Support force on statically indeterminate beam

We wish to determine the equation for the support force and for the slope (angle) at point A for the beam shown in the figure to the right. Consider as given the force P, the lengths a and L, the modulus of Elasticity E, and the central moment of inertia of the beam's cross-section. Points A and B are at the same level (y=0) and the beam comes out of the wall at point B horizontally (dy/dx=0).