<?php
/**
 * Dashboard API Endpoint for Kayal Aqua
 * Provides JSON data for dashboard charts and statistics
 */

require_once '../config/config.php';
require_once '../includes/functions.php';

// Set JSON header
header('Content-Type: application/json');
header('Cache-Control: no-cache, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');

// Check if user is logged in
if (!isLoggedIn()) {
    sendJsonResponse(['error' => 'Unauthorized'], 401);
}

$action = $_GET['action'] ?? '';
$currentUser = getCurrentUser();

try {
    switch ($action) {
        case 'revenue_expenses':
            $data = getRevenueExpensesData();
            sendJsonResponse(['success' => true, 'data' => $data]);
            break;
            
        case 'business_segments':
            $data = getBusinessSegmentsData();
            sendJsonResponse(['success' => true, 'data' => $data]);
            break;
            
        case 'monthly_trends':
            $year = $_GET['year'] ?? date('Y');
            $data = getMonthlyTrendsData($year);
            sendJsonResponse(['success' => true, 'data' => $data]);
            break;
            
        case 'cash_flow':
            $data = getCashFlowData();
            sendJsonResponse(['success' => true, 'data' => $data]);
            break;
            
        case 'top_products':
            $data = getTopProductsData();
            sendJsonResponse(['success' => true, 'data' => $data]);
            break;
            
        case 'dashboard_stats':
            $data = getDashboardStatsData();
            sendJsonResponse(['success' => true, 'data' => $data]);
            break;
            
        default:
            sendJsonResponse(['error' => 'Invalid action'], 400);
    }
    
} catch (Exception $e) {
    error_log('Dashboard API Error: ' . $e->getMessage());
    sendJsonResponse(['error' => 'Internal server error'], 500);
}

/**
 * Get revenue vs expenses data for chart
 */
function getRevenueExpensesData() {
    $period = $_GET['period'] ?? 'year';
    $currentUser = getCurrentUser();
    
    // Determine date range based on period
    switch ($period) {
        case 'month':
            $startDate = date('Y-m-01');
            $endDate = date('Y-m-t');
            $groupBy = 'DAY';
            $dateFormat = '%Y-%m-%d';
            break;
        case 'quarter':
            $startDate = date('Y-m-01', strtotime('first day of -2 months'));
            $endDate = date('Y-m-t');
            $groupBy = 'WEEK';
            $dateFormat = '%Y-%u';
            break;
        default: // year
            $startDate = date('Y-01-01');
            $endDate = date('Y-12-31');
            $groupBy = 'MONTH';
            $dateFormat = '%Y-%m';
    }
    
    // Base conditions for user filtering
    $userCondition = '';
    $params = [$startDate, $endDate];
    
    if ($currentUser['role'] !== 'admin') {
        $userCondition = ' AND created_by = ?';
        $params[] = $currentUser['id'];
    }
    
    // Get revenue data
    $revenueQuery = "
        SELECT 
            DATE_FORMAT(sale_date, '{$dateFormat}') as period,
            SUM(amount) as amount
        FROM sales 
        WHERE sale_date BETWEEN ? AND ? {$userCondition}
        GROUP BY DATE_FORMAT(sale_date, '{$dateFormat}')
        ORDER BY period
    ";
    
    $revenueData = fetchAll($revenueQuery, $params);
    
    // Get expenses data
    $expensesQuery = "
        SELECT 
            DATE_FORMAT(expense_date, '{$dateFormat}') as period,
            SUM(amount) as amount
        FROM expenses 
        WHERE expense_date BETWEEN ? AND ? {$userCondition}
        GROUP BY DATE_FORMAT(expense_date, '{$dateFormat}')
        ORDER BY period
    ";
    
    $expensesData = fetchAll($expensesQuery, $params);
    
    // Combine and format data for Chart.js
    $periods = array_unique(array_merge(
        array_column($revenueData, 'period'),
        array_column($expensesData, 'period')
    ));
    sort($periods);
    
    $revenue = [];
    $expenses = [];
    $labels = [];
    
    foreach ($periods as $period) {
        $revenueAmount = 0;
        $expenseAmount = 0;
        
        foreach ($revenueData as $row) {
            if ($row['period'] === $period) {
                $revenueAmount = (float)$row['amount'];
                break;
            }
        }
        
        foreach ($expensesData as $row) {
            if ($row['period'] === $period) {
                $expenseAmount = (float)$row['amount'];
                break;
            }
        }
        
        $revenue[] = $revenueAmount;
        $expenses[] = $expenseAmount;
        
        // Format label based on period
        if ($period === 'month') {
            $labels[] = date('M j', strtotime($period));
        } elseif ($period === 'quarter') {
            $labels[] = 'Week ' . date('W', strtotime($period . '-01'));
        } else {
            $labels[] = date('M Y', strtotime($period . '-01'));
        }
    }
    
    return [
        'labels' => $labels,
        'datasets' => [
            [
                'label' => 'Revenue',
                'data' => $revenue,
                'backgroundColor' => 'rgba(255, 193, 7, 0.2)',
                'borderColor' => 'rgba(255, 193, 7, 1)',
                'borderWidth' => 2,
                'fill' => true
            ],
            [
                'label' => 'Expenses',
                'data' => $expenses,
                'backgroundColor' => 'rgba(220, 53, 69, 0.2)',
                'borderColor' => 'rgba(220, 53, 69, 1)',
                'borderWidth' => 2,
                'fill' => true
            ]
        ]
    ];
}

/**
 * Get business segments data for pie chart
 */
function getBusinessSegmentsData() {
    $currentUser = getCurrentUser();
    $userCondition = '';
    $params = [];
    
    if ($currentUser['role'] !== 'admin') {
        $userCondition = ' AND s.created_by = ?';
        $params[] = $currentUser['id'];
    }
    
    $query = "
        SELECT 
            bs.name as segment_name,
            COALESCE(SUM(s.amount), 0) as revenue
        FROM business_segments bs
        LEFT JOIN sales s ON bs.id = s.segment_id {$userCondition}
        WHERE bs.status = 'active'
        GROUP BY bs.id, bs.name
        HAVING revenue > 0
        ORDER BY revenue DESC
    ";
    
    $data = fetchAll($query, $params);
    
    $labels = array_column($data, 'segment_name');
    $amounts = array_map(function($row) { return (float)$row['revenue']; }, $data);
    
    $colors = [
        'rgba(30, 58, 95, 1)',   // Primary Navy
        'rgba(255, 193, 7, 1)',  // Yellow
        'rgba(40, 167, 69, 1)',  // Success
        'rgba(23, 162, 184, 1)', // Info
        'rgba(220, 53, 69, 1)'   // Danger
    ];
    
    return [
        'labels' => $labels,
        'datasets' => [
            [
                'data' => $amounts,
                'backgroundColor' => array_slice($colors, 0, count($labels)),
                'borderColor' => '#fff',
                'borderWidth' => 2
            ]
        ]
    ];
}

/**
 * Get monthly trends data
 */
function getMonthlyTrendsData($year) {
    $currentUser = getCurrentUser();
    $userCondition = '';
    $params = [$year];
    
    if ($currentUser['role'] !== 'admin') {
        $userCondition = ' AND created_by = ?';
        $params[] = $currentUser['id'];
    }
    
    $query = "
        SELECT 
            MONTH(transaction_date) as month,
            MONTHNAME(transaction_date) as month_name,
            SUM(CASE WHEN type = 'revenue' THEN amount ELSE 0 END) as revenue,
            SUM(CASE WHEN type = 'expense' THEN amount ELSE 0 END) as expenses
        FROM (
            SELECT 'revenue' as type, amount, sale_date as transaction_date, created_by FROM sales
            UNION ALL
            SELECT 'expense' as type, amount, expense_date as transaction_date, created_by FROM expenses
        ) t
        WHERE YEAR(transaction_date) = ? {$userCondition}
        GROUP BY MONTH(transaction_date), MONTHNAME(transaction_date)
        ORDER BY MONTH(transaction_date)
    ";
    
    $data = fetchAll($query, $params);
    
    // Fill in missing months with zeros
    $months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
    $revenue = array_fill(0, 12, 0);
    $expenses = array_fill(0, 12, 0);
    
    foreach ($data as $row) {
        $monthIndex = (int)$row['month'] - 1;
        $revenue[$monthIndex] = (float)$row['revenue'];
        $expenses[$monthIndex] = (float)$row['expenses'];
    }
    
    return [
        'labels' => $months,
        'datasets' => [
            [
                'label' => 'Revenue',
                'data' => $revenue,
                'borderColor' => 'rgba(30, 58, 95, 1)',
                'backgroundColor' => 'rgba(30, 58, 95, 0.1)',
                'tension' => 0.4,
                'fill' => true
            ],
            [
                'label' => 'Profit',
                'data' => array_map(function($r, $e) { return $r - $e; }, $revenue, $expenses),
                'borderColor' => 'rgba(40, 167, 69, 1)',
                'backgroundColor' => 'rgba(40, 167, 69, 0.1)',
                'tension' => 0.4,
                'fill' => true
            ]
        ]
    ];
}

/**
 * Get cash flow data for bar chart
 */
function getCashFlowData() {
    $currentUser = getCurrentUser();
    $userCondition = '';
    $params = [];
    
    if ($currentUser['role'] !== 'admin') {
        $userCondition = ' AND created_by = ?';
        $params[] = $currentUser['id'];
    }
    
    // Get last 4 weeks of data
    $query = "
        SELECT 
            WEEK(transaction_date) as week_num,
            SUM(CASE WHEN type = 'revenue' THEN amount ELSE -amount END) as net_flow
        FROM (
            SELECT 'revenue' as type, amount, sale_date as transaction_date, created_by FROM sales
            WHERE sale_date >= DATE_SUB(CURDATE(), INTERVAL 4 WEEK)
            UNION ALL
            SELECT 'expense' as type, amount, expense_date as transaction_date, created_by FROM expenses
            WHERE expense_date >= DATE_SUB(CURDATE(), INTERVAL 4 WEEK)
        ) t
        WHERE 1=1 {$userCondition}
        GROUP BY WEEK(transaction_date)
        ORDER BY WEEK(transaction_date) DESC
        LIMIT 4
    ";
    
    $data = fetchAll($query, $params);
    $data = array_reverse($data); // Show oldest to newest
    
    $labels = [];
    $cashFlow = [];
    $colors = [];
    
    for ($i = 0; $i < count($data); $i++) {
        $labels[] = 'Week ' . ($i + 1);
        $amount = (float)$data[$i]['net_flow'];
        $cashFlow[] = $amount;
        $colors[] = $amount >= 0 ? 'rgba(40, 167, 69, 1)' : 'rgba(220, 53, 69, 1)';
    }
    
    return [
        'labels' => $labels,
        'datasets' => [
            [
                'label' => 'Net Cash Flow',
                'data' => $cashFlow,
                'backgroundColor' => $colors,
                'borderColor' => $colors,
                'borderWidth' => 1
            ]
        ]
    ];
}

/**
 * Get top products/services data
 */
function getTopProductsData() {
    $currentUser = getCurrentUser();
    $userCondition = '';
    $params = [];
    
    if ($currentUser['role'] !== 'admin') {
        $userCondition = ' AND created_by = ?';
        $params[] = $currentUser['id'];
    }
    
    $query = "
        SELECT 
            title,
            SUM(amount) as total_revenue,
            COUNT(*) as sales_count
        FROM sales 
        WHERE sale_date >= DATE_SUB(CURDATE(), INTERVAL 30 DAY) {$userCondition}
        GROUP BY title
        ORDER BY total_revenue DESC
        LIMIT 5
    ";
    
    $data = fetchAll($query, $params);
    
    $labels = array_column($data, 'title');
    $revenues = array_map(function($row) { return (float)$row['total_revenue']; }, $data);
    
    $colors = [
        'rgba(30, 58, 95, 1)',
        'rgba(255, 193, 7, 1)',
        'rgba(40, 167, 69, 1)',
        'rgba(23, 162, 184, 1)',
        'rgba(220, 53, 69, 1)'
    ];
    
    return [
        'labels' => $labels,
        'datasets' => [
            [
                'label' => 'Revenue',
                'data' => $revenues,
                'backgroundColor' => array_slice($colors, 0, count($labels)),
                'borderColor' => '#fff',
                'borderWidth' => 1
            ]
        ]
    ];
}

/**
 * Get dashboard statistics summary
 */
function getDashboardStatsData() {
    $currentUser = getCurrentUser();
    $stats = getDashboardStats($currentUser['role'] !== 'admin' ? $currentUser['id'] : null);
    
    // Calculate growth rates (mock data for now - implement actual calculation)
    $growthRates = [
        'revenue_growth' => 12.5,
        'expense_growth' => -5.2,
        'profit_growth' => 18.3,
        'transaction_growth' => 8.1
    ];
    
    return array_merge($stats, $growthRates);
}
?>