"""Memory updater for reading, writing, and updating memory data."""

import json
import os
import uuid
from datetime import datetime
from pathlib import Path
from typing import Any

from src.agents.memory.prompt import (
    MEMORY_UPDATE_PROMPT,
    format_conversation_for_update,
)
from src.config.memory_config import get_memory_config
from src.models import create_chat_model


def _get_memory_file_path() -> Path:
    """Get the path to the memory file."""
    config = get_memory_config()
    # Resolve relative to current working directory (backend/)
    return Path(os.getcwd()) / config.storage_path


def _create_empty_memory() -> dict[str, Any]:
    """Create an empty memory structure."""
    return {
        "version": "1.0",
        "lastUpdated": datetime.utcnow().isoformat() + "Z",
        "user": {
            "workContext": {"summary": "", "updatedAt": ""},
            "personalContext": {"summary": "", "updatedAt": ""},
            "topOfMind": {"summary": "", "updatedAt": ""},
        },
        "history": {
            "recentMonths": {"summary": "", "updatedAt": ""},
            "earlierContext": {"summary": "", "updatedAt": ""},
            "longTermBackground": {"summary": "", "updatedAt": ""},
        },
        "facts": [],
    }


# Global memory data cache
_memory_data: dict[str, Any] | None = None


def get_memory_data() -> dict[str, Any]:
    """Get the current memory data (cached singleton).

    Returns:
        The memory data dictionary.
    """
    global _memory_data
    if _memory_data is None:
        _memory_data = _load_memory_from_file()
    return _memory_data


def reload_memory_data() -> dict[str, Any]:
    """Reload memory data from file.

    Returns:
        The reloaded memory data dictionary.
    """
    global _memory_data
    _memory_data = _load_memory_from_file()
    return _memory_data


def _load_memory_from_file() -> dict[str, Any]:
    """Load memory data from file.

    Returns:
        The memory data dictionary.
    """
    file_path = _get_memory_file_path()

    if not file_path.exists():
        return _create_empty_memory()

    try:
        with open(file_path, encoding="utf-8") as f:
            data = json.load(f)
        return data
    except (json.JSONDecodeError, OSError) as e:
        print(f"Failed to load memory file: {e}")
        return _create_empty_memory()


def _save_memory_to_file(memory_data: dict[str, Any]) -> bool:
    """Save memory data to file.

    Args:
        memory_data: The memory data to save.

    Returns:
        True if successful, False otherwise.
    """
    global _memory_data
    file_path = _get_memory_file_path()

    try:
        # Ensure directory exists
        file_path.parent.mkdir(parents=True, exist_ok=True)

        # Update lastUpdated timestamp
        memory_data["lastUpdated"] = datetime.utcnow().isoformat() + "Z"

        # Write atomically using temp file
        temp_path = file_path.with_suffix(".tmp")
        with open(temp_path, "w", encoding="utf-8") as f:
            json.dump(memory_data, f, indent=2, ensure_ascii=False)

        # Rename temp file to actual file (atomic on most systems)
        temp_path.replace(file_path)

        # Update cache
        _memory_data = memory_data

        print(f"Memory saved to {file_path}")
        return True
    except OSError as e:
        print(f"Failed to save memory file: {e}")
        return False


class MemoryUpdater:
    """Updates memory using LLM based on conversation context."""

    def __init__(self, model_name: str | None = None):
        """Initialize the memory updater.

        Args:
            model_name: Optional model name to use. If None, uses config or default.
        """
        self._model_name = model_name

    def _get_model(self):
        """Get the model for memory updates."""
        config = get_memory_config()
        model_name = self._model_name or config.model_name
        return create_chat_model(name=model_name, thinking_enabled=False)

    def update_memory(self, messages: list[Any], thread_id: str | None = None) -> bool:
        """Update memory based on conversation messages.

        Args:
            messages: List of conversation messages.
            thread_id: Optional thread ID for tracking source.

        Returns:
            True if update was successful, False otherwise.
        """
        config = get_memory_config()
        if not config.enabled:
            return False

        if not messages:
            return False

        try:
            # Get current memory
            current_memory = get_memory_data()

            # Format conversation for prompt
            conversation_text = format_conversation_for_update(messages)

            if not conversation_text.strip():
                return False

            # Build prompt
            prompt = MEMORY_UPDATE_PROMPT.format(
                current_memory=json.dumps(current_memory, indent=2),
                conversation=conversation_text,
            )

            # Call LLM
            model = self._get_model()
            response = model.invoke(prompt)
            response_text = str(response.content).strip()

            # Parse response
            # Remove markdown code blocks if present
            if response_text.startswith("```"):
                lines = response_text.split("\n")
                response_text = "\n".join(lines[1:-1] if lines[-1] == "```" else lines[1:])

            update_data = json.loads(response_text)

            # Apply updates
            updated_memory = self._apply_updates(current_memory, update_data, thread_id)

            # Save
            return _save_memory_to_file(updated_memory)

        except json.JSONDecodeError as e:
            print(f"Failed to parse LLM response for memory update: {e}")
            return False
        except Exception as e:
            print(f"Memory update failed: {e}")
            return False

    def _apply_updates(
        self,
        current_memory: dict[str, Any],
        update_data: dict[str, Any],
        thread_id: str | None = None,
    ) -> dict[str, Any]:
        """Apply LLM-generated updates to memory.

        Args:
            current_memory: Current memory data.
            update_data: Updates from LLM.
            thread_id: Optional thread ID for tracking.

        Returns:
            Updated memory data.
        """
        config = get_memory_config()
        now = datetime.utcnow().isoformat() + "Z"

        # Update user sections
        user_updates = update_data.get("user", {})
        for section in ["workContext", "personalContext", "topOfMind"]:
            section_data = user_updates.get(section, {})
            if section_data.get("shouldUpdate") and section_data.get("summary"):
                current_memory["user"][section] = {
                    "summary": section_data["summary"],
                    "updatedAt": now,
                }

        # Update history sections
        history_updates = update_data.get("history", {})
        for section in ["recentMonths", "earlierContext", "longTermBackground"]:
            section_data = history_updates.get(section, {})
            if section_data.get("shouldUpdate") and section_data.get("summary"):
                current_memory["history"][section] = {
                    "summary": section_data["summary"],
                    "updatedAt": now,
                }

        # Remove facts
        facts_to_remove = set(update_data.get("factsToRemove", []))
        if facts_to_remove:
            current_memory["facts"] = [
                f for f in current_memory.get("facts", []) if f.get("id") not in facts_to_remove
            ]

        # Add new facts
        new_facts = update_data.get("newFacts", [])
        for fact in new_facts:
            confidence = fact.get("confidence", 0.5)
            if confidence >= config.fact_confidence_threshold:
                fact_entry = {
                    "id": f"fact_{uuid.uuid4().hex[:8]}",
                    "content": fact.get("content", ""),
                    "category": fact.get("category", "context"),
                    "confidence": confidence,
                    "createdAt": now,
                    "source": thread_id or "unknown",
                }
                current_memory["facts"].append(fact_entry)

        # Enforce max facts limit
        if len(current_memory["facts"]) > config.max_facts:
            # Sort by confidence and keep top ones
            current_memory["facts"] = sorted(
                current_memory["facts"],
                key=lambda f: f.get("confidence", 0),
                reverse=True,
            )[: config.max_facts]

        return current_memory


def update_memory_from_conversation(
    messages: list[Any], thread_id: str | None = None
) -> bool:
    """Convenience function to update memory from a conversation.

    Args:
        messages: List of conversation messages.
        thread_id: Optional thread ID.

    Returns:
        True if successful, False otherwise.
    """
    updater = MemoryUpdater()
    return updater.update_memory(messages, thread_id)