#!/usr/bin/env bash


cd "$(git root)" || { echo "Can't cd to top level directory";exit 1; }

SUMMARY_BY_LINE=
DEDUP_BY_EMAIL=
MERGES_ARG=
OUTPUT_STYLE=
for arg in "$@"; do
    case "$arg" in
        --line)
            SUMMARY_BY_LINE=1
            ;;
        --dedup-by-email)
            DEDUP_BY_EMAIL=1
            ;;
        --no-merges)
            MERGES_ARG="--no-merges"
            ;;
        --output-style)
            OUTPUT_STYLE="$2"
            shift
            ;;
        -*)
            >&2 echo "unknown argument $arg found"
            exit 1
            ;;
        *)
            # set the argument back
            set -- "$@" "$arg"
            ;;
    esac

    shift
done

if [ -n "$DEDUP_BY_EMAIL" ] && [ -n "$SUMMARY_BY_LINE" ]; then
    >&2 echo "--dedup-by-email used with --line is not supported"
    exit 1
fi

if [ -n "$MERGES_ARG" ] && [ -n "$SUMMARY_BY_LINE" ]; then
    >&2 echo "--no-merges used with --line is not supported"
    exit 1
fi


if [ -n "$SUMMARY_BY_LINE" ]; then
  paths=( "$@" )
else
  commit="HEAD"
  [ $# -ne 0 ] && commit=$*
fi
project=${PWD##*/}

#
# get date for the given <commit>
#
date() {
  # the $1 can be empty
  # shellcheck disable=SC2086
  git log $MERGES_ARG --pretty='format: %ai' $1 | cut -d ' ' -f 2
}

#
# get active days for the given <commit>
#
active_days() {
  # shellcheck disable=SC2086
  date $1 | sort -r | uniq | awk '
    { sum += 1 }
    END { print sum }
  '
}

#
# get the commit total
#
commit_count() {
  # shellcheck disable=SC2086
  git log $MERGES_ARG --oneline $commit | wc -l | tr -d ' '
}

#
# total file count
#
file_count() {
  git ls-files | wc -l | tr -d ' '
}

#
# remove duplicate authors who belong to the same email address
#
dedup_by_email() {
    # in:
    # 27  luo zexuan <LuoZexuan@xxx.com>
    #  7  罗泽轩 <luozexuan@xxx.com>
    # out:
    # 34 luo zexuan
    LC_ALL=C awk '
    {
        sum += $1
        last_field = tolower($NF)
        if (last_field in emails) {
            emails[last_field] += $1
        } else {
            email = last_field
            emails[email] = $1
            # set commits/email to empty
            $1=$NF=""
            sub(/^[[:space:]]+/, "", $0)
            sub(/[[:space:]]+$/, "", $0)
            name = $0
            if (name in names) {
                # when the same name is associated with existed email,
                # merge the previous email into the later one.
                emails[email] += emails[names[name]]
                emails[names[name]] = 0
            }
            names[name] = email
        }
    }
    END {
        for (name in names) {
            email = names[name]
            printf "%6d\t%s\n", emails[email], name
        }
    }' | sort -rn -k 1
}

#
# list authors
#
format_authors() {
  # a rare unicode character is used as separator to avoid conflicting with
  # author name. However, Linux column utility will escape tab if separator
  # specified, so we do unesaping after it.
  LC_ALL=C awk '
  { args[NR] = $0; sum += $0 }
  END {
    for (i = 1; i <= NR; ++i) {
      printf "%s♪%2.1f%%\n", args[i], 100 * args[i] / sum
    }
  }
  ' | column -t -s♪ | sed "s/\\\x09/\t/g"
}

#
# fetch repository age from oldest commit
#
repository_age() {
  git log --reverse --pretty=oneline --format="%ar" | head -n 1 | LC_ALL=C sed 's/ago//'
}

#
# fetch repository age of the latest commit
#
last_active() {
  git log --pretty=oneline --format="%ar" -n 1
}

#
# list the last modified author for each line
#
single_file() {
  while read -r data
  do
    if [[ $(file "$data") = *text* ]]; then
      git blame --line-porcelain "$data" 2>/dev/null | grep "^author " | LC_ALL=C sed -n 's/^author //p';
    fi
  done
}

current_branch_name() {
  git rev-parse --abbrev-ref HEAD
}

#
# list the author for all file
#
lines() {
  git ls-files -- "$@" | single_file
}

#
# get the number of the lines
#
line_count() {
  lines "$@" | wc -l
}

uncommitted_changes_count() {
  git status --porcelain | wc -l
}


COLUMN_CMD_DELIMTER="¬" # Hopefully, this symbol is not used in branch names... I use it as a seperator for columns
SP="$COLUMN_CMD_DELIMTER|"

print_summary_by_line() {
  if [ "$OUTPUT_STYLE" == "tabular" ]; then
    tabular_headers="# Repo $SP Lines"
    echo -e "$tabular_headers\n$project $SP $(line_count "${paths[@]}")" | column -t -s "$COLUMN_CMD_DELIMTER"
  elif [ "$OUTPUT_STYLE" == "oneline" ]; then
    echo "$project / lines: $(line_count "${paths[@]}")"
  elif [ -n "$SUMMARY_BY_LINE" ]; then
    echo
    echo " project     : $project"
    echo " lines       : $(line_count "${paths[@]}")"
    echo " authors     :"
    lines "${paths[@]}" | sort | uniq -c | sort -rn | format_authors
  fi
}

print_summary() {
  if [ "$OUTPUT_STYLE" == "tabular" ]; then
    tabular_headers="# Repo $SP Age $SP Last active $SP Active on $SP Commits $SP Uncommitted $SP Branch"
    echo -e "$tabular_headers\n$project $SP $(repository_age) $SP $(last_active) $SP $(active_days $commit) days $SP $(commit_count $commit) $SP $(uncommitted_changes_count) $SP $(current_branch_name)" | column -t -s "$COLUMN_CMD_DELIMTER"
  elif [ "$OUTPUT_STYLE" == "oneline" ]; then
    echo "$project / age: $(repository_age) / last active: $(last_active) / active on $(active_days $commit) days / commits: $(commit_count $commit) / uncommitted: $(uncommitted_changes_count) / branch: $(current_branch_name)"
  else
    echo
    echo " project     : $project"
    echo " repo age    : $(repository_age)"
    echo " branch:     : $(current_branch_name)"
    echo " last active : $(last_active)"
    # shellcheck disable=SC2086
    echo " active on   : $(active_days $commit) days"
    # shellcheck disable=SC2086
    echo " commits     : $(commit_count $commit)"

    # The file count doesn't support passing a git ref so ignore it if a ref is given
    if [ "$commit" == "HEAD" ]; then
      echo " files       : $(file_count)"
    fi
    echo " uncommitted : $(uncommitted_changes_count)"
    echo " authors     : "
    if [ -n "$DEDUP_BY_EMAIL" ]; then
      # the $commit can be empty
      # shellcheck disable=SC2086
      git shortlog $MERGES_ARG -n -s -e $commit | dedup_by_email | format_authors
    else
      # shellcheck disable=SC2086
      git shortlog $MERGES_ARG -n -s $commit | format_authors
    fi
  fi
}

if [ -n "$SUMMARY_BY_LINE" ]; then
  print_summary_by_line
else
  print_summary
fi