import docker
from fastapi import APIRouter, Depends, HTTPException, Query

from config import DOCKER_HOST
from rbac import require_admin


import time
import logging

logger = logging.getLogger(__name__)

def docker_retry(fn, max_retries=3, base_delay=1):
    """Execute fn with exponential backoff. Returns (result, True) or (None, False)."""
    for attempt in range(max_retries):
        try:
            result = fn()
            return result
        except Exception as e:
            delay = base_delay * (2 ** attempt)
            logger.warning("Docker API error (attempt %d/%d): %s. Retrying in %ds...", attempt+1, max_retries, e, delay)
            if attempt < max_retries - 1:
                time.sleep(delay)
    logger.error("Docker API failed after %d attempts", max_retries)
    return None


router = APIRouter()

_client = None


def get_docker_client():
    """Get or create Docker client (lazy initialization)."""
    global _client
    if _client is None:
        _client = docker.DockerClient(base_url=DOCKER_HOST)
    return _client


@router.get("/containers")
def list_containers():
    client = get_docker_client()
    result = docker_retry(lambda: client.containers.list(all=True))
    if result is None:
        return []
    return [
        {
            "id": c.short_id,
            "name": c.name,
            "status": c.status,
            "health": (c.attrs.get("State", {}).get("Health", {}) or {}).get("Status", ""),
            "image": c.image.tags[0] if c.image.tags else str(c.image.id)[:20],
            "ports": c.ports,
        }
        for c in result
    ]


@router.post("/containers/{container_id}/{action}", dependencies=[Depends(require_admin())])
def container_action(container_id: str, action: str):
    if action not in ("start", "stop", "restart"):
        raise HTTPException(status_code=400, detail="Invalid action. Must be one of: start, stop, restart")
    client = get_docker_client()
    def _do():
        c = client.containers.get(container_id)
        getattr(c, action)()
        return True
    if docker_retry(_do) is None:
        raise HTTPException(status_code=503, detail="Docker API unavailable")
    return {"ok": True}


@router.get("/containers/{container_id}/logs")
def container_logs(container_id: str, tail: int = Query(200, le=10000)):
    client = get_docker_client()
    def _do():
        c = client.containers.get(container_id)
        return {"logs": c.logs(tail=tail, timestamps=True).decode(errors="replace")}
    result = docker_retry(_do)
    if result is None:
        return {"logs": ""}
    return result