Calvin is a famous tour guide of a well known hotel in Taiwan. He is know for his high adventure tours which generates a good income for the hotel. He was offered a job at the rival hotel with a promise of a hefty salary increase. Calvin consulted his co-workers about it and the news reached the management. His manager promised to give him a 50% salary increase and a guaranteed 4-year contract. Calvin opted to stay with his current hotel.

After a few weeks, Calvin was terminated due restructuring and increased liability risk of his tours and he ended up jobless.

CAn this be considered as a breach of contract? what legal theories can you apply?

Can Promissory Estoppel be used in this case too? Thanks!!