CREATE TABLE t_platform_user (
    id BIGSERIAL PRIMARY KEY,
    user_id BIGINT NOT NULL,
    platform_type SMALLINT NOT NULL,
    platform_openid VARCHAR(100) NOT NULL,
    platform_unionid VARCHAR(100),
    platform_session_key VARCHAR(100),
    platform_extra JSONB,
    last_login_time TIMESTAMP,
    create_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    update_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    deleted SMALLINT DEFAULT 0,
    UNIQUE (platform_type, platform_openid),
    CONSTRAINT fk_platform_user_user_id FOREIGN KEY (user_id) REFERENCES t_user(id) ON DELETE CASCADE
);

COMMENT ON TABLE t_platform_user IS '平台用户关联表（微信/抖音小程序用户信息）';
COMMENT ON COLUMN t_platform_user.id IS '平台用户ID（自增）';
COMMENT ON COLUMN t_platform_user.user_id IS '关联t_user.id';
COMMENT ON COLUMN t_platform_user.platform_type IS '平台类型：1-微信小程序，2-抖音小程序，3-支付宝小程序';
COMMENT ON COLUMN t_platform_user.platform_openid IS '平台唯一标识（微信openid/抖音open_id）';
COMMENT ON COLUMN t_platform_user.platform_unionid IS '平台统一标识（微信unionid，多小程序互通用）';
COMMENT ON COLUMN t_platform_user.platform_session_key IS '平台会话密钥（微信session_key，加密存储）';
COMMENT ON COLUMN t_platform_user.platform_extra IS '平台扩展字段（如抖音的user_name、微信的city等）';
COMMENT ON COLUMN t_platform_user.last_login_time IS '最后登录时间';
COMMENT ON COLUMN t_platform_user.create_time IS '创建时间';
COMMENT ON COLUMN t_platform_user.update_time IS '更新时间';
COMMENT ON COLUMN t_platform_user.deleted IS '软删除：0-未删，1-已删';

CREATE OR REPLACE FUNCTION set_update_time()
RETURNS TRIGGER AS $$
BEGIN
    NEW.update_time = CURRENT_TIMESTAMP;
    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER t_platform_user_set_update_time
BEFORE UPDATE ON t_platform_user
FOR EACH ROW
EXECUTE FUNCTION set_update_time();