ALTER TABLE assignment_policies
  ADD COLUMN IF NOT EXISTS name VARCHAR(255),
  ADD COLUMN IF NOT EXISTS description TEXT NOT NULL DEFAULT '',
  ADD COLUMN IF NOT EXISTS assignment_order INTEGER NOT NULL DEFAULT 0,
  ADD COLUMN IF NOT EXISTS conversation_priority INTEGER NOT NULL DEFAULT 0,
  ADD COLUMN IF NOT EXISTS fair_distribution_limit INTEGER NOT NULL DEFAULT 100,
  ADD COLUMN IF NOT EXISTS fair_distribution_window INTEGER NOT NULL DEFAULT 3600;

UPDATE assignment_policies
SET name = COALESCE(NULLIF(policy_type, ''), 'Policy') || ' ' || id
WHERE name IS NULL OR name = '';

ALTER TABLE assignment_policies
  ALTER COLUMN name SET NOT NULL;

CREATE UNIQUE INDEX IF NOT EXISTS idx_account_policy_name
  ON assignment_policies(account_id, name);

DO $$
BEGIN
  IF EXISTS (
    SELECT 1
    FROM assignment_policies
    WHERE inbox_id IS NOT NULL
    GROUP BY inbox_id
    HAVING COUNT(*) > 1
  ) THEN
    RAISE EXCEPTION 'migration 000086: multiple legacy assignment policies target one inbox';
  END IF;

  IF EXISTS (
    SELECT 1
    FROM assignment_policies
    JOIN inboxes ON inboxes.id = assignment_policies.inbox_id
    WHERE assignment_policies.inbox_id IS NOT NULL
      AND assignment_policies.account_id <> inboxes.account_id
  ) THEN
    RAISE EXCEPTION 'migration 000086: legacy assignment policy and inbox belong to different accounts';
  END IF;
END
$$;

CREATE TABLE IF NOT EXISTS inbox_assignment_policies (
  id BIGSERIAL PRIMARY KEY,
  inbox_id BIGINT NOT NULL REFERENCES inboxes(id) ON DELETE CASCADE,
  assignment_policy_id BIGINT NOT NULL REFERENCES assignment_policies(id) ON DELETE CASCADE,
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

INSERT INTO inbox_assignment_policies(inbox_id, assignment_policy_id, created_at, updated_at)
SELECT assignment_policies.inbox_id, assignment_policies.id, assignment_policies.created_at, assignment_policies.updated_at
FROM assignment_policies
WHERE assignment_policies.inbox_id IS NOT NULL
  AND NOT EXISTS (
    SELECT 1
    FROM inbox_assignment_policies
    WHERE inbox_assignment_policies.inbox_id = assignment_policies.inbox_id
  );

CREATE UNIQUE INDEX IF NOT EXISTS idx_inbox_assignment_policies_inbox_id
  ON inbox_assignment_policies(inbox_id);
CREATE INDEX IF NOT EXISTS idx_inbox_assignment_policies_assignment_policy_id
  ON inbox_assignment_policies(assignment_policy_id);