-- +goose Up
CREATE TABLE friendships (
  low_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  high_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  sender_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  accepted boolean NOT NULL DEFAULT false,
  created_at timestamptz NOT NULL DEFAULT now(),
  PRIMARY KEY(low_id,high_id),
  CHECK(low_id < high_id),
  CHECK(sender_id IN (low_id,high_id))
);
CREATE INDEX friendships_high_idx ON friendships(high_id);
CREATE TABLE social_blocks (
  user_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  peer_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  PRIMARY KEY(user_id,peer_id), CHECK(user_id <> peer_id)
);
CREATE TABLE direct_messages (
  seq bigserial PRIMARY KEY,
  id uuid NOT NULL UNIQUE,
  sender_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  recipient_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  text text NOT NULL DEFAULT '',
  attachment_kind text NOT NULL DEFAULT 'none' CHECK(attachment_kind IN ('none','track','playlist')),
  attachment_id uuid,
  created_at timestamptz NOT NULL DEFAULT now(),
  read_at timestamptz,
  CHECK(sender_id <> recipient_id),
  CHECK(length(text) <= 4000),
  CHECK((attachment_kind='none' AND attachment_id IS NULL AND length(trim(text))>0)
     OR (attachment_kind<>'none' AND attachment_id IS NOT NULL))
);
CREATE INDEX direct_messages_pair_idx ON direct_messages(LEAST(sender_id,recipient_id),GREATEST(sender_id,recipient_id),seq DESC);
CREATE INDEX direct_messages_unread_idx ON direct_messages(recipient_id,sender_id,seq) WHERE read_at IS NULL;
CREATE INDEX direct_messages_sender_time_idx ON direct_messages(sender_id,created_at DESC);
CREATE TABLE social_notifications (
  id uuid PRIMARY KEY,
  user_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  actor_id uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  kind text NOT NULL CHECK(kind IN ('friend_request','friend_accepted','message','music')),
  message_seq bigint REFERENCES direct_messages(seq) ON DELETE CASCADE,
  created_at timestamptz NOT NULL DEFAULT now(),
  read_at timestamptz
);
CREATE INDEX social_notifications_user_idx ON social_notifications(user_id,created_at DESC);
CREATE INDEX social_notifications_request_rate_idx ON social_notifications(actor_id,created_at DESC) WHERE kind='friend_request';

-- +goose Down
DROP TABLE social_notifications;
DROP TABLE direct_messages;
DROP TABLE social_blocks;
DROP TABLE friendships;