-- Account deletion as legal retention (not erasure). Two additive pieces.
--
-- retained_identities is an append-only journal of every credential detached from an
-- account — on unlink, email change, or account deletion (reason). It preserves the legal
-- dossier (which email/vk/tg was linked, and when) while the live identities row is
-- removed, so the (kind, external_id) frees for a new account to reuse. No unique
-- constraint and no kind CHECK: the same credential may recur across accounts and events,
-- and the log stays robust to future identity kinds. detached_at drives the retention TTL.
--
-- accounts gains: last_login_at / last_login_ip (stamped on a cold app-load, throttled),
-- deleted_at (the tombstone marker), and deleted_display_name (the real name retained for
-- the admin dossier after the live display_name is scrubbed to the anonymised label).
--
-- Expand-contract: everything is additive (a new table plus nullable columns), so a
-- backend image rollback stays DB-safe — older code simply ignores them. The accounts
-- table shape changes, so its generated go-jet model is regenerated.

-- +goose Up
CREATE TABLE backend.retained_identities (
    retained_id uuid NOT NULL,
    account_id uuid NOT NULL,
    kind text NOT NULL,
    external_id text NOT NULL,
    confirmed boolean DEFAULT false NOT NULL,
    linked_at timestamp with time zone NOT NULL,
    detached_at timestamp with time zone DEFAULT now() NOT NULL,
    reason text NOT NULL,
    CONSTRAINT retained_identities_pkey PRIMARY KEY (retained_id),
    CONSTRAINT retained_identities_reason_chk
        CHECK ((reason = ANY (ARRAY['unlink'::text, 'change'::text, 'delete'::text])))
);
CREATE INDEX retained_identities_account_id_idx ON backend.retained_identities (account_id);
CREATE INDEX retained_identities_detached_at_idx ON backend.retained_identities (detached_at);

ALTER TABLE backend.accounts
    ADD COLUMN last_login_at timestamp with time zone,
    ADD COLUMN last_login_ip text,
    ADD COLUMN deleted_at timestamp with time zone,
    ADD COLUMN deleted_display_name text;

-- +goose Down
ALTER TABLE backend.accounts
    DROP COLUMN last_login_at,
    DROP COLUMN last_login_ip,
    DROP COLUMN deleted_at,
    DROP COLUMN deleted_display_name;
DROP TABLE backend.retained_identities;