-- 邀请奖励：用户邀请码/被邀请关系 + 记录表 + 系统配置
ALTER TABLE "users" ADD COLUMN "referral_code" TEXT;
ALTER TABLE "users" ADD COLUMN "referred_by_id" TEXT;
CREATE UNIQUE INDEX "users_referral_code_key" ON "users"("referral_code");
CREATE TABLE "referral_records" (
    "id" TEXT NOT NULL PRIMARY KEY,
    "referrer_id" TEXT NOT NULL,
    "referee_id" TEXT NOT NULL,
    "referee_email" TEXT NOT NULL,
    "status" TEXT NOT NULL DEFAULT 'registered',
    "register_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    "first_paid_at" TIMESTAMP(3),
    "first_paid_cents" BIGINT,
    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    CONSTRAINT "referral_records_referrer_id_fkey" FOREIGN KEY ("referrer_id") REFERENCES "users"("id") ON DELETE RESTRICT ON UPDATE CASCADE,
    CONSTRAINT "referral_records_referee_id_fkey" FOREIGN KEY ("referee_id") REFERENCES "users"("id") ON DELETE RESTRICT ON UPDATE CASCADE
);
CREATE TABLE "referral_rewards" (
    "id" TEXT NOT NULL PRIMARY KEY,
    "user_id" TEXT NOT NULL,
    "record_id" TEXT NOT NULL,
    "type" TEXT NOT NULL,
    "amount_cents" BIGINT NOT NULL,
    "status" TEXT NOT NULL DEFAULT 'credited',
    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    CONSTRAINT "referral_rewards_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "users"("id") ON DELETE RESTRICT ON UPDATE CASCADE,
    CONSTRAINT "referral_rewards_record_id_fkey" FOREIGN KEY ("record_id") REFERENCES "referral_records"("id") ON DELETE RESTRICT ON UPDATE CASCADE
);
CREATE TABLE "system_configs" (
    "id" TEXT NOT NULL PRIMARY KEY,
    "key" TEXT NOT NULL UNIQUE,
    "value" TEXT NOT NULL,
    "updated_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP
);