What are the legends about the origin of the long summer solar terms?

At the end of the Three Kingdoms, Shu, which was managed by the late ruler Liu Chan, was already very weak. This year, the general of Wei, Deng Ai, was ordered to lead an army to attack Shu, and the soldiers were forced to surrender. Zheng Zheng, a loyal minister in Shu, proposed to Wargo that "Liu Chan is the king of a country. After surrendering to Dewey, he can't be abused or lose a little meat, otherwise he would rather die than surrender". Wargo agreed to this condition.

After Liu Chan surrendered, he was taken to Luoyang, the capital of Wei at that time. Duke Wei named him an Anle Gong and gave him a house, ten thousand silks and satins and a hundred beautiful women. From then on, Liu ate, drank, and was not ashamed to forget his country. The next year, Liu Chan was called to weigh himself, but instead of losing weight, the king who forgot his country gained more than 20 kilograms. This day also happens to be the beginning of summer. There is a poem in the Romance of the Three Kingdoms that says, "Laugh and play, and worry about it." If you are happy in a foreign land and forget your old country, you will know that your late master was a mediocrity. "