With analog:

an LR to generate 0..90
an RC to generate 0..-90
With an operational you can do "Negative resistors" then combinating all you can do the 360.


Without* analog:
*(With digital and analog)

Convert your input ac in to dc. With linear source, swiching...
Then make an "Ondulator" (In Spanish "Ondulador"). Is an oscillator with you wanted waveform (senoidal, scuare...) and your desired frecuency & phase.
You can do it with PWM or DAC (I don´t recommend for high power).
For controlling the parameters of your generated wave you can use a pot trought an analog input, a keboard, serial...

Regards.