from dataclasses import dataclass, field
from typing import Dict, Literal, Optional, List
import logging
from observability import logger as obs_logger
from observability import components as obs_components
from .base import LLMClient

logger = logging.getLogger(__name__)


class CapabilityMismatchError(Exception):
    """Raised when a selected model does not meet the agent's capability requirements."""

    pass


@dataclass
class ModelProfile:
    provider: str
    model_name: str
    supports_tools: bool
    supports_strict_json: bool
    latency_class: Literal["fast", "medium", "slow"]
    cost_class: Literal["cheap", "medium", "expensive"]
    stability_rating: int  # 1–5

    def __post_init__(self):
        if not (1 <= self.stability_rating <= 5):
            raise ValueError(
                f"stability_rating must be between 1 and 5, got {self.stability_rating}"
            )


MODEL_REGISTRY: Dict[str, ModelProfile] = {
    "hf_gpt_oss_20b": ModelProfile(
        provider="litellm",
        model_name="huggingface/openai/gpt-oss-20b",
        supports_tools=False,
        supports_strict_json=False,
        latency_class="medium",
        cost_class="cheap",
        stability_rating=3,
    ),
    "gemini_flash": ModelProfile(
        provider="gemini",
        model_name="gemini-3-flash-preview",
        supports_tools=True,
        supports_strict_json=True,
        latency_class="fast",
        cost_class="cheap",
        stability_rating=5,
    ),
    "openai_gpt5": ModelProfile(
        provider="litellm",
        model_name="openai/gpt-5-mini",
        supports_tools=True,
        supports_strict_json=True,
        latency_class="medium",
        cost_class="expensive",
        stability_rating=5,
    ),
}


def select_model_for_agent(agent_name: str) -> ModelProfile:
    """
    Manually maps an agent to a model profile based on requirements.
    Validates that the selected model meets the agent's capability needs.
    """
    from .agent_capabilities import AGENT_CAPABILITIES

    requirements = AGENT_CAPABILITIES.get(agent_name)
    if not requirements:
        logger.warning(
            f"No capability requirements defined for agent: {agent_name}. Using fallback."
        )
        # Default fallback if unknown agent
        return MODEL_REGISTRY["gemini_flash"]

    # Manual mapping as requested
    mapping = {
        "InsightsAgent": "gemini_flash",
        "PlanAgent": "gemini_flash",
        "VisualizationAgent": "openai_gpt5",
        "Router": "gemini_flash",  # Changed from hf_gpt_oss_20b which lacks strict JSON
        "ChatAgent": "hf_gpt_oss_20b",
        "BriefService": "gemini_flash",
    }

    model_key = mapping.get(agent_name, "gemini_flash")
    model_profile = MODEL_REGISTRY.get(model_key)

    if not model_profile:
        raise ValueError(f"Model key '{model_key}' not found in registry for agent '{agent_name}'")

    # Capability Validation
    mismatches = []
    if requirements.tools_required and not model_profile.supports_tools:
        mismatches.append("tools_required=True but supports_tools=False")

    if requirements.strict_json_required and not model_profile.supports_strict_json:
        mismatches.append("strict_json_required=True but supports_strict_json=False")

    if mismatches:
        error_msg = f"Capability mismatch for agent '{agent_name}' with model '{model_key}': {', '.join(mismatches)}"
        obs_logger.log_event(
            level="error",
            message=error_msg,
            event="capability_mismatch",
            component=obs_components.LLM,
            agent_name=agent_name,
            model_key=model_key,
            mismatches=mismatches,
        )
        raise CapabilityMismatchError(error_msg)

    # Success Log
    obs_logger.log_event(
        level="info",
        message=f"Model selected for agent '{agent_name}': {model_key}",
        event="model_selected",
        component=obs_components.LLM,
        agent_name=agent_name,
        selected_model=model_key,
        provider=model_profile.provider,
        model_name=model_profile.model_name,
        required_capabilities={
            "tools_required": requirements.tools_required,
            "strict_json_required": requirements.strict_json_required,
            "latency_preference": requirements.latency_preference,
        },
    )

    return model_profile