<?php

namespace App\Services;

use App\Core\Database;
use App\Core\Session;

class AuditService
{
    private Database $database;
    private Session $session;

    public function __construct(Database $database, Session $session)
    {
        $this->database = $database;
        $this->session = $session;
    }

    public function log(string $action, string $table, int $recordId, array $oldValue = null, array $newValue = null): void
    {
        $userId = $this->session->getUserId();
        
        if (!$userId) {
            return; // Skip logging if no user
        }

        $data = [
            'user_id' => $userId,
            'action' => $action,
            'table_name' => $table,
            'record_id' => $recordId,
            'old_value' => $oldValue ? json_encode($oldValue) : null,
            'new_value' => $newValue ? json_encode($newValue) : null,
            'created_at' => date('Y-m-d H:i:s')
        ];

        try {
            $this->database->insert('audit_log', $data);
        } catch (\Exception $e) {
            error_log('Audit logging failed: ' . $e->getMessage());
        }
    }

    public function getAuditLog(string $table = null, int $recordId = null, int $limit = 100): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                WHERE 1=1";
        $params = [];

        if ($table) {
            $sql .= " AND al.table_name = :table";
            $params['table'] = $table;
        }

        if ($recordId) {
            $sql .= " AND al.record_id = :record_id";
            $params['record_id'] = $recordId;
        }

        $sql .= " ORDER BY al.created_at DESC LIMIT :limit";
        $params['limit'] = $limit;

        return $this->database->fetchAll($sql, $params);
    }

    public function getAssetHistory(int $assetId): array
    {
        return $this->getAuditLog('assets', $assetId);
    }

    public function getUserActivity(int $userId, int $limit = 50): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                WHERE al.user_id = :user_id 
                ORDER BY al.created_at DESC 
                LIMIT :limit";

        return $this->database->fetchAll($sql, [
            'user_id' => $userId,
            'limit' => $limit
        ]);
    }

    public function getRecentActivity(int $limit = 20): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                ORDER BY al.created_at DESC 
                LIMIT :limit";

        return $this->database->fetchAll($sql, ['limit' => $limit]);
    }

    public function getActivityByDateRange(string $startDate, string $endDate): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                WHERE DATE(al.created_at) BETWEEN :start_date AND :end_date 
                ORDER BY al.created_at DESC";

        return $this->database->fetchAll($sql, [
            'start_date' => $startDate,
            'end_date' => $endDate
        ]);
    }

    public function getActivityByAction(string $action, int $limit = 100): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                WHERE al.action = :action 
                ORDER BY al.created_at DESC 
                LIMIT :limit";

        return $this->database->fetchAll($sql, [
            'action' => $action,
            'limit' => $limit
        ]);
    }

    public function getAssetChanges(int $assetId): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                WHERE al.table_name = 'assets' 
                AND al.record_id = :asset_id 
                AND al.action IN ('update', 'delete') 
                ORDER BY al.created_at DESC";

        return $this->database->fetchAll($sql, ['asset_id' => $assetId]);
    }

    public function getInventoryActivity(int $inventoryId): array
    {
        $sql = "SELECT al.*, u.name as user_name 
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                WHERE al.table_name = 'inventories' 
                AND al.record_id = :inventory_id 
                ORDER BY al.created_at DESC";

        return $this->database->fetchAll($sql, ['inventory_id' => $inventoryId]);
    }

    public function cleanupOldLogs(int $daysToKeep = 365): int
    {
        $sql = "DELETE FROM audit_log 
                WHERE created_at < DATE_SUB(NOW(), INTERVAL :days DAY)";

        return $this->database->query($sql, ['days' => $daysToKeep])->rowCount();
    }

    public function getAuditSummary(): array
    {
        $sql = "SELECT 
                    COUNT(*) as total_entries,
                    COUNT(DISTINCT user_id) as unique_users,
                    COUNT(DISTINCT table_name) as tables_affected,
                    MIN(created_at) as first_entry,
                    MAX(created_at) as last_entry
                FROM audit_log";

        return $this->database->fetch($sql) ?: [];
    }

    public function getTopUsers(int $limit = 10): array
    {
        $sql = "SELECT 
                    u.name as user_name,
                    COUNT(*) as activity_count
                FROM audit_log al 
                LEFT JOIN users u ON al.user_id = u.id 
                GROUP BY al.user_id, u.name 
                ORDER BY activity_count DESC 
                LIMIT :limit";

        return $this->database->fetchAll($sql, ['limit' => $limit]);
    }

    public function getMostActiveTables(int $limit = 10): array
    {
        $sql = "SELECT 
                    table_name,
                    COUNT(*) as activity_count
                FROM audit_log 
                GROUP BY table_name 
                ORDER BY activity_count DESC 
                LIMIT :limit";

        return $this->database->fetchAll($sql, ['limit' => $limit]);
    }
}