#!/bin/bash
# This scipt lints go files for common errors.
#
# Its runs gofmt and go vet, and optionally golint and
# gocyclo, if they are installed.
#
# With no arguments, it lints the current files staged
# for git commit.  Or you can pass it explicit filenames
# (or directories) and it will lint them.
#
# To use this script automatically, run:
#   ln -s ../../bin/lint .git/hooks/pre-commit

set -eu

EXIT_CODE=0

function lint_go {
	filename=$1

	if [ "$(gofmt -d $filename)" != "" ]; then
		EXIT_CODE=1
		echo "$filename: run gofmt -w $filename!"
	fi

	go tool vet ${filename} || EXIT_CODE=$?

	# golint is completely optional.  If you don't like it
	# don't have it installed.
	if [ "$(which golint)" != "" ]; then
		# golint doesn't set an exit code it seems
		lintoutput=$(golint $filename)
		if [ "$lintoutput" != "" ]; then
			echo "$lintoutput"
			EXIT_CODE=1
		fi
	fi

	# gocyclo is completely optional.  If you don't like it
	# don't have it installed.  Also never blocks a commit,
	# it just warns.
	if [ "$(which gocyclo)" != "" ]; then
		gocyclo -over 25 ${filename} | while read line; do
			echo ${filename}: higher than 25 cyclomatic complexity - ${line}
		done
	fi
}

function lint {
	filename=$1
	ext=${filename##*\.}

	# If this is a directory, then lint the files in it
	if [[ -d ${filename} ]]; then
		for filename in $(find ${filename} -type f); do
			lint ${filename}
		done
		return
	fi

	# Don't lint this script
	if [ "${filename}" == "bin/lint" ]; then
		return
	fi

	case "$ext" in
		go) lint_go $filename
		;;
	esac
}

if [ $# -gt 0 ]; then
	for filename in $@; do
		lint ${filename}
	done
else
	for filename in $(git diff --cached --name-only); do
		if [ ! -e "${filename}" ]; then
			continue
		fi

		lint ${filename}
	done
fi

exit $EXIT_CODE