<?php
header('Content-Type: application/json');
require_once __DIR__ . '/../db/config.php';

// --- Configuration ---
$symbol = $_GET['symbol'] ?? 'BTCUSDT';
$time_window_minutes = 30;
$crash_threshold = -20.0; // -20%
$pump_threshold = 100.0;  // +100%

// --- Response Structure ---
$response = [
    'status' => 'Nominal',
    'symbol' => $symbol,
    'change_percent' => 0,
    'details' => 'No significant price change detected.'
];

try {
    $pdo = db();
    
    // 1. Get the most recent price
    $stmt_latest = $pdo->prepare("SELECT price FROM price_history WHERE symbol = :symbol ORDER BY timestamp DESC LIMIT 1");
    $stmt_latest->execute([':symbol' => $symbol]);
    $latest_price_row = $stmt_latest->fetch(PDO::FETCH_ASSOC);
    
    if (!$latest_price_row) {
        $response['details'] = 'No recent price data available for this symbol.';
        echo json_encode($response);
        exit;
    }
    $latest_price = $latest_price_row['price'];

    // 2. Get the oldest price from the 30-minute window
    $stmt_oldest = $pdo->prepare(
        "SELECT price FROM price_history 
         WHERE symbol = :symbol AND timestamp >= NOW() - INTERVAL :minutes MINUTE 
         ORDER BY timestamp ASC LIMIT 1"
    );
    $stmt_oldest->execute([':symbol' => $symbol, ':minutes' => $time_window_minutes]);
    $oldest_price_row = $stmt_oldest->fetch(PDO::FETCH_ASSOC);

    if (!$oldest_price_row) {
        $response['details'] = 'Not enough historical data in the last 30 minutes to calculate change.';
        echo json_encode($response);
        exit;
    }
    $oldest_price = $oldest_price_row['price'];

    // 3. Calculate percentage change
    if ($oldest_price > 0) {
        $change_percent = (($latest_price - $oldest_price) / $oldest_price) * 100;
        $response['change_percent'] = round($change_percent, 2);
    } else {
        $change_percent = 0;
    }

    // 4. Determine status
    if ($change_percent <= $crash_threshold) {
        $response['status'] = 'Crash Alert';
        $response['details'] = "Price dropped by " . $response['change_percent'] . "% in the last $time_window_minutes minutes.";
    } elseif ($change_percent >= $pump_threshold) {
        $response['status'] = 'Pump Alert';
        $response['details'] = "Price surged by " . $response['change_percent'] . "% in the last $time_window_minutes minutes.";
    } else {
        $response['details'] = "Price change of " . $response['change_percent'] . "% is within normal limits.";
    }

} catch (PDOException $e) {
    http_response_code(500);
    $response['status'] = 'Error';
    $response['details'] = 'Database error: ' . $e->getMessage();
}

echo json_encode($response);