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


def get_current_user():
    """Get the current authenticated user from request context (g.current_user)."""
    from flask import g
    return getattr(g, "current_user", None)


def get_or_create_default_user() -> User:
    """Get or create default user.

    .. deprecated::
        Use g.current_user instead. This is kept for backward compatibility
        and will be removed in a future version.
    """
    from flask import g
    user = getattr(g, "current_user", None)
    if user:
        return user
    # Fallback: look up or create default user (should not happen with auth middleware)
    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 message_to_dict(msg: Message) -> dict:
    """Convert message to dict, parsing JSON content.

    For assistant messages, extracts the 'steps' array which preserves the
    ordered sequence of thinking/text/tool_call/tool_result steps, so the
    frontend can render them in the correct interleaved order.
    """
    result = to_dict(msg)

    # Parse content JSON
    if msg.content:
        try:
            content_data = json.loads(msg.content)
            if isinstance(content_data, dict):
                result["text"] = content_data.get("text", "")
                if content_data.get("attachments"):
                    result["attachments"] = content_data["attachments"]
                if content_data.get("tool_calls"):
                    result["tool_calls"] = content_data["tool_calls"]
                # Extract ordered steps array for correct rendering order
                if content_data.get("steps"):
                    result["process_steps"] = content_data["steps"]
            else:
                result["text"] = msg.content
        except (json.JSONDecodeError, TypeError):
            result["text"] = msg.content

    if "text" not in result:
        result["text"] = ""

    return result


def record_token_usage(user_id, model, prompt_tokens, completion_tokens):
    """Record token usage"""
    today = datetime.now(timezone.utc).date()
    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_messages(conv, project_id=None):
    """Build messages list for LLM API from conversation
    
    Args:
        conv: Conversation object
        project_id: Project ID (used for context injection, backend enforces workspace isolation)
    """
    msgs = []
    
    # System prompt (project_id is handled by backend for security)
    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:
        # Skip tool messages — they are ephemeral intermediate results, not
        # meant to be replayed as conversation history (would violate the API
        # protocol that requires tool messages to follow an assistant message
        # with matching tool_calls).
        if m.role == "tool":
            continue

        # Build full content from JSON structure
        full_content = m.content
        try:
            content_data = json.loads(m.content)
            if isinstance(content_data, dict):
                text = content_data.get("text", "")
                attachments = content_data.get("attachments", [])
                
                # Build full content with attachments
                parts = []
                if text:
                    parts.append(text)
                
                for att in attachments:
                    filename = att.get("name", "")
                    file_content = att.get("content", "")
                    if filename and file_content:
                        parts.append(f"```{filename}\n{file_content}\n```")
                
                full_content = "\n\n".join(parts) if parts else ""
        except (json.JSONDecodeError, TypeError):
            # Plain text, use as-is
            pass
        
        msgs.append({"role": m.role, "content": full_content})
    return msgs