#!/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 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'

# ================= 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(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"""
    # 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):
        cached = cache.get()
        if cached != 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):
                            cached = cache.get()
                            if cached != 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() and cache.get():
        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 =================
http_session = requests.Session()
adapter = requests.adapters.HTTPAdapter(
    pool_connections=20,
    pool_maxsize=20,
    max_retries=3
)
http_session.mount('https://', adapter)
http_session.mount('http://', adapter)

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

@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": max(0, cache._expires_at - time.time()) if hasattr(cache, '_expires_at') else 0,
        "blacklisted": len(cache._blacklist) if hasattr(cache, '_blacklist') else 0
    }, 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
    try:
        with open('/etc/huawei-gateway.env', 'w') as f:
            f.write(f'HUAWEI_TOKEN={token}\n')
    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


@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

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

    try:
        # 使用 stream=True 支持 SSE 流式转发
        resp = http_session.request(
            method=request.method,
            url=target_url,
            headers=headers,
            data=request.get_data(),
            cookies=request.cookies,
            allow_redirects=False,
            timeout=60,
            stream=True
        )

        # 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 = http_session.request(
                    method=request.method,
                    url=target_url,
                    headers=headers,
                    data=request.get_data(),
                    cookies=request.cookies,
                    allow_redirects=False,
                    timeout=60,
                    stream=True
                )

        # 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 = []
        for k, v in resp.headers.items():
            if k.lower() not in skip_headers:
                response_headers.append((k, v))

        # 记录上游非200响应
        if resp.status_code != 200:
            try:
                _err_peek = resp.content[:500]
                logger.warning(f"上游返回 {resp.status_code}: {_err_peek.decode('utf-8', errors='replace')}")
            except Exception:
                logger.warning(f"上游返回 {resp.status_code}")

        # 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=4096):
                        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()

            # 华为云 ModelArts 错误 → OpenAI 标准格式
            if resp.status_code >= 400:
                try:
                    import json as _jj
                    err = _jj.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 = _jj.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
            )

    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=32)
    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()