"""
intent_agent.py
---------------
Stage 2: Intent Detection Agent for Notiflow

Uses ModelRouter (Nova primary → Gemini fallback) to classify
the business intent of Hinglish messages.

Supported intents:
    order | payment | credit | return | preparation | other

Integration note (backend upgrade):
    The private _call_model() function now delegates to agent/model_router.py
    instead of calling bedrock_client directly. All parsing and public API
    logic is unchanged.
"""

import json
import logging
import re
from pathlib import Path

PROMPT_PATH = Path(__file__).parent.parent / "prompts" / "intent_prompt.txt"
VALID_INTENTS = {"order", "payment", "credit", "return", "preparation", "other"}

logger = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# Prompt loader
# ---------------------------------------------------------------------------

def _load_prompt(message: str) -> str:
    template = PROMPT_PATH.read_text(encoding="utf-8")
    return template.replace("{message}", message.strip())


# ---------------------------------------------------------------------------
# Model inference  (now via ModelRouter — Nova primary, Gemini fallback)
# ---------------------------------------------------------------------------

def _call_model(prompt: str) -> str:
    """
    Route the prompt through ModelRouter.
    Returns raw text response from whichever model was available.
    """
    from agent.model_router import route
    raw, model_used = route(prompt, max_tokens=64)
    logger.info("Intent inference served by: %s", model_used)
    return raw


# ---------------------------------------------------------------------------
# Response parser
# ---------------------------------------------------------------------------

def _parse_intent_response(raw: str) -> dict:
    cleaned = re.sub(r"```(?:json)?|```", "", raw).strip()
    try:
        result = json.loads(cleaned)
        intent = result.get("intent", "other").lower().strip()
    except json.JSONDecodeError:
        match  = re.search(r'"intent"\s*:\s*"(\w+)"', cleaned)
        intent = match.group(1).lower() if match else "other"

    if intent not in VALID_INTENTS:
        logger.warning("Unknown intent '%s', defaulting to 'other'", intent)
        intent = "other"

    return {"intent": intent}


# ---------------------------------------------------------------------------
# Public API
# ---------------------------------------------------------------------------

def detect_intent(message: str) -> dict:
    """
    Detect the business intent of a Hinglish message.

    Args:
        message: Raw business message (Hinglish or English).

    Returns:
        {"intent": "<intent_string>"}

    Examples:
        >>> detect_intent("bhaiya 2 kilo bhej dena")
        {'intent': 'order'}
        >>> detect_intent("rahul ne 15000 bheja")
        {'intent': 'payment'}
    """
    if not message or not message.strip():
        logger.warning("Empty message received, returning 'other'")
        return {"intent": "other"}

    logger.info("Detecting intent for: %r", message)
    prompt      = _load_prompt(message)
    raw         = _call_model(prompt)
    result      = _parse_intent_response(raw)
    logger.info("Detected intent: %s", result["intent"])
    return result