changelog.sh

#!/bin/bash
set -eu

# Define OUTPUT_FILE variable as CHANGELOG.md, which is the final changelog file.
OUTPUT_FILE=CHANGELOG.md

# If a CHANGELOG.md file is not present in the current directory, then it creates an empty one.
if [ ! -f $OUTPUT_FILE ] 
then
  touch $OUTPUT_FILE
  echo "Created CHANGELOG.md"
fi

# Define TEMP_FILE variable as TEMP.md.
# This will be used as a temporary file that will hold only the latest changelog updates, in order to paste them at the beginning of the existing CHANGELOG.md file.
TEMP_FILE=TEMP.md

# Get the url of the git repository and save it to REPO_TYPE variable in order to use it for configuring the type of the git repository (e.g. Gitblit, GitHub, etc.)
REPO_TYPE=$(git ls-remote --get-url)

# Check if the git repository is in Gitblit or in GitHub
if [[ "$REPO_TYPE" =~ .*"git.eurodyn.com".* ]];
then
  TAG1=`git tag --sort=taggerdate | tail -1` # Get the latest git tag version number
  TAG2_2=`git tag --sort=taggerdate | tail -2` # Get the last two tag version numbers
  TAG2=`echo $TAG2_2 | cut -d' ' -f1` # Keep only the antecedent git tag version number

  URL_REMOTE=`git config --get remote.origin.url` # Get the url of the remote git repository and save it to URL_REMOTE variable
  URL_GIT_ENDING=${URL_REMOTE::-4} # Trim the last 4 characters (i.e. '.git') of the remote url 
  URL_CREDENTIALS=$(echo "$URL_GIT_ENDING" | sed -e 's/\(:\/\/\).*\(@\)/\1\2/') # Trim the user's credentials from the remote url
  URL=`echo "${URL_CREDENTIALS//@}"` # Trim the '@' character and finally save the 'clean' url to URL variable
  COMPARE_URL=`echo "$URL" | sed -r 's|/r/+|/compare/|g'` # Replace '/r/' with '/compare/' and save to COMPARE_URL variable. This url will be used in order to compare the differences between the last two tags.
  CONCAT_URL="$COMPARE_URL/$TAG2..$TAG1" # Concat '/' character and the two last tag version numbers to COMPARE_URL variable, in order to get the hyperlink that displays the comparison of these two tags.
  COMMIT_URL=`echo "$URL" | sed -r 's|/r/+|/commit/|g'` # Replace '/r/' with '/commit/' and save to COMMIT_URL variable. This url will be used in order to create a hyperlink to a specific commit in gitblit.

elif [[ "$REPO_TYPE" =~ .*"github.com".* ]];
then
  TAG1=`git tag --sort=taggerdate | tail -1` # Get the latest git tag version number
  TAG2_2=`git tag --sort=taggerdate | tail -2` # Get the last two tag version numbers
  TAG2=`echo $TAG2_2 | cut -d' ' -f1` # Keep only the antecedent git tag version number

  URL_REMOTE=`git config --get remote.origin.url` # Get the url of the remote git repository and save it to URL_REMOTE variable
  URL_GIT_ENDING=${URL_REMOTE::-4} # Trim the last 4 characters (i.e. '.git') of the remote url
  URL_CREDENTIALS=$(echo "$URL_GIT_ENDING" | sed -e 's/\(:\/\/\).*\(@\)/\1\2/') # Trim the user's credentials from the remote url
  URL=`echo "${URL_CREDENTIALS//@}"` # Trim the '@' character and finally save the 'clean' url to URL variable  
  CONCAT_URL="$URL/compare/$TAG2...$TAG1"  # Concat '/' character and the two last tag version numbers to COMPARE_URL variable, in order to get the hyperlink that displays the comparison of these two tags.
  COMMIT_URL="$URL/commit" # Concat '/commit' to CONCAT_URL variable. This url will be used in order to create a hyperlink to a specific commit in github.

fi

# Retrieve the last git tag and store it in TAG variable.
TAG=`git tag --sort=taggerdate | tail -1`

# Retrieve the date the git tag was generated at, and store it in DATE variable.
DATE=`git log -1 --format=%ci | awk '{print $1; }'`

# Print the release version along with its date as a heading, in the temporary changelog file.
echo "# [RELEASE ${TAG}]($CONCAT_URL) - ${DATE}" >> $TEMP_FILE

# Retrieve the commits that occured between the latest tag and the previous one in chronological order, and store them in GIT_LOG variable. 
# Commits are separated using the + character.
GIT_LOG=`git log --reverse --pretty="+%s (%h)" $(git tag --sort=-taggerdate | head -2)...$(git tag --sort=-taggerdate | head -1)`

# If GIT_LOG variable is empty, i.e. the only tag in the repository is the last one, then retrieve only the commits that occured before the last tag.
# This convention will be triggered e.g. during the first version release of a project.
if [ -z "$GIT_LOG" ]
then
  GIT_LOG=`git log --reverse --pretty="+%s (%h)" $(git tag --sort=-taggerdate | head -1)`
fi

# Define arrays that will be filled with each commit category.
fix=() #A bug Fix
feature=() # A new feature
build=() # Changes that affect the build system or external dependencies
chore=() # Other changes that don't modify src or test files
ci=() # Changes to CI configuration files and scripts
doc=() # Documentation only changes
style=() # Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
refactor=() # A code change that neither fixes a bug nor adds a feature
perf=() # A code change that improves performance
test=() # Adding missing tests or correcting existing tests

# Split commits uppon + character and save to arrays depending on their message
IFS=+ commits=($GIT_LOG)

for i in "${commits[@]}"; do
  if [[ ${i,,} = feat:* ]] || [[ ${i,,} = feat!:* ]]
  then
    feature+=($i)
  elif [[ ${i,,} = fix:* ]] || [[ ${i,,} = fix!:* ]] 
  then
    fix+=($i)
  elif [[ ${i,,} = build:* ]] || [[ ${i,,} = build!:* ]]   
  then
    build+=($i)
  elif [[ ${i,,} = chore:* ]] || [[ ${i,,} = chore!:* ]]   
  then
    chore+=($i)    
  elif [[ ${i,,} = ci:* ]] || [[ ${i,,} = ci!:* ]]   
  then
    ci+=($i)     
  elif [[ ${i,,} = doc:* ]] || [[ ${i,,} = doc!:* ]]   
  then
    doc+=($i) 
  elif [[ ${i,,} = style:* ]] || [[ ${i,,} = style!:* ]]   
  then
    style+=($i) 
  elif [[ ${i,,} = refactor:* ]] || [[ ${i,,} = refactor!:* ]]   
  then
    refactor+=($i) 
  elif [[ ${i,,} = perf:* ]] || [[ ${i,,} = perf!:* ]]   
  then
    perf+=($i) 
  elif [[ ${i,,} = test:* ]] || [[ ${i,,} = test!:* ]]   
  then
    test+=($i) 
  elif [[ -z "${i-}"  ]] || [[ "${i-}" = $'\n' ]]
  then
    :                      
  fi

done

# Parse each array and print their contents (commit messages) under the corresponding category (e.g. Fixes, Features, etc.) in the temporary changelog file. 
# If no commits occured for a specific category, then it prints nothing.
if [ ${#feature[@]} -eq 0 ]; then
  :
else
  echo '### ✨ Features' >> $TEMP_FILE
  for i in "${feature[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done
fi

if [ ${#fix[@]} -eq 0 ]; then
  :
else
  echo '### 🐛 Fixes' >> $TEMP_FILE
  for i in "${fix[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done  
fi

if [ ${#build[@]} -eq 0 ]; then
  :
else
  echo '### 🛠 Builds' >> $TEMP_FILE
  for i in "${build[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#chore[@]} -eq 0 ]; then
  :
else
  echo '### ♻️ Chores' >> $TEMP_FILE
  for i in "${chore[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#ci[@]} -eq 0 ]; then
  :
else
  echo '### ⚙️ Continuous Integrations' >> $TEMP_FILE
  for i in "${ci[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#doc[@]} -eq 0 ]; then
  :
else
  echo '### 📚 Documentation' >> $TEMP_FILE
  for i in "${doc[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#style[@]} -eq 0 ]; then
  :
else
  echo '### 💎 Styles' >> $TEMP_FILE
  for i in "${style[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#refactor[@]} -eq 0 ]; then
  :
else
  echo '### 📦 Code Refactoring' >> $TEMP_FILE
  for i in "${refactor[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#perf[@]} -eq 0 ]; then
  :
else
  echo '### 🚀 Performance Improvements' >> $TEMP_FILE
  for i in "${perf[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

if [ ${#test[@]} -eq 0 ]; then
  :
else
  echo '### 🚨 Tests' >> $TEMP_FILE
  for i in "${test[@]}"
  do
    LINK=$COMMIT_URL/$(git rev-parse $(echo $i | cut -d "(" -f2 | cut -d ")" -f1))
    echo "- [$i]($LINK)" >> $TEMP_FILE
  done   
fi

# Print the contents of TEMP_FILE and OUTPUT_FILE inside a third tmp file and then move tmp file to the final OUTPUT_FILE.
# This way, the latest changelog updates will be appended at the begging of the file and not at the end.
cat $TEMP_FILE $OUTPUT_FILE > tmp && mv tmp $OUTPUT_FILE

# Delete the temporary changelog file
rm $TEMP_FILE