import type { BrowserCookie } from "@umt/contracts";

// BR-2 凭据统一:站点账号里存的是 HTTP `Cookie:` 请求头串("a=1; b=2"),浏览器 profile 里是带域名/路径/期限的 Cookie 对象。
// 这里只做两者互转与比较;值是凭据,不打印、不进错误信息。

/** 注入时 Cookie 头串里没有期限信息:给 30 天,站点响应的 Set-Cookie 会按站点自己的期限覆盖 */
export const INJECTED_COOKIE_TTL_SEC = 30 * 24 * 3600;

/** "a=1; b=2" → [[a, 1], [b, 2]](同名后者覆盖;去掉空段与首尾空白) */
export function parseCookieHeader(header: string | null | undefined): Map<string, string> {
  const out = new Map<string, string>();
  for (const part of (header ?? "").split(";")) {
    const i = part.indexOf("=");
    if (i <= 0) continue;
    const name = part.slice(0, i).trim();
    if (!name || /[\s,;]/.test(name)) continue;
    out.set(name, part.slice(i + 1).trim());
  }
  return out;
}

/** Map → "a=1; b=2"(按名字排序,比较稳定) */
export function formatCookieHeader(jar: Map<string, string>): string {
  return [...jar.entries()]
    .sort(([a], [b]) => (a < b ? -1 : a > b ? 1 : 0))
    .map(([k, v]) => `${k}=${v}`)
    .join("; ");
}

/** 多个 Cookie 头串合并,靠后的优先(用户填的 + 自动登录得到的会话 Cookie → 会话 Cookie 覆盖同名项) */
export function mergeCookieHeaders(...headers: (string | null | undefined)[]): string | null {
  const jar = new Map<string, string>();
  for (const h of headers) for (const [k, v] of parseCookieHeader(h)) jar.set(k, v);
  return jar.size ? formatCookieHeader(jar) : null;
}

/** 两个 Cookie 头串是否等价(忽略顺序与空白) */
export function sameCookieHeader(a: string | null | undefined, b: string | null | undefined): boolean {
  const x = parseCookieHeader(a);
  const y = parseCookieHeader(b);
  if (x.size !== y.size) return false;
  for (const [k, v] of x) if (y.get(k) !== v) return false;
  return true;
}

/** 站点地址 → 注入用 Cookie 对象:域名 = 站点主机(host-only),路径 /,https 站点标 secure */
export function cookiesFromHeader(
  header: string,
  siteUrl: string,
  nowSec = Math.floor(Date.now() / 1000),
): BrowserCookie[] {
  const u = new URL(siteUrl);
  const secure = u.protocol === "https:";
  return [...parseCookieHeader(header)].map(([name, value]) => ({
    name,
    value,
    domain: u.hostname,
    path: "/",
    expires: nowSec + INJECTED_COOKIE_TTL_SEC,
    httpOnly: false,
    secure,
    sameSite: "Lax" as const,
  }));
}

/** Cookie 的 domain 是否作用于该主机(host-only 精确匹配;.根域 匹配子域) */
export function cookieDomainMatches(cookieDomain: string, host: string): boolean {
  const d = cookieDomain.toLowerCase().replace(/^\./, "");
  const h = host.toLowerCase();
  return h === d || h.endsWith(`.${d}`);
}

/**
 * 浏览器读回的 Cookie → 站点 Cookie 头串。只取作用于站点主机、路径为根(或站点路径前缀)且未过期的,
 * 其它域名(统计、CDN、第三方)的 Cookie 一律丢弃(回写只对该站域名)。
 */
export function headerFromCookies(
  cookies: readonly BrowserCookie[],
  siteUrl: string,
  nowSec = Math.floor(Date.now() / 1000),
): string | null {
  const u = new URL(siteUrl);
  const jar = new Map<string, { v: string; specific: number }>();
  for (const c of cookies) {
    if (!cookieDomainMatches(c.domain, u.hostname)) continue;
    if (c.expires !== undefined && c.expires > 0 && c.expires <= nowSec) continue;
    const path = c.path || "/";
    if (!u.pathname.startsWith(path)) continue;
    // 同名多条:更具体的域名 / 路径优先(与浏览器发送顺序一致)
    const specific = c.domain.replace(/^\./, "").length * 1000 + path.length;
    const prev = jar.get(c.name);
    if (!prev || specific >= prev.specific) jar.set(c.name, { v: c.value, specific });
  }
  if (!jar.size) return null;
  return formatCookieHeader(new Map([...jar].map(([k, x]) => [k, x.v])));
}