from __future__ import annotations

from typing import List
import json
import shutil
from pathlib import Path

from ollama import AsyncClient, ChatResponse, Message

from .config import (
    MAX_TOOL_CALL_DEPTH,
    MODEL_NAME,
    EMBEDDING_MODEL_NAME,
    NUM_CTX,
    OLLAMA_HOST,
    SYSTEM_PROMPT,
    UPLOAD_DIR,
)
from .db import (
    Conversation,
    Message as DBMessage,
    User,
    _db,
    init_db,
    add_document,
)
from .log import get_logger
from .schema import Msg
from .tools import execute_terminal, set_vm
from .vm import VMRegistry

_LOG = get_logger(__name__)


class ChatSession:
    def __init__(
        self,
        user: str = "default",
        session: str = "default",
        host: str = OLLAMA_HOST,
        model: str = MODEL_NAME,
        embedding_model: str = EMBEDDING_MODEL_NAME,
    ) -> None:
        init_db()
        self._client = AsyncClient(host=host)
        self._model = model
        self._user, _ = User.get_or_create(username=user)
        self._conversation, _ = Conversation.get_or_create(
            user=self._user, session_name=session
        )
        self._vm = None
        self._messages: List[Msg] = self._load_history()

    async def __aenter__(self) -> "ChatSession":
        self._vm = VMRegistry.acquire(self._user.username)
        set_vm(self._vm)
        return self

    async def __aexit__(self, exc_type, exc, tb) -> None:
        set_vm(None)
        if self._vm:
            VMRegistry.release(self._user.username)
        if not _db.is_closed():
            _db.close()

    def upload_document(self, file_path: str) -> str:
        """Save a document for later access inside the VM.

        The file is copied into ``UPLOAD_DIR`` and recorded in the database. The
        returned path is the location inside the VM (prefixed with ``/data``).
        """

        src = Path(file_path)
        if not src.exists():
            raise FileNotFoundError(file_path)

        dest = Path(UPLOAD_DIR) / self._user.username
        dest.mkdir(parents=True, exist_ok=True)
        target = dest / src.name
        shutil.copy(src, target)
        add_document(self._user.username, str(target), src.name)
        return f"/data/{src.name}"

    def _load_history(self) -> List[Msg]:
        messages: List[Msg] = []
        for msg in self._conversation.messages.order_by(DBMessage.created_at):
            if msg.role == "system":
                # Skip persisted system prompts from older versions
                continue
            if msg.role == "assistant":
                try:
                    calls = json.loads(msg.content)
                except json.JSONDecodeError:
                    messages.append({"role": "assistant", "content": msg.content})
                else:
                    messages.append(
                        {
                            "role": "assistant",
                            "tool_calls": [Message.ToolCall(**c) for c in calls],
                        }
                    )
            elif msg.role == "user":
                messages.append({"role": "user", "content": msg.content})
            else:
                messages.append({"role": "tool", "content": msg.content})
        return messages

    @staticmethod
    def _store_assistant_message(conversation: Conversation, message: Message) -> None:
        """Persist assistant messages, storing tool calls when present."""

        if message.tool_calls:
            content = json.dumps([c.model_dump() for c in message.tool_calls])
        else:
            content = message.content or ""

        DBMessage.create(conversation=conversation, role="assistant", content=content)

    async def ask(self, messages: List[Msg], *, think: bool = True) -> ChatResponse:
        """Send a chat request, automatically prepending the system prompt."""

        if not messages or messages[0].get("role") != "system":
            payload = [{"role": "system", "content": SYSTEM_PROMPT}, *messages]
        else:
            payload = messages

        return await self._client.chat(
            self._model,
            messages=payload,
            think=think,
            tools=[execute_terminal],
            options={"num_ctx": NUM_CTX},
        )

    async def _handle_tool_calls(
        self,
        messages: List[Msg],
        response: ChatResponse,
        conversation: Conversation,
        depth: int = 0,
    ) -> ChatResponse:
        while depth < MAX_TOOL_CALL_DEPTH and response.message.tool_calls:
            for call in response.message.tool_calls:
                if call.function.name == "execute_terminal":
                    result = execute_terminal(**call.function.arguments)
                else:
                    _LOG.warning("Unsupported tool call: %s", call.function.name)
                    result = f"Unsupported tool: {call.function.name}"

                messages.append(
                    {
                        "role": "tool",
                        "name": call.function.name,
                        "content": str(result),
                    }
                )
                DBMessage.create(
                    conversation=conversation,
                    role="tool",
                    content=str(result),
                )

            nxt = await self.ask(messages, think=True)
            self._store_assistant_message(conversation, nxt.message)
            response = nxt
            depth += 1

        return response

    async def chat(self, prompt: str) -> str:
        DBMessage.create(conversation=self._conversation, role="user", content=prompt)
        self._messages.append({"role": "user", "content": prompt})

        response = await self.ask(self._messages)
        self._messages.append(response.message.model_dump())
        self._store_assistant_message(self._conversation, response.message)

        _LOG.info("Thinking:\n%s", response.message.thinking or "<no thinking trace>")

        final_resp = await self._handle_tool_calls(
            self._messages, response, self._conversation
        )
        return final_resp.message.content