#!/bin/bash

# pr-create:
#
# Create a Pull Request and send it to Linus Torvalds
#
# This script:
#
# - Craft a PR and put in an email to Linus.
# - Generate a list of patches in short-form
#
# REMOTE: git remote repo the patches are in
# TGT_BRANCH: Branch to generate the pull request against

REMOTE="xfs-linux"
TGT_BRANCH="linus/master"

#Email headers
RECIPIENT="cem@kernel.org"
SUBJECT=""

# Email tool
NEOMUTT=$(which neomutt)
MUTT_CONFIG="$HOME/.mutt/muttrc-Kernel"

#temp files
PULL_FILE=$(mktemp)
MSG_FILE=$(mktemp)

#We accept a single argument
TAG=$1

_die() {
	echo "${1}..."
	usage
	exit 1
}

usage() {
	echo "usage: pr-create <tag>"
}

check_email() {
	if [ -z $NEOMUTT ]; then
		_die "No neomutt found"
	fi

	if [ -z $MUTT_CONFIG ] || [ ! -f $MUTT_CONFIG ]; then
		_die "Please ensure MUTT_CONFIG var is properly set"
	fi
}

fixes_setup() {
	local V=$1
	local R=$2
	SUBJECT="[GIT PULL] XFS: Fixes for v$V-$R"

}

merge_setup() {
	local V=$1
	SUBJECT="[GIT PULL] XFS: New code for v$V"
}

verify_tag() {
	local T=$1

	git tag --verify $T &> /dev/null
	RES=$?

	if [ $RES -gt 0 ]; then
		echo "Tag: $T"
		_die "Verificaiton failed. Does the tag exist?"
	fi
}

generate_pull() {
	local T=$1

	git request-pull $TGT_BRANCH $REMOTE $T &> $PULL_FILE
	local res=$?

	if [ $res -gt 0 ]; then
		local ret=$(head -5 $PULL_FILE)
		echo "Unable to create pull request:"
		_die "$ret"
	fi
}

craft_message() {

	local PR=$(cat $1)
	cat << ENDL
Hello Linus,

Could you please pull patches included in the tag below?

An attempt merge against your current TOT has been successful.

Thanks,
Carlos

"${PR}"

ENDL

}

generate_email() {
	neomutt -F "${MUTT_CONFIG}" -s "$1" -i "$2" "${RECIPIENT}"
}

check_email

TYPE=$(echo $TAG | sed 's/xfs-//' | awk '{split($0, a, "-"); print a[1]}')
VER=$(echo $TAG | sed 's/xfs-//' | awk '{split($0, a, "-"); print a[2]}')
RC=$(echo $TAG | sed 's/xfs-//' | awk '{split($0, a, "-"); print a[3]}')

if [ $TYPE = "merge" ] && [ $RC ]; then
	_die "Can't have a -RC tag with a merge tag"
fi

if [ $TYPE = "fixes" ] && [ -z $RC ]; then
	_die "A Fixes tag requires a -RC version"
fi

case $TYPE in
	"fixes") fixes_setup $VER $RC;;
	"merge") merge_setup $VER;;
	*) _die "Invalid tag"
esac

verify_tag $TAG

generate_pull $TAG

MSG=$(craft_message $PULL_FILE)

echo "$MSG" > $MSG_FILE

generate_email "$SUBJECT" "$MSG_FILE"

rm $MSG_FILE
rm $PULL_FILE