for when you forgot to update your git `user.email` for personal projects

git-update-email.zsh

  git-change-author-email() {
      if [[ $# -ne 2 ]]; then
          echo "Usage: git-change-author-email <old-email> <new-email>"
          echo "Example: git-change-author-email [email protected] [email protected]"
          return 1
      fi

      local old_email="$1"
      local new_email="$2"

      # Check if the old email exists in git history
      if ! git log --all --pretty=format:"%ae" | grep -q "^$old_email$"; then
          echo "Warning: Email '$old_email' not found in git history"
          echo "Existing author emails in history:"
          git log --all --pretty=format:"%ae" | sort -u
          return 1
      fi

      echo "Changing author email from '$old_email' to '$new_email'"
      echo "This will rewrite git history. Continue? (y/N)"
      read -q "REPLY?> "
      echo

      if [[ "$REPLY" != "y" && "$REPLY" != "Y" ]]; then
          echo "Aborted."
          return 1
      fi

      FILTER_BRANCH_SQUELCH_WARNING=1 git filter-branch --env-filter "
          if [ \"\$GIT_AUTHOR_EMAIL\" = \"$old_email\" ]; then
              export GIT_AUTHOR_EMAIL=\"$new_email\"
          fi
          if [ \"\$GIT_COMMITTER_EMAIL\" = \"$old_email\" ]; then
              export GIT_COMMITTER_EMAIL=\"$new_email\"
          fi
      " --tag-name-filter cat -- --branches --tags

      echo "Author email changed successfully!"
      echo "Updated commit history:"
      git log --oneline --pretty=format:"%h %an <%ae> %s" -5
  }