CREATE TABLE collaboration_workspaces (
    tenant_id bigint PRIMARY KEY REFERENCES tenants(id) ON DELETE CASCADE,
    public_id uuid NOT NULL UNIQUE DEFAULT gen_random_uuid(),
    guests_enabled boolean NOT NULL DEFAULT true
);

CREATE TABLE collaboration_principals (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    kind text NOT NULL CHECK (kind IN ('user','guest','remote')),
    tenant_id bigint REFERENCES tenants(id) ON DELETE CASCADE,
    user_id uuid REFERENCES auth_users(id) ON DELETE CASCADE,
    remote_origin text,
    remote_actor_id uuid,
    display_name text NOT NULL,
    email text,
    disabled boolean NOT NULL DEFAULT false,
    created_at timestamptz NOT NULL DEFAULT now(),
    CHECK ((kind='user' AND tenant_id IS NOT NULL AND user_id IS NOT NULL AND remote_origin IS NULL)
        OR (kind='guest' AND tenant_id IS NOT NULL AND user_id IS NULL AND email IS NOT NULL AND remote_origin IS NULL)
        OR (kind='remote' AND tenant_id IS NULL AND user_id IS NULL AND remote_origin IS NOT NULL AND remote_actor_id IS NOT NULL))
);
CREATE UNIQUE INDEX collaboration_local_actor ON collaboration_principals(tenant_id,user_id) WHERE kind='user';
CREATE UNIQUE INDEX collaboration_guest_actor ON collaboration_principals(tenant_id,email) WHERE kind='guest';
CREATE UNIQUE INDEX collaboration_remote_actor ON collaboration_principals(remote_origin,remote_actor_id) WHERE kind='remote';

CREATE TABLE collaboration_rooms (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    tenant_id bigint NOT NULL REFERENCES tenants(id) ON DELETE CASCADE,
    project_id bigint REFERENCES projects(id) ON DELETE CASCADE,
    name text NOT NULL CHECK (length(name) BETWEEN 1 AND 160),
    topic text NOT NULL DEFAULT '',
    shared_overview jsonb NOT NULL DEFAULT '{}',
    status text NOT NULL DEFAULT 'active' CHECK (status IN ('active','archived','blocked')),
    sequence bigint NOT NULL DEFAULT 0,
    created_by uuid NOT NULL REFERENCES auth_users(id),
    created_at timestamptz NOT NULL DEFAULT now(),
    updated_at timestamptz NOT NULL DEFAULT now()
);
CREATE INDEX collaboration_project_rooms ON collaboration_rooms(tenant_id,project_id);

CREATE TABLE collaboration_members (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    room_id uuid NOT NULL REFERENCES collaboration_rooms(id) ON DELETE CASCADE,
    principal_id uuid NOT NULL REFERENCES collaboration_principals(id),
    status text NOT NULL DEFAULT 'active' CHECK (status IN ('active','revoked')),
    role text NOT NULL DEFAULT 'participant' CHECK (role IN ('participant','reader')),
    overview_allowed boolean NOT NULL DEFAULT false,
    history_from_seq bigint NOT NULL,
    last_read_seq bigint NOT NULL DEFAULT 0,
    revision bigint NOT NULL DEFAULT 1,
    expires_at timestamptz,
    joined_at timestamptz NOT NULL DEFAULT now(),
    revoked_at timestamptz,
    UNIQUE(room_id,principal_id)
);

CREATE TABLE collaboration_messages (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    room_id uuid NOT NULL REFERENCES collaboration_rooms(id) ON DELETE CASCADE,
    seq bigint NOT NULL,
    principal_id uuid NOT NULL REFERENCES collaboration_principals(id),
    client_id uuid NOT NULL,
    body text NOT NULL CHECK (length(body) BETWEEN 1 AND 10000),
    created_at timestamptz NOT NULL DEFAULT now(),
    UNIQUE(room_id,seq),
    UNIQUE(room_id,principal_id,client_id)
);

CREATE TABLE collaboration_invitations (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    room_id uuid NOT NULL REFERENCES collaboration_rooms(id) ON DELETE CASCADE,
    target_principal_id uuid NOT NULL REFERENCES collaboration_principals(id),
    token_hash text NOT NULL UNIQUE,
    role text NOT NULL CHECK (role IN ('participant','reader')),
    overview_allowed boolean NOT NULL DEFAULT false,
    invited_by uuid NOT NULL REFERENCES auth_users(id),
    status text NOT NULL DEFAULT 'pending' CHECK (status IN ('pending','accepted','declined','revoked')),
    expires_at timestamptz NOT NULL,
    access_expires_at timestamptz,
    created_at timestamptz NOT NULL DEFAULT now(),
    accepted_at timestamptz
);
CREATE INDEX collaboration_recipient_invitations ON collaboration_invitations(target_principal_id,status);

CREATE TABLE collaboration_guest_challenges (
    id uuid PRIMARY KEY,
    principal_id uuid NOT NULL REFERENCES collaboration_principals(id) ON DELETE CASCADE,
    code_hash text NOT NULL,
    attempts integer NOT NULL DEFAULT 0,
    expires_at timestamptz NOT NULL,
    consumed_at timestamptz
);
CREATE TABLE collaboration_guest_sessions (
    token_hash text PRIMARY KEY,
    principal_id uuid NOT NULL REFERENCES collaboration_principals(id) ON DELETE CASCADE,
    expires_at timestamptz NOT NULL,
    created_at timestamptz NOT NULL DEFAULT now()
);
CREATE INDEX collaboration_guest_session_expiry ON collaboration_guest_sessions(expires_at);
CREATE TABLE collaboration_rate_limits (
    key text PRIMARY KEY,
    hits integer NOT NULL,
    resets_at timestamptz NOT NULL
);
CREATE TABLE collaboration_audit (
    id bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    tenant_id bigint NOT NULL REFERENCES tenants(id) ON DELETE CASCADE,
    room_id uuid REFERENCES collaboration_rooms(id) ON DELETE SET NULL,
    actor_id uuid REFERENCES collaboration_principals(id),
    action text NOT NULL,
    subject_id uuid,
    created_at timestamptz NOT NULL DEFAULT now()
);

-- This must also hold for direct SQL writes, not just the HTTP validation.
CREATE FUNCTION collaboration_check_project_tenant() RETURNS trigger LANGUAGE plpgsql AS $$
BEGIN
    IF NEW.project_id IS NOT NULL AND NOT EXISTS (
        SELECT 1 FROM projects WHERE id=NEW.project_id AND tenant=NEW.tenant_id
    ) THEN RAISE EXCEPTION 'Project belongs to another tenant' USING ERRCODE='23514'; END IF;
    IF TG_OP='UPDATE' AND (NEW.project_id IS DISTINCT FROM OLD.project_id OR NEW.tenant_id<>OLD.tenant_id)
    THEN RAISE EXCEPTION 'Collaboration ownership is immutable' USING ERRCODE='23514'; END IF;
    RETURN NEW;
END $$;
CREATE TRIGGER collaboration_project_tenant BEFORE INSERT OR UPDATE ON collaboration_rooms
FOR EACH ROW EXECUTE FUNCTION collaboration_check_project_tenant();