from __future__ import annotations

from datetime import datetime
from secrets import token_urlsafe
from pathlib import Path

from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import aliased

from app.models.activity import Activity
from app.models.activity_guest_choice import ActivityGuestChoice
from app.models.registration import Registration
from app.models.user import User
from app.config import settings
from app.services.match_service import _level3_info
from app.utils.media import sanitize_user_media_payload
from app.utils.wx_api import generate_unlimited_qrcode, generate_url_link


ACTIVE_REGISTRATION_STATUSES = {1, 2, 4}
ACTIVE_CHOICE_STATUS = 1
CANCELLED_CHOICE_STATUS = 0
UPLOAD_ROOT = Path(__file__).resolve().parent.parent / "static" / "uploads"


def _format_datetime(value: datetime | None) -> str | None:
    return value.isoformat() if value else None


def _candidate_item(user: User, selected: bool = False) -> dict:
    return {
        "user_id": user.id,
        "nickname": user.nickname,
        "birth_year": user.birth_year,
        "city": user.city,
        "personality_tags": user.personality_tags if isinstance(user.personality_tags, list) else [],
        "avatar_blur_url": user.avatar_blur_url,
        "selected": selected,
    }


def _list_item(user: User, *, selected_at: datetime | None, matched_at: datetime | None, matched: bool) -> dict:
    return {
        "user_id": user.id,
        "nickname": user.nickname,
        "avatar_url": user.avatar_url,
        "city": user.city,
        "education": user.education,
        "hobbies": user.hobbies if isinstance(user.hobbies, list) else [],
        "selected_at": _format_datetime(selected_at),
        "matched_at": _format_datetime(matched_at),
        "match_status": "success" if matched else "pending",
        "match_status_text": "匹配成功" if matched else "待回应",
        "can_view_detail": matched,
    }


def _candidate_item(user: User, selected: bool = False) -> dict:
    return sanitize_user_media_payload({
        "user_id": user.id,
        "nickname": user.nickname,
        "birth_year_range": _birth_year_range(user.birth_year),
        "city": user.city,
        "personality_tags": user.personality_tags if isinstance(user.personality_tags, list) else [],
        "avatar_blur_url": user.avatar_blur_url,
        "selected": selected,
    })


def _list_item(user: User, *, selected_at: datetime | None, matched_at: datetime | None, matched: bool) -> dict:
    return sanitize_user_media_payload({
        "user_id": user.id,
        "nickname": user.nickname,
        "avatar_url": user.avatar_url,
        "city": user.city,
        "education": user.education,
        "hobbies": user.hobbies if isinstance(user.hobbies, list) else [],
        "selected_at": _format_datetime(selected_at),
        "matched_at": _format_datetime(matched_at),
        "match_status": "success" if matched else "pending",
        "match_status_text": "ƥ��ɹ�" if matched else "����Ӧ",
        "can_view_detail": matched,
    })


async def get_activity_by_id(session: AsyncSession, activity_id: int) -> Activity | None:
    result = await session.execute(select(Activity).where(Activity.id == activity_id))
    return result.scalar_one_or_none()


async def get_registration(session: AsyncSession, user_id: int, activity_id: int) -> Registration | None:
    result = await session.execute(
        select(Registration).where(
            Registration.user_id == user_id,
            Registration.activity_id == activity_id,
        )
    )
    return result.scalar_one_or_none()


async def ensure_activity_share_token(session: AsyncSession, activity: Activity) -> Activity:
    if activity.share_token:
        return activity

    while True:
        candidate = token_urlsafe(8).replace("-", "").replace("_", "")[:12]
        exists = await session.execute(select(Activity.id).where(Activity.share_token == candidate))
        if exists.scalar_one_or_none() is None:
            activity.share_token = candidate
            session.add(activity)
            await session.commit()
            await session.refresh(activity)
            return activity


async def get_activity_by_share_token(session: AsyncSession, share_token: str) -> Activity | None:
    result = await session.execute(select(Activity).where(Activity.share_token == share_token))
    return result.scalar_one_or_none()


def _persist_activity_qrcode(activity_id: int, content: bytes) -> str:
    qr_dir = UPLOAD_ROOT / "activities" / str(activity_id)
    qr_dir.mkdir(parents=True, exist_ok=True)
    qr_path = qr_dir / "share_qrcode.png"
    qr_path.write_bytes(content)
    return f"/static/uploads/activities/{activity_id}/{qr_path.name}"


async def ensure_activity_share_qrcode(session: AsyncSession, activity: Activity) -> Activity:
    activity = await ensure_activity_share_token(session, activity)
    if activity.share_qr_url:
        return activity

    page = settings.wx_miniprogram_page_activity_detail or "pages/activity-detail/activity-detail"
    content = await generate_unlimited_qrcode(page=page, scene=f"share_token={activity.share_token}")
    if not content:
        return activity

    activity.share_qr_url = _persist_activity_qrcode(activity.id, content)
    session.add(activity)
    await session.commit()
    await session.refresh(activity)
    return activity


def resolve_activity_stage(activity: Activity) -> str:
    now = datetime.now()
    if activity.start_time and now < activity.start_time:
        return "before_start"
    if activity.end_time and now > activity.end_time:
        return "ended"
    if activity.match_deadline and now > activity.match_deadline:
        return "matching_closed"
    return "matching_open"


async def _require_bound_user(session: AsyncSession, activity: Activity, current_user: User) -> Registration:
    registration = await get_registration(session, current_user.id, activity.id)
    if registration is None or registration.status not in ACTIVE_REGISTRATION_STATUSES:
        raise PermissionError("请先绑定当前活动")
    return registration


async def _active_choice_count(session: AsyncSession, activity_id: int, user_id: int) -> int:
    result = await session.execute(
        select(func.count(ActivityGuestChoice.id)).where(
            ActivityGuestChoice.activity_id == activity_id,
            ActivityGuestChoice.from_user_id == user_id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    return int(result.scalar() or 0)


async def _count_registered_by_gender(session: AsyncSession, activity_id: int, gender: int) -> int:
    stmt = (
        select(func.count(Registration.id))
        .join(User, User.id == Registration.user_id)
        .where(
            Registration.activity_id == activity_id,
            Registration.status.in_(list(ACTIVE_REGISTRATION_STATUSES)),
            User.gender == gender,
        )
    )
    result = await session.execute(stmt)
    return int(result.scalar() or 0)


async def _has_mutual_choice(session: AsyncSession, activity_id: int, user_a_id: int, user_b_id: int) -> bool:
    result = await session.execute(
        select(ActivityGuestChoice.id).where(
            ActivityGuestChoice.activity_id == activity_id,
            ActivityGuestChoice.from_user_id == user_a_id,
            ActivityGuestChoice.to_user_id == user_b_id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    return result.scalar_one_or_none() is not None


async def _matched_at(session: AsyncSession, activity_id: int, user_a_id: int, user_b_id: int) -> datetime | None:
    forward = await session.execute(
        select(ActivityGuestChoice.created_at).where(
            ActivityGuestChoice.activity_id == activity_id,
            ActivityGuestChoice.from_user_id == user_a_id,
            ActivityGuestChoice.to_user_id == user_b_id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    backward = await session.execute(
        select(ActivityGuestChoice.created_at).where(
            ActivityGuestChoice.activity_id == activity_id,
            ActivityGuestChoice.from_user_id == user_b_id,
            ActivityGuestChoice.to_user_id == user_a_id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    times = [forward.scalar_one_or_none(), backward.scalar_one_or_none()]
    times = [item for item in times if item is not None]
    return max(times) if times else None


async def build_activity_share_info(
    session: AsyncSession,
    activity: Activity,
    current_user: User | None,
) -> dict:
    activity = await ensure_activity_share_token(session, activity)
    activity = await ensure_activity_share_qrcode(session, activity)
    registration = None
    if current_user is not None:
        registration = await get_registration(session, current_user.id, activity.id)

    stage = resolve_activity_stage(activity)
    selected_count = 0
    registered_male = await _count_registered_by_gender(session, activity.id, 1)
    registered_female = await _count_registered_by_gender(session, activity.id, 2)
    is_bound = bool(registration and registration.status in ACTIVE_REGISTRATION_STATUSES)
    if current_user is not None and registration and registration.status in ACTIVE_REGISTRATION_STATUSES:
        selected_count = await _active_choice_count(session, activity.id, current_user.id)

    can_register = bool(activity.is_published == 1)
    if activity.signup_deadline and activity.signup_deadline <= datetime.now():
        can_register = False
    if current_user is None:
        can_register = False
    elif current_user.audit_status != 2 and activity.require_audit == 1:
        can_register = False
    elif current_user.gender not in {1, 2}:
        can_register = False
    elif is_bound:
        can_register = True
    elif current_user.gender == 1 and activity.capacity_male > 0 and registered_male >= activity.capacity_male:
        can_register = False
    elif current_user.gender == 2 and activity.capacity_female > 0 and registered_female >= activity.capacity_female:
        can_register = False

    return {
        "id": activity.id,
        "title": activity.title,
        "description": activity.description,
        "category": activity.category,
        "location": activity.location,
        "cover_image": activity.cover_image,
        "start_time": _format_datetime(activity.start_time),
        "end_time": _format_datetime(activity.end_time),
        "signup_deadline": _format_datetime(activity.signup_deadline),
        "match_deadline": _format_datetime(activity.match_deadline),
        "share_token": activity.share_token,
        "share_qr_url": activity.share_qr_url,
        "selection_limit": activity.selection_limit,
        "stage": stage,
        "is_bound": is_bound,
        "is_registered": is_bound,
        "can_register": can_register,
        "registered_male": registered_male,
        "registered_female": registered_female,
        "capacity_male": activity.capacity_male,
        "capacity_female": activity.capacity_female,
        "can_view_candidates": bool(is_bound and stage in {"matching_open", "matching_closed", "ended"}),
        "can_enter_match": bool(is_bound and stage in {"matching_open", "matching_closed"}),
        "selected_count": selected_count,
        "remaining_count": max(activity.selection_limit - selected_count, 0),
    }


async def get_activity_match_state(session: AsyncSession, activity: Activity, current_user: User) -> dict:
    await _require_bound_user(session, activity, current_user)
    stage = resolve_activity_stage(activity)
    selected_count = await _active_choice_count(session, activity.id, current_user.id)
    can_view = stage in {"matching_open", "matching_closed", "ended"}
    can_modify = stage == "matching_open"
    return {
        "activity_id": activity.id,
        "activity_title": activity.title,
        "stage": stage,
        "is_bound": True,
        "can_view_candidates": can_view,
        "can_choose": can_modify,
        "can_modify_choice": can_modify,
        "selection_limit": activity.selection_limit,
        "selected_count": selected_count,
        "remaining_count": max(activity.selection_limit - selected_count, 0),
        "match_deadline": _format_datetime(activity.match_deadline),
        "start_time": _format_datetime(activity.start_time),
    }


async def bind_activity_user(session: AsyncSession, activity: Activity, current_user: User) -> Registration:
    from app.services.activity_service import register_activity

    return await register_activity(session, activity, current_user)


async def list_activity_candidates(session: AsyncSession, activity: Activity, current_user: User) -> list[dict]:
    await _require_bound_user(session, activity, current_user)
    stage = resolve_activity_stage(activity)
    if stage == "before_start":
        raise PermissionError("活动开始前暂不可查看嘉宾资料")

    selected_rows = await session.execute(
        select(ActivityGuestChoice.to_user_id).where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.from_user_id == current_user.id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    selected_ids = {row[0] for row in selected_rows.all()}

    stmt = (
        select(User)
        .join(Registration, Registration.user_id == User.id)
        .where(
            Registration.activity_id == activity.id,
            Registration.status.in_(list(ACTIVE_REGISTRATION_STATUSES)),
            User.id != current_user.id,
            User.audit_status == 2,
            User.is_active == 1,
        )
        .order_by(Registration.created_at.asc(), User.updated_at.desc())
    )
    if current_user.gender in {1, 2}:
        stmt = stmt.where(User.gender == (2 if current_user.gender == 1 else 1))

    result = await session.execute(stmt)
    users = result.scalars().all()
    return [_candidate_item(user, selected=user.id in selected_ids) for user in users]


async def create_activity_choice(
    session: AsyncSession,
    activity: Activity,
    current_user: User,
    target_user: User,
) -> dict:
    await _require_bound_user(session, activity, current_user)
    await _require_bound_user(session, activity, target_user)

    if resolve_activity_stage(activity) != "matching_open":
        raise ValueError("当前活动匹配已锁定，暂不可修改")
    if current_user.id == target_user.id:
        raise ValueError("不能选择自己")
    if current_user.gender in {1, 2} and target_user.gender == current_user.gender:
        raise ValueError("仅可选择异性嘉宾")

    selected_count = await _active_choice_count(session, activity.id, current_user.id)
    existing_result = await session.execute(
        select(ActivityGuestChoice).where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.from_user_id == current_user.id,
            ActivityGuestChoice.to_user_id == target_user.id,
        )
    )
    existing = existing_result.scalar_one_or_none()
    if existing and existing.status == ACTIVE_CHOICE_STATUS:
        raise ValueError("你已选择该嘉宾")

    if existing is None and selected_count >= activity.selection_limit:
        raise ValueError("当前活动下你的可选人数已达上限")
    if existing is not None and existing.status != ACTIVE_CHOICE_STATUS and selected_count >= activity.selection_limit:
        raise ValueError("请先撤销一位已选嘉宾后再继续选择")

    if existing is None:
        existing = ActivityGuestChoice(
            activity_id=activity.id,
            from_user_id=current_user.id,
            to_user_id=target_user.id,
            status=ACTIVE_CHOICE_STATUS,
        )
    else:
        existing.status = ACTIVE_CHOICE_STATUS
        existing.cancelled_at = None
    session.add(existing)
    await session.commit()

    selected_count = await _active_choice_count(session, activity.id, current_user.id)
    is_mutual = await _has_mutual_choice(session, activity.id, target_user.id, current_user.id)
    return {
        "activity_id": activity.id,
        "selected_count": selected_count,
        "remaining_count": max(activity.selection_limit - selected_count, 0),
        "is_mutual": is_mutual,
        "match_user_id": target_user.id if is_mutual else None,
    }


async def cancel_activity_choice(
    session: AsyncSession,
    activity: Activity,
    current_user: User,
    target_user_id: int,
) -> dict:
    await _require_bound_user(session, activity, current_user)
    if resolve_activity_stage(activity) != "matching_open":
        raise ValueError("当前活动匹配已锁定，暂不可修改")

    result = await session.execute(
        select(ActivityGuestChoice).where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.from_user_id == current_user.id,
            ActivityGuestChoice.to_user_id == target_user_id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    choice = result.scalar_one_or_none()
    if choice is None:
        raise ValueError("未找到可撤销的选择记录")

    choice.status = CANCELLED_CHOICE_STATUS
    choice.cancelled_at = datetime.now()
    session.add(choice)
    await session.commit()

    selected_count = await _active_choice_count(session, activity.id, current_user.id)
    return {
        "activity_id": activity.id,
        "selected_count": selected_count,
        "remaining_count": max(activity.selection_limit - selected_count, 0),
        "is_mutual": False,
        "match_user_id": None,
    }


async def list_my_activity_choices(session: AsyncSession, activity: Activity, current_user: User) -> list[dict]:
    await _require_bound_user(session, activity, current_user)
    other_user = aliased(User)
    stmt = (
        select(ActivityGuestChoice, other_user)
        .join(other_user, other_user.id == ActivityGuestChoice.to_user_id)
        .where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.from_user_id == current_user.id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
        .order_by(ActivityGuestChoice.created_at.desc())
    )
    result = await session.execute(stmt)
    rows = result.all()
    items = []
    for choice, user in rows:
        matched = await _has_mutual_choice(session, activity.id, user.id, current_user.id)
        matched_at = await _matched_at(session, activity.id, current_user.id, user.id) if matched else None
        items.append(_list_item(user, selected_at=choice.created_at, matched_at=matched_at, matched=matched))
    return items


async def list_activity_liked_me(session: AsyncSession, activity: Activity, current_user: User) -> list[dict]:
    await _require_bound_user(session, activity, current_user)
    other_user = aliased(User)
    stmt = (
        select(ActivityGuestChoice, other_user)
        .join(other_user, other_user.id == ActivityGuestChoice.from_user_id)
        .where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.to_user_id == current_user.id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
        .order_by(ActivityGuestChoice.created_at.desc())
    )
    result = await session.execute(stmt)
    rows = result.all()
    items = []
    for choice, user in rows:
        matched = await _has_mutual_choice(session, activity.id, current_user.id, user.id)
        matched_at = await _matched_at(session, activity.id, current_user.id, user.id) if matched else None
        items.append(_list_item(user, selected_at=choice.created_at, matched_at=matched_at, matched=matched))
    return items


async def list_activity_mutual_matches(session: AsyncSession, activity: Activity, current_user: User) -> list[dict]:
    await _require_bound_user(session, activity, current_user)
    my_choices = await list_my_activity_choices(session, activity, current_user)
    return [item for item in my_choices if item["match_status"] == "success"]


async def get_activity_match_detail(
    session: AsyncSession,
    activity: Activity,
    current_user: User,
    target_user_id: int,
) -> dict | None:
    await _require_bound_user(session, activity, current_user)
    if not await _has_mutual_choice(session, activity.id, current_user.id, target_user_id):
        raise PermissionError("当前仅可查看互选成功对象的完整资料")
    if not await _has_mutual_choice(session, activity.id, target_user_id, current_user.id):
        raise PermissionError("当前仅可查看互选成功对象的完整资料")

    target_user = await session.get(User, target_user_id)
    if target_user is None:
        return None
    matched_at = await _matched_at(session, activity.id, current_user.id, target_user_id)
    return {
        "activity_id": activity.id,
        "target_user_id": target_user.id,
        "matched_at": _format_datetime(matched_at) or _format_datetime(datetime.now()),
        "other_user": _level3_info(target_user),
    }


async def build_activity_share_path(session: AsyncSession, activity: Activity) -> str:
    activity = await ensure_activity_share_token(session, activity)
    return f"pages/activity-detail/activity-detail?share_token={activity.share_token}"


async def build_activity_share_api_url(session: AsyncSession, activity: Activity, api_base_url: str | None = None) -> str:
    activity = await ensure_activity_share_token(session, activity)
    base_url = (api_base_url or "").rstrip("/")
    if base_url:
        return f"{base_url}/activities/share/{activity.share_token}"
    return activity.share_token or ""


async def build_activity_share_link(session: AsyncSession, activity: Activity, public_site_url: str | None = None) -> str:
    activity = await ensure_activity_share_token(session, activity)
    base_url = (public_site_url or "").rstrip("/")
    if base_url:
        return f"{base_url}/share/activity/{activity.share_token}"
    return f"/share/activity/{activity.share_token}"


async def build_activity_url_link(session: AsyncSession, activity: Activity) -> str | None:
    activity = await ensure_activity_share_token(session, activity)
    page = settings.wx_miniprogram_page_activity_detail or "pages/activity-detail/activity-detail"
    if activity.share_url_link:
        return activity.share_url_link

    url_link, error_message = await generate_url_link(path=page, query=f"share_token={activity.share_token}")
    activity.share_url_link = url_link
    activity.share_url_link_error = error_message
    session.add(activity)
    await session.commit()
    await session.refresh(activity)
    return activity.share_url_link


async def refresh_activity_share_assets(session: AsyncSession, activity: Activity) -> Activity:
    activity.share_qr_url = None
    activity.share_url_link = None
    activity.share_url_link_error = None
    session.add(activity)
    await session.commit()
    await session.refresh(activity)
    activity = await ensure_activity_share_qrcode(session, activity)
    await build_activity_url_link(session, activity)
    await session.refresh(activity)
    return activity


async def get_bound_activity_by_id(session: AsyncSession, activity_id: int, current_user: User) -> Activity:
    activity = await get_activity_by_id(session, activity_id)
    if activity is None:
        raise ValueError("活动不存在")
    await _require_bound_user(session, activity, current_user)
    return activity


async def get_admin_activity_match_overview(session: AsyncSession, activity: Activity) -> dict:
    total_choices_result = await session.execute(
        select(func.count(ActivityGuestChoice.id)).where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    total_choices = int(total_choices_result.scalar() or 0)

    rows = await session.execute(
        select(ActivityGuestChoice.from_user_id, ActivityGuestChoice.to_user_id, ActivityGuestChoice.created_at).where(
            ActivityGuestChoice.activity_id == activity.id,
            ActivityGuestChoice.status == ACTIVE_CHOICE_STATUS,
        )
    )
    active_rows = rows.all()
    active_pairs = {(row.from_user_id, row.to_user_id): row.created_at for row in active_rows}
    matched_pairs = set()
    for from_user_id, to_user_id in active_pairs:
        reverse = (to_user_id, from_user_id)
        key = tuple(sorted((from_user_id, to_user_id)))
        if reverse in active_pairs:
            matched_pairs.add(key)

    users_stmt = (
        select(User.id, User.nickname)
        .join(Registration, Registration.user_id == User.id)
        .where(
            Registration.activity_id == activity.id,
            Registration.status.in_(list(ACTIVE_REGISTRATION_STATUSES)),
        )
    )
    user_rows = await session.execute(users_stmt)
    user_map = {row.id: row.nickname for row in user_rows.all()}

    items = []
    for row in active_rows:
        matched = (min(row.from_user_id, row.to_user_id), max(row.from_user_id, row.to_user_id)) in matched_pairs
        items.append(
            {
                "from_user_id": row.from_user_id,
                "from_nickname": user_map.get(row.from_user_id),
                "to_user_id": row.to_user_id,
                "to_nickname": user_map.get(row.to_user_id),
                "selected_at": _format_datetime(row.created_at),
                "is_mutual": matched,
            }
        )

    items.sort(key=lambda item: (not item["is_mutual"], item["selected_at"] or ""))
    return {
        "activity_id": activity.id,
        "activity_title": activity.title,
        "total_choices": total_choices,
        "mutual_match_count": len(matched_pairs),
        "choices": items,
    }