// Sharing by link. The author makes a link; whoever follows it, signed in,
// accepts, and the resource joins their library as a share (a row in
// user_resource_shares, exactly as before). Only the hash of the token is
// stored, so a database read does not hand out working links; a link can be
// given an expiry and withdrawn.

exports.up = pgm => pgm.sql(`
  CREATE TABLE IF NOT EXISTS user_resource_share_links (
    id SERIAL PRIMARY KEY,
    resource_id INTEGER NOT NULL REFERENCES user_resources(id) ON DELETE CASCADE,
    token_hash TEXT NOT NULL UNIQUE,
    created_by INTEGER REFERENCES users(id) ON DELETE SET NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    expires_at TIMESTAMPTZ,
    revoked_at TIMESTAMPTZ,
    accepted_count INTEGER NOT NULL DEFAULT 0
  );
  CREATE INDEX IF NOT EXISTS idx_resource_share_links_resource ON user_resource_share_links (resource_id);
`);

exports.down = pgm => pgm.sql(`
  DROP TABLE IF EXISTS user_resource_share_links;
`);