"""Chat routes: send messages, stream responses, manage conversations."""

from __future__ import annotations

import asyncio
import logging
import tempfile
import time
from pathlib import Path
from typing import TYPE_CHECKING

from fastapi import APIRouter, Form, Request, UploadFile
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates
from sse_starlette.sse import EventSourceResponse

if TYPE_CHECKING:
    from ..agent_registry import AgentRegistry
    from ..config import Config
    from ..db import Database
    from ..llm import LLMAdapter

log = logging.getLogger(__name__)

router = APIRouter(prefix="/chat")

_registry: AgentRegistry | None = None
_config: Config | None = None
_llm: LLMAdapter | None = None
_db: Database | None = None
_templates: Jinja2Templates | None = None

# Pending responses: conv_id -> {text, files, timestamp}
_pending: dict[str, dict] = {}


def setup(registry, config, llm, db, templates):
    global _registry, _config, _llm, _db, _templates
    _registry = registry
    _config = config
    _llm = llm
    _db = db
    _templates = templates


def _get_agent(name: str):
    if _registry:
        return _registry.get(name) or _registry.default
    return None


def _cleanup_pending():
    """Remove pending entries older than 60s."""
    now = time.time()
    expired = [k for k, v in _pending.items() if now - v["timestamp"] > 60]
    for k in expired:
        del _pending[k]


@router.post("/send")
async def send_message(
    request: Request,
    text: str = Form(""),
    agent_name: str = Form("default"),
    conv_id: str = Form(""),
    files: list[UploadFile] | None = None,
):
    """Accept user message, return user bubble HTML + trigger SSE stream."""
    _cleanup_pending()

    agent = _get_agent(agent_name)
    if not agent:
        return HTMLResponse("<div class='error'>Agent not found</div>", status_code=400)

    # Handle file uploads
    saved_files = []
    for f in (files or []):
        if f.filename and f.size and f.size > 0:
            tmp = Path(tempfile.mkdtemp()) / f.filename
            content = await f.read()
            tmp.write_bytes(content)
            saved_files.append(str(tmp))

    if not text.strip() and not saved_files:
        return HTMLResponse("")

    # Ensure conversation exists
    if not conv_id:
        agent.new_conversation()
        conv_id = agent.ensure_conversation()
    else:
        agent.conv_id = conv_id

    # Build display text
    display_text = text
    if saved_files:
        file_names = [Path(f).name for f in saved_files]
        display_text += f"\n[Attached: {', '.join(file_names)}]"

    # Stash for SSE stream
    _pending[conv_id] = {
        "text": text,
        "files": saved_files,
        "timestamp": time.time(),
        "agent_name": agent_name,
    }

    # Render user bubble + SSE trigger div
    user_html = _templates.get_template("partials/chat_message.html").render(
        role="user", content=display_text
    )
    # The SSE trigger div connects to the stream endpoint
    sse_div = (
        f'<div id="sse-trigger" '
        f'hx-ext="sse" '
        f'sse-connect="/chat/stream/{conv_id}" '
        f'sse-swap="chunk" '
        f'hx-target="#assistant-response" '
        f'hx-swap="beforeend">'
        f'</div>'
        f'<div id="assistant-bubble" class="message assistant">'
        f'<div class="message-avatar">CB</div>'
        f'<div class="message-body">'
        f'<div id="assistant-response" class="message-content"></div>'
        f'</div></div>'
    )

    headers = {
        "HX-Trigger-After-Swap": "scrollChat",
        "HX-Push-Url": f"/?conv={conv_id}",
    }

    return HTMLResponse(user_html + sse_div, headers=headers)


@router.get("/stream/{conv_id}")
async def stream_response(conv_id: str):
    """SSE endpoint: stream assistant response chunks."""
    pending = _pending.pop(conv_id, None)
    if not pending:
        async def empty():
            yield {"event": "done", "data": ""}
        return EventSourceResponse(empty())

    agent = _get_agent(pending["agent_name"])
    if not agent:
        async def error():
            yield {"event": "chunk", "data": "Agent not found"}
            yield {"event": "done", "data": ""}
        return EventSourceResponse(error())

    agent.conv_id = conv_id

    async def generate():
        loop = asyncio.get_event_loop()
        queue: asyncio.Queue = asyncio.Queue()

        def run_agent():
            try:
                for chunk in agent.respond(pending["text"], files=pending.get("files")):
                    loop.call_soon_threadsafe(queue.put_nowait, ("chunk", chunk))
            except Exception as e:
                log.error("Stream error: %s", e, exc_info=True)
                loop.call_soon_threadsafe(
                    queue.put_nowait, ("chunk", f"\n\nError: {e}")
                )
            finally:
                loop.call_soon_threadsafe(queue.put_nowait, ("done", ""))

        # Run agent.respond() in a thread
        import threading
        t = threading.Thread(target=run_agent, daemon=True)
        t.start()

        while True:
            event, data = await queue.get()
            if event == "done":
                yield {"event": "done", "data": conv_id}
                break
            yield {"event": "chunk", "data": data}

    return EventSourceResponse(generate())


@router.get("/conversations")
async def list_conversations(agent_name: str = "default"):
    """Return sidebar conversation list as HTML partial."""
    agent = _get_agent(agent_name)
    if not agent:
        return HTMLResponse("")

    convs = agent.db.list_conversations(limit=50, agent_name=agent_name)
    html = _templates.get_template("partials/chat_sidebar.html").render(
        conversations=convs
    )
    return HTMLResponse(html)


@router.post("/new")
async def new_conversation(agent_name: str = Form("default")):
    """Create a new conversation, return empty chat + updated sidebar."""
    agent = _get_agent(agent_name)
    if not agent:
        return HTMLResponse("")

    agent.new_conversation()
    conv_id = agent.ensure_conversation()

    convs = agent.db.list_conversations(limit=50, agent_name=agent_name)
    sidebar_html = _templates.get_template("partials/chat_sidebar.html").render(
        conversations=convs
    )

    # Return empty chat area + sidebar update via OOB swap
    html = (
        f'<div id="chat-messages"></div>'
        f'<div id="sidebar-conversations" hx-swap-oob="innerHTML">'
        f'{sidebar_html}</div>'
    )

    headers = {"HX-Push-Url": f"/?conv={conv_id}"}
    return HTMLResponse(html, headers=headers)


@router.get("/load/{conv_id}")
async def load_conversation(conv_id: str, agent_name: str = "default"):
    """Load conversation history as HTML."""
    agent = _get_agent(agent_name)
    if not agent:
        return HTMLResponse("")

    messages = agent.load_conversation(conv_id)
    parts = []
    for msg in messages:
        role = msg.get("role", "")
        content = msg.get("content", "")
        if role in ("user", "assistant") and content:
            parts.append(
                _templates.get_template("partials/chat_message.html").render(
                    role=role, content=content
                )
            )

    headers = {"HX-Push-Url": f"/?conv={conv_id}"}
    return HTMLResponse("\n".join(parts), headers=headers)


@router.post("/agent/{name}")
async def switch_agent(name: str):
    """Switch active agent. Returns updated sidebar via OOB."""
    agent = _get_agent(name)
    if not agent:
        return HTMLResponse("<div class='error'>Agent not found</div>", status_code=400)

    agent.new_conversation()
    conv_id = agent.ensure_conversation()

    convs = agent.db.list_conversations(limit=50, agent_name=name)
    sidebar_html = _templates.get_template("partials/chat_sidebar.html").render(
        conversations=convs
    )

    html = (
        f'<div id="chat-messages"></div>'
        f'<div id="sidebar-conversations" hx-swap-oob="innerHTML">'
        f'{sidebar_html}</div>'
    )

    headers = {"HX-Push-Url": f"/?conv={conv_id}"}
    return HTMLResponse(html, headers=headers)