#!/usr/bin/env python3
import os
import sys
import yaml
import json
import time
import glob
from pathlib import Path

# Configuration
WORLD_STATE_PATH = Path(os.getenv("HOMELAB_WORLD_ROOT", "/opt/homelab/world"))
INVENTORY_PATH = Path("hosts")
EVENT_LOG = Path("/tmp/agent-events.log")
CHECKPOINT_FILE = Path("/tmp/supervisor-checkpoint.json")

# Reconcile event types
RECONCILE_REQUIRED = "reconcile_required"
RECONCILE_RECOMMENDED = "reconcile_recommended"
RECONCILE_BLOCKED = "reconcile_blocked"

# Runtime summary states
STATE_NOMINAL = "nominal"
STATE_DEGRADED = "degraded"
STATE_UNSTABLE = "unstable"
STATE_RECONCILING = "reconciling"

def emit_event(event_type, message, details=None):
    """Emit reconciliation events using existing event system (append-only file)."""
    event = {
        "type": event_type,
        "message": message,
        "timestamp": time.time(),
        "details": details or {}
    }
    line = json.dumps(event)
    print(line)
    try:
        # Append-only semantics
        with open(EVENT_LOG, "a", encoding="utf-8") as f:
            f.write(line + "\n")
            f.flush()
    except Exception as e:
        print(f"Error writing to event log: {e}", file=sys.stderr)

def load_desired_state():
    """Load desired state from hosts/*/services.yaml."""
    desired = {"services": [], "nodes": []}
    if not INVENTORY_PATH.exists():
        return desired

    # Inventory model: hosts/{node_name}/services.yaml
    for yaml_file in glob.glob(str(INVENTORY_PATH / "*" / "services.yaml")):
        try:
            with open(yaml_file, "r") as f:
                data = yaml.safe_load(f)
                if data and "services" in data:
                    node_name = Path(yaml_file).parent.name
                    for svc in data["services"]:
                        if isinstance(svc, str):
                            svc = {"name": svc}
                        svc["node"] = node_name
                        desired["services"].append(svc)
                    if node_name not in desired["nodes"]:
                        desired["nodes"].append(node_name)
        except Exception as e:
            print(f"Error loading {yaml_file}: {e}", file=sys.stderr)
    return desired

def load_world_state():
    """Load current world state from /opt/homelab/world/ (filesystem-first)."""
    world = {
        "services": {},
        "nodes": {},
        "deployments": {},
        "incidents": {}
    }
    
    if not WORLD_STATE_PATH.exists():
        return world

    # Filesystem-first design: each category is a directory, each item is a JSON file
    for category in ["services", "nodes", "deployments", "incidents"]:
        cat_path = WORLD_STATE_PATH / category
        if cat_path.exists() and cat_path.is_dir():
            for json_file in cat_path.glob("*.json"):
                try:
                    with open(json_file, "r") as f:
                        world[category][json_file.stem] = json.load(f)
                except Exception as e:
                    print(f"Error loading {json_file}: {e}", file=sys.stderr)
    
    return world

def detect_drift(desired, world):
    """Compare desired infrastructure state with observed runtime state."""
    drifts = []
    
    # 1. Missing service & 2. Unhealthy service
    desired_service_names = set()
    for d_svc in desired["services"]:
        name = d_svc["name"]
        desired_service_names.add(name)
        a_svc = world["services"].get(name)
        
        if not a_svc:
            drifts.append({
                "type": "missing_service",
                "service": name,
                "node": d_svc["node"]
            })
        elif a_svc.get("status") not in ("ok", "healthy", "up"):
            drifts.append({
                "type": "unhealthy_service",
                "service": name,
                "status": a_svc.get("status"),
                "node": a_svc.get("node") or d_svc["node"]
            })

    # 4. Offline node
    for node_name in desired["nodes"]:
        a_node = world["nodes"].get(node_name)
        if not a_node or a_node.get("status") not in ("online", "ok", "up"):
             drifts.append({
                "type": "offline_node",
                "node": node_name,
                "status": a_node.get("status") if a_node else "missing"
            })

    # 3. Failed deployment
    # Check for recent failures in world/deployments
    for d_id, d_data in world["deployments"].items():
        if d_data.get("status") == "failed":
            drifts.append({
                "type": "failed_deployment",
                "deployment_id": d_id,
                "service": d_data.get("service")
            })

    # 5. Unresolved incidents
    for i_id, i_data in world["incidents"].items():
        if i_data.get("status") not in ("resolved", "closed"):
            drifts.append({
                "type": "unresolved_incident",
                "incident_id": i_id,
                "description": i_data.get("description"),
                "status": i_data.get("status")
            })

    return drifts

def recommendation_engine(drifts, world):
    """Recommendation mode only: emit proposed actions without mutation."""
    recommendations = []
    for drift in drifts:
        if drift["type"] == "unhealthy_service":
            recommendations.append({
                "drift": drift,
                "action": "redeploy",
                "message": f"Service {drift['service']} is unhealthy. Recommend redeploy.",
                "type": RECONCILE_REQUIRED
            })
        elif drift["type"] == "failed_deployment":
            service = drift["service"]
            # Recommendation: repeated deployment failures -> recommend diagnostics
            failures = [d for d in world["deployments"].values() if d.get("service") == service and d.get("status") == "failed"]
            if len(failures) > 2:
                recommendations.append({
                    "drift": drift,
                    "action": "diagnostics",
                    "message": f"Repeated deployment failures for {service}. Recommend diagnostics.",
                    "type": RECONCILE_BLOCKED
                })
            else:
                recommendations.append({
                    "drift": drift,
                    "action": "redeploy",
                    "message": f"Deployment failed for {service}. Recommend retry.",
                    "type": RECONCILE_REQUIRED
                })
        elif drift["type"] == "offline_node":
            # Recommendation: node offline -> recommend failover review
            recommendations.append({
                "drift": drift,
                "action": "failover_review",
                "message": f"Node {drift['node']} is offline. Recommend failover review.",
                "type": RECONCILE_REQUIRED
            })
        elif drift["type"] == "missing_service":
            # Recommendation: dependency unavailable -> recommend delayed deployment
            # Mock dependency check: if a service is 'webapp' and 'database' is not healthy
            dependencies_met = True
            if drift["service"] == "webapp":
                db_svc = world["services"].get("database")
                if not db_svc or db_svc.get("status") not in ("ok", "healthy", "up"):
                    dependencies_met = False
            
            if not dependencies_met:
                recommendations.append({
                    "drift": drift,
                    "action": "delayed_deployment",
                    "message": f"Dependency unavailable for {drift['service']}. Recommend delayed deployment.",
                    "type": RECONCILE_RECOMMENDED
                })
            else:
                recommendations.append({
                    "drift": drift,
                    "action": "deploy",
                    "message": f"Service {drift['service']} is missing. Recommend deployment.",
                    "type": RECONCILE_REQUIRED
                })
        elif drift["type"] == "unresolved_incident":
            recommendations.append({
                "drift": drift,
                "action": "review",
                "message": f"Unresolved incident: {drift['description']}. Recommend review.",
                "type": RECONCILE_RECOMMENDED
            })
    return recommendations

def save_checkpoint(state):
    """Checkpoint support for idempotent operation."""
    try:
        with open(CHECKPOINT_FILE, "w") as f:
            json.dump({
                "last_run": time.time(),
                "state": state
            }, f)
    except Exception as e:
         print(f"Error saving checkpoint: {e}", file=sys.stderr)

def load_checkpoint():
    """Load last run checkpoint."""
    if CHECKPOINT_FILE.exists():
        try:
            with open(CHECKPOINT_FILE, "r") as f:
                return json.load(f)
        except Exception as e:
            print(f"Error loading checkpoint: {e}", file=sys.stderr)
    return None

def main():
    print(f"--- Supervisor Run: {time.ctime()} ---")
    
    checkpoint = load_checkpoint()
    if checkpoint:
        print(f"Last run: {time.ctime(checkpoint.get('last_run', 0))}")
    
    # 1. Load desired state
    desired = load_desired_state()
    
    # 2. Load world state
    world = load_world_state()
    
    # 3. Detect drift
    drifts = detect_drift(desired, world)
    
    # 4. Generate recommendations (Recommendation mode only)
    recommendations = recommendation_engine(drifts, world)
    
    # 5. Emit events & Update summary state
    if not recommendations and not drifts:
        emit_event("summary_state", f"System state: {STATE_NOMINAL}", {"state": STATE_NOMINAL})
    else:
        # Extend runtime summary states: nominal, degraded, unstable, reconciling
        has_blocked = any(r["type"] == RECONCILE_BLOCKED for r in recommendations)
        has_required = any(r["type"] == RECONCILE_REQUIRED for r in recommendations)
        
        overall_state = STATE_NOMINAL
        if has_blocked:
            overall_state = STATE_UNSTABLE
        elif has_required:
            overall_state = STATE_DEGRADED
        elif recommendations:
            overall_state = STATE_DEGRADED
            
        emit_event("summary_state", f"System state: {overall_state}", {"state": overall_state})
        
        # Emit reconciliation events
        for rec in recommendations:
            emit_event(rec["type"], rec["message"], rec["drift"])

    # 6. Save checkpoint
    save_checkpoint({
        "drift_count": len(drifts), 
        "recommendation_count": len(recommendations),
        "timestamp": time.time()
    })
    
    print("Run complete.")

if __name__ == "__main__":
    main()