#!/usr/bin/env python3
"""
Art DAG L1 Server

Manages rendering runs and provides access to the cache.
- POST /runs - start a run (recipe + inputs)
- GET /runs/{run_id} - get run status/result
- GET /cache/{content_hash} - get cached content
"""

import hashlib
import json
import os
import uuid
from datetime import datetime, timezone
from pathlib import Path
from typing import Optional

from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse
from pydantic import BaseModel

import redis

from celery_app import app as celery_app
from tasks import render_effect

# Cache directory
CACHE_DIR = Path.home() / ".artdag" / "cache"
CACHE_DIR.mkdir(parents=True, exist_ok=True)

# Redis for persistent run storage
redis_client = redis.Redis(host='localhost', port=6379, db=5)
RUNS_KEY_PREFIX = "artdag:run:"


def save_run(run: "RunStatus"):
    """Save run to Redis."""
    redis_client.set(f"{RUNS_KEY_PREFIX}{run.run_id}", run.model_dump_json())


def load_run(run_id: str) -> Optional["RunStatus"]:
    """Load run from Redis."""
    data = redis_client.get(f"{RUNS_KEY_PREFIX}{run_id}")
    if data:
        return RunStatus.model_validate_json(data)
    return None


def list_all_runs() -> list["RunStatus"]:
    """List all runs from Redis."""
    runs = []
    for key in redis_client.scan_iter(f"{RUNS_KEY_PREFIX}*"):
        data = redis_client.get(key)
        if data:
            runs.append(RunStatus.model_validate_json(data))
    return sorted(runs, key=lambda r: r.created_at, reverse=True)

app = FastAPI(
    title="Art DAG L1 Server",
    description="Distributed rendering server for Art DAG",
    version="0.1.0"
)


class RunRequest(BaseModel):
    """Request to start a run."""
    recipe: str  # Recipe name (e.g., "dog", "identity")
    inputs: list[str]  # List of content hashes
    output_name: Optional[str] = None


class RunStatus(BaseModel):
    """Status of a run."""
    run_id: str
    status: str  # pending, running, completed, failed
    recipe: str
    inputs: list[str]
    output_name: str
    created_at: str
    completed_at: Optional[str] = None
    output_hash: Optional[str] = None
    error: Optional[str] = None
    celery_task_id: Optional[str] = None


def file_hash(path: Path) -> str:
    """Compute SHA3-256 hash of a file."""
    hasher = hashlib.sha3_256()
    with open(path, "rb") as f:
        for chunk in iter(lambda: f.read(65536), b""):
            hasher.update(chunk)
    return hasher.hexdigest()


def cache_file(source: Path) -> str:
    """Copy file to cache, return content hash."""
    content_hash = file_hash(source)
    cache_path = CACHE_DIR / content_hash
    if not cache_path.exists():
        import shutil
        shutil.copy2(source, cache_path)
    return content_hash


@app.get("/")
async def root():
    """Server info."""
    return {
        "name": "Art DAG L1 Server",
        "version": "0.1.0",
        "cache_dir": str(CACHE_DIR),
        "runs_count": len(list_all_runs())
    }


@app.post("/runs", response_model=RunStatus)
async def create_run(request: RunRequest):
    """Start a new rendering run."""
    run_id = str(uuid.uuid4())

    # Generate output name if not provided
    output_name = request.output_name or f"{request.recipe}-{run_id[:8]}"

    # Create run record
    run = RunStatus(
        run_id=run_id,
        status="pending",
        recipe=request.recipe,
        inputs=request.inputs,
        output_name=output_name,
        created_at=datetime.now(timezone.utc).isoformat()
    )

    # Submit to Celery
    # For now, we only support single-input recipes
    if len(request.inputs) != 1:
        raise HTTPException(400, "Currently only single-input recipes supported")

    input_hash = request.inputs[0]

    task = render_effect.delay(input_hash, request.recipe, output_name)
    run.celery_task_id = task.id
    run.status = "running"

    save_run(run)
    return run


@app.get("/runs/{run_id}", response_model=RunStatus)
async def get_run(run_id: str):
    """Get status of a run."""
    run = load_run(run_id)
    if not run:
        raise HTTPException(404, f"Run {run_id} not found")

    # Check Celery task status if running
    if run.status == "running" and run.celery_task_id:
        task = celery_app.AsyncResult(run.celery_task_id)

        if task.ready():
            if task.successful():
                result = task.result
                run.status = "completed"
                run.completed_at = datetime.now(timezone.utc).isoformat()
                run.output_hash = result.get("output", {}).get("content_hash")

                # Cache the output
                output_path = Path(result.get("output", {}).get("local_path", ""))
                if output_path.exists():
                    cache_file(output_path)
            else:
                run.status = "failed"
                run.error = str(task.result)

            # Save updated status
            save_run(run)

    return run


@app.get("/runs")
async def list_runs():
    """List all runs."""
    return list_all_runs()


@app.get("/cache/{content_hash}")
async def get_cached(content_hash: str):
    """Get cached content by hash."""
    cache_path = CACHE_DIR / content_hash

    if not cache_path.exists():
        raise HTTPException(404, f"Content {content_hash} not in cache")

    return FileResponse(cache_path)


@app.get("/cache")
async def list_cache():
    """List cached content hashes."""
    return [f.name for f in CACHE_DIR.iterdir() if f.is_file()]


# Known assets (bootstrap data)
KNOWN_ASSETS = {
    "cat": "33268b6e167deaf018cc538de12dbe562612b33e89a749391cef855b320a269b",
}


@app.get("/assets")
async def list_assets():
    """List known assets."""
    return KNOWN_ASSETS


@app.post("/cache/import")
async def import_to_cache(path: str):
    """Import a local file to cache."""
    source = Path(path)
    if not source.exists():
        raise HTTPException(404, f"File not found: {path}")

    content_hash = cache_file(source)
    return {"content_hash": content_hash, "cached": True}


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8100)