-- ============================================================================
-- Krow — OAuth 2.1 clients
--
-- Phase 3, migration 1 of 3. This table holds the clients that may ask for a
-- token: in practice, one row per Claude installation that has connected.
--
-- Registered DYNAMICALLY (RFC 7591), not seeded. An MCP client discovers this
-- server, registers itself, and gets a client_id back. There is deliberately no
-- pre-provisioned row and no fixture: a seeded client is a credential in the
-- repository, and the whole point of dynamic registration is that nobody has to
-- put one there.
--
-- PUBLIC CLIENTS ONLY, and that is why there is no client_secret column.
-- Claude Desktop and Claude Web are public clients — they run on a machine the
-- user controls, so any secret shipped to them is a secret the user has. OAuth
-- 2.1 handles this with PKCE instead, which is why code_challenge is mandatory
-- in 000013 rather than optional. A column for a secret that must never be
-- trusted is a column somebody will eventually trust.
--
-- Target schema: public. No system schema is read or written.
-- ============================================================================

SET search_path = public;

CREATE TABLE oauth_clients (
  -- The client_id handed back at registration and presented on every
  -- authorization and token request. Opaque and server-generated: a client
  -- that could choose its own id could impersonate one already registered.
  client_id     text        PRIMARY KEY,

  -- What the client calls itself, for the consent screen. Untrusted display
  -- text — it is whatever the registering client sent, so it is shown as a
  -- name and never used for a decision.
  client_name   text        NOT NULL DEFAULT '',

  -- Exact-match redirect targets. An array because a client may legitimately
  -- register more than one (a desktop loopback port and a hosted callback),
  -- and the authorization endpoint matches the presented redirect_uri against
  -- these byte-for-byte. No prefix matching, no wildcards, no normalisation:
  -- every one of those has been an open-redirect CVE somewhere.
  redirect_uris text[]      NOT NULL,

  -- Recorded for auditing which client asked for what. Constrained rather than
  -- free text so an unexpected value is a failed insert instead of a row
  -- nobody notices.
  grant_types   text[]      NOT NULL DEFAULT ARRAY['authorization_code', 'refresh_token'],

  -- The scopes this client may request. Held per-client so tightening the
  -- global policy later does not silently widen an existing registration.
  scopes        text[]      NOT NULL DEFAULT ARRAY['krow.read'],

  created_date  timestamptz NOT NULL DEFAULT now(),
  last_used_at  timestamptz,

  -- A client can be disabled without deleting it, so its tokens can be
  -- revoked and its history kept.
  disabled_at   timestamptz,

  -- At least one redirect URI, or the client can never complete a flow. Caught
  -- here so a malformed registration fails at the point of registration rather
  -- than at the point a person is staring at a broken consent screen.
  CONSTRAINT oauth_clients_redirect_uris_present
    CHECK (array_length(redirect_uris, 1) >= 1),

  -- Bound so a registration cannot be used to store bulk data.
  CONSTRAINT oauth_clients_redirect_uris_bounded
    CHECK (array_length(redirect_uris, 1) <= 10),

  CONSTRAINT oauth_clients_name_bounded
    CHECK (length(client_name) <= 200)
);

-- Listing a user's connected clients is not a query this table answers — that
-- comes from oauth_tokens, which carries user_id. The only index here is the
-- primary key, which is also the lookup path: every request arrives with a
-- client_id and probes exactly that column.

COMMENT ON TABLE oauth_clients IS
  'OAuth 2.1 public clients, registered dynamically per RFC 7591. No secrets '
  'are stored: public clients authenticate with PKCE, not with a credential.';

COMMENT ON COLUMN oauth_clients.redirect_uris IS
  'Exact-match redirect targets. Never prefix-matched or normalised.';

COMMENT ON COLUMN oauth_clients.disabled_at IS
  'Set to disable a client without losing its registration or audit history.';