#!/bin/bash

# Specify a directory with all Git repositories
REPODIR=~/Git

# Regex or fixed name (brackets need to be escaped with a backslash)
REPOUSER="\(structix\|Janek\)"

# Specify the start date, where the statistics should be gathered
STARTDATE="01 Jan 2018"

# Verbose flag
VERBOSE=false

# --------------------
# --- functions

# returns the amount of commits for one repository
function getCommits() {
        # show amount of commits of all users
        committemp=$(git rev-list --count --all --author=$REPOUSER --since="$STARTDATE" 2> /dev/null)
        echo $committemp
}

# get the amount of files, insertions, deletions by specifying parameters
function getDiffChanges() {
        local __files=$1
        local __insert=$2
        local __delete=$3

        # calculate total changes between given date and HEAD
        local extractdiff=$(git diff @{"$STARTDATE"} HEAD --shortstat 2>/dev/null)

        # set the separator to ,
        local IFS=','
        local array=( $extractdiff )
        
        # Parse the numbers
        local extf=${array[0]//[!0-9]}
        local exti=${array[1]//[!0-9]}
        local extd=${array[2]//[!0-9]}

        if [ "$VERBOSE" = true ]; then
                echo "Files: $extf, Insertions: $exti, Deletions: $extd"
        fi
        
        local f=$(( extf + __files))
        local i=$(( exti + __insert))
        local d=$(( extd + __delete))

        eval $__files="'$f'"
        eval $__insert="'$i'"
        eval $__delete="'$d'"

}

function main() {
        # Switch into the REPODIR (silently)
        pushd $REPODIR 1> /dev/null
        
        # Iterate over all subdirectories
        for dir in $REPODIR/*/
        do
                dir=${dir%*/}

                if [ "$VERBOSE" = true ]; then
                        echo ${dir##*/}
                fi
        
                # enter directory
                cd ${dir##*/}
        
                # --- RUN COMMANDS
        
                commtemp=$(getCommits)
                # Add to the total commit counter
                commitcounter=$((commitcounter + commtemp))
                # Output the commit counter of the current iteration

                if [ "$VERBOSE" = true ]; then
                        echo $commtemp
                fi
        
                getDiffChanges totalfiles totalinsertions totaldeletions
                        
                # go back
                cd ..
        done
        
        # Switch back to the original directory state (silently)
        popd 1> /dev/null
        
        
        echo "-------------------------"
        echo "Total commits since $STARTDATE: $commitcounter"
        echo "Total files changed: $totalfiles"
        echo "Total insertions: $totalinsertions"
        echo "Total deletions: $totaldeletions"
}

main