"""
Icarus Router — FastAPI server
==============================
OpenAI-compatible LLM routing gateway. Self-hosted. $0/month.

Endpoints:
  GET  /              — info
  GET  /health        — probe all providers in parallel
  GET  /providers     — list providers, routing table, model map
  POST /command       — general routing (specify task type)
  POST /code          — shortcut: CODE_SMALL chain
  POST /reason        — shortcut: REASONING chain
  POST /chat          — shortcut: CHAT chain
  POST /v1/chat/completions  — OpenAI-compatible endpoint

Run:
  uvicorn server:app --host 0.0.0.0 --port 8000

License: Apache 2.0
Author: Llewellyn Systems — https://www.llewellynsystems.com
"""
from __future__ import annotations

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from typing import Optional
import time

from router import route, health_check, TaskType, MODEL_MAP, ROUTING_TABLE, PROVIDERS

app = FastAPI(
    title="Icarus Router",
    version="1.0.0",
    description="Multi-provider LLM routing gateway — $0/month free-tier focused",
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)


# ============================================================================
# REQUEST / RESPONSE MODELS
# ============================================================================

class CommandRequest(BaseModel):
    prompt: str
    task: Optional[str] = "reasoning"
    max_tokens: Optional[int] = 1000
    preferred: Optional[list[str]] = None


# OpenAI-compatible models
class OAIMessage(BaseModel):
    role: str
    content: str

class OAIChatRequest(BaseModel):
    model: Optional[str] = "auto"
    messages: list[OAIMessage]
    max_tokens: Optional[int] = 1000
    stream: Optional[bool] = False


# ============================================================================
# HELPERS
# ============================================================================

def _task(name: str) -> TaskType:
    try:
        return TaskType(name)
    except ValueError:
        raise HTTPException(status_code=400, detail=f"Unknown task type: '{name}'. Valid: {[t.value for t in TaskType]}")


# ============================================================================
# ROUTES
# ============================================================================

@app.get("/")
async def root():
    return {
        "name": "Icarus Router",
        "version": "1.0.0",
        "description": "Multi-provider LLM routing gateway — $0/month",
        "providers": list(PROVIDERS.keys()),
        "docs": "/docs",
        "health": "/health",
        "built_by": "Llewellyn Systems — https://www.llewellynsystems.com",
    }


@app.get("/health")
async def health():
    """Probe all configured providers in parallel. Shows which are live."""
    return await health_check()


@app.get("/providers")
async def providers():
    """Return the full routing table and model map."""
    return {
        "providers": list(PROVIDERS.keys()),
        "routing_table": {t.value: ps for t, ps in ROUTING_TABLE.items()},
        "model_map": {
            p: {t.value: m for t, m in tm.items()}
            for p, tm in MODEL_MAP.items()
        },
    }


@app.post("/command")
async def command(req: CommandRequest):
    """
    General routing endpoint. Specify task to control provider chain.
    Returns response + provider metadata.
    """
    return await route(
        req.prompt,
        task=_task(req.task or "reasoning"),
        max_tokens=req.max_tokens or 1000,
        preferred=req.preferred,
    )


@app.post("/code")
async def code(req: CommandRequest):
    """Shortcut for CODE_SMALL task routing."""
    return await route(
        req.prompt,
        task=TaskType.CODE_SMALL,
        max_tokens=req.max_tokens or 2000,
        preferred=req.preferred,
    )


@app.post("/reason")
async def reason(req: CommandRequest):
    """Shortcut for REASONING task routing."""
    return await route(
        req.prompt,
        task=TaskType.REASONING,
        max_tokens=req.max_tokens or 1500,
        preferred=req.preferred,
    )


@app.post("/chat")
async def chat(req: CommandRequest):
    """Shortcut for CHAT task routing."""
    return await route(
        req.prompt,
        task=TaskType.CHAT,
        max_tokens=req.max_tokens or 800,
        preferred=req.preferred,
    )


@app.post("/v1/chat/completions")
async def openai_compat(req: OAIChatRequest):
    """
    OpenAI-compatible endpoint. Drop-in replacement for openai.ChatCompletion.

    Usage:
        from openai import OpenAI
        client = OpenAI(base_url="http://localhost:8000/v1", api_key="not-needed")
        response = client.chat.completions.create(
            model="auto",
            messages=[{"role": "user", "content": "Hello"}]
        )
    """
    # Flatten messages to a single prompt (simple approach — extend for multi-turn)
    prompt_parts = []
    for msg in req.messages:
        if msg.role == "system":
            prompt_parts.append(f"[System]: {msg.content}")
        elif msg.role == "user":
            prompt_parts.append(msg.content)
        elif msg.role == "assistant":
            prompt_parts.append(f"[Assistant]: {msg.content}")
    prompt = "\n".join(prompt_parts)

    # Map model hint to task type
    model_hint = (req.model or "auto").lower()
    if "code" in model_hint:
        task = TaskType.CODE_SMALL
    elif "reason" in model_hint:
        task = TaskType.REASONING
    elif "vision" in model_hint:
        task = TaskType.VISION
    else:
        task = TaskType.CHAT

    result = await route(prompt, task=task, max_tokens=req.max_tokens or 1000)

    if not result.get("response"):
        raise HTTPException(status_code=503, detail="All providers failed. Check /health for status.")

    # Return in OpenAI response shape
    created = int(time.time())
    return {
        "id": f"icarus-{created}",
        "object": "chat.completion",
        "created": created,
        "model": result.get("model", "unknown"),
        "choices": [{
            "index": 0,
            "message": {
                "role": "assistant",
                "content": result["response"],
            },
            "finish_reason": "stop",
        }],
        "usage": {
            "prompt_tokens": len(prompt.split()),
            "completion_tokens": len((result.get("response") or "").split()),
            "total_tokens": len(prompt.split()) + len((result.get("response") or "").split()),
        },
        "x_icarus": {
            "provider": result.get("provider"),
            "latency_ms": result.get("latency_ms"),
            "task": result.get("task"),
            "attempts": result.get("attempts", []),
        },
    }


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)