# chat/api/routes.py
"""
DeepSeek V4 chat API — endpoints under /api/v1/chat/*.

Sessions are held in memory (bounded history). Model calls go through
DeepSeekV4Client — API mode with DEEPSEEK_API_KEY, local echo otherwise.
"""

from __future__ import annotations

import time
from typing import Any, Dict, List

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel, Field

from chat.core import SOVEREIGN_SYSTEM_PROMPT, ChatSession, get_client

router = APIRouter(prefix="/api/v1/chat", tags=["chat"])

sessions: Dict[str, ChatSession] = {}


class SendIn(BaseModel):
    message: str = Field(min_length=1)
    session_id: str = ""
    temperature: float = 0.7
    max_tokens: int = 1024


class SessionOut(BaseModel):
    session_id: str
    model: str
    messages: List[Dict[str, Any]]
    created_at: float


def _get_or_create(session_id: str) -> ChatSession:
    if session_id and session_id in sessions:
        return sessions[session_id]
    session = ChatSession()
    session.add("system", SOVEREIGN_SYSTEM_PROMPT)
    sessions[session.session_id] = session
    return session


@router.post("/sessions")
async def create_session() -> Dict[str, Any]:
    """Create a new chat session."""
    session = _get_or_create("")
    return {
        "session_id": session.session_id,
        "model": session.model,
        "mode": "api" if not get_client().local_mode else "local",
        "created_at": session.created_at,
    }


@router.get("/sessions/{session_id}")
async def get_session(session_id: str) -> Dict[str, Any]:
    """Session + message history."""
    session = sessions.get(session_id)
    if session is None:
        raise HTTPException(status_code=404, detail="session not found")
    return {
        "session_id": session.session_id,
        "model": session.model,
        "messages": [{"role": m.role, "content": m.content, "ts": m.timestamp}
                     for m in session.messages],
        "created_at": session.created_at,
    }


@router.post("/send")
async def send_message(body: SendIn) -> Dict[str, Any]:
    """Send a message and get an assistant reply."""
    client = get_client()
    session = _get_or_create(body.session_id)
    session.add("user", body.message)
    try:
        result = client.complete(session, temperature=body.temperature,
                                 max_tokens=body.max_tokens)
    except RuntimeError as exc:
        raise HTTPException(status_code=502, detail=str(exc)) from exc
    session.add("assistant", result["content"])
    return {
        "session_id": session.session_id,
        "reply": result["content"],
        "model": result["model"],
        "mode": result["mode"],
        "usage": result.get("usage", {}),
        "timestamp": time.time(),
    }


@router.get("/models")
async def list_models() -> Dict[str, Any]:
    """Available models."""
    return {"models": get_client().list_models(),
            "active": get_client().model,
            "mode": "api" if not get_client().local_mode else "local"}


@router.get("/status")
async def chat_status() -> Dict[str, Any]:
    """Chat module status."""
    client = get_client()
    return {
        "mode": "api" if not client.local_mode else "local",
        "model": client.model,
        "base_url": client.base_url,
        "sessions": len(sessions),
    }