Alternative to Fermat's Principle for a Moving Mirror?

Addendum Sept. 7, 2022. References 2 and 3 are: 2. https://en.wikipedia.org/wiki/Snell%27s_law 3 Gjurhcinovskci, A. The Doppler Effect from a Uniformly Moving Mirror (2004 or later) https://arxiv.org/pdf/physics/0409014.pdf In (1) the problem of a light reflecting from a mirror moving at constant v in the negative y direction is considered. The incident ray makes an angle AA with the y axis and the reflected, an angle BB with the y axis. Fermat’s principle is used i.e. the minimization of time moving from point A, reflecting from the moving mirror and moving to point B (with A and B being at the same y value). A relationship is found linking cos(BB) to cos(AA). In this note we try to argue that the same relationship follows from considering a constant horizontal velocity H along the x axis with relative velocities of light and the mirror (for the incident and reflected cases) representing adjacent projections of H i.e. H serves as a hypotenuse