#!/usr/bin/php
<?php

function error($message)
{
    file_put_contents('php://stderr', $message."\n");
}

function notice($message)
{
    file_put_contents('php://stdin', $message."\n");
}

function filter(array $data, array $default)
{
    foreach ($data as $k => $v) {
        if (!array_key_exists($k, $default)) {
            unset($data[$k]);
        } elseif (is_array($default[$k]) && !is_array($v)) {
            $data[$k] = (array) $v;
        }
    }

    foreach ($default as $k => $v) {
        if (!array_key_exists($k, $data)) {
            $data[$k] = $v;
        }
    }

    return $data;
}

function filterScreen(array $data)
{
    $default = [
        'name' => null,
        'resolutionX' => null,
        'resolutionY' => null,
    ];

    return filter($data, $default);
}

function filterMode(array $data)
{
    $default = [
        'config' => [],
        'primary' => null,
    ];

    $data = filter($data, $default);

    foreach ($data['config'] as $k => $v) {
        $v = explode(',', $v);
        $v = array_map('trim', $v);

        $data['config'][$k] = $v;
    }

    return $data;
}

function getCurrentModeFile()
{
    return sys_get_temp_dir().'/monitordisplay.tmp';
}

function getCurrentMode()
{
    $currentModeFile = getCurrentModeFile();

    if (file_exists($currentModeFile)) {
        $currentMode = (array) @parse_ini_file($currentModeFile);
    } else {
        $currentMode = [];
    }

    return filter($currentMode, [
        'mode' => null,
        'config' => null,
    ]);
}

function build(array $modes, array $screens, $mode, $toggle, array $currentMode, $addOff)
{
    if ($mode === null) {
        if (!array_key_exists($currentMode['mode'], $modes)) {
            return;
        }

        $tmpMode = $currentMode['mode'];
        $mode = $modes[$currentMode['mode']];
    } else {
        if (!array_key_exists($mode, $modes)) {
            return;
        }

        $tmpMode = $mode;
        $mode = $modes[$mode];
    }

    if ($toggle !== false) {
        if ($currentMode['mode'] === null) {
            return;
        }

        if ($currentMode['config'] === null) {
            return;
        }
        
        $configs = $mode['config'];
        $configsKeys = array_keys($configs);

        if (!array_key_exists($currentMode['config'], $mode['config'])) {
            $currentMode['config'] = $configsKeys[0];
        }

        if ($toggle === true) {
            foreach ($configsKeys as $k => $key) {
                if ($key === $currentMode['config']) {
                    $currentKey = $k;
                }
            }
;
            $config = $configsKeys[($currentKey + 1) % count($configsKeys)];
        } elseif (array_key_exists($toggle, $configs)) {
            $config = $toggle;
        } else {
            error(sprintf('Invalid config "%s"', $toggle));
            die(1);
        }
    } else {
        $config = 0;
    }

    if (!array_key_exists($config, $mode['config'])) {
        return;
    }

    $tmpConfig = $config;
    $config = $mode['config'][$config];

    $command = ['xrandr'];

    $x = 0;

    $screensUsed = [];

    foreach ($config as $screen) {
        if (!array_key_exists($screen, $screens)) {
            return;
        }

        $tScreen = $screens[$screen];
        $name = $tScreen['name'];
        $resolutionX = $tScreen['resolutionX'];
        $resolutionY = $tScreen['resolutionY'];

        if (empty($name) || empty($resolutionX) || empty($resolutionY)) {
            error(sprintf('Invalid screen configuration "%s"', $screen));
            die(1);
        }

        $command[] = '--output';
        $command[] = $name;
        $screensUsed[] = $name;

        if ($mode['primary'] === $name) {
            $command[] = '--primary';
        }

        $command[] = '--mode';
        $command[] = sprintf('%dx%d', $resolutionX, $resolutionY);

        $command[] = '--pos';
        $command[] = sprintf('%dx%d', $x, 0);
        $x += $resolutionX;
    }

    if ($addOff) {
        foreach ($screens as $screen) {
            if (!in_array($screen['name'], $screensUsed)) {
                $command[] = '--output';
                $command[] = $screen['name'];
                $command[] = '--off';
            }
        }
    }

    $command = implode(' ', $command);

    return [
        'config' => sprintf("mode=%s\nconfig=%s", $tmpMode, $tmpConfig),
        'command' => $command,
    ];
}

$files = [
    '/etc/monitordisplay/config.ini',
    getenv('HOME').'/.config/monitordisplay/config.ini',
    getenv('HOME').'/.monitordisplay',
];

$config = [];
$currentMode = getCurrentMode();

foreach ($files as $file) {
    if (file_exists($file)) {
        $parsing = @parse_ini_file($file, true);

        if ($parsing === false) {
            error(sprintf('The file "%s" is not a valid ini file.', $file));

            continue;
        }

        notice(sprintf('Configuration file merged: %s', $file));

        $config = array_merge(
            $config,
            $parsing
        );
    }
}

if (empty($config)) {
    error('No configuration found');
    error(sprintf('Paths checked: %s', implode(', ', $files)));
    die(1);
}

$screens = [];
$modes = [];

foreach ($config as $section => $values) {
    $type = explode(':', $section);

    if (count($type) !== 2) {
        error(sprintf('Invalid section "%s". Ignored.', $section));
    }

    if ($type[0] === 'screen') {
        $screens[$type[1]] = filterScreen($values);
    } elseif ($type[0] === 'mode') {
        $modes[$type[1]] = filterMode($values);
    } else {
        error(sprintf('Invalid section "%s". Ignored.', $section));
    }
}

if (empty($screens)) {
    error('No screen found.');
    die(1);
}

if (empty($modes)) {
    error('No mode found.');
    die(1);
}

$options = getopt('m:t::s');
$mode = isset($options['m']) ? $options['m'] : null;
$toggle = isset($options['t']) ? (false === $options['t'] ? true : $options['t']) : false;
$addOff = !isset($options['s']);
$build = build($modes, $screens, $mode, $toggle, $currentMode, $addOff);

if (!empty($build)) {
    file_put_contents(getCurrentModeFile(), $build['config']);
    shell_exec($build['command']);
}