#! /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=".:sigtool"

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


# -- DO NOT CHANGE ANYTHING AFTER THIS --

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

Static=0
Dryrun=0
Prodver=""
Verbose=0
Go=`which go`

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




usage() {

    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.

If needed, it uses the gogo-slick protobuf compiler [github.com/gogo/protobuf].

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: $Progs (source in ./src/)

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

Options:
    -h, --help          Show this help message and quit
    -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
            ;;

        --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

    local p=$(type -P $tool)
    if [ -n "$p" ]; then
        echo $p
        return 0
    fi

    # from here - we want this dir to find all build artifacts
    PATH=$PATH:$bindir
    export PATH

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

    # build it and stash it in the hostdir
    echo "Building tool $tool from $src .."
    $e $Go get -d      $src || exit 1
    $e $Go build -o $p $src || exit 1
    echo $p
    return 0
}


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
Bindir=$PWD/bin/$cross
Hostbindir=$PWD/bin/$hostos-$hostcpu

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

# Get git/hg version info for the build
if [ -d "./.hg" ]; then
    xrev=$(hg id --id) || exit 1
    brev=${xrev%+}
    if [ "$brev" != "$xrev" ]; then
        rev="hg:${brev}-dirty"
    else
        rev="hg:${brev}"
    fi
    if [ -z "$Prodver" ]; then
        Prodver=$(hg log -r "branch(stable) and tag()" -T "{tags}\n" | tail -1)
    fi
elif [ -d "./.git" ]; then
    xrev=$(git describe --always --dirty --long --abbrev=12) || exit 1
    rev="git:$xrev"
    if [ -z "$Prodver" ]; then
        Prodver=$(git tag --list | tail -1)
    fi
else
    rev="UNKNOWN-VER"
    echo "$0: Can't find version info" 1>&2
fi


# Do Protobufs if needed
if [ -n "$Protobufs" ]; then
    set +e
    slick=$Hostbindir/protoc-gen-gogoslick
    slicksrc=github.com/gogo/protobuf/protoc-gen-gogoslick
    for pc in protoc protoc-c; do
        pc=$(type -p $pc)
        [ -n "$pc" ] && break
    done

    [ -z "$pc" ] && die "Need 'protoc' for building .."

    slick=$(hosttool protoc-gen-gogoslick $Hostbindir $slicksrc) || exit 1
    #if [ ! -f $slick ]; then
    #   echo "Building $slick .."
    #   $e go build -o $slick github.com/gogo/protobuf/protoc-gen-gogoslick || exit 1
    #i

    export PATH=$PATH:$Hostbindir

    for f in $Protobufs; do
        dn=$(dirname $f)
        bn=$(basename $f .proto)
        of=$dn/${bn}.pb.go
        if [ $f -nt $of ]; then
            echo "Running $pc .."
            $e $pc --gogoslick_out=. $f || exit 1
        fi
    done
    set -e
fi

repover="main.RepoVersion=$rev"
prodver="main.ProductVersion=$Prodver"
date="main.Buildtime=`date -u '+%Y-%m-%dT%H:%M.%SZ'`"
ldflags="-ldflags \"-X $repover -X $prodver -X $date $ldflags\""
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

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

        for p in $all; do 
            if echo $p | grep -q ':' ; then
                out=${p##*:}
                dir=${p%%:*}
            else
                out=$p
                dir=$p
            fi
            echo "   $dir: $out .. "
            $e eval $Go build $vflag -o $Bindir/$out $isuffix "$ldflags" ./$dir || exit 1
        done
        ;;
esac

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