<?php
declare(strict_types=1);

/**
 * สาธารณะ — ระบบ "รหัสผู้เล่น" สำหรับ sync โปรไฟล์ข้าม browser/เครื่อง (Guest)
 * ผูกกับ jdPlayerKey (guest account: providerUserId = key) เหมือน player-coins.php
 *
 * GET  ?action=code&playerKey=...&displayName=...&agentId=...
 *        → คืนรหัสของบัญชีนี้ (สร้างถ้ายังไม่มี) + อัปเดตชื่อ/agent ฝั่ง server
 *        { ok, code, codeDisplay }
 *
 * POST { action:'redeem', code }
 *        → ดึงโปรไฟล์จากรหัส → คืน playerKey + ข้อมูลโปรไฟล์ของบัญชีนั้น
 *        { ok, playerKey, coins, colorThemeIndex, skinToneIndex, displayName, agentId }
 *
 * รหัสที่ไม่ถูกใช้เกิน 30 วัน → หมดอายุ (ลบแบบ lazy ตอนมีการเรียก)
 */
require __DIR__ . '/_common.php';

const LINK_CODE_ALPHABET = 'ABCDEFGHJKMNPQRSTUVWXYZ23456789'; // ตัด 0 O 1 I L ที่กำกวม
const LINK_CODE_LEN = 8;
const LINK_CODE_TTL_DAYS = 30;

function valid_player_key(string $key): bool
{
    return (bool)preg_match('/^[a-zA-Z0-9_-]{8,128}$/', $key);
}

function sanitize_display_name(string $raw): string
{
    $s = trim($raw);
    $s = preg_replace('/[\x00-\x1f\x7f]/u', '', $s) ?? '';
    if (function_exists('mb_substr')) {
        $s = mb_substr($s, 0, 24);
    } else {
        $s = substr($s, 0, 24);
    }
    return $s;
}

function sanitize_agent_id(string $raw): string
{
    return preg_match('/^\d{6}$/', trim($raw)) ? trim($raw) : '';
}

function normalize_code(string $raw): string
{
    $s = strtoupper(trim($raw));
    $s = str_replace([' ', '-', '_'], '', $s);
    // กันสับสน: ผู้ใช้พิมพ์ 0/O/1/I/L → map เข้าตัวที่ใช้จริง
    $s = strtr($s, ['0' => 'O', '1' => 'I']);
    return $s;
}

function generate_code(): string
{
    $n = strlen(LINK_CODE_ALPHABET);
    $out = '';
    for ($i = 0; $i < LINK_CODE_LEN; $i++) {
        $out .= LINK_CODE_ALPHABET[random_int(0, $n - 1)];
    }
    return $out;
}

function format_code_display(string $code): string
{
    if (strlen($code) === 8) {
        return substr($code, 0, 4) . '-' . substr($code, 4, 4);
    }
    return $code;
}

function code_is_expired($lastUsedAt): bool
{
    if (!$lastUsedAt) {
        return false;
    }
    $ts = strtotime((string)$lastUsedAt);
    if ($ts === false) {
        return false;
    }
    return (time() - $ts) > (LINK_CODE_TTL_DAYS * 86400);
}

/** ลบรหัสที่หมดอายุออกจากทุกบัญชี (lazy GC) — แก้ใน $store ตรง ๆ */
function gc_expired_codes(array &$store): bool
{
    $changed = false;
    foreach ($store['accounts'] as $i => $a) {
        if (!empty($a['linkCode']) && code_is_expired($a['linkCodeLastUsedAt'] ?? null)) {
            unset($store['accounts'][$i]['linkCode']);
            $store['accounts'][$i]['linkCodeLastUsedAt'] = null;
            $changed = true;
        }
    }
    return $changed;
}

function code_in_use(array $store, string $code, ?string $exceptKey = null): bool
{
    foreach ($store['accounts'] as $a) {
        if (($a['linkCode'] ?? '') !== $code) {
            continue;
        }
        if ($exceptKey !== null && ($a['providerUserId'] ?? '') === $exceptKey) {
            continue;
        }
        if (!code_is_expired($a['linkCodeLastUsedAt'] ?? null)) {
            return true;
        }
    }
    return false;
}

function profile_payload(array $a): array
{
    return [
        'playerKey' => $a['providerUserId'] ?? '',
        'coins' => max(0, (int)($a['coins'] ?? 0)),
        'colorThemeIndex' => ($v = (int)($a['lobbyColorThemeIndex'] ?? 0)) >= 1 && $v <= 8 ? $v : null,
        'skinToneIndex' => ($s = (int)($a['lobbySkinToneIndex'] ?? 0)) >= 1 && $s <= 3 ? $s : null,
        'displayName' => (string)($a['displayName'] ?? ''),
        'agentId' => (string)($a['agentDisplayId'] ?? ''),
    ];
}

$method = $_SERVER['REQUEST_METHOD'] ?? 'GET';

if ($method === 'GET') {
    $action = (string)($_GET['action'] ?? 'code');
    if ($action !== 'code') {
        json_response(['ok' => false, 'error' => 'unknown action'], 400);
    }
    $key = trim((string)($_GET['playerKey'] ?? ''));
    if (!valid_player_key($key)) {
        json_response(['ok' => false, 'error' => 'playerKey ต้องยาว 8–128 (a-z 0-9 _ -)'], 400);
    }
    $displayName = sanitize_display_name((string)($_GET['displayName'] ?? ''));
    $agentId = sanitize_agent_id((string)($_GET['agentId'] ?? ''));

    $store = read_store();
    gc_expired_codes($store);
    $now = gmdate('c');
    $idx = -1;
    foreach ($store['accounts'] as $i => $a) {
        if (($a['loginType'] ?? '') === 'guest' && ($a['providerUserId'] ?? '') === $key) {
            $idx = $i;
            break;
        }
    }
    if ($idx < 0) {
        $store['accounts'][] = [
            'id' => new_id(),
            'email' => '',
            'displayName' => $displayName,
            'loginType' => 'guest',
            'providerUserId' => $key,
            'notes' => 'auto: player-link',
            'blocked' => false,
            'coins' => 0,
            'agentDisplayId' => $agentId,
            'createdAt' => $now,
            'updatedAt' => $now,
        ];
        $idx = count($store['accounts']) - 1;
    } else {
        if ($displayName !== '') {
            $store['accounts'][$idx]['displayName'] = $displayName;
        }
        if ($agentId !== '') {
            $store['accounts'][$idx]['agentDisplayId'] = $agentId;
        }
        $store['accounts'][$idx]['updatedAt'] = $now;
    }

    $code = (string)($store['accounts'][$idx]['linkCode'] ?? '');
    if ($code === '' || code_is_expired($store['accounts'][$idx]['linkCodeLastUsedAt'] ?? null)) {
        do {
            $code = generate_code();
        } while (code_in_use($store, $code, $key));
        $store['accounts'][$idx]['linkCode'] = $code;
    }
    $store['accounts'][$idx]['linkCodeLastUsedAt'] = $now;

    if (!write_store($store)) {
        json_response(['ok' => false, 'error' => 'สร้างรหัสไม่สำเร็จ'], 500);
    }
    json_response(['ok' => true, 'code' => $code, 'codeDisplay' => format_code_display($code)]);
}

if ($method === 'POST') {
    $body = require_json_body();
    $action = (string)($body['action'] ?? 'redeem');
    if ($action !== 'redeem') {
        json_response(['ok' => false, 'error' => 'unknown action'], 400);
    }
    $code = normalize_code((string)($body['code'] ?? ''));
    if (!preg_match('/^[A-Z2-9]{' . LINK_CODE_LEN . '}$/', $code)) {
        json_response(['ok' => false, 'error' => 'รูปแบบรหัสไม่ถูกต้อง'], 400);
    }

    $store = read_store();
    $sweep = gc_expired_codes($store);
    $now = gmdate('c');
    $found = -1;
    foreach ($store['accounts'] as $i => $a) {
        if (($a['linkCode'] ?? '') === $code && !code_is_expired($a['linkCodeLastUsedAt'] ?? null)) {
            $found = $i;
            break;
        }
    }
    if ($found < 0) {
        if ($sweep) {
            write_store($store);
        }
        json_response(['ok' => false, 'error' => 'ไม่พบรหัสนี้ หรือรหัสหมดอายุแล้ว'], 404);
    }

    $store['accounts'][$found]['linkCodeLastUsedAt'] = $now;
    $store['accounts'][$found]['updatedAt'] = $now;
    write_store($store);

    $payload = profile_payload($store['accounts'][$found]);
    $payload['ok'] = true;
    json_response($payload);
}

json_response(['ok' => false, 'error' => 'Use GET or POST'], 405);