<?php

declare(strict_types=1);

namespace Weerscherm;

/**
 * Bouwt de JSON-payload voor /api/data.php: haalt per bron data op (via cache of de WeatherSource),
 * valt bij een storing terug op de laatst gecachte data en markeert die als stale.
 */
final class DashboardService
{
    private const PRESSURE_HOURS = 24;

    private const ERR_NETATMO_AUTH = 'netatmo_auth';
    private const ERR_NETATMO = 'netatmo_unavailable';
    private const ERR_FORECAST = 'forecast_unavailable';

    /** @var list<string> */
    private array $errors = [];

    /**
     * @param array{stations: int, measure: int, pressure: int, forecast: int} $ttl
     * @param array<string, string> $indoorModules
     */
    public function __construct(
        private readonly WeatherSource $source,
        private readonly Cache $cache,
        private readonly array $ttl,
        private readonly string $timezoneFallback,
        private readonly ?float $forecastLat,
        private readonly ?float $forecastLon,
        private readonly array $indoorModules,
        private readonly ?string $deviceId,
        private readonly ?\DateTimeImmutable $now = null,
    ) {
    }

    /** @return array<string, mixed> */
    public function build(): array
    {
        $this->errors = [];
        $nowUtc = $this->now ?? new \DateTimeImmutable('now');

        $stations = $this->fetch('stations', fn() => $this->source->stationsData(), self::ERR_NETATMO);
        $station = StationMapper::map($stations['data'] ?? [], $this->deviceId, $this->indoorModules);

        $tz = $this->timezone($station['timezone']);
        $now = $nowUtc->setTimezone($tz);

        $rain = $this->rain($station, $now);
        $pressure = $this->pressure($station, $now);
        $outdoorHistory = $this->outdoorHistory($station, $now);
        $forecast = $this->forecast($station, $tz);

        return [
            'generated_at' => $now->format(\DATE_ATOM),
            'timezone' => $tz->getName(),
            'station' => [
                'measured_at' => $this->iso($station['measured_at'], $tz),
                'stale' => $stations['stale'],
            ],
            'outdoor' => [
                'temp' => $station['outdoor']['temp'],
                'trend' => $station['outdoor']['trend'],
                'min' => $station['outdoor']['min'],
                'min_at' => $this->iso($station['outdoor']['min_at'], $tz),
                'max' => $station['outdoor']['max'],
                'max_at' => $this->iso($station['outdoor']['max_at'], $tz),
                'humidity' => $station['outdoor']['humidity'],
            ],
            'outdoor_history' => $outdoorHistory,
            'indoor' => $station['indoor'],
            'rain' => $rain,
            'pressure' => $pressure,
            'forecast' => $forecast['days'],
            'forecast_stale' => $forecast['stale'],
            'errors' => $this->errors,
        ];
    }

    /** @return array{today: ?float, previous_days: list<array{date: string, mm: ?float}>, month_total: ?float, stale: bool} */
    private function rain(array $station, \DateTimeImmutable $now): array
    {
        $empty = RainCalculator::compute([], $now, null) + ['stale' => false];
        if ($station['device_id'] === null || $station['rain_module_id'] === null) {
            return $empty;
        }
        $begin = RainCalculator::dateBegin($now)->getTimestamp();
        $measure = $this->fetch(
            'measure',
            fn() => $this->source->measure($station['device_id'], $station['rain_module_id'], $begin, $now->getTimestamp()),
            self::ERR_NETATMO,
        );
        if ($measure['data'] === null) {
            return ['today' => $station['sum_rain_24'], 'stale' => true] + $empty;
        }
        return RainCalculator::compute($measure['data'], $now, $station['sum_rain_24']) + ['stale' => $measure['stale']];
    }

    /** @return array{current: ?float, trend: ?string, history: list<array{at: string, hpa: float}>, stale: bool} */
    private function pressure(array $station, \DateTimeImmutable $now): array
    {
        $base = ['current' => $station['pressure']['current'], 'trend' => $station['pressure']['trend']];
        if ($station['device_id'] === null) {
            return $base + ['history' => [], 'stale' => false];
        }
        $begin = $now->getTimestamp() - self::PRESSURE_HOURS * 3600;
        $measure = $this->fetch(
            'pressure',
            fn() => $this->source->pressureHistory($station['device_id'], $begin, $now->getTimestamp()),
            self::ERR_NETATMO,
        );
        return $base + [
            'history' => $measure['data'] === null ? [] : MeasureSeries::map($measure['data'], $now->getTimezone(), 'hpa'),
            'stale' => $measure['stale'],
        ];
    }

    /**
     * Temperatuurverloop van vandaag: vanaf middernacht lokale tijd tot nu.
     *
     * @return array{points: list<array{at: string, temp: float}>, stale: bool}
     */
    private function outdoorHistory(array $station, \DateTimeImmutable $now): array
    {
        $moduleId = $station['outdoor_module_id'];
        if ($station['device_id'] === null || $moduleId === null) {
            return ['points' => [], 'stale' => false];
        }
        $begin = $now->setTime(0, 0, 0)->getTimestamp();
        $measure = $this->fetch(
            'temperature',
            fn() => $this->source->temperatureHistory($station['device_id'], $moduleId, $begin, $now->getTimestamp()),
            self::ERR_NETATMO,
        );
        return [
            'points' => $measure['data'] === null ? [] : MeasureSeries::map($measure['data'], $now->getTimezone(), 'temp'),
            'stale' => $measure['stale'],
        ];
    }

    /** @return array{days: list<array>, stale: bool} */
    private function forecast(array $station, \DateTimeZone $tz): array
    {
        $lat = $this->forecastLat ?? $station['lat'];
        $lon = $this->forecastLon ?? $station['lon'];
        if ($lat === null || $lon === null) {
            $this->addError(self::ERR_FORECAST);
            return ['days' => [], 'stale' => true];
        }
        $result = $this->fetch('forecast', fn() => $this->source->forecast($lat, $lon, $tz->getName()), self::ERR_FORECAST);
        $daily = is_array($result['data']['daily'] ?? null) ? $result['data']['daily'] : null;
        if ($daily === null) {
            // Data ontbreekt (echte storing, al gemeld door fetch()), of de cache staat nog in een ouder
            // formaat na een deploy dat de opgeslagen vorm wijzigde. In beide gevallen liever zichtbaar
            // niets tonen dan stil een lege verwachting zonder foutmelding.
            if ($result['data'] !== null) {
                $this->addError(self::ERR_FORECAST);
            }
            return ['days' => [], 'stale' => true];
        }

        $days = ForecastMapper::map($daily);
        $hourlyByDate = HourlyForecastMapper::mapByDate($result['data']['hourly'] ?? [], $tz);
        foreach ($days as &$day) {
            $day['hourly'] = $hourlyByDate[$day['date']] ?? [];
        }
        unset($day);

        return ['days' => $days, 'stale' => $result['stale']];
    }

    /**
     * Cache-first per bron. Bij een fout: stale cache (ongeacht leeftijd) en een foutcode, anders null.
     *
     * @param callable(): array $fetcher
     * @return array{data: ?array, stale: bool}
     */
    private function fetch(string $key, callable $fetcher, string $errorCode): array
    {
        $now = ($this->now ?? new \DateTimeImmutable('now'))->getTimestamp();
        $ttl = $this->ttl[$key] ?? 0;
        if ($ttl > 0 && $this->cache->isFresh($key, $ttl, $now)) {
            return ['data' => $this->cache->read($key)['data'], 'stale' => false];
        }
        try {
            $data = $fetcher();
            if ($ttl > 0) {
                $this->cache->write($key, $data, $now);
            }
            return ['data' => $data, 'stale' => false];
        } catch (NetatmoAuthException) {
            $this->addError(self::ERR_NETATMO_AUTH);
        } catch (\Throwable $e) {
            error_log("weerscherm: $key: " . $e->getMessage());
            $this->addError($errorCode);
        }
        $cached = $this->cache->read($key);
        return ['data' => $cached['data'] ?? null, 'stale' => true];
    }

    private function addError(string $code): void
    {
        if (!in_array($code, $this->errors, true)) {
            $this->errors[] = $code;
        }
    }

    private function timezone(?string $name): \DateTimeZone
    {
        foreach ([$name, $this->timezoneFallback, 'UTC'] as $candidate) {
            if ($candidate !== null && in_array($candidate, \DateTimeZone::listIdentifiers(), true)) {
                return new \DateTimeZone($candidate);
            }
        }
        return new \DateTimeZone('UTC');
    }

    private function iso(?int $timestamp, \DateTimeZone $tz): ?string
    {
        return $timestamp === null ? null : (new \DateTimeImmutable('@' . $timestamp))->setTimezone($tz)->format(\DATE_ATOM);
    }
}