#!/usr/bin/env bash

# Default behaviour:
# Reverts all patches in patch dir, notes down the ones
# which were previously applied. Applies all from the beginning
# and reports about previously unapplied patches. If there's
# an error, reverts the last one and stops.
#
# Usage: ./patcher -b <base_path> -r -v
# -b: <base_path> is the target location relative to which patches will be applied
# -p: <patch_path> is where to take the patches from (default is geth)
# -r: reverts all and exit if this flag is present
# -c: reverts all to see what's applied, applies all previously applied back again,
# reports unapplied patches in this branch by comparing with "develop" including
# uncommitted ones and exits (with 1 if there are any)
# -v: verbose error reporting about failed patch
#
# If -b is not present, default path is as below ($basepath).

dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
# Patches path is geth unless specified.
patches=("$dir"/geth/*.patch)

# Use this branch as a reference for comparing patches
# in current branch (-c option).
baseBranch="develop"

# Base path is vendor/github.com/ethereum/go-ethereum
# unless specified.
basepath="vendor/github.com/ethereum/go-ethereum"

gitApply() {
	f=$1
	basepath=$2
	verbose=$3

	if [ $verbose -eq 1 ]; then
		if [ $basepath == "." ]; then
			git apply "$f"
		else
			git apply "$f" --directory="$basepath"
		fi
	else
		if [ $basepath == "." ]; then
			git apply "$f" > /dev/null 2>&1
		else
			git apply "$f" --directory="$basepath" > /dev/null 2>&1
		fi
	fi
}

gitApplyReverse() {
	f=$1
	basepath=$2

	if [ $basepath == "." ]; then
		git apply "$f" -R > /dev/null 2>&1
	else
		git apply "$f" --directory="$basepath" -R > /dev/null 2>&1
	fi
}

verbose=0
revert=0
compare=0
while getopts b:p:rcv opt; do
	case $opt in
	b)
		basepath=$OPTARG
    	;;
	p)
		patches=("$dir"/$OPTARG/*.patch)
    	;;
	r)
		revert=1
		;;
	c)
		compare=1
		;;
	v)
		verbose=1
		;;
    \?)
    	echo "Invalid flag: -$OPTARG" >&2
		exit
    	;;
	esac
done

if [ $revert -eq 1 ]; then
	# Reverts in reverse order and exits.
	for ((i=${#patches[@]}-1; i>=0; i--)); do
		gitApplyReverse "${patches[$i]}" "$basepath" 0
	done
	echo "Reverted all."
	exit
fi
if [ $compare -eq 1 ]; then
	applied=()
	unapplied=()
	# Finds applied patches using reverse order and
	# notes them down.
	for ((i=${#patches[@]}-1; i>=0; i--)); do
		f=${patches[$i]}
		gitApplyReverse "$f" "$basepath"
		if [ $? -eq 1 ]; then
			unapplied+=("$f")
		else
			applied+=("$f")
		fi
	done
	# Applies reverted patches back again.
	for ((i=${#applied[@]}-1; i>=0; i--)); do
		f=${applied[$i]}
		gitApply "$f" "$basepath" 0
	done
	# Sorts out new patches' paths by comparing with base branch.
	fromBaseBranch=($(git diff $baseBranch --stat | grep "\\.patch" |
		while IFS=" " read -r -a line; do
			path="$(pwd)/${line[0]}"
			echo "$path"
		done
	))
	# Also does the same with uncommitted.
	uncommitted=($(git status -u --porcelain | grep "\\.patch" |
		while IFS=" " read -r -a line; do
			length=${#line[@]}
			path="$(pwd)/${line[$((length - 1))]}"
			echo "$path"
		done
	))
	newPatches=( "${fromBaseBranch[@]}" "${uncommitted[@]}" )
	# Checks new patches and exits with 1 if there are unapplied.
	hasUnapplied=0
	for newPatch in "${newPatches[@]}"; do
		for unapp in "${unapplied[@]}"; do
			if [ "$unapp" == "$newPatch" ]; then
				echo "Recently added/changed but not applied: $unapp"
				hasUnapplied=1
				break
			fi
		done
	done
	exit $hasUnapplied
fi

applied=()

echo -en "\\n"
echo "Previously applied:"
echo "==================="
# Reverts every patch in reverse order to see
# which was previously applied.
for ((i=${#patches[@]}-1; i>=0; i--)); do
	f=${patches[$i]}
	gitApplyReverse "$f" "$basepath"
	if [ $? -eq 0 ]; then
		applied+=("$f")
		echo "$f"
	fi
done
echo "==================="
echo -en "\\n"

# Applies every patch from the beginning.
for ((i=0; i<${#patches[@]}; i++)); do
	f=${patches[$i]}
	# If not applied, report it new.
	has=0
	for patch in "${applied[@]}"; do
		if [ "$patch" == "$f" ]; then
			has=1
			break
		fi
	done
	if [ $has -eq 0 ]; then
		echo "Applying new: $f"
		echo -en "\\n"
	fi
	gitApply "$f" "$basepath" $verbose
	if [ $? -eq 1 ]; then
		echo "Failed and reverting: $f"
		gitApplyReverse "$f" "$basepath"
		echo -en "\\n"
		exit
	fi
done

echo -en "\\n"
echo "Done."