<?php

namespace App\Services;

use App\Models\LlmRequest;
use App\Models\User;
use App\Models\UserProviderCredential;
use Illuminate\Support\Facades\DB;

class StatisticsService
{
    /**
     * Get dashboard overview statistics
     */
    public function getDashboardStats(): array
    {
        return [
            'total_users' => User::count(),
            'active_credentials' => UserProviderCredential::where('is_active', true)->count(),
            'total_requests_today' => LlmRequest::whereDate('created_at', today())->count(),
            'total_spend_today' => LlmRequest::whereDate('created_at', today())->sum('total_cost') ?? 0,
            'total_tokens_today' => LlmRequest::whereDate('created_at', today())->sum('total_tokens') ?? 0,
            'total_spend_month' => LlmRequest::whereMonth('created_at', now()->month)
                ->whereYear('created_at', now()->year)
                ->sum('total_cost') ?? 0,
            'total_requests_month' => LlmRequest::whereMonth('created_at', now()->month)
                ->whereYear('created_at', now()->year)
                ->count(),
            'avg_cost_per_request' => LlmRequest::whereMonth('created_at', now()->month)
                ->whereYear('created_at', now()->year)
                ->avg('total_cost') ?? 0,
        ];
    }

    /**
     * Get usage breakdown by provider
     */
    public function getUsageByProvider(int $days = 30)
    {
        return LlmRequest::selectRaw('provider, COUNT(*) as count, SUM(total_cost) as total_cost, SUM(total_tokens) as total_tokens')
            ->where('created_at', '>=', now()->subDays($days))
            ->where('status', 'success')
            ->groupBy('provider')
            ->orderByDesc('count')
            ->get();
    }

    /**
     * Get usage breakdown by model
     */
    public function getUsageByModel(int $days = 30)
    {
        return LlmRequest::selectRaw('model, provider, COUNT(*) as count, SUM(total_tokens) as tokens, SUM(total_cost) as total_cost')
            ->where('created_at', '>=', now()->subDays($days))
            ->where('status', 'success')
            ->groupBy('model', 'provider')
            ->orderByDesc('count')
            ->limit(10)
            ->get();
    }

    /**
     * Get daily usage chart data
     */
    public function getDailyUsageChart(int $days = 30)
    {
        return LlmRequest::selectRaw('DATE(created_at) as date, COUNT(*) as requests, SUM(total_cost) as cost, SUM(total_tokens) as tokens')
            ->where('created_at', '>=', now()->subDays($days))
            ->where('status', 'success')
            ->groupBy('date')
            ->orderBy('date')
            ->get();
    }

    /**
     * Get top users by spend
     */
    public function getTopUsers(int $limit = 10)
    {
        return User::select('users.*')
            ->withCount('llmRequests')
            ->withSum('llmRequests as total_cost', 'total_cost')
            ->withSum('llmRequests as total_tokens', 'total_tokens')
            ->orderByDesc('total_cost')
            ->limit($limit)
            ->get();
    }

    /**
     * Get recent activity
     */
    public function getRecentActivity(int $limit = 20)
    {
        return LlmRequest::with('user')
            ->orderByDesc('created_at')
            ->limit($limit)
            ->get();
    }

    /**
     * Get user statistics
     */
    public function getUserStatistics(int $userId, int $days = 30)
    {
        return LlmRequest::where('user_id', $userId)
            ->where('created_at', '>=', now()->subDays($days))
            ->where('status', 'success')
            ->selectRaw('
                COUNT(*) as total_requests,
                SUM(prompt_tokens) as total_prompt_tokens,
                SUM(completion_tokens) as total_completion_tokens,
                SUM(total_tokens) as total_tokens,
                SUM(total_cost) as total_cost,
                AVG(total_tokens) as avg_tokens_per_request,
                AVG(total_cost) as avg_cost_per_request,
                AVG(response_time_ms) as avg_response_time_ms
            ')
            ->first();
    }

    /**
     * Get provider usage over time
     */
    public function getProviderUsageOverTime(int $days = 30)
    {
        return LlmRequest::selectRaw('DATE(created_at) as date, provider, COUNT(*) as count, SUM(total_cost) as cost')
            ->where('created_at', '>=', now()->subDays($days))
            ->where('status', 'success')
            ->groupBy('date', 'provider')
            ->orderBy('date')
            ->get()
            ->groupBy('provider');
    }

    /**
     * Get cost trends
     */
    public function getCostTrends(int $days = 30)
    {
        $data = LlmRequest::selectRaw('
                DATE(created_at) as date,
                SUM(total_cost) as daily_cost,
                AVG(total_cost) as avg_request_cost,
                COUNT(*) as request_count
            ')
            ->where('created_at', '>=', now()->subDays($days))
            ->where('status', 'success')
            ->groupBy('date')
            ->orderBy('date')
            ->get();

        return [
            'daily_data' => $data,
            'total_cost' => $data->sum('daily_cost'),
            'avg_daily_cost' => $data->avg('daily_cost'),
            'total_requests' => $data->sum('request_count'),
        ];
    }

    /**
     * Get error statistics
     */
    public function getErrorStats(int $days = 30)
    {
        return [
            'total_errors' => LlmRequest::where('created_at', '>=', now()->subDays($days))
                ->where('status', '!=', 'success')
                ->count(),
            'errors_by_status' => LlmRequest::selectRaw('status, COUNT(*) as count')
                ->where('created_at', '>=', now()->subDays($days))
                ->where('status', '!=', 'success')
                ->groupBy('status')
                ->get(),
            'errors_by_provider' => LlmRequest::selectRaw('provider, COUNT(*) as count')
                ->where('created_at', '>=', now()->subDays($days))
                ->where('status', '!=', 'success')
                ->groupBy('provider')
                ->get(),
        ];
    }
}