session-open-group-server/src/schema.sql

PRAGMA journal_mode=WAL;

BEGIN;

CREATE TABLE rooms (
    id INTEGER NOT NULL PRIMARY KEY, /* internal database id of the room */
    token TEXT NOT NULL UNIQUE COLLATE NOCASE, /* case-insensitive room identifier used in URLs, etc. */
    name TEXT NOT NULL, /* Publicly visible room name */
    description TEXT, /* Publicly visible room description */
    image INTEGER REFERENCES files(id) ON DELETE SET NULL,
    created FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch */
    pinned INTEGER REFERENCES messages(id) ON DELETE SET NULL,
    updates INTEGER NOT NULL DEFAULT 0, /* +1 for each new message, edit or deletion */
    info_updated INTEGER NOT NULL DEFAULT 0, /* +1 for any room metadata update (name/desc/image/pinned/mods) */
    read BOOLEAN NOT NULL DEFAULT TRUE, /* Whether users can read by default */
    write BOOLEAN NOT NULL DEFAULT TRUE, /* Whether users can post by default */
    upload BOOLEAN NOT NULL DEFAULT TRUE, /* Whether file uploads are allowed */
    CHECK(token NOT GLOB '*[^a-zA-Z0-9_-]*')
);
CREATE INDEX rooms_token ON rooms(token);

-- Trigger to expire an old room image attachment when the room image is changed
CREATE TRIGGER room_image_expiry AFTER UPDATE ON rooms
FOR EACH ROW WHEN NEW.image IS NOT OLD.image AND OLD.image IS NOT NULL
BEGIN
    UPDATE files SET expiry = 0.0 WHERE id = OLD.image;
END;

-- Trigger to update `info_updated` on metadata column changes
CREATE TRIGGER room_metadata_update AFTER UPDATE ON rooms
FOR EACH ROW WHEN
    NEW.name IS NOT OLD.name OR
    NEW.description IS NOT OLD.description OR
    NEW.image IS NOT OLD.image OR
    NEW.pinned IS NOT OLD.pinned
BEGIN
    UPDATE rooms SET updates = updates + 1, info_updated = updates + 1 WHERE id = NEW.id;
END;
-- Triggers to update `info_updated` when the mod list changes:
CREATE TRIGGER room_metadata_mods_insert AFTER INSERT ON user_permission_overrides
FOR EACH ROW WHEN NEW.moderator OR NEW.admin
BEGIN
    UPDATE rooms SET updates = updates + 1, info_updated = updates + 1 WHERE id = NEW.room;
END;
CREATE TRIGGER room_metadata_mods_update AFTER UPDATE ON user_permission_overrides
FOR EACH ROW WHEN (NEW.moderator OR NEW.admin) != (OLD.moderator OR OLD.admin)
BEGIN
    UPDATE rooms SET updates = updates + 1, info_updated = updates + 1 WHERE id = NEW.room;
END;
CREATE TRIGGER room_metadata_mods_delete AFTER DELETE ON user_permission_overrides
FOR EACH ROW WHEN OLD.moderator OR OLD.admin
BEGIN
    UPDATE rooms SET updates = updates + 1, info_updated = updates + 1 WHERE id = NEW.room;
END;
-- Trigger to update `info_updated` of all rooms whenever we add/remove a global moderator/admin
-- because global mod settings affect the permissions of all rooms (and polling clients need to pick
-- up on this).
CREATE TRIGGER room_metadata_global_mods_insert AFTER INSERT ON users
FOR EACH ROW WHEN NEW.

CREATE TABLE messages (
    id INTEGER NOT NULL PRIMARY KEY,
    room INTEGER NOT NULL REFERENCES rooms(id) ON DELETE CASCADE,
    user INTEGER NOT NULL REFERENCES users(id),
    posted FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch */
    edited FLOAT,
    updated INTEGER NOT NULL DEFAULT 0, /* set to the room's `updates` counter when posted/edited/deleted */
    data BLOB, /* Actual message content; set to null to delete a message */
    signature BLOB /* Signature of `data` by `public_key`; set to null when deleting a message */
);
CREATE INDEX messages_room ON messages(room, posted);
CREATE INDEX messages_updated ON messages(room, updated);
CREATE INDEX messages_id ON messages(room, id);

CREATE TABLE message_history (
    message INTEGER NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
    replaced FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch when this historic value was replaced by an edit or deletion */
    data TEXT NOT NULL, /* the content prior to the update/delete */
    signature BLOB NOT NULL /* signature prior to the update/delete */
);
CREATE INDEX message_history_message ON message_history(message);
CREATE INDEX message_history_replaced ON message_history(replaced);

-- Trigger to increment a room's `updates` counter and assign it to the messages `updated` field for
-- new messages.
CREATE TRIGGER messages_insert_counter AFTER INSERT ON messages
FOR EACH ROW
BEGIN
    UPDATE rooms SET updates = updates + 1 WHERE id = NEW.room;
    UPDATE messages SET updated = (SELECT updates FROM rooms WHERE id = NEW.room) WHERE id = NEW.id;
END;

-- Trigger to do various tasks needed when a message is edited/deleted:
-- * record the old value into message_history
-- * update the room's `updates` counter (so that clients can learn about the update)
-- * update the message's `updated` value to that new counter
-- * update the message's `edit` timestamp
CREATE TRIGGER messages_insert_history AFTER UPDATE OF data ON messages
FOR EACH ROW WHEN NEW.data IS NOT OLD.data
BEGIN
    INSERT INTO message_history (message, data, signature) VALUES (NEW.id, OLD.data, OLD.signature);
    UPDATE rooms SET updates = updates + 1 WHERE id = NEW.room;
    UPDATE messages SET
        updated = (SELECT updates FROM rooms WHERE id = NEW.room),
        edited = (julianday('now') - 2440587.5)*86400.0
    WHERE id = NEW.id;
END;

-- Trigger to remove the room's pinned message when that message is deleted
CREATE TRIGGER messages_unpin_on_delete AFTER UPDATE OF data ON messages
FOR EACH ROW WHEN NEW.data IS NULL
BEGIN
    UPDATE rooms SET pinned = NULL WHERE id = OLD.room AND pinned = OLD.id;
END;

-- Trigger to handle moving a message from one room to another; we reset the posted time to now, and
-- reset the updated value to the new room's value so that the moved message is treated as a brand new message in
-- the new room.  We also clear the message as the pinned message from the moved-from room.
-- FIXME TODO: this isn't right because the old room won't have any record of it being moved, and so
-- clients won't know that they should remove it.  Perhaps instead we should implement moving as a
-- delete + reinsert, via a INSTEAD OF trigger.
/*
CREATE TRIGGER message_mover AFTER UPDATE OF room ON messages
FOR EACH ROW WHEN NEW.room != OLD.room
BEGIN
    UPDATE messages SET posted = ((julianday('now') - 2440587.5)*86400.0), updated = FALSE
        WHERE messages.id = NEW.id;
    UPDATE rooms SET pinned = NULL WHERE id = OLD.room AND pinned = OLD.id;
END;
*/

CREATE TABLE files (
    id INTEGER NOT NULL PRIMARY KEY,
    room INTEGER REFERENCES rooms(id) ON DELETE SET NULL,
    uploader INTEGER REFERENCES users(id),
    size INTEGER NOT NULL,
    uploaded FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch */
    expiry FLOAT DEFAULT ((julianday('now') - 2440587.5 + 15.0)*86400.0), /* unix epoch */
    filename TEXT, /* user-provided filename */
    path TEXT NOT NULL /* path on disk */
);
CREATE INDEX files_room ON files(room);
CREATE INDEX files_expiry ON files(expiry);
-- When we delete a room all its files will have room set to NULL but we *also* need to make them
-- for immediate expiry so that the file pruner finds them to clean them up at the next cleanup
-- check.
CREATE TRIGGER room_expire_roomless AFTER UPDATE OF room ON files
FOR EACH ROW WHEN NEW.room IS NULL
BEGIN
    UPDATE files SET expiry = 0.0 WHERE id = NEW.id;
END;

CREATE TABLE users (
    id INTEGER NOT NULL PRIMARY KEY,
    session_id TEXT NOT NULL UNIQUE,
    created FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch */
    last_active FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch */
    banned BOOLEAN NOT NULL DEFAULT FALSE, /* true = globally banned from all rooms */
    moderator BOOLEAN NOT NULL DEFAULT FALSE, /* true = moderator of all rooms, and can add global bans */
    admin BOOLEAN NOT NULL DEFAULT FALSE, /* true = admin of all rooms, and can appoint global bans/mod/admins */
    visible_mod BOOLEAN NOT NULL DEFAULT FALSE, /* if true this user's moderator status is viewable by regular room users of all rooms */
    CHECK(NOT (banned AND (moderator OR admin))) /* someone cannot be banned *and* a moderator at the same time */
);
CREATE INDEX users_last_active ON users(last_active);
-- Create a trigger to maintain the implication "admin implies moderator"
CREATE TRIGGER user_update_admins_are_mods AFTER UPDATE OF moderator, admin ON users
FOR EACH ROW WHEN NEW.admin AND NOT NEW.moderator
BEGIN
    UPDATE users SET moderator = TRUE WHERE id = NEW.id;
END;
CREATE TRIGGER user_insert_admins_are_mods AFTER INSERT ON users
FOR EACH ROW WHEN NEW.admin AND NOT NEW.moderator
BEGIN
    UPDATE users SET moderator = TRUE WHERE id = NEW.id;
END;


-- Effectively the same as `messages` except that it also includes the `session_id` from the users
-- table of the user who posted it, which we often need when returning a message list to clients.
CREATE VIEW message_details AS
SELECT messages.*, users.session_id FROM messages JOIN users ON messages.user = users.id;

-- View of `messages` that is useful for manually inspecting table contents by only returning the
-- length (rather than raw bytes) for data/signature.
CREATE VIEW message_metadata AS
SELECT id, room, user, session_id, posted, edited, updated, length(data) AS data_length, length(signature) as signature_length
    FROM message_details;



CREATE TABLE room_users (
    room INTEGER NOT NULL REFERENCES rooms(id) ON DELETE CASCADE,
    user INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    last_active FLOAT NOT NULL DEFAULT ((julianday('now') - 2440587.5)*86400.0), /* unix epoch */
    PRIMARY KEY(room, user)
) WITHOUT ROWID;
CREATE INDEX room_users_room_activity ON room_users(room, last_active);
CREATE INDEX room_users_activity ON room_users(last_active);

-- Stores permissions or restrictions on a user.  Null values (for read/write) mean "user the room's
-- default".
CREATE TABLE user_permission_overrides (
    room INTEGER NOT NULL REFERENCES rooms(id) ON DELETE CASCADE,
    user INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    banned BOOLEAN NOT NULL DEFAULT FALSE, /* If true the user is banned */
    read BOOLEAN, /* If false the user may not fetch messages; null uses room default; true allows reading */
    write BOOLEAN, /* If false the user may not post; null uses room default; true allows posting */
    upload BOOLEAN, /* If false the user may not upload files; null uses room default; true allows uploading */
    moderator BOOLEAN NOT NULL DEFAULT FALSE, /* If true the user may moderate non-moderators */
    admin BOOLEAN NOT NULL DEFAULT FALSE, /* If true the user may moderate anyone (including other moderators and admins) */
    visible_mod BOOLEAN NOT NULL DEFAULT TRUE, /* If true then this user (if a moderator) is included in the list of a room's public moderators */
    PRIMARY KEY(room, user),
    CHECK(NOT (banned AND (moderator OR admin))) /* Mods/admins cannot be banned */
) WITHOUT ROWID;
CREATE INDEX user_permission_overrides_public_mods ON
    user_permission_overrides(room) WHERE moderator OR admin;

-- Create a trigger to maintain the implication "admin implies moderator"
CREATE TRIGGER user_perms_update_admins_are_mods AFTER UPDATE OF moderator, admin ON user_permission_overrides
FOR EACH ROW WHEN NEW.admin AND NOT NEW.moderator
BEGIN
    UPDATE user_permission_overrides SET moderator = TRUE WHERE room = NEW.room AND user = NEW.user;
END;
CREATE TRIGGER user_perms_insert_admins_are_mods AFTER INSERT ON user_permission_overrides
FOR EACH ROW WHEN NEW.admin AND NOT NEW.moderator
BEGIN
    UPDATE user_permission_overrides SET moderator = TRUE WHERE room = NEW.room AND user = NEW.user;
END;

-- Trigger that removes useless empty permission override rows (e.g. after a ban gets removed, and
-- no other permissions roles are set).
CREATE TRIGGER user_perms_empty_cleanup AFTER UPDATE ON user_permission_overrides
FOR EACH ROW WHEN NOT (NEW.banned OR NEW.moderator OR NEW.admin) AND COALESCE(NEW.read, NEW.write, NEW.upload) IS NULL
BEGIN
    DELETE from user_permission_overrides WHERE room = NEW.room AND user = NEW.user;
END;

-- Triggers than remove a user from `room_users` when they are banned from the room
CREATE TRIGGER room_users_remove_banned AFTER UPDATE OF banned ON user_permission_overrides
FOR EACH ROW WHEN NEW.banned
BEGIN
    DELETE FROM room_users WHERE room = NEW.room AND user = NEW.user;
END;

-- View of permissions; for users with an entry in user_permissions we use those values; for null
-- values or no user_permissions entry we return the room's default read/write values (and false for
-- the other fields).
CREATE VIEW user_permissions AS
SELECT
    rooms.id AS room,
    users.id AS user,
    users.session_id,
    CASE WHEN users.banned THEN TRUE ELSE COALESCE(user_permission_overrides.banned, FALSE) END AS banned,
    COALESCE(user_permission_overrides.read, rooms.read) AS read,
    COALESCE(user_permission_overrides.write, rooms.write) AS write,
    COALESCE(user_permission_overrides.upload, rooms.upload) AS upload,
    CASE WHEN users.moderator THEN TRUE ELSE COALESCE(user_permission_overrides.moderator, FALSE) END AS moderator,
    CASE WHEN users.admin THEN TRUE ELSE COALESCE(user_permission_overrides.admin, FALSE) END AS admin,
    -- room_moderator will be TRUE if the user is specifically listed as a moderator of the room
    COALESCE(user_permission_overrides.moderator OR user_permission_overrides.admin, FALSE) AS room_moderator,
    -- global_moderator will be TRUE if the user is a global moderator/admin (note that this is
    -- *not* exclusive of room_moderator: a moderator/admin could be listed in both).
    COALESCE(users.moderator OR users.admin, FALSE) as global_moderator,
    -- visible_mod will be TRUE if this mod is a publicly viewable moderator of the room
    CASE
        WHEN user_permission_overrides.moderator OR user_permission_overrides.admin THEN user_permission_overrides.visible_mod
        WHEN users.moderator OR users.admin THEN users.visible_mod
        ELSE FALSE
    END AS visible_mod
FROM
    users JOIN rooms LEFT OUTER JOIN user_permission_overrides ON
        users.id = user_permission_overrides.user AND rooms.id = user_permission_overrides.room;

-- Scheduled changes to user permissions.  For example, to implement a 2-day timeout you would set
-- their user_permissions.write to false, then set a `write = true` entry with a +2d timestamp here.
-- Or to implement a join delay you could set room defaults to false then insert a value here to be
-- applied after a delay.
CREATE TABLE user_permission_futures (
    room INTEGER NOT NULL REFERENCES rooms(id) ON DELETE CASCADE,
    user INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    at FLOAT NOT NULL, /* when the change should take effect (unix epoch) */
    read BOOLEAN, /* Set this value @ at, if non-null */
    write BOOLEAN, /* Set this value @ at, if non-null */
    upload BOOLEAN, /* Set this value @ at, if non-null */
    PRIMARY KEY(room, user)
) WITHOUT ROWID;
CREATE INDEX user_permissions_future_at ON user_permission_futures(at);

COMMIT;