"""Hunter profiles: the identity an account buys you.

The open door means a séance needs no account at all, so registering has to
be worth something on its own. This is that something — a name other hunters
see, a rank that grows from what you have actually contacted, and a public
page. Device pairing and messages are the other two.

Privacy rules that the tests pin, because they are easy to regress:

  - `email` is returned by GET /api/profile/me and by NOTHING else. It
    exists for account recovery; it is never part of a public payload.
  - `profile_public = False` makes the public page 404 and drops the hunter
    from the roster. It deliberately does NOT stop messages arriving —
    privacy here is about being browsed, not about being unreachable.
  - Guests (`wanderer-` accounts) have profiles like anyone else. They are
    real rows; nothing here special-cases them.
"""

import re

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

from app import rank
from app.db import get_db
from app.deps import get_current_user
from app.models.entity import Entity
from app.models.entity_sighting import EntitySighting
from app.models.user import User
from app.rate_limit import RateLimiter

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

# Editing a profile is cheap, but it is still a write — enough headroom for
# someone fiddling with a hue slider, tight enough to be uninteresting to
# abuse.
profile_limiter = RateLimiter(max_requests=30, window_seconds=60)

GENDERS = {"male", "female", "unspecified"}
AVATAR_FORMS = {"wisp", "banshee", "fairy", "shade"}
BIO_MAX = 280
DISPLAY_NAME_MAX = 48
HUE_MAX = 359
ROSTER_LIMIT = 24
RECENT_ENTITIES = 12

# Same shape as routes/shop.py's — deliberately permissive, since this is a
# recovery hint rather than a verified identity.
_EMAIL_RE = re.compile(r"^[^@\s]{1,64}@[^@\s]{1,255}\.[^@\s]{2,}$")


async def _encounter_count(db: AsyncSession, user_id) -> int:
    """Distinct spirits this hunter has contacted."""
    return int(
        await db.scalar(
            select(func.count(func.distinct(EntitySighting.entity_id))).where(
                EntitySighting.user_id == user_id
            )
        )
        or 0
    )


def _rank_block(encounters: int, user: User) -> dict:
    return rank.progress_for(encounters, user.essence or 0, user.favor or 0.0)


def _avatar(user: User) -> dict:
    return {
        "avatar_form": user.avatar_form,
        "avatar_hue": user.avatar_hue,
    }


def _public_fields(user: User) -> dict:
    """Everything safe to show a stranger. Note the absence of `email` — that
    omission is the point of this helper existing."""
    return {
        "username": user.username,
        "display_name": user.display_name,
        "bio": user.bio,
        "gender": user.gender or "unspecified",
        **_avatar(user),
    }


@router.get("/profile/me")
async def my_profile(
    user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)
):
    encounters = await _encounter_count(db, user.id)
    return {
        **_public_fields(user),
        "profile_public": bool(user.profile_public),
        # Own profile only.
        "email": user.email,
        "rank": _rank_block(encounters, user),
    }


@router.patch("/profile")
async def update_profile(
    payload: dict,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    """Partial update: only keys actually present are touched, so a client
    can send one field without having to echo the rest back."""
    if not profile_limiter.allow(str(user.id)):
        raise HTTPException(
            status.HTTP_429_TOO_MANY_REQUESTS, "too many changes — slow down"
        )
    if not isinstance(payload, dict):
        raise HTTPException(status.HTTP_422_UNPROCESSABLE_ENTITY, "expected an object")

    def _optional_text(key: str, limit: int) -> str | None:
        """Trim, cap, and treat empty string as an explicit clear."""
        raw = payload[key]
        if raw is None:
            return None
        if not isinstance(raw, str):
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY, f"{key} must be text"
            )
        text_value = raw.strip()
        if len(text_value) > limit:
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY,
                f"{key} must be {limit} characters or fewer",
            )
        return text_value or None

    if "display_name" in payload:
        user.display_name = _optional_text("display_name", DISPLAY_NAME_MAX)
    if "bio" in payload:
        user.bio = _optional_text("bio", BIO_MAX)

    if "gender" in payload:
        gender = payload["gender"]
        if gender not in GENDERS:
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY, "no such gender option"
            )
        user.gender = gender

    if "avatar_form" in payload:
        form = payload["avatar_form"]
        if form not in AVATAR_FORMS:
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY, "no such sigil form"
            )
        user.avatar_form = form

    if "avatar_hue" in payload:
        hue = payload["avatar_hue"]
        # bool is an int subclass in Python — reject it explicitly so
        # `avatar_hue: true` can't silently become hue 1.
        if not isinstance(hue, int) or isinstance(hue, bool) or not (0 <= hue <= HUE_MAX):
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY, f"hue must be 0-{HUE_MAX}"
            )
        user.avatar_hue = hue

    if "profile_public" in payload:
        visible = payload["profile_public"]
        if not isinstance(visible, bool):
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY, "profile_public must be true/false"
            )
        user.profile_public = visible

    if "email" in payload:
        email = payload["email"]
        if email is None or (isinstance(email, str) and not email.strip()):
            user.email = None
        elif isinstance(email, str) and _EMAIL_RE.match(email.strip().lower()):
            user.email = email.strip().lower()
        else:
            raise HTTPException(
                status.HTTP_422_UNPROCESSABLE_ENTITY, "that address does not reach us"
            )

    await db.commit()
    await db.refresh(user)
    encounters = await _encounter_count(db, user.id)
    return {
        **_public_fields(user),
        "profile_public": bool(user.profile_public),
        "email": user.email,
        "rank": _rank_block(encounters, user),
    }


@router.get("/hunters")
async def hunter_roster(db: AsyncSession = Depends(get_db)):
    """Public hunters, most-travelled first.

    Encounter counts come from ONE grouped query rather than a lookup per
    hunter — the roster is the most-hit public endpoint here and an N+1
    would show immediately.
    """
    counts_q = (
        select(
            EntitySighting.user_id,
            func.count(func.distinct(EntitySighting.entity_id)).label("n"),
        )
        .group_by(EntitySighting.user_id)
        .subquery()
    )
    rows = (
        await db.execute(
            select(User, func.coalesce(counts_q.c.n, 0).label("encounters"))
            .outerjoin(counts_q, counts_q.c.user_id == User.id)
            .where(User.profile_public.is_(True))
            .order_by(func.coalesce(counts_q.c.n, 0).desc(), User.created_at)
            .limit(ROSTER_LIMIT)
        )
    ).all()

    return {
        "hunters": [
            {
                "username": user.username,
                "display_name": user.display_name,
                **_avatar(user),
                "rank": _rank_block(int(encounters or 0), user),
            }
            for user, encounters in rows
        ]
    }


@router.get("/hunters/{username}")
async def hunter_profile(username: str, db: AsyncSession = Depends(get_db)):
    user = await db.scalar(select(User).where(User.username == username))
    # A hidden profile is indistinguishable from one that never existed —
    # confirming the account exists would leak exactly what hiding it was
    # meant to prevent.
    if user is None or not user.profile_public:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "no such hunter walks here")

    encounters = await _encounter_count(db, user.id)

    # Most recently contacted spirits, distinct, newest first.
    latest = (
        select(
            EntitySighting.entity_id,
            func.max(EntitySighting.seen_at).label("last_seen"),
        )
        .where(EntitySighting.user_id == user.id)
        .group_by(EntitySighting.entity_id)
        .subquery()
    )
    recent = (
        await db.execute(
            select(Entity, latest.c.last_seen)
            .join(latest, latest.c.entity_id == Entity.id)
            .order_by(latest.c.last_seen.desc())
            .limit(RECENT_ENTITIES)
        )
    ).all()

    return {
        **_public_fields(user),
        "joined_at": user.created_at.isoformat() if user.created_at else None,
        "rank": _rank_block(encounters, user),
        "recent_entities": [
            {
                "id": str(entity.id),
                "name": entity.name,
                "epithet": entity.epithet,
                "rarity": entity.rarity_tier,
                "visual": entity.visual_profile or {},
            }
            for entity, _seen in recent
        ],
    }