#!/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.

# This comment is used to simplify checking local copies of the script.  Bump
# this number every time a significant change is made to this script.
#
# AdGuard-Project-Version: 1

# 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 [ "$verbose" -gt '1' ]
then
	env
	set -x
	v_flags='-v=1'
	x_flags='-x=1'
elif [ "$verbose" -gt '0' ]
then
	set -x
	v_flags='-v=1'
	x_flags='-x=0'
else
	set +x
	v_flags='-v=0'
	x_flags='-x=0'
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:?please set CHANNEL}"
readonly channel

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

# Check VERSION against the default value from the Makefile.  If it is that, use
# the version calculation script.
version="${VERSION:-}"
if [ "$version" = 'v0.0.0' ] || [ "$version" = '' ]
then
	version="$( sh ./scripts/make/version.sh )"
fi
readonly version

# Set date and time of the latest commit unless already set.
committime="${SOURCE_DATE_EPOCH:-$( git log -1 --pretty=%ct )}"
readonly committime

# 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 ${version_pkg}.committime=${committime}"
if [ "${GOARM:-}" != '' ]
then
	ldflags="${ldflags} -X ${version_pkg}.goarm=${GOARM}"
elif [ "${GOMIPS:-}" != '' ]
then
	ldflags="${ldflags} -X ${version_pkg}.gomips=${GOMIPS}"
fi
readonly ldflags

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

# Use GOFLAGS for -p, because -p=0 simply disables the build instead of leaving
# the default value.
if [ "${parallelism}" != '' ]
then
        GOFLAGS="${GOFLAGS:-} -p=${parallelism}"
fi
readonly GOFLAGS
export GOFLAGS

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

o_flags="-o=${out}"
readonly o_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='--race=0'
else
	CGO_ENABLED='1'
	race_flags='--race=1'
fi
readonly CGO_ENABLED race_flags
export CGO_ENABLED

GO111MODULE='on'
export GO111MODULE

# Build the new binary if requested.
if [ "${NEXTAPI:-0}" -eq '0' ]
then
	tags_flags='--tags='
else
	tags_flags='--tags=next'
fi
readonly tags_flags

if [ "$verbose" -gt '0' ]
then
	"$go" env
fi

"$go" build\
	--ldflags="$ldflags"\
	"$race_flags"\
	"$tags_flags"\
	--trimpath\
	"$o_flags"\
	"$v_flags"\
	"$x_flags"