merge_log

#!/bin/bash

# example usage:
# files=($(find . -name "*PATTERN.log"))
# for file in  ${files[@]}; do
# 	if [[ -f "second/$file" ]]; then
#		./merge_logs "$file" "second/$file";
#	fi;
# done;


first_log="$1"
second_log="$2"
merged_log="$3"
if [[ -z "$merged_log" ]]; then
	mkdir -p merged
	merged_log="merged/${second_log##*/}"
fi

mapfile first < "$first_log"
mapfile second < "$second_log"

f_lines=${#first[@]}
s_lines=${#second[@]}


first_lineno=0
second_lineno=0

printf "first: \"%s\", lines: %s\n" "$first_log" "$f_lines"
printf "second: \"%s\", lines: %s\n" "$second_log" "$s_lines"

while [[ $first_lineno -lt $f_lines ]]; do

	f_line="${first[$first_lineno]}"
	s_line="${second[$second_lineno]}"
	f_compare="${f_line:10}"
	s_compare="${s_line:10}"

	if [[ "$f_compare" == "$s_compare" ]]; then
		printf "first (%s) and second (%s) match!\n" "$first_lineno" "$second_lineno"
		printf "=>  first: %s" "$f_line"
		printf "=> second: %s" "$s_line"

		# found first matching, ensure the match goes to the end of file
		printf "\nchecking if this is a match to the end of the first file:\n"

		f_lineno=$first_lineno
		s_lineno=$second_lineno
		while [[ f_lineno -lt f_lines ]]; do
			f_line="${first[$f_lineno]}"
			s_line="${second[$s_lineno]}"
			f_compare="${f_line:10}"
			s_compare="${s_line:10}"

			printf "  first: %s" "$f_line"
			printf " second: %s" "$s_line"
			if [[ "$f_compare" == "$s_compare" ]]; then
				printf " => first (%s) and second (%s) match!\n" "$f_lineno" "$s_lineno"
			else
				printf " => first (%s) and second (%s) DONT match!\n" "$f_lineno" "$s_lineno"

				# resume the first loop as this is just a stray match before the end.
				second_lineno=0
				continue 2
			fi
	
			((f_lineno++))
			((s_lineno++))
		done

		# loop completed without errors, end
		break
	fi
	((first_lineno++))
done

end_of_first=$first_lineno

((first_lineno++))
((second_lineno++))

if [[ end_of_first -eq f_lines ]]; then
	printf "files don't have common lines, clamping them together\n"
fi

# print the resulting file
f_lineno=0
while [[ f_lineno -lt end_of_first ]]; do
	printf "%s" "${first[$f_lineno]}" >> "$merged_log"
	(( f_lineno++ ))
done

for line in "${second[@]}"; do
	printf "%s" "$line" >> "$merged_log"
done

printf "Successfully merged\n\n"