prepare-commit-msg

#!/bin/bash

# Auto-wraps the commit message body to the length allowed by gitlint.
# Does not special-case the commit title because it cannot be fixed automatically;
# wrapping is not allowed there. If needed, gitlint's `commit-msg` hook will
# give us a chance to edit interactively.
#
# This runs after the commit message has been entered (even if with "git commit -m ...")
# but before gitlint runs in the commit-msg hook.

COMMIT_MSG_FILE=$1
_COMMIT_SOURCE=$2
_SHA1=$3

WIDTH=80

# Re-wraps file $1 to $WIDTH characters per line, using prettier, in-place.
rewrap() {
  # Suppress the output of prettier, as it's overly verbose. Show only on failure.
  prettier --no-config --no-editorconfig --prose-wrap always --print-width "$WIDTH" --write "$1" >/tmp/prettier.out \
    || { cat /tmp/prettier.out; exit 1; }
}

# If gitlint is already happy, do nothing
gitlint <"$COMMIT_MSG_FILE" >/tmp/gitlint.out 2>&1 && exit 0

# If this is a fixup commit, do nothing
<"$1" head -n1 | grep -q 'fixup!' && exit 0

echo "Rewrapping \"$(<"$COMMIT_MSG_FILE" head -n1 | cut -c-50)[...]\" to $WIDTH chars per line"