<?php
header('Content-Type: application/json');

require_once __DIR__ . '/../db/config.php';

// --- Parameters ---
// Example: /api/analysis.php?symbol=BTCUSDT&indicator=sma&period=20
$symbol = $_GET['symbol'] ?? 'BTCUSDT';
$indicator = $_GET['indicator'] ?? 'sma';
$period = (int)($_GET['period'] ?? 20);

if ($period <= 0) {
    echo json_encode(['error' => 'Period must be a positive integer.']);
    exit;
}

function calculate_sma($symbol, $period) {
    $pdo = db();
    
    // Fetch the last 'period' number of closing prices for the given symbol, most recent first.
    $stmt = $pdo->prepare(
        "SELECT close FROM candlestick_data 
         WHERE symbol = :symbol 
         ORDER BY timestamp DESC 
         LIMIT :period"
    );
    
    $stmt->bindParam(':symbol', $symbol, PDO::PARAM_STR);
    $stmt->bindParam(':period', $period, PDO::PARAM_INT);
    
    $stmt->execute();
    
    $closes = $stmt->fetchAll(PDO::FETCH_COLUMN);
    
    if (count($closes) < $period) {
        return null; // Not enough data to calculate SMA
    }
    
    $sum = array_sum($closes);
    $sma = $sum / $period;
    
    return $sma;
}

$result = null;
if (strtolower($indicator) === 'sma') {
    $result = calculate_sma($symbol, $period);
} else {
    echo json_encode(['error' => 'Invalid indicator specified.']);
    exit;
}

$response = [
    'symbol' => $symbol,
    'indicator' => 'SMA',
    'period' => $period,
    'value' => $result,
    'timestamp' => time()
];

echo json_encode($response);