<?php
/**
 * AI Usage Stats Endpoint
 * GET /api/v1/ai-usage/stats
 *
 * Returns AI token consumption stats for the current tenant.
 * Super admin sees system-wide; admin sees their tenant only.
 */

use App\Core\Database;
use App\Middleware\RoleMiddleware;

$decoded = RoleMiddleware::require(['super_admin', 'admin']);

$db = Database::getInstance();

$period = $_GET['period'] ?? 'month'; // day, week, month, all
$tenantId = $decoded['tenant_id'];
$isSuperAdmin = $decoded['role'] === 'super_admin';

// Date range
$dateCondition = match ($period) {
    'day'   => "AND a.created_at >= DATE_SUB(NOW(), INTERVAL 1 DAY)",
    'week'  => "AND a.created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)",
    'month' => "AND a.created_at >= DATE_SUB(NOW(), INTERVAL 30 DAY)",
    default => "",
};

$tenantCondition = $isSuperAdmin ? "" : "AND a.tenant_id = ?";
$params = $isSuperAdmin ? [] : [$tenantId];

// Totals
$sql = "SELECT
            COUNT(*) as total_requests,
            COALESCE(SUM(a.prompt_tokens), 0) as total_prompt_tokens,
            COALESCE(SUM(a.completion_tokens), 0) as total_completion_tokens,
            COALESCE(SUM(a.total_tokens), 0) as total_tokens,
            COALESCE(SUM(a.estimated_cost), 0) as total_cost
        FROM ai_usage_log a
        WHERE 1=1 $tenantCondition $dateCondition";

$stmt = $db->prepare($sql);
$stmt->execute($params);
$totals = $stmt->fetch(\PDO::FETCH_ASSOC);

// Breakdown by action type
$sql2 = "SELECT
            a.action_type,
            COUNT(*) as requests,
            COALESCE(SUM(a.total_tokens), 0) as tokens,
            COALESCE(SUM(a.estimated_cost), 0) as cost
        FROM ai_usage_log a
        WHERE 1=1 $tenantCondition $dateCondition
        GROUP BY a.action_type
        ORDER BY tokens DESC";

$stmt2 = $db->prepare($sql2);
$stmt2->execute($params);
$breakdown = $stmt2->fetchAll(\PDO::FETCH_ASSOC);

// Breakdown by model
$sql3 = "SELECT
            a.model_name,
            COUNT(*) as requests,
            COALESCE(SUM(a.total_tokens), 0) as tokens,
            COALESCE(SUM(a.estimated_cost), 0) as cost
        FROM ai_usage_log a
        WHERE 1=1 $tenantCondition $dateCondition
        GROUP BY a.model_name
        ORDER BY tokens DESC";

$stmt3 = $db->prepare($sql3);
$stmt3->execute($params);
$modelBreakdown = $stmt3->fetchAll(\PDO::FETCH_ASSOC);

// Daily trend (last 30 days)
$sql4 = "SELECT
            DATE(a.created_at) as date,
            COALESCE(SUM(a.total_tokens), 0) as tokens,
            COALESCE(SUM(a.estimated_cost), 0) as cost,
            COUNT(*) as requests
        FROM ai_usage_log a
        WHERE 1=1 $tenantCondition AND a.created_at >= DATE_SUB(NOW(), INTERVAL 30 DAY)
        GROUP BY DATE(a.created_at)
        ORDER BY date ASC";

$stmt4 = $db->prepare($sql4);
$stmt4->execute($params);
$dailyTrend = $stmt4->fetchAll(\PDO::FETCH_ASSOC);

json_success([
    'period'          => $period,
    'totals'          => [
        'requests'           => (int) $totals['total_requests'],
        'prompt_tokens'      => (int) $totals['total_prompt_tokens'],
        'completion_tokens'  => (int) $totals['total_completion_tokens'],
        'total_tokens'       => (int) $totals['total_tokens'],
        'estimated_cost_usd' => round((float) $totals['total_cost'], 4),
    ],
    'by_action'       => $breakdown,
    'by_model'        => $modelBreakdown,
    'daily_trend'     => $dailyTrend,
]);