BEGIN;

INSERT INTO system_config (key, value, description)
VALUES ('auth', '{"email_verification_required": true}', '认证功能开关')
ON CONFLICT (key) DO NOTHING;

ALTER TABLE usage_periods
  ADD COLUMN IF NOT EXISTS grant_used_units INTEGER NOT NULL DEFAULT 0;

DO $$ BEGIN
  ALTER TABLE usage_periods
    ADD CONSTRAINT usage_periods_grant_used_units_nonnegative
    CHECK (grant_used_units >= 0 AND grant_used_units <= used_units);
EXCEPTION
  WHEN duplicate_object THEN NULL;
END $$;

CREATE TABLE IF NOT EXISTS redemption_codes (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  code_hash VARCHAR(64) NOT NULL UNIQUE,
  code_hint VARCHAR(32) NOT NULL,
  benefit_kind VARCHAR(16) NOT NULL CHECK (benefit_kind IN ('plan', 'units')),
  plan_id UUID REFERENCES plans(id),
  units INTEGER,
  duration_days INTEGER NOT NULL,
  redeem_before TIMESTAMPTZ,
  is_active BOOLEAN NOT NULL DEFAULT true,
  note TEXT,
  created_by UUID NOT NULL REFERENCES users(id),
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

  CHECK (duration_days BETWEEN 1 AND 3650),
  CHECK (
    (benefit_kind = 'plan' AND plan_id IS NOT NULL AND units IS NULL)
    OR
    (benefit_kind = 'units' AND plan_id IS NULL AND units BETWEEN 1 AND 10000000)
  )
);

CREATE INDEX IF NOT EXISTS idx_redemption_codes_created_at
  ON redemption_codes(created_at DESC);
CREATE INDEX IF NOT EXISTS idx_redemption_codes_active_deadline
  ON redemption_codes(is_active, redeem_before);

CREATE TABLE IF NOT EXISTS redemption_records (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  code_id UUID NOT NULL UNIQUE REFERENCES redemption_codes(id),
  user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  benefit_kind VARCHAR(16) NOT NULL CHECK (benefit_kind IN ('plan', 'units')),
  plan_id UUID REFERENCES plans(id),
  units INTEGER,
  benefit_starts_at TIMESTAMPTZ NOT NULL,
  benefit_expires_at TIMESTAMPTZ NOT NULL,
  redeemed_ip INET,
  redeemed_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

  CHECK (benefit_expires_at > benefit_starts_at)
);

CREATE INDEX IF NOT EXISTS idx_redemption_records_user_time
  ON redemption_records(user_id, redeemed_at DESC);

CREATE TABLE IF NOT EXISTS unit_grants (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  redemption_record_id UUID NOT NULL UNIQUE REFERENCES redemption_records(id) ON DELETE CASCADE,
  total_units INTEGER NOT NULL CHECK (total_units > 0),
  remaining_units INTEGER NOT NULL CHECK (remaining_units >= 0 AND remaining_units <= total_units),
  starts_at TIMESTAMPTZ NOT NULL,
  expires_at TIMESTAMPTZ NOT NULL,
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

  CHECK (expires_at > starts_at)
);

CREATE INDEX IF NOT EXISTS idx_unit_grants_available
  ON unit_grants(user_id, expires_at, created_at)
  WHERE remaining_units > 0;

COMMIT;