import os
import asyncio
from langchain_openai import ChatOpenAI
from langchain_core.messages import HumanMessage, SystemMessage
from langgraph.graph import StateGraph, START, END
from typing import TypedDict, Annotated
from langgraph.graph.message import add_messages
from pydantic import BaseModel, Field
from langchain_core.output_parsers import PydanticOutputParser

# LLM setup
llm = ChatOpenAI(
    model="gpt-4o-mini",
    base_url="https://openrouter.ai/api/v1",
    api_key=os.getenv("OPENAI_API_KEY"),
    temperature=0.0,
)

# State definition
class CodeReviewState(TypedDict):
    code: str
    draft_review: str
    criteria_scores: dict[str, int]
    weakest_criterion: str
    verdict: str
    round: int
    max_rounds: int

# Node: draft_review
async def draft_review(state: CodeReviewState):
    prompt = f"Write a concise code review (3-6 points) for the following Python function:\n\n{state['code']}"
    msg = await llm.ainvoke([HumanMessage(content=prompt)])
    state['draft_review'] = msg.content
    return state

# Node: reflect
class ReflectOutput(BaseModel):
    scores: dict[str, int]
    weakest: str
    verdict: str

parser = PydanticOutputParser(pydantic_object=ReflectOutput)

async def reflect(state: CodeReviewState):
    prompt = f"Evaluate the draft review and assign scores 0-10 for PEP8, type_hints, edge_cases, naming. Return JSON with keys scores, weakest, verdict (ok or needs_revision).\n\nDraft review:\n{state['draft_review']}"
    msg = await llm.ainvoke([HumanMessage(content=prompt)])
    out = parser.parse(msg.content)
    state['criteria_scores'] = out.scores
    state['weakest_criterion'] = out.weakest
    state['verdict'] = out.verdict
    return state

# Node: rewrite
async def rewrite(state: CodeReviewState):
    prompt = f"Rewrite the part of the draft review that addresses the weakest criterion '{state['weakest_criterion']}'. Keep other points unchanged.\n\nOriginal draft:\n{state['draft_review']}"
    msg = await llm.ainvoke([HumanMessage(content=prompt)])
    state['draft_review'] = msg.content
    state['round'] += 1
    return state

# Graph
graph = StateGraph(CodeReviewState)
graph.add_node("draft_review", draft_review)
graph.add_node("reflect", reflect)
graph.add_node("rewrite", rewrite)

graph.set_entry_point("draft_review")
graph.add_edge("draft_review", "reflect")
graph.add_conditional_edges(
    "reflect",
    lambda s: "rewrite" if s['verdict']=='needs_revision' and s['round']<s['max_rounds'] else END,
)
graph.add_edge("rewrite", "reflect")

app = graph.compile()

# Demo function
async def demo():
    code = """def sort_numbers(arr):
    return sorted(arr)"""
    state: CodeReviewState = {
        "code": code,
        "draft_review": "",
        "criteria_scores": {},
        "weakest_criterion": "",
        "verdict": "",
        "round": 0,
        "max_rounds": 2,
    }
    final = await app.ainvoke(state)
    print("Final draft review:\n", final['draft_review'])
    print("Scores:", final['criteria_scores'])
    print("Verdict:", final['verdict'])

if __name__ == "__main__":
    asyncio.run(demo())