<?php
/**
 * System-wide alerts include
 * 
 * Include this file in data pages to display conditional alerts.
 * Expects $value array to be populated from items.php or shared endpoint.
 * 
 * Usage: require __DIR__ . '/../includes/alerts.php';
 */

$alerts = [];

// ============================================================================
// Database Connection for Alerts (singleton)
// ============================================================================
function getAlertConnection() {
    static $connection = null;
    
    if ($connection === null) {
        $connection = mysqli_connect('192.168.0.16', 'lasucaai', 'is413#dfslw', 'controls');
        if ($connection) {
            mysqli_set_charset($connection, 'utf8mb4');
            
            // Create tables if not exists
            $createLogTable = "CREATE TABLE IF NOT EXISTS alert_log (
                id INT AUTO_INCREMENT PRIMARY KEY,
                alert_type VARCHAR(50) NOT NULL,
                alert_tag VARCHAR(100) NOT NULL,
                alert_value DECIMAL(18,4) NULL,
                threshold_value DECIMAL(18,4) NULL,
                alert_message VARCHAR(500) NOT NULL,
                source_page VARCHAR(255) NULL,
                logged_at DATETIME DEFAULT CURRENT_TIMESTAMP,
                INDEX idx_alert_type (alert_type),
                INDEX idx_alert_tag (alert_tag),
                INDEX idx_logged_at (logged_at)
            )";
            mysqli_query($connection, $createLogTable);
            
            // Create throttle table to track last log time per alert
            $createThrottleTable = "CREATE TABLE IF NOT EXISTS alert_throttle (
                alert_key VARCHAR(150) PRIMARY KEY,
                last_logged DATETIME NOT NULL,
                INDEX idx_last_logged (last_logged)
            )";
            mysqli_query($connection, $createThrottleTable);
            
            // Create condition state table to track duration
            $createStateTable = "CREATE TABLE IF NOT EXISTS alert_condition_state (
                alert_key VARCHAR(150) PRIMARY KEY,
                condition_started DATETIME NOT NULL,
                last_seen DATETIME NOT NULL,
                INDEX idx_last_seen (last_seen)
            )";
            mysqli_query($connection, $createStateTable);
        }
    }
    
    return $connection;
}

// ============================================================================
// Check if condition has persisted for required duration (in seconds)
// Returns true if condition has been active for >= duration seconds
// ============================================================================
function checkAlertDuration($alertKey, $conditionMet, $durationSeconds = 0) {
    if ($durationSeconds <= 0) {
        // No duration requirement - trigger immediately
        return $conditionMet;
    }
    
    $conn = getAlertConnection();
    if (!$conn) {
        return $conditionMet; // Fallback to immediate if no DB
    }
    
    $now = date('Y-m-d H:i:s');
    
    if ($conditionMet) {
        // Condition is currently true - check/update state
        $stmt = mysqli_prepare($conn, 
            "SELECT condition_started FROM alert_condition_state WHERE alert_key = ?"
        );
        
        if ($stmt) {
            mysqli_stmt_bind_param($stmt, 's', $alertKey);
            mysqli_stmt_execute($stmt);
            $result = mysqli_stmt_get_result($stmt);
            $row = mysqli_fetch_assoc($result);
            mysqli_stmt_close($stmt);
            
            if ($row) {
                // Condition already being tracked - update last_seen
                $updateStmt = mysqli_prepare($conn,
                    "UPDATE alert_condition_state SET last_seen = ? WHERE alert_key = ?"
                );
                if ($updateStmt) {
                    mysqli_stmt_bind_param($updateStmt, 'ss', $now, $alertKey);
                    mysqli_stmt_execute($updateStmt);
                    mysqli_stmt_close($updateStmt);
                }
                
                // Check if duration has been met
                $started = strtotime($row['condition_started']);
                $elapsed = time() - $started;
                
                return $elapsed >= $durationSeconds;
            } else {
                // First time seeing this condition - start tracking
                $insertStmt = mysqli_prepare($conn,
                    "INSERT INTO alert_condition_state (alert_key, condition_started, last_seen) 
                     VALUES (?, ?, ?)"
                );
                if ($insertStmt) {
                    mysqli_stmt_bind_param($insertStmt, 'sss', $alertKey, $now, $now);
                    mysqli_stmt_execute($insertStmt);
                    mysqli_stmt_close($insertStmt);
                }
                
                return false; // Just started, duration not met yet
            }
        }
    } else {
        // Condition is false - clear the tracking state
        $deleteStmt = mysqli_prepare($conn,
            "DELETE FROM alert_condition_state WHERE alert_key = ?"
        );
        if ($deleteStmt) {
            mysqli_stmt_bind_param($deleteStmt, 's', $alertKey);
            mysqli_stmt_execute($deleteStmt);
            mysqli_stmt_close($deleteStmt);
        }
        
        return false;
    }
    
    return $conditionMet;
}

// ============================================================================
// Alert Logging Function (throttled to once per minute per alert)
// ============================================================================
function logAlert($alertType, $alertTag, $alertValue, $alertMessage, $threshold = null) {
    $conn = getAlertConnection();
    if (!$conn) {
        return;
    }
    
    try {
        // Check throttle - only log once per minute per alert type+tag
        $alertKey = $alertType . ':' . $alertTag;
        $throttleCheck = mysqli_prepare($conn,
            "SELECT last_logged FROM alert_throttle 
             WHERE alert_key = ? AND last_logged > DATE_SUB(NOW(), INTERVAL 1 MINUTE)"
        );
        
        if ($throttleCheck) {
            mysqli_stmt_bind_param($throttleCheck, 's', $alertKey);
            mysqli_stmt_execute($throttleCheck);
            $result = mysqli_stmt_get_result($throttleCheck);
            $recentLog = mysqli_fetch_assoc($result);
            mysqli_stmt_close($throttleCheck);
            
            if ($recentLog) {
                return; // Skip - already logged within last minute
            }
        }
        
        // Log the alert
        $sourcePage = $_SERVER['PHP_SELF'] ?? 'unknown';
        
        $stmt = mysqli_prepare($conn, 
            "INSERT INTO alert_log (alert_type, alert_tag, alert_value, threshold_value, alert_message, source_page) 
             VALUES (?, ?, ?, ?, ?, ?)"
        );
        
        if ($stmt) {
            mysqli_stmt_bind_param($stmt, 'ssddss', 
                $alertType, 
                $alertTag, 
                $alertValue, 
                $threshold, 
                $alertMessage, 
                $sourcePage
            );
            mysqli_stmt_execute($stmt);
            mysqli_stmt_close($stmt);
            
            // Update throttle timestamp
            $throttleUpdate = mysqli_prepare($conn,
                "INSERT INTO alert_throttle (alert_key, last_logged) VALUES (?, NOW())
                 ON DUPLICATE KEY UPDATE last_logged = NOW()"
            );
            if ($throttleUpdate) {
                mysqli_stmt_bind_param($throttleUpdate, 's', $alertKey);
                mysqli_stmt_execute($throttleUpdate);
                mysqli_stmt_close($throttleUpdate);
            }
        }
    } catch (Exception $e) {
        // Silent fail - logging should never break the page
        error_log('Alert logging failed: ' . $e->getMessage());
    }
}

// ============================================================================
// Alert Definitions (Now managed via alerts-admin.php)
// ============================================================================
// All alerts are now loaded from the alert_definitions table below.
// Use the admin panel at /alerts-admin.php to add, edit, or disable alerts.

// ============================================================================
// Database-Driven Alerts (from alerts-admin.php)
// ============================================================================
$alertConn = getAlertConnection();
if ($alertConn) {
    $defResult = mysqli_query($alertConn, 
        "SELECT * FROM alert_definitions WHERE is_active = 1"
    );
    
    if ($defResult) {
        while ($def = mysqli_fetch_assoc($defResult)) {
            $tagName = $def['tag_name'];
            $tagValue = $value[$tagName] ?? null;
            
            if ($tagValue === null) {
                continue; // Tag not found in current data
            }
            
            // Evaluate condition based on comparison operator
            $conditionMet = false;
            $threshold = floatval($def['threshold_value']);
            
            switch ($def['comparison']) {
                case '<':
                    $conditionMet = ($tagValue < $threshold);
                    break;
                case '<=':
                    $conditionMet = ($tagValue <= $threshold);
                    break;
                case '>':
                    $conditionMet = ($tagValue > $threshold);
                    break;
                case '>=':
                    $conditionMet = ($tagValue >= $threshold);
                    break;
                case '=':
                    $conditionMet = ($tagValue == $threshold);
                    break;
                case '!=':
                    $conditionMet = ($tagValue != $threshold);
                    break;
            }
            
            // Check duration requirement
            $alertKey = 'db_' . $def['id'] . '_' . $tagName;
            $durationMet = checkAlertDuration($alertKey, $conditionMet, intval($def['duration_seconds']));
            
            if ($durationMet) {
                // Build message from template
                $alertMessage = str_replace(
                    ['{value}', '{threshold}', '{tag}'],
                    [$tagValue, $threshold, $tagName],
                    $def['message_template']
                );
                
                $alerts[] = [
                    'type' => $def['alert_type'],
                    'icon' => $def['icon'],
                    'tag' => $tagName,
                    'value' => $tagValue,
                    'threshold' => $threshold,
                    'display' => $def['display_alert'],
                    'message' => htmlspecialchars($alertMessage, ENT_QUOTES, 'UTF-8')
                ];
                
                logAlert($def['alert_type'], $tagName, $tagValue, $alertMessage, $threshold);
            }
        }
    }
}

// ============================================================================
// Render Alerts (info alerts are logged only, not displayed)
// ============================================================================
if (!empty($alerts)) {
    foreach ($alerts as $alert) {
        // Skip info alerts - they are logged but not displayed
        if ($alert['type'] === 'info') {
            continue;
        }
        
        // Skip alerts with display=0 (database-driven alerts can disable display)
        if (isset($alert['display']) && !$alert['display']) {
            continue;
        }
        
        $bgColor = '#c62828'; // danger (red)
        if ($alert['type'] === 'warning') {
            $bgColor = '#f57c00'; // warning (orange)
        }
        
        echo '<tr>';
        echo '<td colspan="4" style="background: ' . $bgColor . '; color: white; text-align: center; font-weight: bold; padding: 10px;">';
        echo $alert['icon'] . ' ' . $alert['message'];
        echo '</td>';
        echo '</tr>';
    }
}