<?php namespace MapGuesser\Controller;

use MapGuesser\Database\Query\Select;
use MapGuesser\Http\Request;
use MapGuesser\Interfaces\Database\IResultSet;
use MapGuesser\Util\Geo\Position;
use MapGuesser\Response\JsonContent;
use MapGuesser\Interfaces\Response\IContent;

class PositionController
{
    const NUMBER_OF_ROUNDS = 5;
    const MAX_SCORE = 1000;

    public function getPosition(array $parameters): IContent
    {
        $mapId = (int) $parameters['mapId'];

        if (!isset($_SESSION['state']) || $_SESSION['state']['mapId'] !== $mapId) {
            $data = ['error' => 'No valid session found!'];
            return new JsonContent($data);
        }

        if (count($_SESSION['state']['rounds']) === 0) {
            $newPosition = $this->getNewPosition($mapId);
            $_SESSION['state']['rounds'][] = $newPosition;

            $data = ['panoId' => $newPosition['panoId']];
        } else {
            $rounds = count($_SESSION['state']['rounds']);
            $last = $_SESSION['state']['rounds'][$rounds - 1];

            $history = [];
            for ($i = 0; $i < $rounds - 1; ++$i) {
                $round = $_SESSION['state']['rounds'][$i];
                $history[] = [
                    'position' => $round['position']->toArray(),
                    'guessPosition' => $round['guessPosition']->toArray(),
                    'distance' => $round['distance'],
                    'score' => $round['score']
                ];
            }

            $data = [
                'history' => $history,
                'panoId' => $last['panoId']
            ];
        }

        return new JsonContent($data);
    }

    public function evaluateGuess(array $parameters): IContent
    {
        $mapId = (int) $parameters['mapId'];

        if (!isset($_SESSION['state']) || $_SESSION['state']['mapId'] !== $mapId) {
            $data = ['error' => 'No valid session found!'];
            return new JsonContent($data);
        }

        $last = &$_SESSION['state']['rounds'][count($_SESSION['state']['rounds']) - 1];

        $position = $last['position'];
        $guessPosition = new Position((float) $_POST['lat'], (float) $_POST['lng']);

        $last['guessPosition'] = $guessPosition;

        $distance = $this->calculateDistance($position, $guessPosition);
        $score = $this->calculateScore($distance, $_SESSION['state']['area']);

        $last['distance'] = $distance;
        $last['score'] = $score;

        if (count($_SESSION['state']['rounds']) < static::NUMBER_OF_ROUNDS) {
            $exclude = [];

            foreach ($_SESSION['state']['rounds'] as $round) {
                $exclude = array_merge($exclude, $round['placesWithoutPano'], [$round['placeId']]);
            }

            $newPosition = $this->getNewPosition($mapId, $exclude);
            $_SESSION['state']['rounds'][] = $newPosition;

            $panoId = $newPosition['panoId'];
        } else {
            $_SESSION['state']['rounds'] = [];

            $panoId = null;
        }

        $data = [
            'result' => [
                'position' => $position->toArray(),
                'distance' => $distance,
                'score' => $score
            ],
            'panoId' => $panoId
        ];
        return new JsonContent($data);
    }

    private function getNewPosition(int $mapId, array $exclude = []): array
    {
        $placesWithoutPano = [];

        do {
            $place = $this->selectNewPlace($mapId, $exclude);
            $position = new Position($place['lat'], $place['lng']);
            $panoId = $this->getPanorama($position);

            if ($panoId === null) {
                $placesWithoutPano[] = $place['id'];
            }
        } while ($panoId === null);

        return [
            'placesWithoutPano' => $placesWithoutPano,
            'placeId' => $place['id'],
            'position' => $position,
            'panoId' => $panoId
        ];
    }

    private function selectNewPlace(int $mapId, array $exclude): array
    {
        $select = new Select(\Container::$dbConnection, 'places');
        $select->columns(['id', 'lat', 'lng']);
        $select->where('id', 'NOT IN', $exclude);
        $select->where('map_id', '=', $mapId);

        $numberOfPlaces = $select->count();// TODO: what if 0
        $randomOffset = random_int(0, $numberOfPlaces - 1);

        $select->orderBy('id');
        $select->limit(1, $randomOffset);

        $place = $select->execute()->fetch(IResultSet::FETCH_ASSOC);

        return $place;
    }

    private function getPanorama(Position $position): ?string
    {
        $request = new Request('https://maps.googleapis.com/maps/api/streetview/metadata', Request::HTTP_GET);
        $request->setQuery([
            'key' => $_ENV['GOOGLE_MAPS_SERVER_API_KEY'],
            'location' => $position->getLat() . ',' . $position->getLng(),
            'source' => 'outdoor'
        ]);

        $response = $request->send();

        $panoData = json_decode($response->getBody(), true);

        if ($panoData['status'] !== 'OK') {
            return null;
        }

        return $panoData['pano_id'];
    }

    private function calculateDistance(Position $realPosition, Position $guessPosition): float
    {
        return $realPosition->calculateDistanceTo($guessPosition);
    }

    private function calculateScore(float $distance, float $area): int
    {
        $goodness = 1.0 - ($distance / sqrt($area));

        return (int) round(pow(static::MAX_SCORE, $goodness));
    }
}