#! /bin/sh

set -e

root="$1"
typ="$2"

case "$typ" in
    'commits') ;;
    'changes') ;;
    '') typ='commits';;
    *)
        echo "Usage: $0 DIRECTORY [commits|changes]" >&2
        exit 1
esac

find "$root" -type d -name '.git' \
| while read -r dir
    do
        cd "$dir" || exit 1
        git log --format=%ci --numstat
    done \
| gawk '
    /^[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2} / {
        date = $1
        split(date, d, "-")
        year = d[1]
        commits[year]++
    }

    /^[0-9]+\s+[0-9]+\s+/ {
        additions = $1
        deletions = $2
        changes[year] += additions + deletions
    }

    END {
        for (year in changes) {
            print year, "commits", commits[year]
            print year, "changes", changes[year]
        }
    }' \
| awk -v type_selected="$typ" '
    {
        year = $1
        type = $2
        value = $3
        d[year, type] = value
        if (value > max[type])
            max[type] = value
    }

    END {
        for (yeartype in d) {
            split(yeartype, yt, SUBSEP)
            year = yt[1]
            type = yt[2]
            value = d[yeartype]
            if (type == type_selected) {
                printf "%s ", year
                for (i = 1; i <= (value * 100) / max[type]; i++) {
                    printf "|"
                }
                printf "\n"
            }
        }
    }' \
| sort -n -k 1