<?php

namespace App\Services;

use App\Models\Device;
use App\Models\PageVisit;
use App\Models\User;
use App\Support\AgentScope;
use Carbon\Carbon;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Facades\DB;

class DashboardStatsService
{
    /**
     * @param  array{
     *   range?: string,
     *   channel_id?: string,
     *   channel_exact?: bool,
     *   agent_user_id?: int,
     *   agent?: ?User
     * }  $filters
     * @return array{
     *   total: int,
     *   new_count: int,
     *   active_count: int,
     *   pv: int,
     *   uv: int,
     *   effective_pv: int,
     *   effective_uv: int,
     *   by_os: list<array{label: string, pv: int, uv: int, pct: float}>,
     *   by_ios_version: list<array{label: string, pv: int, uv: int, pct: float}>,
     *   range: string,
     *   from: string,
     *   to: string
     * }
     */
    public function collect(array $filters = []): array
    {
        $range = (string) ($filters['range'] ?? '30d');
        [$from, $to] = $this->rangeBounds($range);

        $channelId = trim((string) ($filters['channel_id'] ?? ''));
        $channelExact = (bool) ($filters['channel_exact'] ?? false);
        $agent = $filters['agent'] ?? null;
        $agentUserId = (int) ($filters['agent_user_id'] ?? 0);

        $base = Device::query();
        AgentScope::applyDeviceChannelScope($base, $agent);
        if ($agent === null && $agentUserId > 0) {
            AgentScope::applyAgentUserFilter($base, $agentUserId);
        }
        if ($channelId !== '') {
            if ($channelExact) {
                $base->where('channel_id', $channelId);
            } else {
                $base->where('channel_id', 'like', '%'.$channelId.'%');
            }
        }

        $total = (clone $base)->count();
        $newCount = (clone $base)->whereBetween('created_at', [$from, $to])->count();
        $activeCount = (clone $base)->whereBetween('updated_at', [$from, $to])->count();

        $visits = PageVisit::query();
        AgentScope::applyChannelIdScope($visits, $agent);
        if ($agent === null && $agentUserId > 0) {
            AgentScope::applyChannelIdAgentUserFilter($visits, $agentUserId);
        }
        if ($channelId !== '') {
            if ($channelExact) {
                $visits->where('channel_id', $channelId);
            } else {
                $visits->where('channel_id', 'like', '%'.$channelId.'%');
            }
        }
        $visits->whereBetween('created_at', [$from, $to]);

        $pv = (clone $visits)->count();
        $uv = (int) (clone $visits)->selectRaw('COUNT(DISTINCT client_uid) as aggregate')->value('aggregate');
        $effectiveVisits = (clone $visits)->tap(fn (Builder $q) => $this->applyEffectiveFilter($q));
        $effectivePv = (clone $effectiveVisits)->count();
        $effectiveUv = (int) (clone $effectiveVisits)->selectRaw('COUNT(DISTINCT client_uid) as aggregate')->value('aggregate');

        $iosVisits = (clone $visits)->where('os', 'iOS');
        $iosPv = (clone $iosVisits)->count();
        $iosUv = (int) (clone $iosVisits)->selectRaw('COUNT(DISTINCT client_uid) as aggregate')->value('aggregate');

        $otherVisits = (clone $visits)->where(function (Builder $q) {
            $q->whereNull('os')->orWhere('os', '!=', 'iOS');
        });
        $otherPv = (clone $otherVisits)->count();
        $otherUv = (int) (clone $otherVisits)->selectRaw('COUNT(DISTINCT client_uid) as aggregate')->value('aggregate');

        $byOs = [
            $this->row('iOS', $iosPv, $iosUv, $pv),
            $this->row('其他', $otherPv, $otherUv, $pv),
        ];

        $byIosVersion = (clone $iosVisits)
            ->select('os_version')
            ->selectRaw('COUNT(*) as pv')
            ->selectRaw('COUNT(DISTINCT client_uid) as uv')
            ->groupBy('os_version')
            ->orderByDesc('pv')
            ->limit(20)
            ->get()
            ->map(fn ($r) => $this->row(
                ((string) ($r->os_version ?? '')) !== '' ? (string) $r->os_version : 'Unknown',
                (int) $r->pv,
                (int) $r->uv,
                $iosPv > 0 ? $iosPv : $pv,
            ))
            ->values()
            ->all();

        return [
            'total' => $total,
            'new_count' => $newCount,
            'active_count' => $activeCount,
            'pv' => $pv,
            'uv' => $uv,
            'effective_pv' => $effectivePv,
            'effective_uv' => $effectiveUv,
            'by_os' => $byOs,
            'by_ios_version' => $byIosVersion,
            'range' => $range,
            'from' => $from->toDateTimeString(),
            'to' => $to->toDateTimeString(),
        ];
    }

    /**
     * Map telegram /data day token to dashboard range key.
     * Empty / omitted → today.
     */
    public function rangeFromDays(?string $days): string
    {
        $days = $days === null ? '' : trim($days);
        if ($days === '' || $days === '1') {
            return 'today';
        }

        return match ($days) {
            '7' => '7d',
            '30' => '30d',
            default => throw new \InvalidArgumentException('Days must be 1, 7, or 30'),
        };
    }

    /**
     * @return array{0: Carbon, 1: Carbon}
     */
    public function rangeBounds(string $range): array
    {
        $now = Carbon::now();

        return match ($range) {
            'today', '1', '1d' => [$now->copy()->startOfDay(), $now->copy()->endOfDay()],
            'yesterday' => [
                $now->copy()->subDay()->startOfDay(),
                $now->copy()->subDay()->endOfDay(),
            ],
            '7d', '7' => [$now->copy()->subDays(6)->startOfDay(), $now->copy()->endOfDay()],
            default => [$now->copy()->subDays(29)->startOfDay(), $now->copy()->endOfDay()],
        };
    }

    /**
     * Effective traffic: Safari on iOS ≤ 17.2 (includes 17.2.x patch builds; excludes 17.3+).
     */
    private function applyEffectiveFilter(Builder $query): void
    {
        $query->where('os', 'iOS')
            ->where('browser', 'Safari')
            ->whereNotNull('os_version')
            ->where('os_version', '!=', '');

        $driver = DB::connection()->getDriverName();
        if ($driver === 'sqlite') {
            // major < 17 OR (major = 17 AND minor ≤ 2)
            $query->whereRaw(
                "(CAST(os_version AS INTEGER) < 17)
                 OR (
                   CAST(os_version AS INTEGER) = 17
                   AND CAST(
                     CASE
                       WHEN INSTR(os_version, '.') > 0
                       THEN SUBSTR(os_version, INSTR(os_version, '.') + 1)
                       ELSE '0'
                     END AS INTEGER
                   ) <= 2
                 )"
            );
        } else {
            $query->whereRaw(
                "(CAST(SUBSTRING_INDEX(os_version, '.', 1) AS UNSIGNED) < 17)
                 OR (
                   CAST(SUBSTRING_INDEX(os_version, '.', 1) AS UNSIGNED) = 17
                   AND CAST(
                     SUBSTRING_INDEX(SUBSTRING_INDEX(CONCAT(os_version, '.0'), '.', 2), '.', -1) AS UNSIGNED
                   ) <= 2
                 )"
            );
        }
    }

    /**
     * @return array{label: string, pv: int, uv: int, pct: float}
     */
    private function row(string $label, int $pv, int $uv, int $totalPv): array
    {
        $pct = $totalPv > 0 ? round(($pv / $totalPv) * 100, 1) : 0.0;

        return [
            'label' => $label,
            'pv' => $pv,
            'uv' => $uv,
            'pct' => $pct,
        ];
    }
}