arduino with gsm sheild

hello
I am working on project in which arduino,gsm sheild and four sensors are used.
this project is supposed to take supply from street light.some queries

1.How to convert three phase supply from street light to DC to power arduino ?
2.What will be alternative to it in morning because street light will be off ?

thankyou

1.How to convert three phase supply from street light to DC to power arduino ?

What country is this? What is the 3-phase voltage? Try to find a simple power supply that operates from the voltage.

2.What will be alternative to it in morning because street light will be off ?

Charge a small battery from the same power supply. Run the Arduino from that battery all the time.

thankyou for reply
I am from india.
It is mandatory to use supply from street lights only which is powered by three phase ac voltage of 230v.
If i use battery,it need to be charge at night and supply power in morning.How would I switch it for supplying power at morning and charge at night?