge == "falling") {
                $edge.= CS::chr(0x21A7)." falling";
            } else {
                $edge.= "\e[0m".$this->edge;
            }*/
        } else {
            $status = "********** GPIO{$this->pin} **********\n";
            $direction = $this->direction;
        }
    
    
        foreach(array(    
            "Direction" => $this->getDirection(),
            "Value" => ($this->getValue()?1:0),
            "Edge" => $this->getEdge(),
            "Label" => $this->label,
            "Hardware" => $this->hardware,
            "Int count" => 0
        ) as $k=>$v) {
            if ($ansi) {
                $status.= sprintf("  \e[32;1m%10s\e[0m: \e[0m%s\e[0m\n", $k, $v);
            } else {
                $status.= sprintf("  %-10s: %s\n", $k, $v);
            }
        }
        error_log($status);
        return $this;
    }
   
}