-- Migration 025: server admin RPCs + server_settings + section_enabled() server layer (Fase 13.2)
--
-- Every privileged RPC follows the same shape:
--   1. SECURITY DEFINER.
--   2. Pull v_actor := auth.uid() (NULL → 'unauthenticated' / errcode 28000).
--   3. `if not public.is_server_admin(v_actor) then raise 'forbidden' using errcode = 'P0001';`
--   4. Validate args (raise '<reason>' using errcode = '22023' for bad input).
--   5. INSERT into public.admin_actions BEFORE the mutation (so a failing
--      mutation still leaves a trace). The audit row + the mutation share one
--      transaction (the RPC body is implicit).
--   6. Perform the mutation; return a void or the affected rows.
--
-- The `is_server_admin()` call short-circuits on the (PK-indexed) lookup so the
-- guard is sub-millisecond.
--
-- ── deleted_at on collectives ──────────────────────────────────────────────
-- Soft delete. The plan keeps the original SELECT/UPDATE RLS policies untouched
-- — non-admin members of a soft-deleted collective WILL still see it in
-- queries unless callers add `WHERE deleted_at IS NULL`. We document the
-- contract here: the RLS layer does not enforce soft-delete invisibility,
-- the app layer does. The /admin area surfaces all rows including deleted ones.
-- Hard-delete (cascade) is the operator's escape valve for permanent removal.

ALTER TABLE public.collectives
    ADD COLUMN deleted_at timestamptz NULL;

COMMENT ON COLUMN public.collectives.deleted_at IS
    'Set by admin_soft_delete_collective; cleared by admin_restore_collective. '
    'NULL = active. App-level callers MUST filter on this where soft-delete '
    'invisibility matters — RLS does not enforce it.';

-- ── server_settings ────────────────────────────────────────────────────────
-- Generic key/jsonb-value bag. First use: 'default_sections' jsonb of
-- {section: bool} consumed by section_enabled(). Adding new server-level
-- settings is a row insert, not a schema change.

CREATE TABLE public.server_settings (
    key   text  PRIMARY KEY,
    value jsonb NOT NULL DEFAULT '{}'::jsonb,
    updated_at  timestamptz NOT NULL DEFAULT now(),
    updated_by  uuid        NULL REFERENCES public.users(id) ON DELETE SET NULL
);

ALTER TABLE public.server_settings ENABLE ROW LEVEL SECURITY;

-- Everyone can READ server_settings (section_enabled() needs to evaluate it
-- from a normal user session). Writes go through admin_set_default_section()
-- under SECURITY DEFINER — no INSERT/UPDATE/DELETE policy.
CREATE POLICY "select_all" ON public.server_settings
    FOR SELECT
    USING (true);

COMMENT ON TABLE public.server_settings IS
    'Server-level key/value bag. Read by everyone, written only by admin RPCs.';

-- Seed an empty default_sections row so section_enabled never sees a missing
-- row vs missing key difference (both behave as "no opinion" anyway, but the
-- presence of the row keeps PostgREST queries on this single record cheap).
INSERT INTO public.server_settings (key, value)
VALUES ('default_sections', '{}'::jsonb)
ON CONFLICT (key) DO NOTHING;

-- ── section_enabled() extension ────────────────────────────────────────────
-- Prepend a server layer. Precedence becomes:
--   server (server_settings.default_sections[p_section])
--     > collective (collectives.feature_flags[p_section])
--     > user       (users.feature_flags[p_section])
--     > default true
-- This is the one-line diff that migration 023 was designed for; the rest of
-- the function body is untouched.

CREATE OR REPLACE FUNCTION public.section_enabled(
    p_section    text,
    p_user       uuid,
    p_collective uuid
)
RETURNS boolean
LANGUAGE sql
STABLE
SECURITY DEFINER
SET search_path = public
AS $$
    SELECT COALESCE(
        (SELECT (value ->> p_section)::boolean
           FROM   public.server_settings
          WHERE   key = 'default_sections'),
        (SELECT (feature_flags ->> p_section)::boolean
           FROM   public.collectives
          WHERE   id = p_collective),
        (SELECT (feature_flags ->> p_section)::boolean
           FROM   public.users
          WHERE   id = p_user),
        true
    );
$$;

COMMENT ON FUNCTION public.section_enabled(text, uuid, uuid) IS
    'Effective ON/OFF of a top-level section for (user, collective). '
    'Precedence: server > collective > user > default true.';

-- ── Helper: internal audit writer ──────────────────────────────────────────
-- Centralises the INSERT INTO admin_actions so RPCs read cleanly. NOT exposed
-- to anyone — only the other SECURITY DEFINER functions in this file call it.

CREATE OR REPLACE FUNCTION public._log_admin_action(
    p_actor       uuid,
    p_action      text,
    p_target_type text,
    p_target_id   uuid,
    p_payload     jsonb DEFAULT '{}'::jsonb
)
RETURNS void
LANGUAGE sql
VOLATILE
SECURITY DEFINER
SET search_path = public
AS $$
    INSERT INTO public.admin_actions (actor_id, action, target_type, target_id, payload)
    VALUES (p_actor, p_action, p_target_type, p_target_id, p_payload);
$$;

REVOKE ALL ON FUNCTION public._log_admin_action(uuid, text, text, uuid, jsonb) FROM PUBLIC;
-- No GRANT; only invoked by sibling functions in the same migration.

-- ── grant_server_admin ─────────────────────────────────────────────────────
CREATE OR REPLACE FUNCTION public.grant_server_admin(p_user uuid)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_user IS NULL THEN
        RAISE EXCEPTION 'user_required' USING ERRCODE = '22023';
    END IF;
    IF NOT EXISTS (SELECT 1 FROM public.users WHERE id = p_user) THEN
        RAISE EXCEPTION 'user_not_found' USING ERRCODE = 'P0002';
    END IF;

    INSERT INTO public.server_admins (user_id, granted_by)
    VALUES (p_user, v_actor)
    ON CONFLICT (user_id) DO NOTHING;

    PERFORM public._log_admin_action(
        v_actor,
        'grant_server_admin',
        'user',
        p_user,
        jsonb_build_object()
    );
END;
$$;

REVOKE ALL ON FUNCTION public.grant_server_admin(uuid) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.grant_server_admin(uuid) TO authenticated;

-- ── revoke_server_admin ────────────────────────────────────────────────────
-- Guard: the last remaining admin cannot be removed (would lock the instance
-- out of its own admin area irrecoverably).
CREATE OR REPLACE FUNCTION public.revoke_server_admin(p_user uuid)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
    v_remaining int;
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_user IS NULL THEN
        RAISE EXCEPTION 'user_required' USING ERRCODE = '22023';
    END IF;

    -- Compute remaining admins AFTER hypothetical removal.
    SELECT count(*) INTO v_remaining
    FROM   public.server_admins
    WHERE  user_id <> p_user;

    IF v_remaining = 0 THEN
        RAISE EXCEPTION 'last_admin' USING ERRCODE = 'P0003';
    END IF;

    DELETE FROM public.server_admins WHERE user_id = p_user;

    PERFORM public._log_admin_action(
        v_actor,
        'revoke_server_admin',
        'user',
        p_user,
        jsonb_build_object()
    );
END;
$$;

REVOKE ALL ON FUNCTION public.revoke_server_admin(uuid) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.revoke_server_admin(uuid) TO authenticated;

-- ── admin_list_collectives ─────────────────────────────────────────────────
CREATE OR REPLACE FUNCTION public.admin_list_collectives(
    p_search text DEFAULT NULL,
    p_limit  int  DEFAULT 50
)
RETURNS TABLE (
    id           uuid,
    name         text,
    emoji        text,
    member_count bigint,
    created_at   timestamptz,
    deleted_at   timestamptz
)
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;

    RETURN QUERY
    SELECT  c.id,
            c.name,
            c.emoji,
            (SELECT count(*) FROM public.collective_members cm WHERE cm.collective_id = c.id) AS member_count,
            c.created_at,
            c.deleted_at
    FROM    public.collectives c
    WHERE   p_search IS NULL OR c.name ILIKE '%' || p_search || '%'
    ORDER   BY c.deleted_at NULLS FIRST, c.created_at DESC
    LIMIT   LEAST(GREATEST(p_limit, 1), 500);
END;
$$;

REVOKE ALL ON FUNCTION public.admin_list_collectives(text, int) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.admin_list_collectives(text, int) TO authenticated;

-- ── admin_soft_delete_collective ───────────────────────────────────────────
CREATE OR REPLACE FUNCTION public.admin_soft_delete_collective(
    p_collective_id uuid,
    p_reason        text
)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_collective_id IS NULL THEN
        RAISE EXCEPTION 'collective_required' USING ERRCODE = '22023';
    END IF;
    IF p_reason IS NULL OR length(btrim(p_reason)) = 0 THEN
        RAISE EXCEPTION 'reason_required' USING ERRCODE = '22023';
    END IF;
    IF NOT EXISTS (SELECT 1 FROM public.collectives WHERE id = p_collective_id) THEN
        RAISE EXCEPTION 'collective_not_found' USING ERRCODE = 'P0002';
    END IF;

    UPDATE public.collectives
       SET deleted_at = now()
     WHERE id = p_collective_id
       AND deleted_at IS NULL;

    PERFORM public._log_admin_action(
        v_actor,
        'soft_delete_collective',
        'collective',
        p_collective_id,
        jsonb_build_object('reason', p_reason)
    );
END;
$$;

REVOKE ALL ON FUNCTION public.admin_soft_delete_collective(uuid, text) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.admin_soft_delete_collective(uuid, text) TO authenticated;

-- ── admin_restore_collective ───────────────────────────────────────────────
CREATE OR REPLACE FUNCTION public.admin_restore_collective(p_collective_id uuid)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_collective_id IS NULL THEN
        RAISE EXCEPTION 'collective_required' USING ERRCODE = '22023';
    END IF;
    IF NOT EXISTS (SELECT 1 FROM public.collectives WHERE id = p_collective_id) THEN
        RAISE EXCEPTION 'collective_not_found' USING ERRCODE = 'P0002';
    END IF;

    UPDATE public.collectives
       SET deleted_at = NULL
     WHERE id = p_collective_id;

    PERFORM public._log_admin_action(
        v_actor,
        'restore_collective',
        'collective',
        p_collective_id,
        jsonb_build_object()
    );
END;
$$;

REVOKE ALL ON FUNCTION public.admin_restore_collective(uuid) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.admin_restore_collective(uuid) TO authenticated;

-- ── admin_hard_delete_collective ───────────────────────────────────────────
-- Guard: only allowed when deleted_at IS NOT NULL AND >= 30 days old, OR
-- p_force = true. This protects against accidental "soft-delete then
-- hard-delete by reflex".
CREATE OR REPLACE FUNCTION public.admin_hard_delete_collective(
    p_collective_id uuid,
    p_force         boolean DEFAULT false
)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
    v_row   public.collectives%ROWTYPE;
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_collective_id IS NULL THEN
        RAISE EXCEPTION 'collective_required' USING ERRCODE = '22023';
    END IF;

    SELECT * INTO v_row FROM public.collectives WHERE id = p_collective_id;
    IF NOT FOUND THEN
        RAISE EXCEPTION 'collective_not_found' USING ERRCODE = 'P0002';
    END IF;

    IF NOT p_force THEN
        IF v_row.deleted_at IS NULL THEN
            RAISE EXCEPTION 'not_soft_deleted' USING ERRCODE = 'P0001';
        END IF;
        IF v_row.deleted_at > now() - INTERVAL '30 days' THEN
            RAISE EXCEPTION 'too_recent' USING ERRCODE = 'P0001';
        END IF;
    END IF;

    -- Audit FIRST so the action row exists even if the cascade somehow trips.
    PERFORM public._log_admin_action(
        v_actor,
        'hard_delete_collective',
        'collective',
        p_collective_id,
        jsonb_build_object(
            'force',          p_force,
            'name_snapshot',  v_row.name,
            'created_at',     v_row.created_at,
            'deleted_at',     v_row.deleted_at
        )
    );

    DELETE FROM public.collectives WHERE id = p_collective_id;
END;
$$;

REVOKE ALL ON FUNCTION public.admin_hard_delete_collective(uuid, boolean) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.admin_hard_delete_collective(uuid, boolean) TO authenticated;

-- ── admin_remove_member ────────────────────────────────────────────────────
CREATE OR REPLACE FUNCTION public.admin_remove_member(
    p_collective_id uuid,
    p_user          uuid,
    p_reason        text
)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
    v_role  public.member_role;
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_collective_id IS NULL OR p_user IS NULL THEN
        RAISE EXCEPTION 'args_required' USING ERRCODE = '22023';
    END IF;
    IF p_reason IS NULL OR length(btrim(p_reason)) = 0 THEN
        RAISE EXCEPTION 'reason_required' USING ERRCODE = '22023';
    END IF;

    SELECT role INTO v_role
    FROM   public.collective_members
    WHERE  collective_id = p_collective_id AND user_id = p_user;

    IF NOT FOUND THEN
        RAISE EXCEPTION 'membership_not_found' USING ERRCODE = 'P0002';
    END IF;

    -- Audit before mutation so we record the role the user used to have.
    PERFORM public._log_admin_action(
        v_actor,
        'remove_member',
        'collective_member',
        p_collective_id,
        jsonb_build_object('user_id', p_user, 'role_was', v_role, 'reason', p_reason)
    );

    DELETE FROM public.collective_members
     WHERE collective_id = p_collective_id AND user_id = p_user;
END;
$$;

REVOKE ALL ON FUNCTION public.admin_remove_member(uuid, uuid, text) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.admin_remove_member(uuid, uuid, text) TO authenticated;

-- ── admin_set_default_section ──────────────────────────────────────────────
-- Patches public.server_settings(key='default_sections') so the section
-- toggle applies as the server-layer override read by section_enabled().
CREATE OR REPLACE FUNCTION public.admin_set_default_section(
    p_section text,
    p_enabled boolean
)
RETURNS void
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = public
AS $$
DECLARE
    v_actor uuid := auth.uid();
    v_current jsonb;
    v_next    jsonb;
BEGIN
    IF v_actor IS NULL THEN
        RAISE EXCEPTION 'unauthenticated' USING ERRCODE = '28000';
    END IF;
    IF NOT public.is_server_admin(v_actor) THEN
        RAISE EXCEPTION 'forbidden' USING ERRCODE = 'P0001';
    END IF;
    IF p_section IS NULL OR p_section = '' THEN
        RAISE EXCEPTION 'section_required' USING ERRCODE = '22023';
    END IF;
    -- Reject unknown sections to prevent typos from silently shaping the
    -- visibility surface forever. Future sections require a migration that
    -- updates known_sections() (see migration 023 comment).
    IF NOT (p_section = ANY (public.known_sections())) THEN
        RAISE EXCEPTION 'unknown_section: %', p_section USING ERRCODE = '22023';
    END IF;

    -- Read-modify-write the JSONB row. CONCURRENT writes are not a real
    -- concern here (admin UI, low frequency); a row-level lock from the
    -- UPDATE-RETURNING below is sufficient.
    INSERT INTO public.server_settings (key, value, updated_by, updated_at)
    VALUES ('default_sections', jsonb_build_object(p_section, p_enabled), v_actor, now())
    ON CONFLICT (key) DO UPDATE
        SET value      = public.server_settings.value || jsonb_build_object(p_section, p_enabled),
            updated_by = v_actor,
            updated_at = now()
    RETURNING value INTO v_next;

    PERFORM public._log_admin_action(
        v_actor,
        'set_default_section',
        'server_setting',
        NULL,
        jsonb_build_object('section', p_section, 'enabled', p_enabled, 'value_after', v_next)
    );
END;
$$;

REVOKE ALL ON FUNCTION public.admin_set_default_section(text, boolean) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION public.admin_set_default_section(text, boolean) TO authenticated;