"""Common helper functions"""
import json
from datetime import date, datetime
from typing import Any
from flask import jsonify
from backend import db
from backend.models import Conversation, Message, TokenUsage, User


def get_or_create_default_user() -> User:
    """Get or create default user"""
    user = User.query.filter_by(username="default").first()
    if not user:
        user = User(username="default", password=None)
        db.session.add(user)
        db.session.commit()
    return user


def ok(data=None, message=None):
    """Success response helper"""
    body = {"code": 0}
    if data is not None:
        body["data"] = data
    if message is not None:
        body["message"] = message
    return jsonify(body)


def err(code, message):
    """Error response helper"""
    return jsonify({"code": code, "message": message}), code


def to_dict(inst, **extra):
    """Convert model instance to dict"""
    d = {c.name: getattr(inst, c.name) for c in inst.__table__.columns}
    for k in ("created_at", "updated_at"):
        if k in d and hasattr(d[k], "strftime"):
            d[k] = d[k].strftime("%Y-%m-%dT%H:%M:%SZ")
    
    # Filter out None values for cleaner API response
    d = {k: v for k, v in d.items() if v is not None}
    
    d.update(extra)
    return d


def record_token_usage(user_id, model, prompt_tokens, completion_tokens):
    """Record token usage"""
    today = date.today()
    usage = TokenUsage.query.filter_by(
        user_id=user_id, date=today, model=model
    ).first()
    if usage:
        usage.prompt_tokens += prompt_tokens
        usage.completion_tokens += completion_tokens
        usage.total_tokens += prompt_tokens + completion_tokens
    else:
        usage = TokenUsage(
            user_id=user_id,
            date=today,
            model=model,
            prompt_tokens=prompt_tokens,
            completion_tokens=completion_tokens,
            total_tokens=prompt_tokens + completion_tokens,
        )
        db.session.add(usage)
    db.session.commit()


def build_glm_messages(conv):
    """Build messages list for GLM API from conversation"""
    msgs = []
    if conv.system_prompt:
        msgs.append({"role": "system", "content": conv.system_prompt})
    # Query messages directly to avoid detached instance warning
    messages = Message.query.filter_by(conversation_id=conv.id).order_by(Message.created_at.asc()).all()
    for m in messages:
        msgs.append({"role": m.role, "content": m.content})
    return msgs