<?php
// Public read-only API for the dashboard page.
// GET api.php            → latest price + latest report per timeframe
// GET api.php?what=price → latest price only (cheap 2-second poll)
declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');
header('Cache-Control: no-store');

function fail(int $code, string $msg): never {
    http_response_code($code);
    echo json_encode(['ok' => false, 'error' => $msg]);
    exit;
}

if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
    fail(405, 'GET only');
}

$cfg = require __DIR__ . '/config.php';

$symbol = (string)($_GET['symbol'] ?? $cfg['symbols'][0]);
if (!in_array($symbol, $cfg['symbols'], true)) {
    fail(400, 'unknown symbol');
}
$what = (string)($_GET['what'] ?? 'all');

try {
    $pdo = new PDO($cfg['db_dsn'], $cfg['db_user'], $cfg['db_pass'], [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    ]);
} catch (PDOException $e) {
    fail(500, 'db unavailable');
}

$out = ['ok' => true, 'server_time' => gmdate('Y-m-d H:i:s')];

try {
    $st = $pdo->prepare(
        'SELECT price, prev_price, tick_at,
                TIMESTAMPDIFF(SECOND, tick_at, UTC_TIMESTAMP()) AS age_sec
         FROM live_price WHERE symbol = :s'
    );
    $st->execute([':s' => $symbol]);
    $row = $st->fetch(PDO::FETCH_ASSOC);
    $out['price'] = $row === false ? null : [
        'price' => (float)$row['price'],
        'prev_price' => $row['prev_price'] === null ? null : (float)$row['prev_price'],
        'tick_at' => $row['tick_at'],
        'age_sec' => (int)$row['age_sec'],
    ];

    if ($what !== 'price') {
        $st = $pdo->prepare(
            'SELECT r.timeframe, r.payload, r.updated_at,
                    TIMESTAMPDIFF(SECOND, r.updated_at, UTC_TIMESTAMP()) AS age_sec
             FROM signal_reports r
             JOIN (SELECT timeframe, MAX(id) AS mid
                   FROM signal_reports WHERE symbol = :s
                   GROUP BY timeframe) x ON x.mid = r.id'
        );
        $st->execute([':s' => $symbol]);
        $reports = [];
        foreach ($st->fetchAll(PDO::FETCH_ASSOC) as $r) {
            $p = json_decode((string)$r['payload'], true);
            if (is_array($p)) {
                $p['stored_at'] = $r['updated_at'];
                $p['age_sec'] = (int)$r['age_sec'];
                $reports[$r['timeframe']] = $p;
            }
        }
        $out['reports'] = $reports;
    }
} catch (PDOException $e) {
    error_log('api.php: ' . $e->getMessage());
    fail(500, 'db error');
}

echo json_encode($out, JSON_UNESCAPED_UNICODE);