"""chat.z.ai reverse-engineered Python client."""

from __future__ import annotations

import asyncio
import base64
import hashlib
import hmac
import json
import logging
import os
import time
import uuid
from datetime import datetime, timezone, timedelta
from urllib.parse import urlencode

import httpx

logger = logging.getLogger("zai.client")

BASE_URL = "https://chat.z.ai"
HMAC_SECRET = "key-@@@@)))()((9))-xxxx&&&%%%%%"
FE_VERSION = "prod-fe-1.0.231"
CLIENT_VERSION = "0.0.1"
DEFAULT_MODEL = "glm-5"
ENABLE_THINKING_DEFAULT = os.getenv("ENABLE_THINKING", "1") == "1"
USER_AGENT = (
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
    "AppleWebKit/537.36 (KHTML, like Gecko) "
    "Chrome/144.0.0.0 Safari/537.36"
)


class ZaiClient:
    def __init__(self) -> None:
        # 分离超时配置：connect快速失败，read支持长时间流式响应
        timeout_config = httpx.Timeout(
            connect=5.0,      # 连接超时 5秒
            read=180.0,       # 读取超时 3分钟（支持长文生成）
            write=10.0,       # 写入超时 10秒
            pool=5.0,         # 连接池获取超时 5秒
        )
        self.client = httpx.AsyncClient(
            base_url=BASE_URL,
            timeout=timeout_config,
            headers={
                "User-Agent": USER_AGENT,
                "Accept-Language": "zh-CN",
                "Referer": f"{BASE_URL}/",
                "Origin": BASE_URL,
            },
            # 限制连接池大小，避免连接泄漏
            limits=httpx.Limits(max_keepalive_connections=5, max_connections=10),
        )
        self.token: str | None = None
        self.user_id: str | None = None
        self.username: str | None = None

    async def close(self) -> None:
        await self.client.aclose()

    # ── auth ────────────────────────────────────────────────────────

    async def auth_as_guest(self) -> dict:
        """GET /api/v1/auths/ — creates a guest session and returns user info."""
        resp = await self.client.get(
            "/api/v1/auths/",
            headers={"Content-Type": "application/json"},
        )
        resp.raise_for_status()
        data = resp.json()
        self.token = data["token"]
        self.user_id = data["id"]
        self.username = data.get("name") or data.get("email", "").split("@")[0]
        return data

    # ── models ──────────────────────────────────────────────────────

    async def get_models(self) -> list:
        """GET /api/models — returns available model list."""
        resp = await self.client.get(
            "/api/models",
            headers={
                "Content-Type": "application/json",
                "Accept": "application/json",
                **({"Authorization": f"Bearer {self.token}"} if self.token else {}),
            },
        )
        resp.raise_for_status()
        return resp.json()

    # ── chat CRUD ───────────────────────────────────────────────────

    async def create_chat(
        self,
        user_message: str,
        model: str = DEFAULT_MODEL,
        *,
        enable_thinking: bool | None = None,
    ) -> dict:
        """POST /api/v1/chats/new — creates a new chat session.

        The content placed in history is only for session initialization;
        actual conversation content is sent via chat_completions later.
        We truncate long prompts to avoid 400 errors from the upstream API.
        """
        # Truncate the user_message for chat creation to avoid 400 errors
        # when the prompt is too long (e.g. contains tool definitions,
        # multi-turn history, or large system prompts).
        MAX_INIT_CONTENT_LEN = 500
        init_content = user_message
        if len(init_content) > MAX_INIT_CONTENT_LEN:
            init_content = init_content[:MAX_INIT_CONTENT_LEN] + "..."

        msg_id = str(uuid.uuid4())
        ts = int(time.time())
        body = {
            "chat": {
                "id": "",
                "title": "新聊天",
                "models": [model],
                "params": {},
                "history": {
                    "messages": {
                        msg_id: {
                            "id": msg_id,
                            "parentId": None,
                            "childrenIds": [],
                            "role": "user",
                            "content": init_content,
                            "timestamp": ts,
                            "models": [model],
                        }
                    },
                    "currentId": msg_id,
                },
                "tags": [],
                "flags": [],
                "features": [
                    {
                        "type": "tool_selector",
                        "server": "tool_selector_h",
                        "status": "hidden",
                    }
                ],
                "mcp_servers": [],
                "enable_thinking": (
                    ENABLE_THINKING_DEFAULT
                    if enable_thinking is None
                    else bool(enable_thinking)
                ),
                "auto_web_search": False,
                "message_version": 1,
                "extra": {},
                "timestamp": int(time.time() * 1000),
            }
        }
        resp = await self.client.post(
            "/api/v1/chats/new",
            headers={
                "Content-Type": "application/json",
                "Accept": "application/json",
                **({"Authorization": f"Bearer {self.token}"} if self.token else {}),
            },
            json=body,
        )
        if resp.status_code != 200:
            error_body = resp.text
            logger.warning(
                "create_chat failed: status=%d body=%s (prompt_len=%d, truncated_len=%d)",
                resp.status_code, error_body[:500], len(user_message), len(init_content),
            )
            resp.raise_for_status()
        return resp.json()

    # ── chat cleanup ─────────────────────────────────────────────────

    async def delete_chat(self, chat_id: str) -> bool:
        """DELETE /api/v1/chats/{chat_id} — deletes a chat session.

        Returns True if deleted successfully, False otherwise.
        This should be called after each request to free up concurrency slots.
        """
        try:
            resp = await self.client.delete(
                f"/api/v1/chats/{chat_id}",
                headers={
                    "Content-Type": "application/json",
                    "Accept": "application/json",
                    **({
                        "Authorization": f"Bearer {self.token}"
                    } if self.token else {}),
                },
            )
            if resp.status_code == 200:
                return True
            logger.debug(
                "delete_chat %s: status=%d body=%s",
                chat_id, resp.status_code, resp.text[:200],
            )
            return False
        except Exception as e:
            logger.debug("delete_chat %s failed: %s", chat_id, e)
            return False

    async def delete_all_chats(self) -> bool:
        """DELETE /api/v1/chats/ — deletes all chats for the current user.

        Useful for cleaning up accumulated chats when hitting concurrency limits.
        """
        try:
            resp = await self.client.delete(
                "/api/v1/chats/",
                headers={
                    "Content-Type": "application/json",
                    "Accept": "application/json",
                    **({
                        "Authorization": f"Bearer {self.token}"
                    } if self.token else {}),
                },
            )
            if resp.status_code == 200:
                logger.info("delete_all_chats: success")
                return True
            logger.warning(
                "delete_all_chats: status=%d body=%s",
                resp.status_code, resp.text[:200],
            )
            return False
        except Exception as e:
            logger.warning("delete_all_chats failed: %s", e)
            return False

    # ── signature ───────────────────────────────────────────────────

    @staticmethod
    def _generate_signature(
        sorted_payload: str, prompt: str, timestamp: str
    ) -> str:
        """
        Two-layer HMAC-SHA256 matching DLHfQWwv.js.

        1. b64_prompt  = base64(utf8(prompt))
        2. message     = "{sorted_payload}|{b64_prompt}|{timestamp}"
        3. time_bucket = floor(int(timestamp) / 300_000)
        4. derived_key = HMAC-SHA256(HMAC_SECRET, str(time_bucket)) → hex string
        5. signature   = HMAC-SHA256(derived_key_hex_bytes, message) → hex
        """
        b64_prompt = base64.b64encode(prompt.encode("utf-8")).decode("ascii")
        message = f"{sorted_payload}|{b64_prompt}|{timestamp}"
        time_bucket = int(timestamp) // (5 * 60 * 1000)

        derived_key_hex = hmac.new(
            HMAC_SECRET.encode("utf-8"),
            str(time_bucket).encode("utf-8"),
            hashlib.sha256,
        ).hexdigest()

        signature = hmac.new(
            derived_key_hex.encode("utf-8"),
            message.encode("utf-8"),
            hashlib.sha256,
        ).hexdigest()
        return signature

    def _build_query_and_signature(
        self, prompt: str, chat_id: str
    ) -> tuple[str, str]:
        """Build the full URL query string and X-Signature header.

        Returns (full_query_string, signature).
        """
        timestamp_ms = str(int(time.time() * 1000))
        request_id = str(uuid.uuid4())

        now = datetime.now(timezone.utc)

        # Core params (used for sortedPayload)
        core = {
            "timestamp": timestamp_ms,
            "requestId": request_id,
            "user_id": self.user_id,
        }

        # sortedPayload: Object.entries(core).sort(by key).join(",")
        sorted_payload = ",".join(
            f"{k},{v}" for k, v in sorted(core.items(), key=lambda x: x[0])
        )

        # Compute signature over the prompt
        signature = self._generate_signature(sorted_payload, prompt, timestamp_ms)

        # Browser/device fingerprint params
        extra = {
            "version": CLIENT_VERSION,
            "platform": "web",
            "token": self.token or "",
            "user_agent": USER_AGENT,
            "language": "zh-CN",
            "languages": "zh-CN",
            "timezone": "Asia/Shanghai",
            "cookie_enabled": "true",
            "screen_width": "1920",
            "screen_height": "1080",
            "screen_resolution": "1920x1080",
            "viewport_height": "919",
            "viewport_width": "944",
            "viewport_size": "944x919",
            "color_depth": "24",
            "pixel_ratio": "1.25",
            "current_url": f"{BASE_URL}/c/{chat_id}",
            "pathname": f"/c/{chat_id}",
            "search": "",
            "hash": "",
            "host": "chat.z.ai",
            "hostname": "chat.z.ai",
            "protocol": "https:",
            "referrer": "",
            "title": "Z.ai - Free AI Chatbot & Agent powered by GLM-5 & GLM-4.7",
            "timezone_offset": "-480",
            "local_time": now.strftime("%Y-%m-%dT%H:%M:%S.")
            + f"{now.microsecond // 1000:03d}Z",
            "utc_time": now.strftime("%a, %d %b %Y %H:%M:%S GMT"),
            "is_mobile": "false",
            "is_touch": "false",
            "max_touch_points": "10",
            "browser_name": "Chrome",
            "os_name": "Windows",
            "signature_timestamp": timestamp_ms,
        }

        all_params = {**core, **extra}
        query_string = urlencode(all_params)

        return query_string, signature

    # ── chat completions (SSE) ──────────────────────────────────────

    async def chat_completions(
        self,
        chat_id: str,
        messages: list[dict],
        prompt: str,
        *,
        model: str = DEFAULT_MODEL,
        parent_message_id: str | None = None,
        tools: list[dict] | None = None,
        enable_thinking: bool | None = None,
    ):
        """POST /api/v2/chat/completions — streams SSE response.

        Yields the full event ``data`` dict for each SSE frame.
        """
        query_string, signature = self._build_query_and_signature(prompt, chat_id)

        msg_id = str(uuid.uuid4())
        user_msg_id = str(uuid.uuid4())

        now = datetime.now(timezone(timedelta(hours=8)))
        variables = {
            "{{USER_NAME}}": self.username or "Guest",
            "{{USER_LOCATION}}": "Unknown",
            "{{CURRENT_DATETIME}}": now.strftime("%Y-%m-%d %H:%M:%S"),
            "{{CURRENT_DATE}}": now.strftime("%Y-%m-%d"),
            "{{CURRENT_TIME}}": now.strftime("%H:%M:%S"),
            "{{CURRENT_WEEKDAY}}": now.strftime("%A"),
            "{{CURRENT_TIMEZONE}}": "Asia/Shanghai",
            "{{USER_LANGUAGE}}": "zh-CN",
        }

        body = {
            "stream": True,
            "model": model,
            "messages": messages,
            "signature_prompt": prompt,
            "params": {},
            "extra": {},
            "features": {
                "image_generation": False,
                "web_search": False,
                "auto_web_search": False,
                "preview_mode": True,
                "flags": [],
                "enable_thinking": (
                    ENABLE_THINKING_DEFAULT
                    if enable_thinking is None
                    else bool(enable_thinking)
                ),
            },
            "variables": variables,
            "chat_id": chat_id,
            "id": msg_id,
            "current_user_message_id": user_msg_id,
            "current_user_message_parent_id": parent_message_id,
            "background_tasks": {
                "title_generation": True,
                "tags_generation": True,
            },
        }

        if tools:
            body["tools"] = tools

        headers = {
            "Content-Type": "application/json",
            "Accept": "*/*",
            "Accept-Language": "zh-CN",
            "X-FE-Version": FE_VERSION,
            "X-Signature": signature,
            **({"Authorization": f"Bearer {self.token}"} if self.token else {}),
        }

        url = f"{BASE_URL}/api/v2/chat/completions?{query_string}"

        async with self.client.stream(
            "POST", url, headers=headers, json=body,
        ) as resp:
            if resp.status_code != 200:
                error_body = (await resp.aread()).decode("utf-8", errors="replace")
                raise httpx.HTTPStatusError(
                    f"chat/completions {resp.status_code}: {error_body[:500]}",
                    request=resp.request,
                    response=resp,
                )
            async for line in resp.aiter_lines():
                if not line.startswith("data: "):
                    continue
                raw = line[6:]
                if raw.strip() == "[DONE]":
                    return
                try:
                    event = json.loads(raw)
                except json.JSONDecodeError:
                    continue
                data = event.get("data", {})
                yield data
                if data.get("done"):
                    return


async def main() -> None:
    client = ZaiClient()
    try:
        # 1. Authenticate as guest
        print("[1] Authenticating as guest...")
        auth = await client.auth_as_guest()
        print(f"    user_id : {auth['id']}")
        print(f"    email   : {auth.get('email', 'N/A')}")
        print(f"    token   : {auth['token'][:40]}...")

        # 2. Fetch models
        print("\n[2] Fetching models...")
        models_resp = await client.get_models()
        if isinstance(models_resp, dict) and "data" in models_resp:
            names = [m.get("id", m.get("name", "?")) for m in models_resp["data"]]
        elif isinstance(models_resp, list):
            names = [m.get("id", m.get("name", "?")) for m in models_resp]
        else:
            names = [str(models_resp)[:80]]
        print(f"    models  : {', '.join(names[:10])}")

        # 3. Create chat
        user_message = "Hello"
        print(f"\n[3] Creating chat with first message: {user_message!r}")
        messages = [{"role": "user", "content": user_message}]
        chat = await client.create_chat(user_message)
        chat_id = chat["id"]
        print(f"    chat_id : {chat_id}")

        # 4. Stream chat completions
        print(f"\n[4] Streaming chat completions (model={DEFAULT_MODEL})...\n")
        messages = [{"role": "user", "content": user_message}]

        thinking_started = False
        answer_started = False
        async for data in client.chat_completions(
            chat_id=chat_id,
            messages=messages,
            prompt=user_message,
        ):
            phase = data.get("phase", "")
            delta = data.get("delta_content", "")
            if phase == "thinking":
                if not thinking_started:
                    print("[thinking] ", end="", flush=True)
                    thinking_started = True
                print(delta, end="", flush=True)
            elif phase == "answer":
                if not answer_started:
                    if thinking_started:
                        print("\n")
                    print("[answer]   ", end="", flush=True)
                    answer_started = True
                print(delta, end="", flush=True)
            elif phase == "done":
                break
        print("\n\n[done]")

    finally:
        await client.close()


if __name__ == "__main__":
    asyncio.run(main())