<?php

namespace App\Services\Api;

use App\Models\ApiUsageLog;
use Illuminate\Database\Eloquent\Builder;

class ApiUsageReporter
{
    /**
     * @return array<string, mixed>
     */
    public function report(?string $from = null, ?string $to = null, ?int $userId = null, ?int $statusCode = null, int $top = 10): array
    {
        $baseQuery = $this->baseQuery($from, $to, $userId, $statusCode);

        $totalRequests = (clone $baseQuery)->count();

        return [
            'generated_at' => now()->toIso8601String(),
            'filters' => [
                'from' => $from,
                'to' => $to,
                'user_id' => $userId,
                'status_code' => $statusCode,
                'top' => $top,
            ],
            'summary' => [
                'total_requests' => $totalRequests,
                'unique_users' => (clone $baseQuery)->whereNotNull('user_id')->distinct('user_id')->count('user_id'),
                'unique_tokens' => (clone $baseQuery)->whereNotNull('personal_access_token_id')->distinct('personal_access_token_id')->count('personal_access_token_id'),
                'successful_requests' => (clone $baseQuery)->whereBetween('status_code', [200, 299])->count(),
                'client_error_requests' => (clone $baseQuery)->whereBetween('status_code', [400, 499])->count(),
                'server_error_requests' => (clone $baseQuery)->whereBetween('status_code', [500, 599])->count(),
                'average_duration_ms' => $totalRequests > 0 ? round((float) (clone $baseQuery)->avg('duration_ms'), 2) : 0.0,
            ],
            'top_paths' => $this->topRows($baseQuery, 'path', $top),
            'status_codes' => $this->topRows($baseQuery, 'status_code', $top),
            'top_users' => $this->topRows($baseQuery, 'user_id', $top),
            'top_tokens' => $this->topRows($baseQuery, 'personal_access_token_id', $top),
            'recent_requests' => $this->recentRequests($baseQuery, $top),
        ];
    }

    private function baseQuery(?string $from, ?string $to, ?int $userId, ?int $statusCode): Builder
    {
        return ApiUsageLog::query()
            ->when($from !== null, fn (Builder $query) => $query->where('requested_at', '>=', $from))
            ->when($to !== null, fn (Builder $query) => $query->where('requested_at', '<=', $to))
            ->when($userId !== null, fn (Builder $query) => $query->where('user_id', $userId))
            ->when($statusCode !== null, fn (Builder $query) => $query->where('status_code', $statusCode));
    }

    /**
     * @return list<array{value: mixed, requests: int}>
     */
    private function topRows(Builder $baseQuery, string $column, int $limit): array
    {
        return (clone $baseQuery)
            ->selectRaw("{$column} as value, count(*) as requests")
            ->whereNotNull($column)
            ->groupBy($column)
            ->orderByDesc('requests')
            ->limit($limit)
            ->get()
            ->map(fn ($row): array => [
                'value' => $row->value,
                'requests' => (int) $row->requests,
            ])
            ->all();
    }

    /**
     * @return list<array<string, mixed>>
     */
    private function recentRequests(Builder $baseQuery, int $limit): array
    {
        return (clone $baseQuery)
            ->latest('requested_at')
            ->latest('id')
            ->limit($limit)
            ->get([
                'id',
                'user_id',
                'personal_access_token_id',
                'method',
                'path',
                'route_name',
                'status_code',
                'duration_ms',
                'requested_at',
            ])
            ->map(fn (ApiUsageLog $log): array => [
                'id' => $log->id,
                'user_id' => $log->user_id,
                'personal_access_token_id' => $log->personal_access_token_id,
                'method' => $log->method,
                'path' => $log->path,
                'route_name' => $log->route_name,
                'status_code' => $log->status_code,
                'duration_ms' => $log->duration_ms,
                'requested_at' => $log->requested_at?->toIso8601String(),
            ])
            ->all();
    }
}