#!/usr/bin/env bash

set -Eeuo pipefail

app_name="m9zCtrlTty"
app_package="./apps/m9zCtrlTty"
script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
repo_root="$(cd -- "${script_dir}/../.." && pwd)"

usage() {
    cat <<'EOF'
Usage:
  ./apps/m9zCtrlTty/build.sh <goos> <goarch> [goarm]

Examples:
  ./apps/m9zCtrlTty/build.sh linux arm 7
  ./apps/m9zCtrlTty/build.sh linux arm64
  ./apps/m9zCtrlTty/build.sh windows amd64
  ./apps/m9zCtrlTty/build.sh darwin arm64

Arguments:
  goos    Target operating system accepted by "go tool dist list".
  goarch  Target CPU architecture accepted by "go tool dist list".
  goarm   ARM generation for 32-bit GOARCH=arm: 5, 6, or 7 (default: 7).
          Soft-float targets may use 5,softfloat, 6,softfloat, or 7,softfloat.

Environment variables:
  OUTPUT_ROOT     Output root directory (default: dist).
  CGO_ENABLED     CGO mode (default: 0 for cross-compilation).
  BUILD_TAGS      Optional Go build tags.
  BUILD_LDFLAGS   Go linker flags (default: -s -w; set to an empty value to keep symbols).
EOF
}

if [[ $# -lt 2 || $# -gt 3 ]]; then
    usage >&2
    exit 2
fi

if ! command -v go >/dev/null 2>&1; then
    printf 'Go toolchain was not found in PATH.\n' >&2
    exit 127
fi

target_os="$1"
target_arch="$2"
target_pair="${target_os}/${target_arch}"

supported_target=false
while IFS= read -r candidate; do
    if [[ "$candidate" == "$target_pair" ]]; then
        supported_target=true
        break
    fi
done < <(go tool dist list)

if [[ "$supported_target" != true ]]; then
    printf 'Unsupported Go build target: %s\n' "$target_pair" >&2
    printf 'Run "go tool dist list" to see supported targets.\n' >&2
    exit 2
fi

arch_label="$target_arch"
if [[ "$target_arch" == "arm" ]]; then
    target_goarm="${3:-${GOARM:-7}}"
    case "$target_goarm" in
        5|6|7|5,softfloat|6,softfloat|7,softfloat) ;;
        *)
            printf 'Invalid GOARM value: %s\n' "$target_goarm" >&2
            exit 2
            ;;
    esac
    export GOARM="$target_goarm"
    arm_generation="${target_goarm%%,*}"
    arch_label="armv${arm_generation}"
    if [[ "$target_goarm" == *,softfloat ]]; then
        arch_label="${arch_label}-softfloat"
    fi
elif [[ $# -eq 3 ]]; then
    printf 'The third argument (goarm) is only valid when GOARCH=arm.\n' >&2
    exit 2
fi

output_root="${OUTPUT_ROOT:-dist}"
if [[ "$output_root" != /* ]]; then
    output_root="${repo_root}/${output_root}"
fi
output_dir="${output_root}/${target_os}-${arch_label}"

extension=""
case "$target_os" in
    windows) extension=".exe" ;;
    js|wasip1)
        if [[ "$target_arch" == "wasm" ]]; then
            extension=".wasm"
        fi
        ;;
esac

output_path="${output_dir}/${app_name}${extension}"
mkdir -p "$output_dir"

export GOOS="$target_os"
export GOARCH="$target_arch"
export CGO_ENABLED="${CGO_ENABLED:-0}"

if [[ "${BUILD_LDFLAGS+x}" == "x" ]]; then
    build_ldflags="$BUILD_LDFLAGS"
else
    build_ldflags="-s -w"
fi

build_args=(build -mod=readonly -trimpath -o "$output_path")
if [[ -n "${BUILD_TAGS:-}" ]]; then
    build_args+=(-tags "$BUILD_TAGS")
fi
if [[ -n "$build_ldflags" ]]; then
    build_args+=(-ldflags "$build_ldflags")
fi
build_args+=("$app_package")

printf 'Building %s for %s (CGO_ENABLED=%s)\n' "$app_name" "$target_pair" "$CGO_ENABLED"
if [[ "$target_arch" == "arm" ]]; then
    printf 'Using GOARM=%s\n' "$GOARM"
fi

(
    cd "$repo_root"
    go "${build_args[@]}"
)

printf 'Build complete: %s\n' "$output_path"
if command -v file >/dev/null 2>&1; then
    file "$output_path"
fi