from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.deps import require_role
from app.db.database import get_db
from app.db.models import User
from app.schemas.vote import VoteCreate, VoteUpdate, VoteSubmit, VoteOptionOut, VoteOut
from app.schemas.common import PageResponse
from app.services.vote_service import (
    create_vote,
    get_vote_by_id,
    list_votes,
    submit_vote,
    close_vote,
    delete_vote,
)

router = APIRouter(prefix="/api/votes", tags=["votes"])


def _build_vote_out(vote: any, user_id: int) -> VoteOut:
    # Compute per-option stats
    options_out = []
    for opt in (vote.options or []):
        responses = opt.responses or []
        vote_count = len(responses)
        voter_names = None
        if not vote.is_anonymous:
            voter_names = [r.voter.name for r in responses if r.voter]
        options_out.append(VoteOptionOut(
            id=opt.id,
            content=opt.content,
            sort_order=opt.sort_order,
            vote_count=vote_count,
            voter_names=voter_names,
        ))

    # Total unique voters
    all_voter_ids = set()
    my_option_ids = []
    for opt in (vote.options or []):
        for r in (opt.responses or []):
            all_voter_ids.add(r.voter_id)
            if r.voter_id == user_id:
                my_option_ids.append(opt.id)

    return VoteOut(
        id=vote.id,
        class_id=vote.class_id,
        creator_id=vote.creator_id,
        creator_name=vote.creator.name if vote.creator else "Unknown",
        title=vote.title,
        description=vote.description,
        vote_type=vote.vote_type,
        is_anonymous=vote.is_anonymous,
        max_choices=vote.max_choices,
        deadline=vote.deadline,
        status=vote.status,
        total_voters=len(all_voter_ids),
        has_voted=user_id in all_voter_ids,
        my_option_ids=my_option_ids if my_option_ids else None,
        options=options_out,
        created_at=vote.created_at,
        updated_at=vote.updated_at,
    )


@router.get("/", response_model=PageResponse[VoteOut])
async def get_votes(
    page: int = 1,
    page_size: int = 20,
    class_id: int | None = None,
    user: User = Depends(require_role("super_admin", "class_admin", "student")),
    db: AsyncSession = Depends(get_db),
):
    effective_class_id = class_id if user.role == "super_admin" and class_id else user.class_id
    if effective_class_id is None:
        return PageResponse(items=[], total=0, page=page, page_size=page_size, total_pages=0)

    votes, total = await list_votes(db, effective_class_id, page, page_size)
    total_pages = (total + page_size - 1) // page_size
    items = [_build_vote_out(v, user.id) for v in votes]
    return PageResponse(items=items, total=total, page=page, page_size=page_size, total_pages=total_pages)


@router.post("/", response_model=VoteOut)
async def create_new_vote(
    data: VoteCreate,
    class_id: int | None = None,
    user: User = Depends(require_role("super_admin", "class_admin", "student")),
    db: AsyncSession = Depends(get_db),
):
    if len(data.options) < 2:
        raise HTTPException(status_code=400, detail="至少需要 2 个选项")
    if data.vote_type == "multiple" and data.max_choices < 2:
        raise HTTPException(status_code=400, detail="多选投票最多可选数不能小于 2")

    effective_class_id = class_id if user.role == "super_admin" and class_id else user.class_id
    if effective_class_id is None:
        raise HTTPException(status_code=400, detail="You are not assigned to a class")

    vote = await create_vote(db, effective_class_id, user.id, data)
    # Reload with relationships
    vote = await get_vote_by_id(db, vote.id)
    return _build_vote_out(vote, user.id)


@router.get("/{vote_id}", response_model=VoteOut)
async def get_vote_detail(
    vote_id: int,
    user: User = Depends(require_role("super_admin", "class_admin", "student")),
    db: AsyncSession = Depends(get_db),
):
    vote = await get_vote_by_id(db, vote_id)
    if vote is None:
        raise HTTPException(status_code=404, detail="Vote not found")
    if user.role != "super_admin" and vote.class_id != user.class_id:
        raise HTTPException(status_code=403, detail="Access denied")
    return _build_vote_out(vote, user.id)


@router.post("/{vote_id}/submit")
async def submit_vote_response(
    vote_id: int,
    data: VoteSubmit,
    user: User = Depends(require_role("super_admin", "class_admin", "student")),
    db: AsyncSession = Depends(get_db),
):
    vote = await get_vote_by_id(db, vote_id)
    if vote is None:
        raise HTTPException(status_code=404, detail="Vote not found")
    if user.role != "super_admin" and vote.class_id != user.class_id:
        raise HTTPException(status_code=403, detail="Access denied")

    try:
        await submit_vote(db, vote_id, user.id, data.option_ids)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))

    return {"message": "投票成功"}


@router.put("/{vote_id}/close")
async def close_vote_endpoint(
    vote_id: int,
    user: User = Depends(require_role("super_admin", "class_admin", "student")),
    db: AsyncSession = Depends(get_db),
):
    vote = await get_vote_by_id(db, vote_id)
    if vote is None:
        raise HTTPException(status_code=404, detail="Vote not found")
    # Only creator or admin can close
    if user.role == "student" and vote.creator_id != user.id:
        raise HTTPException(status_code=403, detail="只有创建者或管理员可以关闭投票")
    if user.role != "super_admin" and vote.class_id != user.class_id:
        raise HTTPException(status_code=403, detail="Access denied")

    await close_vote(db, vote)
    return {"message": "投票已关闭"}


@router.delete("/{vote_id}")
async def delete_vote_endpoint(
    vote_id: int,
    user: User = Depends(require_role("super_admin", "class_admin", "student")),
    db: AsyncSession = Depends(get_db),
):
    vote = await get_vote_by_id(db, vote_id)
    if vote is None:
        raise HTTPException(status_code=404, detail="Vote not found")
    if user.role == "student" and vote.creator_id != user.id:
        raise HTTPException(status_code=403, detail="只有创建者或管理员可以删除投票")
    if user.role != "super_admin" and vote.class_id != user.class_id:
        raise HTTPException(status_code=403, detail="Access denied")

    await delete_vote(db, vote)
    return {"message": "投票已删除"}