<?php

namespace NoccyLabs\Linux\Cpu;

class Cpu
{
    /**
     * @var string The path to the sys control files
     */
    protected $sys_path = "/sys/devices/system/cpu";

    /**
     * @var int The number of CPUs in this system
     */
    protected $num_cpus;

    /**
     * @var int[] The available scaling frequencies
     */
    protected $available_frequencies;

    /**
     * @var string[] The available governors
     */
    protected $available_governors;

    /**
     *
     */
    public function __construct($path=null)
    {
        if ($path) {
            $this->sys_path = $path;
        }
        $this->readSysInfo();
    }

    /**
     * Read and cache information from sysfs
     *
     */
    protected function readSysInfo()
    {
        // Get number of CPU cores
        $cpus = glob($this->sys_path . "/cpu?");
        $this->num_cpus = count($cpus);
	
	    // Get the available CPU frequencies
	    $freq_raw = file_get_contents($this->sys_path."/cpu0/cpufreq/scaling_available_frequencies");
	    $freq_list = explode(" ", trim($freq_raw));
	    sort($freq_list);
	    $this->available_frequencies = array_map("intval", $freq_list);

        // Get the available CPU governor
	    $govr_raw = file_get_contents($this->sys_path."/cpu0/cpufreq/scaling_available_governors");
	    $govr_list = explode(" ", trim($govr_raw));
	    sort($govr_list);
	    $this->available_governors = $govr_list;
    }

    /**
     * Get the number of CPU cores in the system. The operations by the CPU
     * class will operate on all cores.
     *
     * @return int The number of CPU cores
     */    
    public function getNumCpus()
    {
        return $this->num_cpus;
    }
    
    /**
     * Get the available CPU frequencies in hertz for scaling.
     *
     * @return int[] The available CPU frequencies
     */
    public function getAvailableFrequencies()
    {
        return $this->available_frequencies;
    }
    
    /**
     * Get the current scaling frequency of the CPU in hertz.
     *
     * @return int The CPU frequency in Hz
     */
    public function getCurrentFrequency()
    {
        $freq_curr = file_get_contents($this->sys_path."/cpu0/cpufreq/scaling_cur_freq");
        return (int)$freq_curr;
    }
    
    public function setCurrentFrequency($freq)
    {
        if (!in_array((int)$freq, $this->available_frequencies)) {
            $avail = join(", ", $this->available_frequencies);
            throw new \InvalidArgumentException("CPU frequency {$freq} not supported (available: {$avail}");
        }
        file_put_contents($this->sys_path."/cpu0/cpufreq/scaling_cur_freq", (int)$freq);
    }

    /**
     * Get a list of the available governors
     *
     * @return string[] The available governors
     */    
    public function getAvailableGovernors()
    {
        return $this->available_governors;
    }
    
    /**
     * Get the currently active governor
     *
     * @return string The name of the currently active governor
     */
    public function getCurrentGovernor()
    {
        $govr_curr = file_get_contents($this->sys_path."/cpu0/cpufreq/scaling_governor");
        return trim($govr_curr);
    }

    public function setCurrentGovernor($governor)
    {
        if (!in_array((int)$governor, $this->available_governors)) {
            $avail = join(", ", $this->available_governors);
            throw new \InvalidArgumentException("Governor {$governor} not supported (available: {$avail}");
        }
        file_put_contents($this->sys_path."/cpu0/cpufreq/scaling_governor", $governor);
    }
    
}