from pathlib import Path
from typing import TypedDict
from langgraph.graph import StateGraph, START, END
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.types import interrupt, Command

class Job(TypedDict, total=False):
    note: str
    report: str
    approved: bool
    verified: bool

def prepare(state: Job):
    text = state["note"].strip()
    if not text:
        raise ValueError("The note must not be empty")
    return {"report": "Reviewed lab note: " + text + "\n"}

def approve(state: Job):
    decision = interrupt({"proposed_report": state["report"]})
    return {"approved": decision is True}

def route(state: Job):
    return "write" if state["approved"] else "stop"

def write(state: Job):
    Path("output").mkdir(exist_ok=True)
    Path("output/report.txt").write_text(state["report"], encoding="utf-8")
    return {}

def verify(state: Job):
    actual = Path("output/report.txt").read_text(encoding="utf-8")
    if actual != state["report"]:
        raise RuntimeError("Verification failed")
    return {"verified": True}

builder = StateGraph(Job)
builder.add_node("prepare", prepare)
builder.add_node("approve", approve)
builder.add_node("write", write)
builder.add_node("verify", verify)
builder.add_edge(START, "prepare")
builder.add_edge("prepare", "approve")
builder.add_conditional_edges("approve", route, {"write": "write", "stop": END})
builder.add_edge("write", "verify")
builder.add_edge("verify", END)
graph = builder.compile(checkpointer=InMemorySaver())

if __name__ == "__main__":
    config = {"configurable": {"thread_id": "lab-1"}}
    pending = graph.invoke({"note": "Backups belong in ./backups."}, config)
    print("Proposal:", pending["__interrupt__"][0].value)
    approved = input("Write this local report? [y/N] ").strip().lower() == "y"
    result = graph.invoke(Command(resume=approved), config)
    print("Approved:", result.get("approved", False))
    print("Verified:", result.get("verified", False))