<?php

namespace App\Services\Qr;

use App\Models\QrCode;
use App\Models\QrScanEvent;
use App\Models\User;
use App\Support\Qr\QrTypeCatalog;
use Carbon\Carbon;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;

class QrAnalyticsService
{
    /**
     * @return array<string, mixed>
     */
    public function summaryForAccount(User $account): array
    {
        $codeIds = $this->codeIdsFor($account);

        if ($codeIds === []) {
            return $this->emptySummary();
        }

        $codes = QrCode::query()->whereIn('id', $codeIds)->get(['id', 'scans_total', 'unique_scans_total', 'last_scanned_at']);
        $now = now();
        $events = QrScanEvent::query()->whereIn('qr_code_id', $codeIds);

        return [
            'total_scans' => (int) $codes->sum('scans_total'),
            'unique_scans' => (int) $codes->sum('unique_scans_total'),
            'scans_7d' => (clone $events)->where('scanned_at', '>=', $now->copy()->subDays(7))->count(),
            'scans_30d' => (clone $events)->where('scanned_at', '>=', $now->copy()->subDays(30))->count(),
            'last_scanned_at' => $codes->max('last_scanned_at'),
        ];
    }

    /**
     * @return Collection<int, object{date: string, total: int}>
     */
    public function dailyScansForAccount(User $account, int $days = 30): Collection
    {
        $codeIds = $this->codeIdsFor($account);
        $start = now()->subDays($days - 1)->startOfDay();

        if ($codeIds === []) {
            return $this->emptyDailySeries($start, $days);
        }

        $rows = QrScanEvent::query()
            ->selectRaw('DATE(scanned_at) as scan_date, COUNT(*) as total')
            ->whereIn('qr_code_id', $codeIds)
            ->where('scanned_at', '>=', $start)
            ->groupBy('scan_date')
            ->orderBy('scan_date')
            ->get()
            ->keyBy('scan_date');

        return $this->buildDailySeries($start, $days, $rows);
    }

    /**
     * @return array<int, array{label: string, total: int}>
     */
    public function breakdownForAccount(User $account, string $column, int $limit = 5): array
    {
        $codeIds = $this->codeIdsFor($account);

        if ($codeIds === []) {
            return [];
        }

        return QrScanEvent::query()
            ->select($column, DB::raw('COUNT(*) as total'))
            ->whereIn('qr_code_id', $codeIds)
            ->whereNotNull($column)
            ->groupBy($column)
            ->orderByDesc('total')
            ->limit($limit)
            ->get()
            ->map(fn ($row) => [
                'label' => (string) $row->{$column},
                'total' => (int) $row->total,
            ])
            ->all();
    }

    /**
     * @return \Illuminate\Database\Eloquent\Collection<int, QrScanEvent>
     */
    public function recentScansForAccount(User $account, int $limit = 20)
    {
        $codeIds = $this->codeIdsFor($account);

        if ($codeIds === []) {
            return QrScanEvent::query()->whereRaw('0 = 1')->get();
        }

        return QrScanEvent::query()
            ->whereIn('qr_code_id', $codeIds)
            ->with('qrCode:id,label,short_code')
            ->latest('scanned_at')
            ->limit($limit)
            ->get();
    }

    /**
     * @return \Illuminate\Database\Eloquent\Collection<int, QrCode>
     */
    public function topCodesForAccount(User $account, int $limit = 10)
    {
        return $account->qrCodes()
            ->whereIn('type', QrTypeCatalog::plusTypes())
            ->orderByDesc('scans_total')
            ->limit($limit)
            ->get(['id', 'label', 'short_code', 'type', 'scans_total', 'last_scanned_at']);
    }

    /**
     * @return array<string, mixed>
     */
    public function summaryFor(QrCode $qrCode): array
    {
        $now = now();
        $events = QrScanEvent::query()->where('qr_code_id', $qrCode->id);

        return [
            'total_scans' => (int) $qrCode->scans_total,
            'unique_scans' => (int) $qrCode->unique_scans_total,
            'scans_7d' => (clone $events)->where('scanned_at', '>=', $now->copy()->subDays(7))->count(),
            'scans_30d' => (clone $events)->where('scanned_at', '>=', $now->copy()->subDays(30))->count(),
            'last_scanned_at' => $qrCode->last_scanned_at,
        ];
    }

    /**
     * @return Collection<int, object{date: string, total: int}>
     */
    public function dailyScans(QrCode $qrCode, int $days = 30): Collection
    {
        $start = now()->subDays($days - 1)->startOfDay();

        $rows = QrScanEvent::query()
            ->selectRaw('DATE(scanned_at) as scan_date, COUNT(*) as total')
            ->where('qr_code_id', $qrCode->id)
            ->where('scanned_at', '>=', $start)
            ->groupBy('scan_date')
            ->orderBy('scan_date')
            ->get()
            ->keyBy('scan_date');

        return $this->buildDailySeries($start, $days, $rows);
    }

    /**
     * @return array<int, array{label: string, total: int}>
     */
    public function breakdown(QrCode $qrCode, string $column, int $limit = 5): array
    {
        return QrScanEvent::query()
            ->select($column, DB::raw('COUNT(*) as total'))
            ->where('qr_code_id', $qrCode->id)
            ->whereNotNull($column)
            ->groupBy($column)
            ->orderByDesc('total')
            ->limit($limit)
            ->get()
            ->map(fn ($row) => [
                'label' => (string) $row->{$column},
                'total' => (int) $row->total,
            ])
            ->all();
    }

    /**
     * @return \Illuminate\Database\Eloquent\Collection<int, QrScanEvent>
     */
    public function recentScans(QrCode $qrCode, int $limit = 20)
    {
        return QrScanEvent::query()
            ->where('qr_code_id', $qrCode->id)
            ->latest('scanned_at')
            ->limit($limit)
            ->get();
    }

    /** @return list<int> */
    private function codeIdsFor(User $account): array
    {
        return $account->qrCodes()
            ->whereIn('type', QrTypeCatalog::plusTypes())
            ->pluck('id')
            ->all();
    }

    /** @return array<string, mixed> */
    private function emptySummary(): array
    {
        return [
            'total_scans' => 0,
            'unique_scans' => 0,
            'scans_7d' => 0,
            'scans_30d' => 0,
            'last_scanned_at' => null,
        ];
    }

    /** @return Collection<int, object{date: string, total: int}> */
    private function emptyDailySeries(Carbon $start, int $days): Collection
    {
        return $this->buildDailySeries($start, $days, collect());
    }

    /**
     * @param  Collection<string, object{scan_date?: string, total?: int}>  $rows
     * @return Collection<int, object{date: string, total: int}>
     */
    private function buildDailySeries(Carbon $start, int $days, Collection $rows): Collection
    {
        $series = collect();
        for ($i = 0; $i < $days; $i++) {
            $date = $start->copy()->addDays($i)->toDateString();
            $series->push((object) [
                'date' => $date,
                'total' => (int) ($rows->get($date)?->total ?? 0),
            ]);
        }

        return $series;
    }
}