#!/bin/sh
# Installs Larva, the toolchain of the Antril language, on Linux and macOS:
#
#   curl -fsSL https://antril.org/install.sh | sh
#   curl -fsSL https://antril.org/install.sh | sh -s -- --no-path
#
# It reads the latest release from https://antril.org/download/latest.json, downloads Larva-<version>-<os>-<arch>.tar.gz
# into a temporary folder, checks its SHA-256, unpacks it and runs the install.sh inside with the options given here:
# --prefix <folder>, --no-path, --no-hive, --no-types (that install.sh's --help lists them). Larva goes to your user,
# no root needed.
#
# Settings:
#   --dry-run or LARVA_INSTALL_DRYRUN=1   download, check and unpack, then stop before installing
#   LARVA_INSTALL_OS, LARVA_INSTALL_ARCH  another system's build (linux or osx; x64 or arm64)
set -eu

main() {
    base=${LARVA_INSTALL_BASE:-https://antril.org}
    dry=${LARVA_INSTALL_DRYRUN:-0}
    [ "$dry" = 0 ] && dry=no || dry=yes

    # --dry-run is this script's; every other option goes to Larva's install.sh.
    for option do
        shift
        if [ "$option" = --dry-run ]; then dry=yes; else set -- "$@" "$option"; fi
    done

    case "${LARVA_INSTALL_OS:-$(uname -s)}" in
        Linux|linux) os=linux ;;
        Darwin|osx|macos) os=osx ;;
        *) fail "Larva's archives are for Linux and macOS (this is $(uname -s)). On Windows, in PowerShell: irm $base/install.ps1 | iex" ;;
    esac
    case "${LARVA_INSTALL_ARCH:-$(uname -m)}" in
        x86_64|amd64|x64) arch=x64 ;;
        aarch64|arm64) arch=arm64 ;;
        *) fail "no Larva build for the $(uname -m) processor" ;;
    esac

    if command -v curl > /dev/null 2>&1; then
        fetch() { curl -fsSL -H 'Cache-Control: no-cache' "$1"; }
        download() { curl -fSL --progress-bar -o "$2" "$1"; }
    elif command -v wget > /dev/null 2>&1; then
        fetch() { wget -q -O - "$1"; }
        download() { wget -q -O "$2" "$1"; }
    else
        fail "curl or wget is needed"
    fi
    if command -v sha256sum > /dev/null 2>&1; then
        sha256() { sha256sum "$1" | cut -d ' ' -f 1; }
    elif command -v shasum > /dev/null 2>&1; then
        sha256() { shasum -a 256 "$1" | cut -d ' ' -f 1; }
    else
        fail "sha256sum or shasum is needed to check the download"
    fi
    command -v tar > /dev/null 2>&1 || fail "tar is needed"

    step "Looking for the latest Larva at $base"
    latest=$(fetch "$base/download/latest.json") || fail "could not read $base/download/latest.json"
    version=$(printf '%s\n' "$latest" | sed -n 's/^  "version": *"\([^"]*\)".*/\1/p' | head -n 1)
    [ -n "$version" ] || fail "$base/download/latest.json names no version"

    name="Larva-$version-$os-$arch.tar.gz"
    # latest.json has one property per line; each asset's name comes before its sha256 and url.
    found=$(printf '%s\n' "$latest" | awk -v want="$name" '
        /"name":/ { n = $0; sub(/.*"name": *"/, "", n); sub(/".*/, "", n) }
        /"sha256":/ && n == want { s = $0; sub(/.*"sha256": *"/, "", s); sub(/".*/, "", s); print "sha256 " s }
        /"url":/ && n == want { u = $0; sub(/.*"url": *"/, "", u); sub(/".*/, "", u); print "url " u }')
    url=$(printf '%s\n' "$found" | sed -n 's/^url //p')
    expected=$(printf '%s\n' "$found" | sed -n 's/^sha256 //p')
    [ -n "$url" ] || fail "Larva $version has no build for $os-$arch. See $base/download"
    [ -n "$expected" ] || fail "$name has no SHA-256 to check it against. See $base/download"

    folder=$(mktemp -d 2> /dev/null || mktemp -d -t larva-install)
    trap 'rm -rf "$folder"' EXIT
    trap 'exit 130' INT TERM

    step "Downloading $name"
    download "$url" "$folder/$name" || fail "could not download $url"

    step "Checking its SHA-256"
    actual=$(sha256 "$folder/$name")
    if [ "$actual" != "$expected" ]; then
        fail "the SHA-256 of $name is $actual, not $expected: the download is damaged or not Larva's. Nothing was installed."
    fi
    say "    $actual  ok"

    step "Unpacking"
    tar -xzf "$folder/$name" -C "$folder" || fail "could not unpack $name"
    installer="$folder/Larva-$version-$os-$arch/install.sh"
    [ -f "$installer" ] || installer=$(find "$folder" -name install.sh -type f | head -n 1)
    [ -n "$installer" ] && [ -f "$installer" ] || fail "$name holds no install.sh"

    if [ "$dry" = yes ]; then
        step "Dry run: would run $(basename "$(dirname "$installer")")/install.sh $*"
        say "Nothing was installed (--dry-run)."
        return 0
    fi

    step "Installing Larva $version"
    sh "$installer" "$@" || fail "Larva's install.sh failed"
    say ""
    say "Next: larva new Console-App Hello --lang antril && cd Hello && larva run"
    say "(Open a new terminal first if larva is not found: ~/.local/bin was added to your PATH.)"
    say "Documentation: $base/docs"
}

say() { printf '%s\n' "$*"; }
step() { printf '==> %s\n' "$*"; }
fail() { printf 'error: %s\n' "$*" >&2; exit 1; }

# Everything runs from here: a download cut short runs nothing.
main "$@"