#!/bin/sh

# AdGuard Home Build Script
#
# The commentary in this file is written with the assumption that the reader
# only has superficial knowledge of the POSIX shell language and alike.
# Experienced readers may find it overly verbose.

# The default verbosity level is 0.  Show every command that is run and every
# package that is processed if the caller requested verbosity level greater than
# 0.  Also show subcommands if the requested verbosity level is greater than 1.
# Otherwise, do nothing.
verbose="${VERBOSE:-0}"
readonly verbose

if [ "$verbose" -gt '1' ]
then
	env
	set -x
	v_flags='-v'
	x_flags='-x'
elif [ "$verbose" -gt '0' ]
then
	set -x
	v_flags='-v'
	x_flags=''
else
	set +x
	v_flags=''
	x_flags=''
fi
readonly x_flags v_flags

# Exit the script if a pipeline fails (-e), prevent accidental filename
# expansion (-f), and consider undefined variables as errors (-u).
set -e -f -u

# Allow users to override the go command from environment.  For example, to
# build two releases with two different Go versions and test the difference.
go="${GO:-go}"
readonly go

# Require the channel to be set and validate the value.
channel="$CHANNEL"
readonly channel

case "$channel"
in
('development'|'edge'|'beta'|'release')
	# All is well, go on.
	;;
(*)
	echo "invalid channel '$channel', supported values are\
		'development', 'edge', 'beta', and 'release'" 1>&2
	exit 1
	;;
esac

# Require the version to be set.
#
# TODO(a.garipov): Additional validation?
version="$VERSION"
readonly version

# Set date and time of the current build unless already set.
buildtime="${BUILD_TIME:-$( date -u +%FT%TZ%z )}"
readonly buildtime

# Set the linker flags accordingly: set the release channel and the current
# version as well as goarm and gomips variable values, if the variables are set
# and are not empty.
version_pkg='github.com/AdguardTeam/AdGuardHome/internal/version'
readonly version_pkg

ldflags="-s -w"
ldflags="${ldflags} -X ${version_pkg}.version=${version}"
ldflags="${ldflags} -X ${version_pkg}.channel=${channel}"
ldflags="${ldflags} -X ${version_pkg}.buildtime=${buildtime}"
if [ "${GOARM:-}" != '' ]
then
	ldflags="${ldflags} -X ${version_pkg}.goarm=${GOARM}"
elif [ "${GOMIPS:-}" != '' ]
then
	ldflags="${ldflags} -X ${version_pkg}.gomips=${GOMIPS}"
fi

# Allow users to limit the build's parallelism.
parallelism="${PARALLELISM:-}"
readonly parallelism

if [ "${parallelism}" != '' ]
then
	par_flags="-p ${parallelism}"
else
	par_flags=''
fi
readonly par_flags

# Allow users to specify a different output name.
out="${OUT:-}"
readonly out

if [ "$out" != '' ]
then
	out_flags="-o ${out}"
else
	out_flags=''
fi
readonly out_flags

# Allow users to enable the race detector.  Unfortunately, that means that cgo
# must be enabled.
if [ "${RACE:-0}" -eq '0' ]
then
	cgo_enabled='0'
	race_flags=''
else
	cgo_enabled='1'
	race_flags='--race'
fi
readonly cgo_enabled race_flags

CGO_ENABLED="$cgo_enabled"
GO111MODULE='on'
export CGO_ENABLED GO111MODULE

build_flags="${BUILD_FLAGS:-$race_flags --trimpath $out_flags $par_flags $v_flags $x_flags}"
readonly build_flags

# Don't use quotes with flag variables to get word splitting.
"$go" generate $v_flags $x_flags ./main.go

# Don't use quotes with flag variables to get word splitting.
"$go" build --ldflags "$ldflags" $build_flags