#!/bin/bash

# Specify a directory with all Git repositories
REPODIR=$(pwd)

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

# Specify the start date, where the statistics should be gathered
STARTDATE="1 year ago"

# 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'"

}

# repository size (only show in verbose mode)
function getRepoSize() {
        if [ "$VERBOSE" = true ]; then
                git count-objects -H
        fi
}

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

                getRepoSize
                        
                # go back
                cd ..
        done
        
        # Switch back to the original directory state (silently)
        popd 1> /dev/null
        
        
        echo "-------------------------"
        echo "Total commits starting from $STARTDATE: $commitcounter"
        echo "Total files changed: $totalfiles"
        echo "Total insertions: $totalinsertions"
        echo "Total deletions: $totaldeletions"
}




# display the help on the screen
print_usage() {
  echo "$0 - git statistics over multiple directories"
  echo ""
  echo "options:"
  echo "-h                  show this help page"
  echo "-u <user/regex>     set a repository username or a regex pattern (brackets etc. must be escaped with \ )"
  echo "-r <directory>      set a directory with your repositories"
  echo "-s <date>           set the date (e.g. 01 JAN 2018) where the stats should start"
  echo "-v                  show verbose output"
}

# process the arguments
while getopts 'u:r:s:vh' flag; do
  case "${flag}" in
    u) REPOUSER="${OPTARG}" ;;
    r) REPODIR="${OPTARG}" ;;
    s) STARTDATE="${OPTARG}" ;;
    v) VERBOSE=true ;;
    h) print_usage; exit 0 ;;
    *) print_usage
       exit 1 ;;
  esac
done

# Start the main function
main