#!/usr/bin/env python3
import argparse
import sys
from pathlib import Path
import yaml

ROOT = Path(__file__).resolve().parents[1]


def find_cycle(node, adj, visited, stack):
    visited.add(node)
    stack.add(node)
    for neighbor in adj.get(node, []):
        if neighbor not in visited:
            if find_cycle(neighbor, adj, visited, stack):
                return True
        elif neighbor in stack:
            return True
    stack.remove(node)
    return False


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--dag", default="spec/41_release_dag.yaml")
    parser.add_argument("--strict", action="store_true")
    args = parser.parse_args()

    dag_path = ROOT / args.dag
    if not dag_path.exists():
        print(f"DAG file not found: {dag_path}")
        return 1

    try:
        data = yaml.safe_load(dag_path.read_text(encoding="utf-8"))
    except Exception as e:
        print(f"Error parsing YAML: {e}")
        return 1

    if not isinstance(data, dict) or "dag" not in data or "nodes" not in data["dag"]:
        print("Invalid DAG format: missing 'dag.nodes'")
        return 1

    nodes = data["dag"]["nodes"]
    
    # 1. Field validation
    required_fields = ["id", "command", "inputs", "outputs", "depends_on", "timeout_sec"]
    for nid, node in nodes.items():
        if not isinstance(node, dict):
            print(f"Node {nid} is not a dictionary")
            return 1
        for field in required_fields:
            if field not in node:
                print(f"Node {nid} is missing required field: {field}")
                return 1

    # 2. Cycle detection
    adj = {}
    for nid, node in nodes.items():
        adj[nid] = node["depends_on"]

    visited = set()
    stack = set()
    for nid in nodes:
        if nid not in visited:
            if find_cycle(nid, adj, visited, stack):
                print("Cycle detected in DAG dependencies!")
                return 1

    # 3. Duplicate output owner detection
    outputs_map = {}
    for nid, node in nodes.items():
        for out in node.get("outputs") or []:
            if out in outputs_map:
                print(f"Duplicate output owner detected! Both {nid} and {outputs_map[out]} output {out}")
                return 1
            outputs_map[out] = nid

    print("PASS")
    return 0


if __name__ == "__main__":
    sys.exit(main())