Worst job interview ever

I applied to a job and was called for a job interview a few days later. I went to the job interview and everything went smoothly, they were enthusiastic about having me join the company and their team and promised to send me a job offer “soon”. :) :) :) :)

The very next morning they email me saying that there was a mix-up, that they were sorry but that they thought they were talking to another candidate during the interview, that candidate had a name close to mine, and that everything they told me in the job interview doesn’t really apply to me … and that I have to go see them again and start the process from scratch! Nba3asna