Read git commits

gitreader.sh

#!/usr/bin/env bash

# Consider creating a soft link for the script under /usr/local/bin
# ln -s ~/path/to/script /usr/local/bin/gitreader
# And perhaps give it a better name

if [[ -z $1 || $1 == "help" ]]
then
   echo "
gitreader first      to checkout the first commit
gitreader next       to checkout the next commit
gitreader last       to checkout the last commit
gitreader commit NUM to checkout commit #NUM
gitreader progress   to view current progress
gitreader calibrate  to set progress to the current commit
                     use it after a git checkout
gitreader previously to jump back to the position bookmarked by gitreader
                     use it after interrupted by git commands like git checkout
gitreader reset      to reset gitreader for the current repository
                     use it when you want to start afresh

Enjoy!
"
else
   # get the name of this git repo
   LOC="$(git rev-parse --show-toplevel)"
   if [[ $? -ne 0 ]]; then exit; fi
   NAME="$(basename $LOC)"

   DIR="${HOME}/.config/gitreader/${NAME}"
   HST="${DIR}/hst.txt" # entire history
   PRG="${DIR}/prg.txt" # progress


   if [ !  -e "$HST" ]
   then
      mkdir -p "$DIR"
      touch "$HST"
      git log --all --reverse --pretty=%H > $HST
   fi

   if [ ! -e "$PRG" ]
   then
      git rev-list HEAD --count > $PRG
   fi

   CNT=$(wc -l $HST | awk '{print $1}')  # number of commits

   if [[ $1 == "first" ]]
   then
      echo 1 > $PRG
      head -1 $HST | xargs git checkout
      echo "Currently commit #$(cat $PRG)"
   fi

   if [[ $1 == "next" ]]
   then
      CUR="$(cat $PRG)"
      NEXT=$(($CUR + 1))

      if [[ $NEXT -gt $CNT ]]
      then
         echo "Already the latest commit"
         exit
      fi
      echo $NEXT > $PRG
      
      awk "NR==${NEXT}" $HST | xargs git checkout
      echo "Currently commit #$(cat $PRG)"
   fi

   if [[ $1 == "last" ]]
   then
      CUR="$(cat $PRG)"
      LAST=$(($CUR - 1))
      
      if [[ $LAST -lt 1 ]]
      then
         echo "Already the first commit!"
         exit
      fi
      echo $LAST > $PRG

      awk "NR==${LAST}" $HST | xargs git checkout
      echo "Currently commit #$(cat $PRG)"
   fi

   if [[ $1 == "progress" ]]
   then
      echo "Currently $(cat $PRG)/$CNT"
   fi

   if [[ $1 == "calibrate" ]]
   then
      git rev-list HEAD --count > $PRG
   fi

   if [[ $1 == "previously" ]]
   then
      CUR="$(cat $PRG)"
      awk "NR==${CUR}" $HST | xargs git checkout
      echo "Currently commit #$(cat $PRG)"
   fi
      

   if [[ $1 == "commit" ]]
   then

      if [[ -z $2 ]]
      then
         echo "Usage: gitreader commit NUM"
         exit
      fi

      awk "NR==$2" $HST | xargs git checkout
      echo $2 > $PRG
      echo "Currently commit #$(cat $PRG)"
   fi

   if [[ $1 == "reset" ]]
   then
      rm $HST $PRG
   fi
fi