Do I file taxes in CA for all or part of my income?

I work for a California employer and live in Washington state. However, I commute to my California office 3 days a week. Do I have to pay taxes for all of my income earned through a California employer? Or do I only pay California taxes for the income corresponding to the days I spent in California? 

 

Also, Am I considered a California Resident because I spend 3 work days in CA, and 2 work days +2 weekend days in WA? Even though I stay at hotels in CA, and my home is in WA.