ui/api_client.py

"""
API Client for the ERP AI Procurement Assistant backend.
Handles the HTTP communication with the LangGraph FastAPI backend.
"""

import sys
import os
import requests
from typing import List
from pydantic import BaseModel, Field

# Ensure project root is in path
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
from src.config import API_URL

class HistoryTurn(BaseModel):
    role: str
    content: str

class ChunkDetail(BaseModel):
    content: str
    source: str

class TraceEventModel(BaseModel):
    node: str
    status: str
    duration_ms: float
    summary: str = ""
    payload: dict = Field(default_factory=dict)

class ToolResultModel(BaseModel):
    tool_name: str
    input: dict = Field(default_factory=dict)
    output: dict = Field(default_factory=dict)

class AskRequest(BaseModel):
    query: str
    history: List[HistoryTurn] = Field(default_factory=list)
    memory_summary: str = ""
    session_id: str = "default"

class AskResponse(BaseModel):
    query: str
    answer: str
    sources: List[str]
    chunks: List[ChunkDetail]
    query_type: str
    confidence: float
    trace: List[TraceEventModel]
    tool_results: List[ToolResultModel]
    memory_summary: str
    history: List[HistoryTurn]

class BackendError(Exception):
    pass

def ask_backend(query: str, history: List[dict], memory_summary: str, session_id: str) -> AskResponse:
    """
    Sends the user query to the FastAPI backend and returns the typed response.
    """
    req_data = AskRequest(
        query=query,
        history=[HistoryTurn(**t) for t in history],
        memory_summary=memory_summary,
        session_id=session_id
    )
    
    try:
        resp = requests.post(API_URL, json=req_data.model_dump())
        resp.raise_for_status()
        return AskResponse(**resp.json())
    except requests.exceptions.RequestException as e:
        raise BackendError(f"Failed to connect to backend: {e}")