Git Monthly based Log Extractor

main.sh

#!/bin/bash

# Usage

# **NOTE** Use at own risk!
# Improved version of this script: https://gist.github.com/pdobacz/90f8e204d4b2728c8b7e916f4bc279ae

# 1. checkout the desired branch in all relevant repos first!
# 2. `cd` into a dir where you can reference your repos by relative paths
# 3. ./main.sh <author> <Month Year> <Month Year> repo1 repo2 ... >

# Example
# ./main.sh "mdtanrikulu" Dec 2019 Jan 2020 ../my-repo/
set -xe

MONTHS=('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec')

function get_index() {
  local index

  for i in "${!MONTHS[@]}"; 
  do
   if [ "${MONTHS[$i]%,}" = "$1" ]; then
       index=$i
   fi
  done
  echo $index
}

AUTHOR=$1
shift

MONTH1=$1
shift

YEAR1=$1
shift

MONTH2=$1
shift

YEAR2=$1
shift

YEAR_DIFF=$(( $YEAR2-$YEAR1 ))
#2020 - 2018 = 2
if [ $YEAR_DIFF -gt 0 ]; then
  YEAR_DIFF=$(( $YEAR_DIFF - 1))
fi
echo "YEAR DIFF $YEAR_DIFF"
MONTH_FROM=$(($(get_index $MONTH1) + 1))
#FEB = 2
MONTH_TO=$(($(get_index $MONTH2) + 1))
#MAR = 3
TOTAL_MONTH=$(( (12 - $MONTH_FROM) + $MONTH_TO + ($YEAR_DIFF * 12) ))
# 10 months from 2018 + 3 months from 2020 + 12 months form 2019 = 23
for (( i = $MONTH_FROM ; i <= $(( $TOTAL_MONTH + $MONTH_FROM )); i++ )); do
  for REPO_PATH in "$@"; do
    echo ""
    echo "Repository: $REPO_PATH"
    echo ""

    DATE1="${MONTHS[$((($i - 1) % 12))]%,} 01 00:00:00 $YEAR1 +0100"
    YEAR2=$YEAR1
    if [ $(( $i % 12 )) -eq 0 ]; then
      YEAR2=$(( $YEAR1 + 1 ))
    fi
    DATE2="${MONTHS[$(($i % 12))]%,} 01 00:00:00 $YEAR2 +0100"
    REPO_NAME="${REPO_PATH///}"
    REPO_NAME="${REPO_NAME//.}"
    git \
      -C $REPO_PATH --no-pager \
      log \
      --since="$DATE1" --until="$DATE2" \
      --author="$AUTHOR" \
      --reverse --date-order \
      --patch --raw \
      >> $(( $i - $MONTH_FROM + 1 ))-${MONTHS[$((($i - 1) % 12))]%,}-$YEAR1-$REPO_NAME.txt
    YEAR1=$YEAR2
  done
done