#!/usr/bin/env python3
"""
华为云 Token 动态网关
- 6小时缓存机制
- 支持内存扫描自动刷新
- HUAWEI_TOKEN 环境变量最高优先级
- Token 持久化到 /etc/huawei-gateway.env
- SSE 流式转发
- 连接池 (20 连接)
- 401 自动重试
- 兼容生产环境 (Waitress 32线程 / Gunicorn)
"""
import os
import re
import sys
import json
import time
import logging
import threading
import traceback
from concurrent.futures import ThreadPoolExecutor, as_completed

from flask import Flask, request, Response

# 尝试导入 requests，失败则给出明确提示
try:
    import requests
except ImportError:
    print("错误：缺少 requests 模块。请运行: pip install requests")
    sys.exit(1)

# ================= 配置 =================
CACHE_TTL = 19800          # 5.5 小时（安全线）
MAX_WORKERS = 8            # 内存扫描线程数
MAX_MEM_SEGMENT = 200 * 1024 * 1024  # 单段最大扫描 200MB
TOKEN_PATTERN = re.compile(b'Bearer ([A-Za-z0-9+/=_-]{100,})')
TARGET_HOST = 'tokenhub.developer.huaweicloud.com'

# ================= 请求体限制配置 =================
UPSTREAM_BODY_LIMIT = 1200 * 1024    # 上游 APIG 请求体限制 ~1.2MB (实测边界1260KB)
UPSTREAM_TIMEOUT_MIN = 60        # 小请求超时 60s
UPSTREAM_TIMEOUT_MAX = 300       # 大请求超时 300s
RETRY_ON_429 = 2                 # 429限流重试次数
RETRY_ON_504 = 1                 # 504超时重试次数

# ================= 并发配置 =================
POOL_CONNECTIONS = 64            # 连接池大小（须 ≥ Waitress 线程数）
POOL_MAXSIZE = 64               # 单主机最大连接数
WAITRESS_THREADS = 64           # Waitress 工作线程数
SSE_CHUNK_SIZE = 4096           # SSE 流式转发块大小（越小首 token 延迟越低）

# ================= 日志 =================
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s [%(levelname)s] %(message)s',
    handlers=[
        logging.StreamHandler(sys.stdout)
    ]
)
logger = logging.getLogger('huawei-gateway')

# ================= 缓存 =================
class TokenCache:
    def __init__(self):
        self._token = None
        self._expires_at = 0
        self._lock = threading.RLock()
        self._last_scan = 0
        self._scan_interval = 60  # 扫描间隔最小 60 秒
        self._blacklist = set()   # 已失效的 token 指纹

    def _fingerprint(self, token):
        """取 token 前 16 + 后 16 字符做指纹"""
        if len(token) <= 32:
            return token
        return token[:16] + token[-16:]

    def get(self):
        with self._lock:
            now = time.time()
            if self._token and now < self._expires_at:
                return self._token
            return None

    def set(self, token, ttl=CACHE_TTL):
        with self._lock:
            self._token = token
            self._expires_at = time.time() + ttl
            self._last_scan = time.time()
            self._blacklist.discard(self._fingerprint(token))

    def blacklist_current(self):
        """将当前 token 加入黑名单"""
        with self._lock:
            if self._token:
                self._blacklist.add(self._fingerprint(self._token))
            self._token = None
            self._expires_at = 0

    def is_blacklisted(self, token):
        with self._lock:
            return self._fingerprint(token) in self._blacklist

    def is_scan_cooldown(self):
        with self._lock:
            return (time.time() - self._last_scan) < self._scan_interval

    def clear_blacklist(self):
        """清空黑名单"""
        with self._lock:
            self._blacklist.clear()

    def get_expires_in(self):
        """返回 token 剩余有效期（秒）"""
        with self._lock:
            return max(0, self._expires_at - time.time())

    def get_blacklist_count(self):
        """返回黑名单大小"""
        with self._lock:
            return len(self._blacklist)

    def fingerprint(self, token):
        """公开方法：获取 token 指纹"""
        with self._lock:
            return self._fingerprint(token)

    def clear(self):
        with self._lock:
            self._token = None
            self._expires_at = 0


cache = TokenCache()

# ================= 内存扫描 =================
def scan_pid_mem(pid):
    """扫描单个进程的内存寻找 Token"""
    maps_path = f'/proc/{pid}/maps'
    mem_path = f'/proc/{pid}/mem'

    if not os.path.exists(maps_path) or not os.path.exists(mem_path):
        return None

    try:
        with open(maps_path, 'r') as f:
            for line in f:
                parts = line.split()
                if len(parts) < 2:
                    continue
                perms = parts[1]
                if 'r' not in perms or 'w' not in perms:
                    continue

                addrs = parts[0].split('-')
                if len(addrs) != 2:
                    continue

                start = int(addrs[0], 16)
                end = int(addrs[1], 16)
                size = end - start

                if size > MAX_MEM_SEGMENT or size < 1024:
                    continue

                try:
                    with open(mem_path, 'rb') as mem:
                        mem.seek(start)
                        chunk_size = 64 * 1024
                        remaining = size
                        while remaining > 0:
                            to_read = min(chunk_size, remaining)
                            data = mem.read(to_read)
                            if not data:
                                break

                            for match in TOKEN_PATTERN.finditer(data):
                                token = match.group(1).decode('ascii', errors='replace')
                                if len(token) > 200:
                                    return token

                            remaining -= len(data)
                except (PermissionError, OSError, ValueError):
                    continue

    except (PermissionError, OSError, ProcessLookupError):
        pass
    return None


def find_token_in_memory():
    """在所有进程中扫描 Token"""
    # 快速路径：缓存有效直接返回（避免每次请求都查环境变量/文件）
    cached = cache.get()
    if cached:
        return cached

    # HUAWEI_TOKEN 环境变量优先级最高
    env_token = os.environ.get('HUAWEI_TOKEN', '').strip()
    if env_token and len(env_token) > 200 and not cache.is_blacklisted(env_token):
        cache.set(env_token)
        logger.info("Token 从 HUAWEI_TOKEN 环境变量加载")
        return env_token

    # 从持久化文件加载
    env_file = '/etc/huawei-gateway.env'
    if os.path.isfile(env_file):
        try:
            with open(env_file, 'r') as f:
                for line in f:
                    line = line.strip()
                    if line.startswith('HUAWEI_TOKEN='):
                        file_token = line.split('=', 1)[1].strip().strip('"').strip("'")
                        if file_token and len(file_token) > 200 and not cache.is_blacklisted(file_token):
                            cache.set(file_token)
                            logger.info("Token 从持久化文件加载")
                            return file_token
                        break
        except (OSError, IOError):
            pass

    if cache.is_scan_cooldown():
        return cache.get()

    try:
        pids = [pid for pid in os.listdir('/proc') if pid.isdigit()]
    except OSError:
        logger.error("无法访问 /proc 目录")
        return None

    # 优先扫描常见进程
    priority_pids = []
    other_pids = []

    for pid in pids:
        try:
            exe_path = os.readlink(f'/proc/{pid}/exe')
            if any(x in exe_path for x in ['python', 'node', 'java', 'chrome', 'electron']):
                priority_pids.append(pid)
            else:
                other_pids.append(pid)
        except (OSError, PermissionError):
            other_pids.append(pid)

    all_pids = priority_pids + other_pids

    found_tokens = []
    with ThreadPoolExecutor(max_workers=MAX_WORKERS) as executor:
        futures = {executor.submit(scan_pid_mem, pid): pid for pid in all_pids}
        for future in as_completed(futures):
            try:
                token = future.result(timeout=5)
                if token and not cache.is_blacklisted(token):
                    found_tokens.append((token, futures[future]))
            except Exception:
                continue

    for token, pid in found_tokens:
        cache.set(token)
        logger.info(f"Token 已刷新 (来源 PID: {pid})")
        return token

    return cache.get()


# ================= HTTP 会话池 =================
# max_retries=0：禁用 urllib3 自动重试，由 proxy 手动控制重试逻辑（避免双重重试）
http_session = requests.Session()
adapter = requests.adapters.HTTPAdapter(
    pool_connections=POOL_CONNECTIONS,
    pool_maxsize=POOL_MAXSIZE,
    max_retries=0
)
http_session.mount('https://', adapter)
http_session.mount('http://', adapter)

# ================= Flask 应用 =================
app = Flask(__name__)


# ================= 全局请求日志（捕获所有请求，包括404） =================
@app.before_request
def log_every_request():
    body_preview = ""
    if request.method in ('POST', 'PUT', 'PATCH') and request.content_length and request.content_length < 2048:
        body_preview = request.get_data()[:200].decode('utf-8', errors='replace')
    logger.info(f">>> {request.method} {request.full_path} | body={request.content_length or 0}bytes | from={request.remote_addr} | {body_preview}")


@app.route('/health')
def health():
    """健康检查端点"""
    token = cache.get()
    return {
        "status": "healthy",
        "token_cached": token is not None,
        "token_expires_in": cache.get_expires_in(),
        "blacklisted": cache.get_blacklist_count()
    }, 200


@app.route('/set_token', methods=['POST'])
def set_token():
    """手动注入有效 Token"""
    data = request.get_json(force=True, silent=True) if request.is_json else {}
    token = data.get('token', '')
    if not token or len(token) < 100:
        return {"error": "请提供有效的 token"}, 400
    cache.set(token)
    # 持久化到文件以便重启后恢复
    env_file = '/etc/huawei-gateway.env'
    try:
        with open(env_file, 'w') as f:
            f.write(f'HUAWEI_TOKEN={token}\n')
        os.chmod(env_file, 0o600)
    except (OSError, IOError):
        pass
    logger.info("Token 已手动注入并持久化")
    return {"status": "ok", "token_fingerprint": cache.fingerprint(token)}, 200


# ================= 通用上游请求 =================
def _forward_upstream(method, target_url, headers, raw_body, cookies, timeout):
    """向上游发起请求并返回 response 对象（stream=True）"""
    return http_session.request(
        method=method,
        url=target_url,
        headers=headers,
        data=raw_body,
        cookies=cookies,
        allow_redirects=False,
        timeout=timeout,
        stream=True
    )


def _build_response(resp):
    """根据上游 response 构建转发给客户端的 Flask Response"""
    # 过滤 hop-by-hop 头和压缩编码头
    skip_headers = {'transfer-encoding', 'content-encoding', 'content-length',
                    'connection', 'keep-alive', 'upgrade'}
    response_headers = [(k, v) for k, v in resp.headers.items() if k.lower() not in skip_headers]

    # SSE 流式转发
    content_type = resp.headers.get('Content-Type', '')
    if 'text/event-stream' in content_type or resp.headers.get('Transfer-Encoding', '') == 'chunked':
        def sse_stream():
            try:
                for chunk in resp.iter_content(chunk_size=SSE_CHUNK_SIZE):
                    if chunk:
                        yield chunk
            finally:
                resp.close()

        return Response(
            sse_stream(),
            status=resp.status_code,
            headers=response_headers,
            direct_passthrough=True
        )
    else:
        # 非流式响应：读取完整内容
        content = resp.content
        resp.close()

        # 记录上游非 200 响应（在读取 content 之后，避免提前消费流）
        if resp.status_code != 200:
            try:
                logger.warning(f"上游返回 {resp.status_code}: {content[:500].decode('utf-8', errors='replace')}")
            except Exception:
                logger.warning(f"上游返回 {resp.status_code}")

        # 华为云 ModelArts 错误 → OpenAI 标准格式
        if resp.status_code >= 400:
            try:
                err = json.loads(content)
                if 'error_code' in err and 'error_msg' in err:
                    openai_err = {
                        "error": {
                            "message": err.get('error_msg', ''),
                            "type": err.get('error', {}).get('type', 'server_error'),
                            "code": err.get('error_code', ''),
                            "param": None
                        }
                    }
                    content = json.dumps(openai_err).encode('utf-8')
                    response_headers = [(k, v) for k, v in response_headers if k.lower() != 'content-length']
            except Exception:
                pass

        return Response(
            content,
            status=resp.status_code,
            headers=response_headers
        )


@app.route('/v1/<path:subpath>', methods=['POST', 'GET', 'OPTIONS', 'PUT', 'DELETE'])
@app.route('/v2/<path:subpath>', methods=['POST', 'GET', 'OPTIONS', 'PUT', 'DELETE'])
def proxy(subpath):
    if request.method == 'OPTIONS':
        return Response(status=200, headers={
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
            'Access-Control-Allow-Headers': 'Content-Type, Authorization'
        })

    real_token = find_token_in_memory()
    if not real_token:
        logger.error("未在内存中找到华为云 Token")
        return {"error": "未在内存中找到华为云Token，请确保华为云相关应用正在运行"}, 500

    # 构建请求头
    headers = {}
    for k, v in request.headers:
        kl = k.lower()
        if kl not in ('host', 'content-length', 'connection', 'accept-encoding', 'transfer-encoding'):
            headers[k] = v

    headers['Authorization'] = f'Bearer {real_token}'
    headers['Host'] = TARGET_HOST
    headers['Connection'] = 'keep-alive'

    target_url = f'https://{TARGET_HOST}/v2/{subpath}'

    # ============ /models 请求直接返回，不转发上游 ============
    if subpath in ('models', 'models/'):
        return {
            "object": "list",
            "data": [
                {"id": "glm-5.1", "object": "model", "owned": "zhipu"},
            ]
        }

    # ============ 请求体处理：大小校验 + 动态超时 ============
    raw_body = request.get_data()
    body_size = len(raw_body)

    # 请求体超过上游限制，直接返回清晰错误
    if body_size > UPSTREAM_BODY_LIMIT:
        logger.warning(f"请求体超限: {body_size // 1024}KB > {UPSTREAM_BODY_LIMIT // 1024}KB")
        return {
            "error": {
                "message": f"请求体过大({body_size // 1024}KB)，超过API网关限制({UPSTREAM_BODY_LIMIT // 1024}KB)。请减少请求内容长度。",
                "type": "invalid_request_error",
                "code": "content_too_large",
                "param": None
            }
        }, 413

    # 动态超时：根据请求体大小自动调整
    if body_size > 800 * 1024:
        upstream_timeout = UPSTREAM_TIMEOUT_MAX
    elif body_size > 200 * 1024:
        upstream_timeout = 180
    else:
        upstream_timeout = UPSTREAM_TIMEOUT_MIN

    try:
        resp = _forward_upstream(request.method, target_url, headers, raw_body, request.cookies, upstream_timeout)

        # 401 兜底：Token 可能提前过期，加入黑名单后强制刷新重试
        if resp.status_code == 401:
            resp.close()
            logger.warning("收到 401，将当前 Token 加入黑名单并强制刷新...")
            cache.blacklist_current()
            new_token = find_token_in_memory()
            if new_token and new_token != real_token:
                headers['Authorization'] = f'Bearer {new_token}'
                resp = _forward_upstream(request.method, target_url, headers, raw_body, request.cookies, upstream_timeout)
                # 如果新 Token 也 401，清空黑名单避免锁死
                if resp.status_code == 401:
                    resp.close()
                    logger.warning("新 Token 也 401，清空黑名单避免锁死")
                    cache.clear_blacklist()
                    new_token2 = find_token_in_memory()
                    if new_token2:
                        headers['Authorization'] = f'Bearer {new_token2}'
                        resp = _forward_upstream(request.method, target_url, headers, raw_body, request.cookies, upstream_timeout)

        # ============ 429 限流重试 ============
        if resp.status_code == 429:
            for retry_i in range(1, RETRY_ON_429 + 1):
                resp.close()
                wait = retry_i * 5  # 5s, 10s
                logger.warning(f"上游 429 限流，等待{wait}s后重试({retry_i}/{RETRY_ON_429})...")
                time.sleep(wait)
                resp = _forward_upstream(request.method, target_url, headers, raw_body, request.cookies, upstream_timeout)
                if resp.status_code != 429:
                    break
                logger.warning("重试仍返回 429")

        # ============ 504 超时重试 ============
        if resp.status_code == 504:
            for retry_i in range(1, RETRY_ON_504 + 1):
                resp.close()
                wait = retry_i * 3
                logger.warning(f"上游 504 超时，等待{wait}s后重试({retry_i}/{RETRY_ON_504})...")
                time.sleep(wait)
                resp = _forward_upstream(request.method, target_url, headers, raw_body, request.cookies, upstream_timeout)
                if resp.status_code != 504:
                    break

        return _build_response(resp)

    except requests.exceptions.Timeout:
        logger.error("请求华为云 API 超时")
        return {"error": "网关超时，请稍后重试"}, 504
    except requests.exceptions.ConnectionError:
        logger.error("无法连接到华为云 API")
        return {"error": "无法连接到华为云服务"}, 502
    except Exception as e:
        logger.error(f"网关转发失败: {traceback.format_exc()}")
        return {"error": f"网关转发失败: {str(e)}"}, 500


def main():
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 8080
    host = sys.argv[2] if len(sys.argv) > 2 else '127.0.0.1'

    # 从持久化文件加载 token
    env_file = '/etc/huawei-gateway.env'
    if os.path.isfile(env_file):
        try:
            with open(env_file, 'r') as f:
                for line in f:
                    line = line.strip()
                    if line.startswith('HUAWEI_TOKEN=') and 'HUAWEI_TOKEN' not in os.environ:
                        val = line.split('=', 1)[1].strip().strip('"').strip("'")
                        if val and len(val) > 200:
                            os.environ['HUAWEI_TOKEN'] = val
                            logger.info("从持久化文件恢复 Token")
                        break
        except (OSError, IOError):
            pass

    # 尝试使用生产级 WSGI 服务器
    try:
        import waitress
        logger.info(f"使用 Waitress 启动网关 ({host}:{port})")
        waitress.serve(app, host=host, port=port, threads=WAITRESS_THREADS)
    except ImportError:
        try:
            import gunicorn.app.wsgiapp
            logger.info(f"使用 Gunicorn 启动网关 ({host}:{port})")
            os.execlp('gunicorn', 'gunicorn', '-w', '4', '-b', f'{host}:{port}', '--access-logfile', '-', 'huawei_gateway:app')
        except (ImportError, OSError):
            logger.warning("未安装 Waitress/Gunicorn，使用 Flask 开发服务器（建议生产环境安装 waitress）")
            logger.info(f"启动网关 ({host}:{port})")
            app.run(host=host, port=port, debug=False, threaded=True)


if __name__ == '__main__':
    main()