replace-default-with-profile.zsh

#!/bin/zsh

function replace-default-with-profile {
    #reads through an aws credentials file,
    #takes the contents of the profile give in $1
    #and copies those credentials into the default profile
    declare profileName=$1
    declare fileName=${2:-~/.aws/credentials}

    declare profileBody=""
    declare currentProfile=""

    #read through file to extract profile data to copy
    declare firstLine=0
    while read -r line; do
        [[ -n $BASH_VERSION ]] && [[ $line =~ \[(.*)\] ]] && currentProfile="${BASH_REMATCH[1]}" && firstLine=1 && continue
        [[ -n $ZSH_VERSION ]]  && [[ $line =~ '\[(.*)\]' ]] && currentProfile="${match[1]}" && firstLine=1 && continue

        [[ $firstLine == 1 ]] && [[ $currentProfile == $profileName ]] && profileBody="${line}"
        [[ $firstLine == 0 ]] && [[ $currentProfile == $profileName ]] && profileBody="${profileBody}"$'\n'"${line}"
        firstLine=0
    done < "$fileName"

    #replace default profile with lines found in first pass
    declare firstLine=1
    declare newfileContents=''
    while read -r line; do
        declare isHeader=0
        [[ -n $BASH_VERSION ]] && [[ $line =~ \[(.*)\] ]] && currentProfile="${BASH_REMATCH[1]}" && isHeader=1
        [[ -n $ZSH_VERSION ]]  && [[ $line =~ '\[(.*)\]' ]] && currentProfile="${match[1]}" && isHeader=1

        [[ $isHeader == 1 ]] && [[ $firstLine == 1 ]] && newfileContents="${line}"
        [[ $isHeader == 1 ]] && [[ $firstLine == 0 ]] && newfileContents="${newfileContents}"$'\n'"${line}"

        [[ $isHeader == 1 ]] && [[ $currentProfile == 'default' ]] && newfileContents="${newfileContents}"$'\n'"${profileBody}"$'\n'
        [[ $isHeader == 0 ]] && [[ $currentProfile != 'default' ]] && newfileContents="${newfileContents}"$'\n'"${line}"
        firstLine=0
    done < "$fileName"

    echo "$newfileContents" > "$fileName"
}