Extracting info from blocks inside text file

Question

I have a text file which has blocks like

dir1/dir2/dir3/name_run_number1:
line1_run_number1_part1
line2_run_number1_part2
line3_run_number1_part3...

Each block is separated with a blank line and there is the ":" in the "header" of each one while each block has a unique "number1" after "run_" suffix which is also present in the lines inside the block

What I want to do is for each block, extract the "number1" as shown in the first line and then for the lines below count from 1-20 and give a message if a "partX" line is missing. Any bash or python would be fine

Thanks

Answer 1

Based on given example of input|output decision can be:

awk -F_ '
    /:/ {
        for (i=0;i<20;i++) {
            getline
            sub("chunk","",$7)
            while ( i != +$7 ) {
                print "for " $2 " and " $5"_"$6 " you are missing chunk " i
                i++
                if (i>20)
                    break
                }
            }
    }' text.file