#
# SPDX-FileCopyrightText: Hadad <hadad@linuxmail.org>
# SPDX-License-Identifier: Apache-2.0
#

import codecs # Reasoning
import httpx
import json

from src.cores.session import marked_item
from src.config import LINUX_SERVER_ERRORS, LINUX_SERVER_PROVIDER_KEYS_MARKED, LINUX_SERVER_PROVIDER_KEYS_ATTEMPTS, RESPONSES

async def fetch_response_stream_async(host, key, model, msgs, cfg, sid, stop_event, cancel_token):
    """
    Async generator that streams AI responses from a backend server.
    Implements retry logic and marks failing keys to avoid repeated failures.
    Streams reasoning and content separately for richer UI updates.
    """
    for timeout in [5, 10]:
        try:
            async with httpx.AsyncClient(timeout=timeout) as client:
                async with client.stream(
                    "POST",
                    host,
                    json={**{"model": model, "messages": msgs, "session_id": sid, "stream": True}, **cfg},
                    headers={"Authorization": f"Bearer {key}"}
                ) as response:
                    if response.status_code in LINUX_SERVER_ERRORS:
                        marked_item(key, LINUX_SERVER_PROVIDER_KEYS_MARKED, LINUX_SERVER_PROVIDER_KEYS_ATTEMPTS)
                        return
                    async for line in response.aiter_lines():
                        if stop_event.is_set() or cancel_token["cancelled"]:
                            return
                        if not line:
                            continue
                        if line.startswith("data: "):
                            data = line[6:]
                            if data.strip() == RESPONSES["RESPONSE_10"]:
                                return
                            try:
                                j = json.loads(data)
                                if isinstance(j, dict) and j.get("choices"):
                                    for ch in j["choices"]:
                                        delta = ch.get("delta", {})
                                        # Stream reasoning text separately for UI
                                        if "reasoning" in delta and delta["reasoning"]:
                                            decoded = delta["reasoning"].encode('utf-8').decode('unicode_escape')
                                            yield ("reasoning", decoded)
                                        # Stream main content text
                                        if "content" in delta and delta["content"]:
                                            yield ("content", delta["content"])
                            except Exception:
                                # Ignore malformed JSON or unexpected data
                                continue
        except Exception:
            # Network or other errors, try next timeout or mark key
            continue
        marked_item(key, LINUX_SERVER_PROVIDER_KEYS_MARKED, LINUX_SERVER_PROVIDER_KEYS_ATTEMPTS)
    return