<?php

namespace KupShop\MetricsBundle;

use Prometheus\CollectorRegistry;
use Prometheus\Counter;

class PrometheusWrapper
{
    /** @var CollectorRegistry */
    private $registry;

    /** @var array */
    private $countersData = [];
    private array $histogramData = [];

    /** @var array */
    private $registeredCounters = [];

    /** @var array */
    private $labels = ['custom' => null];

    public function __construct(PrometheusRegistryAccessor $prometheusRegistryAccessor)
    {
        $this->registry = $prometheusRegistryAccessor->getRegistry();
    }

    public function addLabel(string $label, $optionalValue = true): self
    {
        $this->labels[$label] = $optionalValue;

        return $this;
    }

    /**
     * @internal
     */
    public function getLabels(): array
    {
        return $this->labels;
    }

    public function setCounter(
        string $namespace,
        string $name,
        string $description = '',
        float $value = 1,
        array $labels = [],
    ): PrometheusWrapper {
        if (isset($this->countersData[$name])) {
            $this->countersData[$name]['increments'][] = [
                'value' => $value,
                'labels' => $labels,
            ];
        } else {
            $this->countersData[$name] = [
                'namespace' => $namespace,
                'name' => $name,
                'description' => $description,
                'increments' => [
                    [
                        'value' => $value,
                        'labels' => $labels,
                    ],
                ],
            ];
        }

        return $this;
    }

    public function setHistogram(
        string $namespace,
        string $name,
        string $description = '',
        float $value = 1,
        array $labels = [],
        ?array $buckets = null,
    ): PrometheusWrapper {
        if (isset($this->histogramData[$name])) {
            $this->histogramData[$name]['increments'][] = [
                'value' => $value,
                'labels' => $labels,
            ];
        } else {
            $this->histogramData[$name] = [
                'namespace' => $namespace,
                'name' => $name,
                'description' => $description,
                'buckets' => $buckets,
                'increments' => [
                    [
                        'value' => $value,
                        'labels' => $labels,
                    ],
                ],
            ];
        }

        return $this;
    }

    /**
     * @throws \Prometheus\Exception\MetricsRegistrationException
     *
     *@internal
     */
    public function flush(): self
    {
        $this->flushCounters();
        $this->flushHistograms();

        return $this;
    }

    private function flushCounters()
    {
        foreach ($this->countersData as $name => $counterData) {
            if (!isset($this->registeredCounters[$name])) {
                $this->registeredCounters[$name] = $this->registry->registerCounter(
                    $counterData['namespace'],
                    $counterData['name'],
                    $counterData['description'],
                    array_keys(reset($counterData['increments'])['labels'])
                );
            }
            /** @var $counter Counter */
            $counter = $this->registeredCounters[$name];
            foreach ($counterData['increments'] as $increment) {
                $counter->incBy($increment['value'], array_values($increment['labels']));
            }
            $this->countersData[$name]['increments'] = [];
        }
    }

    private function flushHistograms()
    {
        foreach ($this->histogramData as $name => $histData) {
            $histogram = $this->registry->getOrRegisterHistogram(
                $histData['namespace'],
                $histData['name'],
                $histData['description'],
                array_keys(reset($histData['increments'])['labels']),
                $histData['buckets']
            );

            foreach ($histData['increments'] as $increment) {
                $histogram->observe($increment['value'], array_values($increment['labels']));
            }
            $this->histogramData[$name]['increments'] = [];
        }
    }
}