#! /usr/bin/env bash

# Tool to build go programs in this repo
#
# - it tacks on a version number for use by the individual tools
# - it supports git and mercurial version#
#
# NB:
#   o the attempt at decoding dirty repo state for mercurial is
#     borked. It doesn't know about untracked files
#
# (c) 2016 Sudhi Herle
#
# License: GPLv2
#
Progs="src:sigtool"

# Relative path to protobuf sources
# e.g. src/foo/a.proto
Protobufs="internal/pb/hdr.proto"

#set -x

# -- DO NOT CHANGE ANYTHING AFTER THIS --

Z=`basename $0`
PWD=`pwd`

Static=0
Dryrun=0
Prodver=""
Repover=""
Verbose=0
Go=`which go`
Bindir=$PWD/bin

die() {
    echo "$Z: $@" 1>&2
    exit 0
}

warn() {
    echo "$Z: $@" 1>&2
}

case $BASH_VERSION in
    4.*|5.*) ;;

    *) die "I need bash 4.x to run!"
        ;;
esac

getvcs_version() {
    local rev=
    local prodv=
    local git=`which git`
    local hg=`which hg`

    if [ -n "$git" ]; then
        local xrev=$(git describe --always --dirty --long --abbrev=12) || exit 1
        rev="git:$xrev"
        prodv=$(git tag --list | sort -V | tail -1)
    elif [ -n "$hg" ]; then
        local xrev=$(hg id --id) || exit 1
        local brev=${xrev%+}
        if [ "$brev" != "$xrev" ]; then
            rev="hg:${brev}-dirty"
        else
            rev="hg:${brev}"
        fi
        prodv=$(hg log -r "branch(stable) and tag()" -T "{tags}\n" | sort -V | tail -1)
    else
        warn "no git or hg found; can't get VCS info"
        rev="UNKNOWN-VER"
    fi

    [ -n "$Prodver" ] && prodv=$Prodver

    echo "$rev $prodv"
    return 0
}

read -r Repover Prodver <<< $(getvcs_version)


usage() {
    declare -a progv=($Progs)
    declare n=${#progv[@]}
    declare pstr=

    for ((i=0; i < n; i++)); do
        local ent=${progv[$i]}
        local dir=${ent%%:*}
        local tool=${ent##*:}
        pstr=$(printf "$pstr\n\t%s $Prodver $Repover (from ./%s)" $tool $dir)
    done

    cat <<EOF
$0 - A Go production build tool that adds git-repository information,
product version, build-timestamp etc. It supports cross-compilation,
static linking and generating protobuf output.

Build output is in bin/\$OS-\$CPU for a given OS, CPU combination.

Usage: $0
       $0 [options] [PROGS]

Where OS-ARCH denotes one of the valid OS, ARCH combinations supported by 'go'.
And, PROGS is one or more go programs.

With no arguments, $0 builds: $pstr

The repository's latest tag is used as the default version of the software being
built. The current repository version is $Repover.

Options:
    -h, --help          Show this help message and quit
    -b D, --bindir=D    Put the binaries in the directory 'D' [$Bindir]
    -s, --static        Build a statically linked binary [False]
    -V N, --version=N   Use 'N' as the product version string [$Prodver]
    -a X, --arch=X      Cross compile for OS-CPU 'X' [$hostos-$hostcpu]
    -n, --dry-run       Dry-run, don't actually build anything [False]
    -t, --test          Run "go test" on modules named on the command line [False]
    -v, --verbose       Build verbosely (adds "-v" to go tooling) [False]
    --vet               Run "go vet" on modules named on the command line [False]
    --mod               Run "go mod ..." [False]
    --go=G              Use Go in 'G' [$Go]
    -x                  Run in debug/trace mode [False]
    --print-arch        Print the target architecture and exit
EOF

    exit 0
}

host=`uname|tr '[A-Z]' '[a-z]'`

declare -A oses
declare -A cpus
declare -A cgo

# Supported & Verified OS/CPU combos for this script
oslist="linux android openbsd freebsd darwin dragonfly netbsd windows"
needcgo="android"
cpulist="i386 amd64 arm arm64"
cpualias_i386="i486 i586 i686"
cpualias_amd64="x86_64"
cpualias_arm64="aarch64"

# CGO Cross-Compilers for various CPU+OS combinations of Android
android_i386=i686-linux-android-gcc
android_arm64=aarch64-linux-android-gcc
android_arm=arm-linux-androideabi-gcc

# initialize the various hash tables
for o in $oslist;  do oses[$o]=$o; done
for o in $needcgo; do cgo[$o]=$o;  done
for c in $cpulist; do
    cpus[$c]=$c
    a="cpualias_$c"
    a=${!a}
    for x in $a; do cpus[$x]=$c; done
done


Tool=
doinit=0
args=
Printarch=0

#set -x
ac_prev=
for ac_option
do
  shift

  if [ -n "$ac_prev" ]; then
    eval "$ac_prev=\$ac_option"
    ac_prev=
    continue
  fi

  case "$ac_option" in
      -*=*) ac_optarg=`echo "$ac_option" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
      *) ac_optarg= ;;
  esac


  case "$ac_option" in
        --help|-h|--hel|--he|--h)
            usage;
            ;;

        --arch=*)
            Arch=$ac_optarg
            ;;

        -a|--arch)
            ac_prev=Arch
            ;;

        -b|--bindir)
            ac_prev=Bindir
            ;;

        --bindir=*)
            Bindir=$ac_optarg
            ;;

        --version=*)
            Prodver=$ac_optarg
            ;;

        --test|-t)
            Tool=test
            ;;

        --vet)
            Tool=vet
            ;;

        --mod)
            Tool=mod
            ;;

        -V|--version)
            ac_prev=Prodver
            ;;

        -v|--verbose)
            Verbose=1
            ;;

        -s|--static)
            Static=1
            ;;

        --dry-run|-n)
            Dryrun=1
            ;;

        --debug|-x)
            set -x
            ;;

        --go-root=*)
            GoRoot=$ac_optarg
            ;;

        --print-arch)
            Printarch=1
            ;;

        *) # first non option terminates option processing.
           # we gather all remaining args and bundle them up.
            args="$args $ac_option"
            for xx
            do
                args="$args $xx"
            done
            break
            ;;
  esac
done

[ $Dryrun  -gt 0 ] && e=echo

# let every error abort
set -e

# build a tool that runs on the host - if needed.
hosttool() {
    local tool=$1
    local bindir=$2
    local src=$3

    p=$bindir/$tool
    if [ -x $p ]; then
        return 0
    fi

    local tmpdir=/tmp/$tool.$$
    mkdir $tmpdir || die "can't make $tmpdir"

    # since go1.20 - install uses env vars to decide where to put
    # build artifacts. Why are all the google tooling so bloody dev
    # hostile! WTF is wrong with command line args?!
    export GOBIN=$bindir

    # build it and stash it in the hostdir
    echo "Building tool $tool from $src .."
    (
       cd $tmpdir
       $e $Go install  $src@latest || die "can't install $tool"
    )
    $e rm -rf  $tmpdir

    return 0
}

# protobuf gen
buildproto() {
    local pbgo=protoc-gen-go
    local vtgo=protoc-gen-go-vtproto
    local vtgo_src=github.com/planetscale/vtprotobuf/cmd/protoc-gen-go-vtproto
    local pc
    local args="$*"

    local pgen=$(type -p protoc)
    local gogen=$(type -p $pbgo)
    local vt=$Hostbindir/$vtgo

    [ -z $pgen  ] && die "install protoc tools"
    [ -z $gogen ] && die "install protoc-gen-go"

    # now install the vtproto generator
    hosttool $vtgo $Hostbindir $vtgo_src

    for f in $args; do
        local dn=$(dirname $f)
        local bn=$(basename $f .proto)


        $e $pgen  \
            --go_out=. --plugin protoc-gen-go=$gogen \
            --go-vtproto_out=. --plugin protoc-gen-go-vtproto="$vt" \
            --go-vtproto_opt=features=marshal+unmarshal+size  \
             $f || die "can't generate protobuf output for $f .."
    done

    return 0
}


# the rest has to execute in the context of main shell (not funcs)

hostos=$($Go  env GOHOSTOS)      || exit 1
hostcpu=$($Go env GOHOSTARCH)    || exit 1

# This fragment can't be in a function - since it exports several vars
if [ -n "$Arch" ]; then
    ox=${Arch%%-*}
    cx=${Arch##*-}
    [ "$ox" = "$cx" ] && cx=$hostcpu

    os=${oses[$ox]}
    cpu=${cpus[$cx]}
    [ -z "$os" ]  && die "Don't know anything about OS $ox"
    [ -z "$cpu" ] && die "Don't know anything about CPU $cx"

    export GOOS=$os GOARCH=$cpu
    cross=$os-$cpu

else
    os=$hostos
    cpu=$hostcpu
    cross=$os-$cpu
fi

# If we don't need CGO, then we can attempt a static link
if [ -n "${cgo[$os]}" ]; then
    export CGO_ENABLED=1

    # See if we have a specific cross-compiler for this CPU+OS combo
    xcc="${GOOS}_${GOARCH}"
    xcc=${!xcc}
    if [ -n "$xcc" ]; then
        p=`type -p $xcc`
        [ -n "$p" ] || die "Can't find $xcc! Do you have compilers for $GOARCH available in PATH?"
        export CC=$xcc
    else
        echo "$Z: No Cross compiler defined for $GOOS-$GOARCH. Build may fail.." 1>&2
    fi
else
    if [ $Static -gt 0 ]; then
        export CGO_ENABLED=0

        isuffix="--installsuffix cgo"
        ldflags="-s"
        msg="statically linked"
    fi
fi

if [ $Printarch -gt 0 ]; then
    echo "$hostos-$hostcpu"
    exit 0
fi


# This is where build outputs go
Outdir=$Bindir/$cross
Hostbindir=$Bindir/$hostos-$hostcpu
export PATH=$Hostbindir:$PATH

[ -d $Outdir ]     || mkdir -p $Outdir
[ -d $Hostbindir ] || mkdir -p $Hostbindir


# Do Protobufs if needed
if [ -n "$Protobufs" ]; then
    set +e
    buildproto $Protobufs
    set -e
fi

# Get git/hg version info for the build
repover="main.RepoVersion=$Repover"
prodver="main.ProductVersion=$Prodver"
date="main.Buildtime=`date -u '+%Y-%m-%dT%H:%M.%SZ'`"
ldflags="-ldflags \"-X $repover -X $prodver -X $date $ldflags -buildid=\""
vflag=""

[ $Verbose -gt 0 ] && vflag="-v"

case $Tool in
    test)
        set -- $args
        $e $Go test $vflag "$@"
        ;;

    vet)
        set -- $args
        $e $Go vet $vflag "$@"
        ;;

    mod)
        set -- $args
        $e $Go mod $vflag "$@"
        ;;

    *) # Default is to build programs
        set -- $args
        if [ -z "$1" ]; then
            all=$Progs
        else
            all="$@"
        fi

        [ -z "$all" ] && die "No programs specified. Try '$Z --help'"

        echo "Building $Prodver ($Repover), $cross $msg .."

        for p in $all; do
            if echo $p | grep -q ':' ; then
                out=${p##*:}
                dir=${p%%:*}
            else
                out=$p
                dir=$p
            fi

            # Add .exe suffix to out if needed
            if [ "$GOOS" = "windows" ]; then
                base=${out%%.exe}
                out="${base}.exe"
            fi

            echo "   $dir: $out .. "
            $e eval $Go build $vflag -trimpath -o $Outdir/$out $isuffix "$ldflags" ./$dir || exit 1
        done
        ;;
esac

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