# ========= Copyright 2025-2026 @ Eigent.ai All Rights Reserved. =========
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ========= Copyright 2025-2026 @ Eigent.ai All Rights Reserved. =========

"""v1 Chat Step - H1 auth, H2 ownership, P2 dedicated Update model.
STATUS: full-rewrite (security: H1, H2, P2 Update model)
"""

import asyncio
import json
from typing import List, Optional

from fastapi import APIRouter, Depends, HTTPException, Response
from fastapi.responses import StreamingResponse
from loguru import logger
from sqlalchemy import or_
from sqlalchemy.sql.expression import case
from sqlmodel import Session, asc, desc, select

from app.core.database import session
from app.model.chat.chat_step import ChatStep, ChatStepOut, ChatStepIn, ChatStepUpdate
from app.model.chat.chat_history import ChatHistory

from app.shared.auth import auth_must
from app.domains.chat.service import ChatService
from app.domains.chat.schema import TaskOwnershipCheckReq
from app.domains.remote_control.service.remote_control_service import RemoteControlService

router = APIRouter(prefix="/chat", tags=["V1 Chat Step"])


def _task_owned_by_user(db: Session, task_id: str, user_id: int) -> bool:
    return ChatService.verify_task_ownership(TaskOwnershipCheckReq(task_id=task_id, user_id=user_id))


def _history_for_run(db: Session, run_id: str, user_id: int) -> ChatHistory | None:
    return db.exec(
        select(ChatHistory)
        .where(ChatHistory.user_id == user_id)
        .where((ChatHistory.run_id == run_id) | (ChatHistory.task_id == run_id))
        .order_by(
            desc(case((ChatHistory.run_id == run_id, 1), else_=0)),
            desc(ChatHistory.created_at),
            desc(ChatHistory.id),
        )
    ).first()


def _steps_for_run_stmt(run_id: str, task_id: str):
    return select(ChatStep).where(ChatStep.task_id == task_id).where(
        or_(
            ChatStep.run_id == run_id,
            ChatStep.run_id.is_(None),
            ChatStep.run_id == task_id,
        )
    )


def _ordered_steps_stmt(stmt):
    return stmt.order_by(
        asc(case((ChatStep.timestamp.is_(None), 1), else_=0)),
        asc(ChatStep.timestamp),
        asc(ChatStep.id),
    )


async def _playback_event_generator(
    steps: list[ChatStep],
    *,
    delay_time: float,
    empty_message: str,
):
    if not steps:
        yield f"data: {json.dumps({'error': empty_message})}\n\n"
        return
    for s in steps:
        step_data = {
            "id": s.id,
            "task_id": s.task_id,
            "run_id": s.run_id or s.task_id,
            "step": s.step,
            "data": s.data,
            "timestamp": s.timestamp,
            "created_at": s.created_at.isoformat() if s.created_at else None,
        }
        yield f"data: {json.dumps(step_data)}\n\n"
        if delay_time > 0:
            await asyncio.sleep(delay_time)


@router.get("/steps", name="list chat steps", response_model=List[ChatStepOut])
async def list_chat_steps(
    task_id: str,
    run_id: Optional[str] = None,
    step: Optional[str] = None,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    if not _task_owned_by_user(db_session, task_id, auth.user.id):
        return []
    query = select(ChatStep).where(ChatStep.task_id == task_id)
    if run_id is not None:
        query = query.where((ChatStep.run_id == run_id) | ChatStep.run_id.is_(None))
    if step is not None:
        query = query.where(ChatStep.step == step)
    return list(db_session.exec(query).all())


@router.get("/runs/{run_id}/steps", name="list chat steps by run", response_model=List[ChatStepOut])
async def list_chat_steps_by_run(
    run_id: str,
    step: Optional[str] = None,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    history = _history_for_run(db_session, run_id, auth.user.id)
    if history is None:
        return []
    query = _steps_for_run_stmt(run_id, history.task_id)
    if step is not None:
        query = query.where(ChatStep.step == step)
    return list(db_session.exec(query).all())


@router.get("/steps/playback/{task_id}", name="Playback Chat Step via SSE")
async def share_playback(
    task_id: str,
    delay_time: float = 0,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    if delay_time > 5:
        delay_time = 5
    if not _task_owned_by_user(db_session, task_id, auth.user.id):
        raise HTTPException(status_code=404, detail="Task not found")

    async def event_generator():
        stmt = _ordered_steps_stmt(select(ChatStep).where(ChatStep.task_id == task_id))
        steps = db_session.exec(stmt).all()
        async for event in _playback_event_generator(
            list(steps),
            delay_time=delay_time,
            empty_message="No steps found for this task.",
        ):
            yield event

    return StreamingResponse(event_generator(), media_type="text/event-stream")


@router.get("/runs/{run_id}/steps/playback", name="Playback Chat Run Step via SSE")
async def run_playback(
    run_id: str,
    delay_time: float = 0,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    if delay_time > 5:
        delay_time = 5
    history = _history_for_run(db_session, run_id, auth.user.id)
    if history is None:
        raise HTTPException(status_code=404, detail="Run not found")

    async def event_generator():
        stmt = _ordered_steps_stmt(_steps_for_run_stmt(run_id, history.task_id))
        steps = db_session.exec(stmt).all()
        async for event in _playback_event_generator(
            list(steps),
            delay_time=delay_time,
            empty_message="No steps found for this run.",
        ):
            yield event

    return StreamingResponse(event_generator(), media_type="text/event-stream")


@router.get("/steps/{step_id}", name="get chat step", response_model=ChatStepOut)
async def get_chat_step(
    step_id: int,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    chat_step = db_session.get(ChatStep, step_id)
    if not chat_step:
        raise HTTPException(status_code=404, detail="Chat step not found")
    if not _task_owned_by_user(db_session, chat_step.task_id, auth.user.id):
        raise HTTPException(status_code=404, detail="Chat step not found")
    return chat_step


@router.post("/steps", name="create chat step")
async def create_chat_step(
    step: ChatStepIn,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    if not _task_owned_by_user(db_session, step.task_id, auth.user.id):
        raise HTTPException(status_code=403, detail="Task not found or access denied")
    chat_step = ChatStep(
        task_id=step.task_id,
        run_id=step.run_id or step.task_id,
        step=step.step,
        data=step.data,
        timestamp=step.timestamp,
    )
    db_session.add(chat_step)
    db_session.commit()
    db_session.refresh(chat_step)
    try:
        RemoteControlService.publish_chat_step(chat_step, db_session)
    except Exception as exc:
        logger.warning(
            "Remote-control step publish failed",
            extra={"task_id": chat_step.task_id, "error": str(exc)},
        )
    return {"code": 200, "msg": "success"}


@router.put("/steps/{step_id}", name="update chat step", response_model=ChatStepOut)
async def update_chat_step(
    step_id: int,
    chat_step_update: ChatStepUpdate,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    db_chat_step = db_session.get(ChatStep, step_id)
    if not db_chat_step:
        raise HTTPException(status_code=404, detail="Chat step not found")
    if not _task_owned_by_user(db_session, db_chat_step.task_id, auth.user.id):
        raise HTTPException(status_code=404, detail="Chat step not found")
    for key, value in chat_step_update.model_dump(exclude_unset=True).items():
        setattr(db_chat_step, key, value)
    db_session.add(db_chat_step)
    db_session.commit()
    db_session.refresh(db_chat_step)
    return db_chat_step


@router.delete("/steps/{step_id}", name="delete chat step")
async def delete_chat_step(
    step_id: int,
    db_session: Session = Depends(session),
    auth=Depends(auth_must),
):
    db_chat_step = db_session.get(ChatStep, step_id)
    if not db_chat_step:
        raise HTTPException(status_code=404, detail="Chat step not found")
    if not _task_owned_by_user(db_session, db_chat_step.task_id, auth.user.id):
        raise HTTPException(status_code=404, detail="Chat step not found")
    db_session.delete(db_chat_step)
    db_session.commit()
    return Response(status_code=204)