dimming ac LED lamp

Hello there , i have to make a project in order to graduate ... So i've benn thinking to make a project of an automatic house and i was wandering if i could control an AC LED lamp but not simply ON/Off . i would like to use an LDR and control the power of the lamp . I've already made the circuit of this (Ac lamp , relay, arduino mega 2560 and LDR) and i want to try to dimmer the lamp. Is tha possible ???? i mean it can be easily done with PWM and a DC led ..
Thank you very much!

What is an AC LED lamp? Is it a LED bulb with integrated switching supply (AC/DC adapter) which can run with 60 to 250 V AC? No way to dim that.
There are LED bulbs with integrated adapter and sensing of input voltage. They can be dimmed, but regulating it with Arduino on the mains side is somehow not right, if then the bulb's electronics must make another regulation on the DC side.

It's not my line of expertise so my be something like AC LED exists, but diode and AC...