// Sharing a resource with other people on this site.
//
// A resource was private to its author with no way out but the author's own
// Nextcloud. A share is a row per (resource, person): the person can open,
// preview and download it — not modify, re-skin or delete it — and the author
// can withdraw it. shared_with_all opens a resource to every signed-in account
// without naming them.
//
// Rows go with the resource and with the person: a deleted account leaves no
// dangling grant, and a deleted resource leaves no orphan share.

exports.up = pgm => pgm.sql(`
  ALTER TABLE user_resources ADD COLUMN IF NOT EXISTS shared_with_all BOOLEAN NOT NULL DEFAULT FALSE;
  CREATE TABLE IF NOT EXISTS user_resource_shares (
    resource_id INTEGER NOT NULL REFERENCES user_resources(id) ON DELETE CASCADE,
    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    shared_by INTEGER REFERENCES users(id) ON DELETE SET NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    PRIMARY KEY (resource_id, user_id)
  );
  CREATE INDEX IF NOT EXISTS idx_resource_shares_user ON user_resource_shares (user_id);
`);

exports.down = pgm => pgm.sql(`
  DROP TABLE IF EXISTS user_resource_shares;
  ALTER TABLE user_resources DROP COLUMN IF EXISTS shared_with_all;
`);