<?php
declare(strict_types=1);

session_start();

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

function tleChecksum(string $line): int {
    $sum = 0;
    for ($i = 0; $i < 68; $i++) {
        $c = $line[$i];
        if (ctype_digit($c)) {
            $sum += (int)$c;
        } elseif ($c === '-') {
            $sum += 1;
        }
    }
    return $sum % 10;
}

function tleExp(float $val): string {
    if (abs($val) < 1e-99) {
        return ' 00000-0';
    }

    $sign = $val >= 0 ? '+' : '-';
    $abs = abs($val);
    $exp = (int)floor(log10($abs)) + 1;
    $mantissa = (int)round($abs / pow(10, $exp) * 1e5);
    if ($mantissa >= 100000) {
        $mantissa = 10000;
        $exp++;
    }

    $expSign = $exp >= 0 ? '+' : '-';
    return sprintf('%s%05d%s%d', $sign, $mantissa, $expSign, abs($exp));
}

function tleMmDot(float $val): string {
    $sign = $val >= 0 ? ' ' : '-';
    return sprintf('%s.%08d', $sign, (int)round(abs($val) * 1e8));
}

function tleEpoch(string $epochStr): string {
    $dt = new DateTimeImmutable($epochStr, new DateTimeZone('UTC'));
    $yy = (int)$dt->format('Y') % 100;
    $jan1 = new DateTimeImmutable($dt->format('Y') . '-01-01 00:00:00', new DateTimeZone('UTC'));
    $secs = (float)$dt->format('U') - (float)$jan1->format('U');
    $day = $secs / 86400.0 + 1.0;
    return sprintf('%02d%012.8f', $yy, $day);
}

function tleIntlDesig(?string $objectId): string {
    if (!$objectId) {
        return str_repeat(' ', 8);
    }

    if (preg_match('/^(\d{4})-(\d+)([A-Z]*)$/i', trim($objectId), $m)) {
        $yy = substr($m[1], 2, 2);
        $launch = str_pad($m[2], 3, '0', STR_PAD_LEFT);
        $piece = str_pad(strtoupper($m[3]), 3, ' ', STR_PAD_RIGHT);
        return substr(str_pad($yy . $launch . $piece, 8, ' '), 0, 8);
    }

    return str_pad(substr($objectId, 0, 8), 8);
}

function buildLine1(array $sat, array $tle): string {
    $norad = (int)$sat['norad_cat_id'];
    $class = in_array($sat['classification_type'] ?? '', ['U', 'C', 'S'], true)
        ? $sat['classification_type']
        : 'U';

    $line = sprintf(
        '1 %05d%1s %-8s %14s %10s %8s %8s %1d %4d',
        $norad,
        $class,
        tleIntlDesig($sat['object_id'] ?? null),
        tleEpoch((string)$tle['epoch']),
        tleMmDot((float)($tle['mean_motion_dot'] ?? 0)),
        tleExp((float)($tle['mean_motion_ddot'] ?? 0)),
        tleExp((float)($tle['bstar'] ?? 0)),
        (int)($tle['ephemeris_type'] ?? 0),
        (int)($tle['element_set_no'] ?? 0)
    );

    $line = str_pad($line, 68);
    return $line . tleChecksum($line);
}

function buildLine2(array $sat, array $tle): string {
    $norad = (int)$sat['norad_cat_id'];
    $ecc = (float)($tle['eccentricity'] ?? 0);
    $eccStr = substr(sprintf('%.7f', $ecc), 2);

    $line = sprintf(
        '2 %05d %8.4f %8.4f %7s %8.4f %8.4f %11.8f%5d',
        $norad,
        (float)($tle['inclination'] ?? 0),
        (float)($tle['ra_of_asc_node'] ?? 0),
        $eccStr,
        (float)($tle['arg_of_pericenter'] ?? 0),
        (float)($tle['mean_anomaly'] ?? 0),
        (float)($tle['mean_motion'] ?? 0),
        (int)($tle['rev_at_epoch'] ?? 0)
    );

    $line = str_pad($line, 68);
    return $line . tleChecksum($line);
}

$userId = isset($_SESSION['user_id']) ? (int)$_SESSION['user_id'] : 0;
if ($userId <= 0) {
    http_response_code(401);
    echo json_encode(['error' => 'Nicht angemeldet.']);
    exit;
}

$requestedIds = array_values(array_filter(
    array_map('intval', explode(',', (string)($_GET['ids'] ?? ''))),
    static fn(int $id): bool => $id > 0
));

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

try {
    $dsn = sprintf(
        'mysql:host=%s;dbname=%s;charset=%s',
        $cfg['host'],
        $cfg['dbname'],
        $cfg['charset'] ?? 'utf8mb4'
    );
    $pdo = new PDO($dsn, $cfg['user'], $cfg['pass'], [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
    ]);
} catch (PDOException $e) {
    http_response_code(500);
    echo json_encode(['error' => 'DB-Verbindung fehlgeschlagen.']);
    exit;
}

$sql = "
    SELECT
        s.id,
        s.norad_cat_id,
        s.object_name,
        s.object_id,
        s.classification_type,
        us.is_favorite,
        t.epoch,
        t.mean_motion,
        t.eccentricity,
        t.inclination,
        t.ra_of_asc_node,
        t.arg_of_pericenter,
        t.mean_anomaly,
        t.ephemeris_type,
        t.element_set_no,
        t.rev_at_epoch,
        t.bstar,
        t.mean_motion_dot,
        t.mean_motion_ddot
    FROM app_user_satellites us
    INNER JOIN sat_satellites s
        ON s.id = us.satellite_id
    INNER JOIN sat_tle_current t
        ON t.satellite_id = s.id
    WHERE us.user_id = :user_id
      AND t.epoch IS NOT NULL
      AND t.mean_motion IS NOT NULL
";

$params = [':user_id' => $userId];
if ($requestedIds !== []) {
    $idPlaceholders = [];
    foreach ($requestedIds as $index => $noradId) {
        $placeholder = ':norad_' . $index;
        $idPlaceholders[] = $placeholder;
        $params[$placeholder] = $noradId;
    }
    $sql .= ' AND s.norad_cat_id IN (' . implode(', ', $idPlaceholders) . ')';
}

$sql .= ' ORDER BY us.is_favorite DESC, s.object_name ASC';

try {
    $stmt = $pdo->prepare($sql);
    $stmt->execute($params);
    $rows = $stmt->fetchAll();
} catch (PDOException $e) {
    http_response_code(500);
    echo json_encode(['error' => 'Abfrage fehlgeschlagen.']);
    exit;
}

$result = [];
foreach ($rows as $row) {
    $result[] = [
        'id' => (int)$row['id'],
        'norad_cat_id' => (int)$row['norad_cat_id'],
        'object_name' => (string)$row['object_name'],
        'object_id' => $row['object_id'] !== null ? (string)$row['object_id'] : null,
        'classification_type' => $row['classification_type'] !== null ? (string)$row['classification_type'] : null,
        'is_favorite' => (int)($row['is_favorite'] ?? 0) === 1,
        'epoch' => (string)$row['epoch'],
        'mean_motion' => (float)$row['mean_motion'],
        'eccentricity' => (float)$row['eccentricity'],
        'inclination' => (float)$row['inclination'],
        'ra_of_asc_node' => (float)$row['ra_of_asc_node'],
        'arg_of_pericenter' => (float)$row['arg_of_pericenter'],
        'mean_anomaly' => (float)$row['mean_anomaly'],
        'ephemeris_type' => (int)$row['ephemeris_type'],
        'element_set_no' => (int)$row['element_set_no'],
        'rev_at_epoch' => (int)$row['rev_at_epoch'],
        'bstar' => (float)$row['bstar'],
        'mean_motion_dot' => (float)$row['mean_motion_dot'],
        'mean_motion_ddot' => (float)$row['mean_motion_ddot'],
        'tle_line1' => buildLine1($row, $row),
        'tle_line2' => buildLine2($row, $row),
    ];
}

echo json_encode($result, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);