<?php

declare(strict_types=1);

namespace Orrisroot\Rrd;

class Temperature
{
    /**
     * @var string database directory path
     */
    private string $databasePath;

    /**
     * @var array sensor ids
     */
    private array $sensorIds;

    /**
     * constructor.
     *
     * @param string $fpath database directory path
     */
    public function __construct(string $fpath)
    {
        $this->databasePath = $fpath;
        $this->sensorIds = [];
    }

    /**
     * add sensor.
     *
     * @param string $id sensor id
     */
    public function addSensor(string $id)
    {
        $this->sensorIds[] = $id;
    }

    /**
     * update database.
     *
     * @param string $id    sensor id
     * @param int    $time  timestamp
     * @param float  $value temperature value
     *
     * @return bool false if failure
     */
    public function update(string $id, int $time, float $value): bool
    {
        $fpath = $this->getFilePath($id);
        if (!file_exists($fpath)) {
            if (!$this->_createDatabase($fpath)) {
                return false;
            }
        }
        $options = [sprintf('%u:%lf', $time, $value)];

        return rrd_update($fpath, $options);
    }

    /**
     * read last data.
     *
     * @param string $id sensor id
     *
     * @return ?array last data
     */
    public function readLastData(string $id): ?array
    {
        static $options = [
            'LAST',
        ];
        $fpath = $this->getFilePath($id);
        $res = rrd_fetch($fpath, $options);
        if (false === $res) {
            return null;
        }
        $latest = 0;
        $start = $res['start'];
        $step = $res['step'];
        $data = [];
        foreach ($res['data'][$id] as $key => $datum) {
            if (!is_nan($datum) && 0 != $datum) {
                $data[] = $datum;
                $latest = $start + ($key + 1) * $step;
            }
        }
        if (empty($data)) {
            return null;
        }
        $ret['id'] = $id;
        $ret['min'] = min($data);
        $ret['max'] = max($data);
        $ret['average'] = array_sum($data) / count($data);
        $ret['latest'] = $data[count($data) - 1];
        $ret['timestamp'] = $latest;

        return $ret;
    }

    /**
     * create database.
     *
     * @param string $id sensor id
     *
     * @return bool false if failure
     */
    private function create(string $id): boolean
    {
        $fpath = $this->getFilePath($id);
        $options = [
            '--step', '60', // 1min step
            sprintf('DS:%s:GAUGE:600:0:100', $this->id), // 10min hartbeat
            'RRA:LAST:0.5:1:1440',    // last/m   - 1day(1440min)
            'RRA:LAST:0.5:30:52560',  // last/30m - 3years(365day=30min*17520)*3
        ];

        return rrd_create($fpath, $options);
    }

    /**
     * get rrd file path.
     *
     * @param string $id sensor id
     *
     * @return string rrd file path
     */
    private function getFilePath(string $id): string
    {
        return $this->databasePath.'/'.$id.'.rrd';
    }

    /**
     * output graph.
     *
     * @param string $type  output graph type
     * @param string $fpath output image file path
     *
     * @return bool false if failure
     */
    public function outputGraph(string $type, string $fpath): bool
    {
        static $colors = [
            '#FF0000', '#00FF00', '#0000FF', '#FFFF00', '#00FFFF', '#FF00FF',
            '#FF9999', '#99FF99', '#9999FF', '#FFFF99', '#99FFFF', '#FF99FF',
        ];
        static $types = ['hour', 'day', 'week', 'month', 'year', '3year'];
        if (!in_array($type, $types)) {
            return false;
        }
        $start = '3year' == $type ? '-3year' : '-1'.$type;
        $options = [
            '--imgformat', 'PNG',
            '--lower-limit', '10',
            '--upper-limit', '40',
            '--start', $start,
            '--end', 'now',
            '--width', '400',
            '--height', '200',
            '--units-exponent', '0',
            '--vertical-label', "Temperature [\xc2\xb0C]",
            '--title', 'Server Room Temperature - by '.$type,
        ];
        $idlen = 0;
        foreach ($this->sensorIds as $key => $id) {
            if (strlen($id) > $idlen) {
                $idlen = strlen($id);
            }
            $options[] = sprintf('DEF:B%d=%s:%s:LAST', $key, $this->getFilePath($id), $id);
        }
        $options[] = sprintf('COMMENT:  %s     Cur\:        Min\:         Avg\:        Max\:', str_repeat(' ', $idlen));
        $options[] = sprintf('COMMENT:\l');
        foreach ($this->sensorIds as $key => $id) {
            $color = $colors[$key % count($colors)];
            $options[] = sprintf('LINE2:B%d%s:%s%s', $key, $color, $id, str_repeat(' ', $idlen - strlen($id)));
            $options[] = sprintf('GPRINT:B%d:LAST:   %%-6.2lf', $key);
            $options[] = sprintf('GPRINT:B%d:MIN:    %%-6.2lf', $key);
            $options[] = sprintf('GPRINT:B%d:AVERAGE:    %%-6.2lf', $key);
            $options[] = sprintf('GPRINT:B%d:MAX:    %%-6.2lf\l', $key);
        }
        $options[] = sprintf('COMMENT:Last update\: %s\r', str_replace(':', '\:', date('Y-m-d H:i:s T')));

        $res = rrd_graph($fpath, $options);

        return false !== $res;
    }
}