Hair is dead so nothing can be permanently repaired. You can patch up some of the damage with certain ingredients in products - hydrolysed proteins, ceramides, 18-MEA, panthenol, cationic surfactants and fatty alcohols - but the effect is always temporary.
The Natural Haven blog and the 'curl chemist' articles here on NC are all worth reading when you have time
Porosity and Curly Hair
Komaza Care HAIR ANALYSIS Service - Rave! - Long Hair Care Forum
Mineral Oil Versus Coconut Oil: Which is better?
THE NATURAL HAVEN: Do you need to deep condition your hair? Can you over-condition hair?
More geeky science
Chemical and Physical Behavior of Human Hair - Clarence R. Robbins - Google Books
2a-2c, medium texture, porous/ colour treated. Three years CG, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
CO-wash: Inecto coconut
Treatments: Komaza Matani, coconut oil, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume, Inecto argan
Styler: Umberto Giannini jelly, Boots Essentials gel
Experimenting with: going back to basics