"""Offline-first sync schemas (delta pull + idempotent push).

The client keeps an opaque ``cursor`` (a server-clock timestamp). It pulls
everything changed in the half-open window ``(since, cursor]`` and pushes the
append-only events it accumulated offline. Events carry a client-generated
``id`` so a replay is idempotent.
"""

import datetime as dt
import uuid
from typing import Literal

from pydantic import BaseModel, Field

from app.api.schemas.track import TrackOut

LikeValue = Literal["like", "dislike", "neutral"]


# -- pull (server -> client) --------------------------------------------------
class LikeEventOut(BaseModel):
    id: uuid.UUID
    track_id: uuid.UUID
    value: str
    created_at: dt.datetime


class PlayEventOut(BaseModel):
    id: uuid.UUID
    track_id: uuid.UUID
    played_at: dt.datetime
    play_duration_seconds: int | None
    completed: bool


class PlaylistSyncOut(BaseModel):
    id: uuid.UUID
    name: str
    description: str | None
    version: int
    updated_at: dt.datetime
    track_ids: list[uuid.UUID]


class SyncChangesOut(BaseModel):
    """Everything that changed for the caller since their last cursor. Feed
    ``cursor`` back as ``?since=`` on the next pull."""

    cursor: dt.datetime
    likes: list[LikeEventOut]
    plays: list[PlayEventOut]
    playlists: list[PlaylistSyncOut]
    tracks: list[TrackOut]


# -- push (client -> server) --------------------------------------------------
class LikeEventIn(BaseModel):
    id: uuid.UUID
    track_id: uuid.UUID
    value: LikeValue
    created_at: dt.datetime


class PlayEventIn(BaseModel):
    id: uuid.UUID
    track_id: uuid.UUID
    played_at: dt.datetime
    play_duration_seconds: int | None = None
    completed: bool = False


class SyncPushIn(BaseModel):
    likes: list[LikeEventIn] = Field(default_factory=list)
    plays: list[PlayEventIn] = Field(default_factory=list)


class SyncPushOut(BaseModel):
    """How many events were newly stored (a replay reports 0) + a fresh cursor."""

    cursor: dt.datetime
    accepted_likes: int
    accepted_plays: int