"""
Nodes API — list nodes, get/set node roles + policies, probe agents.
"""

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel
from typing import Optional, Dict, Any

from backend.nodes.roles_store import load_roles, save_roles, get_role, DEFAULT_ROLE
from backend.nodes.roles import NodeRole
from backend.nodes.probe import probe_async, normalize
from backend.config import CONFIG

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


class PolicyBody(BaseModel):
    policy: Optional[str] = None  # preferred | avoid | neutral
    compile_weight: Optional[float] = None
    cache_writer: Optional[bool] = None
    cache_reader: Optional[bool] = None
    max_thermal_state: Optional[float] = None
    distcc_enabled: Optional[bool] = None


def _registry():
    """Lazy import of the singleton registry from api.api."""
    from backend.api.api import registry
    return registry


def _node_view(n: dict, role: NodeRole) -> dict:
    """Combine config + role + live registry state into a single view."""
    name = n["name"]
    reg = _registry().get(name)
    return {
        "name": name,
        "host": n.get("host"),
        "max_jobs": n.get("max_jobs", 1),
        "state": "online" if (reg is None or not getattr(reg, "offline", False)) else "offline",
        "policy": _policy_from_role(role),
        "role": _role_summary(role),
        # Live metrics from the registry (may be None if no agent has reported)
        "heat": getattr(reg, "temp", None) if reg else None,
        "jobs": getattr(reg, "active_jobs", None) if reg else None,
        "cpu_load": getattr(reg, "cpu_load", None) if reg else None,
        "memory_load": getattr(reg, "memory_load", None) if reg else None,
        "instability": getattr(reg, "instability", None) if reg else None,
        "last_seen": getattr(reg, "last_seen", None) if reg else None,
    }


# -----------------------------
# LIST NODES
# -----------------------------
@router.get("")
def list_nodes():
    """List configured nodes with their current role + policy + live metrics."""
    roles = load_roles()
    nodes = [_node_view(n, roles.get(n["name"], DEFAULT_ROLE)) for n in CONFIG.get("nodes", [])]
    return {"master": CONFIG.get("master"), "nodes": nodes}


# -----------------------------
# GET ONE NODE
# -----------------------------
@router.get("/{name}")
def get_node(name: str):
    roles = load_roles()
    for n in CONFIG.get("nodes", []):
        if n["name"] == name:
            return _node_view(n, roles.get(name, DEFAULT_ROLE))
    return {"error": "not found"}


# -----------------------------
# SET NODE POLICY
# -----------------------------
@router.post("/{name}/policy")
def set_node_policy(name: str, body: PolicyBody):
    roles = load_roles()
    role = roles.get(name, NodeRole(name=name))

    if body.policy is not None:
        # Translate policy keyword into compile_weight + thermal cap
        if body.policy == "preferred":
            role.compile_weight = 2.0
            role.max_thermal_state = 0.95
        elif body.policy == "avoid":
            role.compile_weight = 0.2
            role.max_thermal_state = 0.5
        elif body.policy == "neutral":
            role.compile_weight = 1.0
            role.max_thermal_state = 0.85

    if body.compile_weight is not None:
        role.compile_weight = body.compile_weight
    if body.cache_writer is not None:
        role.cache_writer = body.cache_writer
    if body.cache_reader is not None:
        role.cache_reader = body.cache_reader
    if body.max_thermal_state is not None:
        role.max_thermal_state = body.max_thermal_state
    if body.distcc_enabled is not None:
        role.distcc_enabled = body.distcc_enabled

    roles[name] = role
    save_roles(roles)
    return {"status": "ok", "node": name, "role": role.__dict__}


# -----------------------------
# PROBE A NODE (manual)
# -----------------------------
@router.post("/{name}/probe")
async def probe_node_endpoint(name: str):
    """Manually trigger a probe of the named node's agent.
    Updates the registry and returns the normalized state."""
    # Find the node config
    cfg = None
    for n in CONFIG.get("nodes", []):
        if n["name"] == name:
            cfg = n
            break
    if not cfg:
        raise HTTPException(404, f"node {name} not configured")

    host = cfg.get("host")
    if not host:
        return {"error": "node has no host configured", "node": name}

    raw = await probe_async(host)
    state = normalize(raw, name)

    if raw is not None:
        # Update the registry with the fresh probe data
        reg = _registry()
        reg.update(
            name,
            cpu_load=state["cpu_load"],
            memory_load=state["memory_load"],
            temp=state["temp"],
            instability=state["instability"],
            active_jobs=state["active_jobs"],
            last_seen=state["last_seen"],
        )
        return {"status": "ok", "node": name, "source": "agent", "state": state, "raw": raw}
    else:
        return {"status": "unreachable", "node": name, "host": host, "state": state}


# -----------------------------
# PROBE ALL NODES
# -----------------------------
@router.post("/probe-all")
async def probe_all_nodes_endpoint():
    """Probe every configured node in parallel."""
    import asyncio
    cfg_nodes = CONFIG.get("nodes", [])

    async def probe_one(n):
        host = n.get("host")
        if not host:
            return {"node": n["name"], "host": None, "reachable": False,
                    "state": normalize(None, n["name"])}
        raw = await probe_async(host)
        state = normalize(raw, n["name"])
        if raw is not None:
            reg = _registry()
            reg.update(
                n["name"],
                cpu_load=state["cpu_load"],
                memory_load=state["memory_load"],
                temp=state["temp"],
                instability=state["instability"],
                active_jobs=state["active_jobs"],
                last_seen=state["last_seen"],
            )
        return {"node": n["name"], "host": host, "reachable": raw is not None, "state": state}

    results = await asyncio.gather(*[probe_one(n) for n in cfg_nodes])
    return {"results": list(results)}


# -----------------------------
# HELPERS
# -----------------------------
def _policy_from_role(role: NodeRole) -> str:
    if role.compile_weight >= 2.0:
        return "preferred"
    if role.compile_weight <= 0.2:
        return "avoid"
    return "neutral"


def _role_summary(role: NodeRole) -> Dict[str, Any]:
    return {
        "compile_weight": role.compile_weight,
        "cache_writer": role.cache_writer,
        "cache_reader": role.cache_reader,
        "distcc_enabled": role.distcc_enabled,
        "max_thermal_state": role.max_thermal_state,
    }


# -----------------------------
# Legacy wrapper for api.py facade
# -----------------------------
def nodes_endpoint(registry=None):
    """Legacy entrypoint — returns the same data as GET /api/nodes."""
    return list_nodes()