import json
import uuid
import os
from pathlib import Path
from typing import Dict, Optional, Tuple, Iterator, List, Generator, Any
import struct
import requests

class StreamTracker:
    def __init__(self):
        self.has_content = False
    
    def track(self, gen: Generator[str, None, None]) -> Generator[str, None, None]:
        for item in gen:
            if item:
                self.has_content = True
            yield item

def _get_proxies() -> Optional[Dict[str, str]]:
    proxy = os.getenv("HTTP_PROXY", "").strip()
    if proxy:
        return {"http": proxy, "https": proxy}
    return None

BASE_DIR = Path(__file__).resolve().parent
TEMPLATE_PATH = BASE_DIR / "templates" / "streaming_request.json"

def load_template() -> Tuple[str, Dict[str, str], Dict[str, Any]]:
    data = json.loads(TEMPLATE_PATH.read_text(encoding="utf-8"))
    url, headers, body = data
    assert isinstance(url, str) and isinstance(headers, dict) and isinstance(body, dict)
    return url, headers, body

def _merge_headers(as_log: Dict[str, str], bearer_token: str) -> Dict[str, str]:
    headers = dict(as_log)
    for k in list(headers.keys()):
        kl = k.lower()
        if kl in ("content-length","host","connection","transfer-encoding"):
            headers.pop(k, None)
    def set_header(name: str, value: str):
        for key in list(headers.keys()):
            if key.lower() == name.lower():
                del headers[key]
        headers[name] = value
    set_header("Authorization", f"Bearer {bearer_token}")
    set_header("amz-sdk-invocation-id", str(uuid.uuid4()))
    return headers

def _parse_event_headers(raw: bytes) -> Dict[str, object]:
    headers: Dict[str, object] = {}
    i = 0
    n = len(raw)
    while i < n:
        if i + 1 > n:
            break
        name_len = raw[i]
        i += 1
        if i + name_len + 1 > n:
            break
        name = raw[i : i + name_len].decode("utf-8", errors="ignore")
        i += name_len
        htype = raw[i]
        i += 1
        if htype == 0:
            val = True
        elif htype == 1:
            val = False
        elif htype == 2:
            if i + 1 > n: break
            val = raw[i]; i += 1
        elif htype == 3:
            if i + 2 > n: break
            val = int.from_bytes(raw[i:i+2],"big",signed=True); i += 2
        elif htype == 4:
            if i + 4 > n: break
            val = int.from_bytes(raw[i:i+4],"big",signed=True); i += 4
        elif htype == 5:
            if i + 8 > n: break
            val = int.from_bytes(raw[i:i+8],"big",signed=True); i += 8
        elif htype == 6:
            if i + 2 > n: break
            l = int.from_bytes(raw[i:i+2],"big"); i += 2
            if i + l > n: break
            val = raw[i:i+l]; i += l
        elif htype == 7:
            if i + 2 > n: break
            l = int.from_bytes(raw[i:i+2],"big"); i += 2
            if i + l > n: break
            val = raw[i:i+l].decode("utf-8", errors="ignore"); i += l
        elif htype == 8:
            if i + 8 > n: break
            val = int.from_bytes(raw[i:i+8],"big",signed=False); i += 8
        elif htype == 9:
            if i + 16 > n: break
            import uuid as _uuid
            val = str(_uuid.UUID(bytes=bytes(raw[i:i+16]))); i += 16
        else:
            break
        headers[name] = val
    return headers

class AwsEventStreamParser:
    def __init__(self):
        self._buf = bytearray()
    def feed(self, data: bytes) -> List[Tuple[Dict[str, object], bytes]]:
        if not data:
            return []
        self._buf.extend(data)
        out: List[Tuple[Dict[str, object], bytes]] = []
        while True:
            if len(self._buf) < 12:
                break
            total_len, headers_len, _prelude_crc = struct.unpack(">I I I", self._buf[:12])
            if total_len < 16 or headers_len > total_len:
                self._buf.pop(0)
                continue
            if len(self._buf) < total_len:
                break
            msg = bytes(self._buf[:total_len])
            del self._buf[:total_len]
            headers_raw = msg[12:12+headers_len]
            payload = msg[12+headers_len: total_len-4]
            headers = _parse_event_headers(headers_raw)
            out.append((headers, payload))
        return out

def _try_decode_event_payload(payload: bytes) -> Optional[dict]:
    try:
        return json.loads(payload.decode("utf-8"))
    except Exception:
        return None

def _extract_text_from_event(ev: dict) -> Optional[str]:
    for key in ("assistantResponseEvent","assistantMessage","message","delta","data"):
        if key in ev and isinstance(ev[key], dict):
            inner = ev[key]
            if isinstance(inner.get("content"), str) and inner.get("content"):
                return inner["content"]
    if isinstance(ev.get("content"), str) and ev.get("content"):
        return ev["content"]
    for list_key in ("chunks","content"):
        if isinstance(ev.get(list_key), list):
            buf = []
            for item in ev[list_key]:
                if isinstance(item, dict):
                    if isinstance(item.get("content"), str):
                        buf.append(item["content"])
                    elif isinstance(item.get("text"), str):
                        buf.append(item["text"])
                elif isinstance(item, str):
                    buf.append(item)
            if buf:
                return "".join(buf)
    for k in ("text","delta","payload"):
        v = ev.get(k)
        if isinstance(v, str) and v:
            return v
    return None

def openai_messages_to_text(messages: List[Dict[str, Any]]) -> str:
    lines: List[str] = []
    for m in messages:
        role = m.get("role","user")
        content = m.get("content","")
        if isinstance(content, list):
            parts = []
            for seg in content:
                if isinstance(seg, dict) and isinstance(seg.get("text"), str):
                    parts.append(seg["text"])
                elif isinstance(seg, str):
                    parts.append(seg)
            content = "\n".join(parts)
        elif not isinstance(content, str):
            content = str(content)
        lines.append(f"{role}:\n{content}")
    return "\n\n".join(lines)

def inject_history(body_json: Dict[str, Any], history_text: str) -> None:
    try:
        cur = body_json["conversationState"]["currentMessage"]["userInputMessage"]
        content = cur.get("content","")
        if isinstance(content, str):
            cur["content"] = content.replace("你好，你必须讲个故事", history_text)
    except Exception:
        pass

def inject_model(body_json: Dict[str, Any], model: Optional[str]) -> None:
    if not model:
        return
    try:
        body_json["conversationState"]["currentMessage"]["userInputMessage"]["modelId"] = model
    except Exception:
        pass

def send_chat_request(access_token: str, messages: List[Dict[str, Any]], model: Optional[str] = None, stream: bool = False, timeout: Tuple[int,int] = (15,300)) -> Tuple[Optional[str], Optional[Generator[str, None, None]], bool]:
    url, headers_from_log, body_json = load_template()
    headers_from_log["amz-sdk-invocation-id"] = str(uuid.uuid4())
    try:
        body_json["conversationState"]["conversationId"] = str(uuid.uuid4())
    except Exception:
        pass
    history_text = openai_messages_to_text(messages)
    inject_history(body_json, history_text)
    inject_model(body_json, model)
    payload_str = json.dumps(body_json, ensure_ascii=False)
    headers = _merge_headers(headers_from_log, access_token)
    session = requests.Session()
    proxies = _get_proxies()
    resp = session.post(url, headers=headers, data=payload_str, stream=True, timeout=timeout, proxies=proxies)
    if resp.status_code >= 400:
        try:
            err = resp.text
        except Exception:
            err = f"HTTP {resp.status_code}"
        raise requests.HTTPError(f"Upstream error {resp.status_code}: {err}", response=resp)
    parser = AwsEventStreamParser()
    tracker = StreamTracker()
    def _iter_text() -> Generator[str, None, None]:
        for chunk in resp.iter_content(chunk_size=None):
            if not chunk:
                continue
            events = parser.feed(chunk)
            for _ev_headers, payload in events:
                parsed = _try_decode_event_payload(payload)
                if parsed is not None:
                    text = _extract_text_from_event(parsed)
                    if isinstance(text, str) and text:
                        yield text
                else:
                    try:
                        txt = payload.decode("utf-8", errors="ignore")
                        if txt:
                            yield txt
                    except Exception:
                        pass
    if stream:
        return None, tracker.track(_iter_text()), tracker
    else:
        buf = []
        for t in tracker.track(_iter_text()):
            buf.append(t)
        return "".join(buf), None, tracker