#!/usr/bin/env bash

# Installs the latest (or a specific) version of joltc, the self-contained jolt
# binary. It bundles the runtime, compiler, jolt-core + stdlib, and the Chez
# boots, so there is nothing else to install — no Chez, no cc, no JVM.

set -euo pipefail

version=""
checksum=""
default_install_dir="/usr/local/bin"
install_dir="$default_install_dir"
download_dir=""

repo="jolt-lang/jolt"

print_help() {
    echo "Installs the latest (or a specific) version of joltc."
    echo "Installation directory defaults to ${default_install_dir}."
    echo
    echo "Usage:"
    echo "  install [--dir <dir>] [--download-dir <dir>] [--version <version>] [--checksum <sha256>]"
    echo
    echo "Defaults:"
    echo " * Installation directory: ${default_install_dir}"
    echo " * Download directory: a temporary directory"
    echo " * Version: the latest release on GitHub"
    echo " * Checksum: fetched from the release and verified automatically"
    exit 1
}

has() {
    command -v "$1" >/dev/null 2>&1
}

fetch() {
    local url=$1
    local outfile=${2:-}
    if has curl; then
        if [[ -n $outfile ]]; then curl -fsSL "$url" -o "$outfile"; else curl -fsSL "$url"; fi
    elif has wget; then
        if [[ -n $outfile ]]; then wget -qO "$outfile" "$url"; else wget -qO - "$url"; fi
    else
        >&2 echo "Either 'curl' or 'wget' needs to be on PATH."
        exit 1
    fi
}

while [[ $# -gt 0 ]]; do
    case "$1" in
        --dir)          install_dir="$2"; shift 2 ;;
        --download-dir) download_dir="$2"; shift 2 ;;
        --version)      version="$2"; shift 2 ;;
        --checksum)     checksum="$2"; shift 2 ;;
        --help|-h)      print_help ;;
        *)              print_help ;;
    esac
done

if [[ -z "$download_dir" ]]; then
    download_dir="$(mktemp -d)"
    trap 'rm -rf "$download_dir"' EXIT
fi

# --- resolve platform / arch to a release target -----------------------------
case "$(uname -s)" in
    Linux*)  platform=linux ;;
    Darwin*) platform=macos ;;
    *) >&2 echo "Unsupported OS: $(uname -s). Prebuilt binaries exist for Linux and macOS."; exit 1 ;;
esac

case "$(uname -m)" in
    x86_64|amd64)   arch=x86_64 ;;
    aarch64|arm64)  arch=aarch64 ;;
    *) >&2 echo "Unsupported architecture: $(uname -m)."; exit 1 ;;
esac

target="${arch}-${platform}"
case "$target" in
    x86_64-linux|aarch64-macos) ;;
    x86_64-macos)
       >&2 echo "No prebuilt joltc for Intel macOS (GitHub retired the Intel runner)."
       >&2 echo "Build from source: https://github.com/${repo} (needs Chez Scheme + cc)."
       exit 1 ;;
    *) >&2 echo "No prebuilt joltc for ${target}."
       >&2 echo "Available: x86_64-linux, aarch64-macos."
       >&2 echo "Build from source: https://github.com/${repo} (make joltc-release)."
       exit 1 ;;
esac

# --- resolve version ---------------------------------------------------------
if [[ -z "$version" ]]; then
    version="$(fetch "https://api.github.com/repos/${repo}/releases/latest" \
        | grep -m1 '"tag_name"' | sed -E 's/.*"tag_name": *"([^"]+)".*/\1/')"
    if [[ -z "$version" ]]; then
        >&2 echo "Could not determine the latest release. Pass --version explicitly."
        exit 1
    fi
fi
tag="v${version#v}"   # accept 0.1.0 or v0.1.0; the tag/asset carry the leading v

filename="joltc-${tag}-${target}.tar.gz"
download_url="https://github.com/${repo}/releases/download/${tag}/${filename}"

if has sha256sum; then
    sha256sum_cmd="sha256sum"
elif has shasum; then
    sha256sum_cmd="shasum -a 256"
else
    sha256sum_cmd=""
fi

mkdir -p "$download_dir" && (
    cd "$download_dir"
    echo "Downloading ${download_url}"
    fetch "$download_url" "$filename"

    # verify: an explicit --checksum wins; otherwise fetch the release's .sha256.
    if [[ -z "$checksum" ]]; then
        checksum="$(fetch "${download_url}.sha256" 2>/dev/null | cut -d' ' -f1 || true)"
    fi
    if [[ -n "$checksum" && -n "$sha256sum_cmd" ]]; then
        got="$($sha256sum_cmd "$filename" | cut -d' ' -f1)"
        if [[ "$got" != "$checksum" ]]; then
            >&2 echo "Checksum mismatch on ${filename}"
            >&2 echo "  got:      ${got}"
            >&2 echo "  expected: ${checksum}"
            exit 1
        fi
    elif [[ -z "$sha256sum_cmd" ]]; then
        >&2 echo "Note: no sha256sum/shasum on PATH; skipping checksum verification."
    fi

    tar -zxf "$filename"
    rm -f "$filename"
)

# the tarball unpacks to a directory holding the binary
extracted="${download_dir}/joltc-${tag}-${target}/joltc"
if [[ ! -f "$extracted" ]]; then
    >&2 echo "Expected ${extracted} in the archive but it was not found."
    exit 1
fi

mkdir -p "$install_dir"
if [[ -f "$install_dir/joltc" ]]; then
    echo "Moving existing $install_dir/joltc to $install_dir/joltc.old"
    mv -f "$install_dir/joltc" "$install_dir/joltc.old"
fi
mv -f "$extracted" "$install_dir/joltc"
chmod +x "$install_dir/joltc"

# clear the macOS quarantine flag so Gatekeeper doesn't block the fresh download
if [[ "$platform" == "macos" ]] && has xattr; then
    xattr -d com.apple.quarantine "$install_dir/joltc" 2>/dev/null || true
fi

echo "Successfully installed joltc ${tag} to ${install_dir}/joltc"
if ! echo ":$PATH:" | grep -q ":${install_dir}:"; then
    echo "Note: ${install_dir} is not on your PATH."
fi