/**
 * Fingerprint manager — builds headers that mimic the Codex Desktop client.
 *
 * Based on Codex source: applyDesktopAuthHeaders / buildDesktopUserAgent
 */

import { getConfig, getFingerprint } from "../config.js";
import { extractChatGptAccountId } from "../auth/jwt-utils.js";

/**
 * Reorder headers according to the fingerprint header_order config.
 * Keys not in the order list are appended at the end.
 */
function orderHeaders(
  headers: Record<string, string>,
  order: string[],
): Record<string, string> {
  const ordered: Record<string, string> = {};
  for (const key of order) {
    if (key in headers) {
      ordered[key] = headers[key];
    }
  }
  for (const key of Object.keys(headers)) {
    if (!(key in ordered)) {
      ordered[key] = headers[key];
    }
  }
  return ordered;
}

/**
 * Build the dynamic sec-ch-ua value based on chromium_version from config.
 */
function buildSecChUa(): string {
  const cv = getConfig().client.chromium_version;
  return `"Chromium";v="${cv}", "Not:A-Brand";v="24"`;
}

/**
 * Build the User-Agent string from config + fingerprint template.
 */
function buildUserAgent(): string {
  const config = getConfig();
  const fp = getFingerprint();
  return fp.user_agent_template
    .replace("{version}", config.client.app_version)
    .replace("{platform}", config.client.platform)
    .replace("{arch}", config.client.arch);
}

/**
 * Build raw headers (unordered) with all fingerprint fields.
 * Does NOT include Authorization, ChatGPT-Account-Id, Content-Type, or Accept.
 */
function buildRawDefaultHeaders(): Record<string, string> {
  const fp = getFingerprint();
  const raw: Record<string, string> = {};

  raw["User-Agent"] = buildUserAgent();
  raw["sec-ch-ua"] = buildSecChUa();

  // Add static default headers (Accept-Encoding, Accept-Language, sec-fetch-*, etc.)
  if (fp.default_headers) {
    for (const [key, value] of Object.entries(fp.default_headers)) {
      raw[key] = value;
    }
  }

  return raw;
}

/**
 * Build anonymous headers for non-authenticated requests (OAuth, appcast, etc.).
 * Contains User-Agent, sec-ch-ua, Accept-Encoding, Accept-Language, sec-fetch-*
 * but NOT Authorization, Cookie, or ChatGPT-Account-Id.
 * Headers are ordered per fingerprint config.
 */
export function buildAnonymousHeaders(): Record<string, string> {
  const fp = getFingerprint();
  const raw = buildRawDefaultHeaders();
  return orderHeaders(raw, fp.header_order);
}

export function buildHeaders(
  token: string,
  accountId?: string | null,
): Record<string, string> {
  const config = getConfig();
  const fp = getFingerprint();
  const raw: Record<string, string> = {};

  raw["Authorization"] = `Bearer ${token}`;

  const acctId = accountId ?? extractChatGptAccountId(token);
  if (acctId) raw["ChatGPT-Account-Id"] = acctId;

  raw["originator"] = config.client.originator;

  // Merge default headers (User-Agent, sec-ch-ua, Accept-Encoding, etc.)
  const defaults = buildRawDefaultHeaders();
  for (const [key, value] of Object.entries(defaults)) {
    raw[key] = value;
  }

  return orderHeaders(raw, fp.header_order);
}

export function buildHeadersWithContentType(
  token: string,
  accountId?: string | null,
): Record<string, string> {
  const fp = getFingerprint();
  const config = getConfig();
  const raw: Record<string, string> = {};

  raw["Authorization"] = `Bearer ${token}`;

  const acctId = accountId ?? extractChatGptAccountId(token);
  if (acctId) raw["ChatGPT-Account-Id"] = acctId;

  raw["originator"] = config.client.originator;

  // Merge default headers
  const defaults = buildRawDefaultHeaders();
  for (const [key, value] of Object.entries(defaults)) {
    raw[key] = value;
  }

  raw["Content-Type"] = "application/json";

  // Single orderHeaders call (no double-sorting)
  return orderHeaders(raw, fp.header_order);
}