Calculation of the “Highest/Lowest Candle Body point” in different time period

I need functions to calculate the “Highest/Lowest Candle Body point” of different periods for my own coding, I know it is easy to code the HIGH and LOW point of a candle/period, but it is not what I want, what I want is the point of “highest/lowest candle body”. So the functions should return that number to me. Pls refer the following graphic.

I will apply this function in different time chart, including daily, 4 hour, 1 hour, 15min...etc. For 4 hour chat, period is a week, for 1 hour chat or below, period is a day, however, pls note that the “Highest candle point” and “Lowest candle point” may different in 1 hour, 30 min, 15 min, 5 min and 1 min chart. What i need are 3 functions for 5-periods, last period and current period, pls refer the following graphic.

Finally ,  Since i am a rookie of programming, i hope you can give me simple description on important line of code , and if you can  code some way for me to easier checking your code, for example, if i can put put your code to a 1m chart and run, and there is a messagebox/alert can show me the code is running and keep update the result , then i can pay you faster, and both of us win-wn.

If you have any inquiry, pls let me know.