import logging
import os
from logging.handlers import RotatingFileHandler
from pathlib import Path

from fastapi import FastAPI, HTTPException, Depends, Request
from fastapi.responses import JSONResponse, StreamingResponse
from sqlalchemy.orm import Session
from database import get_db
import crud
import httpx

_log_dir = Path(os.getenv("LOG_FILE", "logs/usage.log")).parent
_log_dir.mkdir(parents=True, exist_ok=True)
_fmt = logging.Formatter("%(asctime)s | %(message)s", datefmt="%Y-%m-%d %H:%M:%S")

# Rotating usage log (8 KB per file, 3 backups)
_usage_handler = RotatingFileHandler(str(_log_dir / "usage.log"), maxBytes=8192, backupCount=3, encoding="utf-8")
_usage_handler.setFormatter(_fmt)
usage_log = logging.getLogger("proxy.usage")
usage_log.setLevel(logging.INFO)
usage_log.addHandler(_usage_handler)
usage_log.propagate = False

# Rotating error log (64 KB per file, 5 backups)
_error_handler = RotatingFileHandler(str(_log_dir / "error.log"), maxBytes=65536, backupCount=5, encoding="utf-8")
_error_handler.setFormatter(_fmt)
error_log = logging.getLogger("proxy.error")
error_log.setLevel(logging.ERROR)
error_log.addHandler(_error_handler)
error_log.propagate = False

def _content_to_str(content) -> str:
    """Normalize OpenAI content: string or array of content parts → plain string."""
    if isinstance(content, list):
        return " ".join(
            part.get("text", "") if isinstance(part, dict) else str(part)
            for part in content
        )
    return content or ""


def _last_user_msg(messages: list, max_len: int = 120) -> str:
    for msg in reversed(messages):
        if msg.get("role") == "user":
            text = _content_to_str(msg.get("content")).replace("\n", " ").strip()
            return text[:max_len] + ("…" if len(text) > max_len else "")
    return ""

async def require_api_key(request: Request, db: Session = Depends(get_db)):
    auth_header = request.headers.get("Authorization", "")
    if auth_header.startswith("Bearer "):
        api_key = auth_header[7:]
    elif auth_header.startswith("sk-"):
        api_key = auth_header
    else:
        raise HTTPException(status_code=401, detail="Invalid or missing API key")
    db_key = crud.verify_api_key(db, api_key)
    if not db_key:
        raise HTTPException(status_code=401, detail="Invalid API key")
    request.state.api_key_id = db_key.id
    request.state.api_key_name = db_key.name

app = FastAPI(title="Ollama Proxy", dependencies=[Depends(require_api_key)])

@app.on_event("startup")
def apply_env_settings():
    """Write env-configured values into DB so they take effect until next restart."""
    db = next(get_db())
    try:
        if url := os.getenv("OLLAMA_URL"):
            crud.set_setting(db, "ollama_url", url)
        if model := os.getenv("DEFAULT_MODEL"):
            crud.set_setting(db, "default_model", model)
        db.commit()
    finally:
        db.close()

@app.exception_handler(Exception)
async def unhandled_exception_handler(request: Request, exc: Exception):
    error_log.error("Unhandled exception | %s %s | %s: %s",
                    request.method, request.url.path, type(exc).__name__, exc, exc_info=exc)
    return JSONResponse(status_code=500, content={"error": {"message": "Internal server error", "type": "server_error"}})

async def proxy_request(url: str, method: str = "GET", json_data: dict = None):
    async with httpx.AsyncClient(timeout=300.0) as client:
        response = await client.request(method=method, url=url, json=json_data)
        return response

@app.post("/api/generate")
async def generate(request: Request, db: Session = Depends(get_db)):
    ollama_url = crud.get_setting(db, "ollama_url", os.getenv("OLLAMA_URL", "http://localhost:11434"))
    body = await request.json()
    prompt_tokens = crud.count_tokens(body.get("prompt", ""))

    if not crud.check_and_increment_quota(db, request.state.api_key_id, tokens=prompt_tokens, requests=1):
        raise HTTPException(status_code=429, detail="Quota exceeded")

    prompt_preview = (body.get("prompt", "").replace("\n", " ").strip())[:120]
    usage_log.info('%s | /api/generate | %s | ~%d tokens | "%s"',
                   request.state.api_key_name, body.get("model", "?"), prompt_tokens, prompt_preview)
    try:
        response = await proxy_request(f"{ollama_url}/api/generate", method="POST", json_data=body)
        resp_json = response.json()
        usage_log.info('%s | /api/generate | %s | actual ↑%d ↓%d tokens',
                       request.state.api_key_name, body.get("model", "?"),
                       resp_json.get("prompt_eval_count", 0), resp_json.get("eval_count", 0))
        return JSONResponse(content=resp_json, status_code=response.status_code)
    except Exception as exc:
        error_log.error("Proxy error | %s | /api/generate | %s | %s: %s",
                        request.state.api_key_name, body.get("model", "?"), type(exc).__name__, exc, exc_info=exc)
        raise

@app.post("/api/chat")
async def chat(request: Request, db: Session = Depends(get_db)):
    ollama_url = crud.get_setting(db, "ollama_url", os.getenv("OLLAMA_URL", "http://localhost:11434"))
    body = await request.json()
    messages = body.get("messages", [])
    prompt_tokens = sum(crud.count_tokens(_content_to_str(msg.get("content"))) for msg in messages)

    if not crud.check_and_increment_quota(db, request.state.api_key_id, tokens=prompt_tokens, requests=1):
        raise HTTPException(status_code=429, detail="Quota exceeded")

    usage_log.info('%s | /api/chat | %s | ~%d tokens | "%s"',
                   request.state.api_key_name, body.get("model", "?"), prompt_tokens, _last_user_msg(messages))
    try:
        response = await proxy_request(f"{ollama_url}/api/chat", method="POST", json_data=body)
        resp_json = response.json()
        usage_log.info('%s | /api/chat | %s | actual ↑%d ↓%d tokens',
                       request.state.api_key_name, body.get("model", "?"),
                       resp_json.get("prompt_eval_count", 0), resp_json.get("eval_count", 0))
        return JSONResponse(content=resp_json, status_code=response.status_code)
    except Exception as exc:
        error_log.error("Proxy error | %s | /api/chat | %s | %s: %s",
                        request.state.api_key_name, body.get("model", "?"), type(exc).__name__, exc, exc_info=exc)
        raise

@app.get("/api/tags")
async def list_models(db: Session = Depends(get_db)):
    ollama_url = crud.get_setting(db, "ollama_url", os.getenv("OLLAMA_URL", "http://localhost:11434"))
    response = await proxy_request(f"{ollama_url}/api/tags", method="GET")
    return JSONResponse(content=response.json(), status_code=response.status_code)

@app.get("/api/versions")
async def versions(db: Session = Depends(get_db)):
    ollama_url = crud.get_setting(db, "ollama_url", os.getenv("OLLAMA_URL", "http://localhost:11434"))
    response = await proxy_request(f"{ollama_url}/api/versions", method="GET")
    return JSONResponse(content=response.json(), status_code=response.status_code)

@app.get("/v1/models")
async def list_openai_models(db: Session = Depends(get_db)):
    ollama_url = crud.get_setting(db, "ollama_url", os.getenv("OLLAMA_URL", "http://localhost:11434"))
    response = await proxy_request(f"{ollama_url}/v1/models", method="GET")
    return JSONResponse(content=response.json(), status_code=response.status_code)

@app.post("/v1/chat/completions")
async def openai_chat_completions(request: Request, db: Session = Depends(get_db)):
    ollama_url = crud.get_setting(db, "ollama_url", os.getenv("OLLAMA_URL", "http://localhost:11434"))
    default_model = crud.get_setting(db, "default_model", os.getenv("DEFAULT_MODEL", "llama3"))

    body = await request.json()
    messages = body.get("messages", [])
    prompt_tokens = sum(crud.count_tokens(_content_to_str(msg.get("content"))) for msg in messages)

    if not crud.check_and_increment_quota(db, request.state.api_key_id, tokens=prompt_tokens, requests=1):
        raise HTTPException(status_code=429, detail="Quota exceeded")

    if "model" not in body:
        body = {**body, "model": default_model}

    model_name = body["model"]
    usage_log.info('%s | /v1/chat/completions | %s | ~%d tokens | "%s"',
                   request.state.api_key_name, model_name, prompt_tokens, _last_user_msg(messages))

    target = f"{ollama_url}/v1/chat/completions"

    if body.get("stream"):
        async def generate():
            try:
                async with httpx.AsyncClient(timeout=300.0) as client:
                    async with client.stream("POST", target, json=body) as resp:
                        async for chunk in resp.aiter_bytes():
                            yield chunk
            except Exception as exc:
                error_log.error("Stream error | %s | /v1/chat/completions | %s | %s: %s",
                                request.state.api_key_name, model_name, type(exc).__name__, exc, exc_info=exc)
                raise
        return StreamingResponse(
            generate(),
            media_type="text/event-stream",
            headers={"Cache-Control": "no-cache", "X-Accel-Buffering": "no"},
        )

    try:
        response = await proxy_request(target, method="POST", json_data=body)
        resp_json = response.json()
        usage = resp_json.get("usage", {})
        usage_log.info('%s | /v1/chat/completions | %s | actual ↑%d ↓%d tokens',
                       request.state.api_key_name, model_name,
                       usage.get("prompt_tokens", 0), usage.get("completion_tokens", 0))
        return JSONResponse(content=resp_json, status_code=response.status_code)
    except Exception as exc:
        error_log.error("Proxy error | %s | /v1/chat/completions | %s | %s: %s",
                        request.state.api_key_name, model_name, type(exc).__name__, exc, exc_info=exc)
        raise