#!/bin/sh
# shellcheck shell=dash
# shellcheck disable=SC3043 # Assume `local` extension

# The official vpm installer.
#
# It runs on Unix shells like {a,ba,da,k,z}sh. It uses the common `local`
# extension. Note: Most shells limit `local` to 1 var per line, contra bash.

main() {
    # The version of ksh93 that ships with many illumos systems does not support the "local"
    # extension. Print a message rather than fail in subtle ways later on:
    if [ "${KSH_VERSION-}" = 'Version JM 93t+ 2010-03-05' ]; then
        err 'the installer does not work with this ksh93 version; please try bash'
    fi

    set -u

    parse_args "$@"

    local _arch
    _arch="${ARCH:-$(ensure get_architecture)}"
    assert_nz "${_arch}" "arch"
    echo "Detected architecture: ${_arch}"

    local _bin_name
    case "${_arch}" in
    *windows*) _bin_name="vpm.exe" ;;
    *) _bin_name="vpm" ;;
    esac

    # Create and enter a temporary directory.
    local _tmp_dir
    _tmp_dir="$(mktemp -d)" || err "mktemp: could not create temporary directory"
    cd "${_tmp_dir}" || err "cd: failed to enter directory: ${_tmp_dir}"

    # Download and extract vpm.
    local _package
    _package="$(ensure download_vpm "${_arch}")"
    assert_nz "${_package}" "package"
    echo "Downloaded package: ${_package}"
    case "${_package}" in
    *.tar.gz)
        need_cmd tar
        ensure tar -xf "${_package}"
        ;;
    *.zip)
        need_cmd unzip
        ensure unzip -oq "${_package}"
        ;;
    *)
        err "unsupported package format: ${_package}"
        ;;
    esac

    # Install binary.
    ensure try_sudo mkdir -p -- "${BIN_DIR}"
    ensure try_sudo cp -- "${_bin_name}" "${BIN_DIR}/${_bin_name}"
    ensure try_sudo chmod +x "${BIN_DIR}/${_bin_name}"
    echo "Installed vpm to ${BIN_DIR}"

    # Print success message and check $PATH.
    echo ""
    echo "vpm is installed!"
    if ! echo ":${PATH}:" | grep -Fq ":${BIN_DIR}:"; then
        echo "Note: ${BIN_DIR} is not on your \$PATH. vpm will not work unless it is added to \$PATH."
    fi
}

# Parse the arguments passed and set variables accordingly.
parse_args() {
    # BIN_DIR_DEFAULT="${HOME}/.local/bin"
    BIN_DIR_DEFAULT=/usr/local/bin
    # MAN_DIR_DEFAULT="${HOME}/.local/share/man"
    SUDO_DEFAULT="sudo"

    BIN_DIR="${BIN_DIR_DEFAULT}"
    # MAN_DIR="${MAN_DIR_DEFAULT}"
    SUDO="${SUDO_DEFAULT}"

    while [ "$#" -gt 0 ]; do
        case "$1" in
        --arch) ARCH="$2" && shift 2 ;;
        --arch=*) ARCH="${1#*=}" && shift 1 ;;
        --bin-dir) BIN_DIR="$2" && shift 2 ;;
        --bin-dir=*) BIN_DIR="${1#*=}" && shift 1 ;;
        # --man-dir) MAN_DIR="$2" && shift 2 ;;
        # --man-dir=*) MAN_DIR="${1#*=}" && shift 1 ;;
        --sudo) SUDO="$2" && shift 2 ;;
        --sudo=*) SUDO="${1#*=}" && shift 1 ;;
        -h | --help) usage && exit 0 ;;
        *) err "Unknown option: $1" ;;
        esac
    done
}

usage() {
    # heredocs are not defined in POSIX.
    local _text_heading _text_reset
    _text_heading="$(tput bold || true 2>/dev/null)$(tput smul || true 2>/dev/null)"
    _text_reset="$(tput sgr0 || true 2>/dev/null)"

    local _arch
    _arch="$(get_architecture || true)"

    echo "\
${_text_heading}vpm installer${_text_reset}
Instachip <team@getinstachip.com>
https://github.com/getinstachip/vpm

Fetches and installs vpm. If vpm is already installed, it will be updated to the latest version.

${_text_heading}Usage:${_text_reset}
  install.sh [OPTIONS]

${_text_heading}Options:${_text_reset}
      --arch     Override the architecture identified by the installer [current: ${_arch}]
      --bin-dir  Override the installation directory [default: ${BIN_DIR_DEFAULT}]
      # --man-dir  Override the manpage installation directory [default: ${MAN_DIR_DEFAULT}]
      --sudo     Override the command used to elevate to root privileges [default: ${SUDO_DEFAULT}]
  -h, --help     Print help"
}

download_vpm() {
    local _arch="$1"

    if check_cmd curl; then
        _dld=curl
    elif check_cmd wget; then
        _dld=wget
    else
        need_cmd 'curl or wget'
    fi
    need_cmd grep

    local _releases_url="https://api.github.com/repos/getinstachip/vpm/releases/latest"
    local _releases
    case "${_dld}" in
    curl) _releases="$(curl -sL "${_releases_url}")" ||
        err "curl: failed to download ${_releases_url}" ;;
    wget) _releases="$(wget -qO- "${_releases_url}")" ||
        err "wget: failed to download ${_releases_url}" ;;
    *) err "unsupported downloader: ${_dld}" ;;
    esac
    (echo "${_releases}" | grep -q 'API rate limit exceeded') &&
        err "you have exceeded GitHub's API rate limit. Please try again later, or use a different installation method: https://github.com/getinstachip/vpm/#installation"

    local _package_url
    _package_url="$(echo "${_releases}" | grep "browser_download_url" | cut -d '"' -f 4 | grep -- "${_arch}")" ||
        err "vpm has not yet been packaged for your architecture (${_arch}), please file an issue: https://github.com/getinstachip/vpm/issues"

    local _ext
    case "${_package_url}" in
    *.tar.gz) _ext="tar.gz" ;;
    *.zip) _ext="zip" ;;
    *) err "unsupported package format: ${_package_url}" ;;
    esac

    local _package="vpm.${_ext}"
    case "${_dld}" in
    curl) _releases="$(curl -sLo "${_package}" "${_package_url}")" || err "curl: failed to download ${_package_url}" ;;
    wget) _releases="$(wget -qO "${_package}" "${_package_url}")" || err "wget: failed to download ${_package_url}" ;;
    *) err "unsupported downloader: ${_dld}" ;;
    esac

    echo "${_package}"
}

try_sudo() {
    if "$@" >/dev/null 2>&1; then
        return 0
    fi

    need_sudo
    "${SUDO}" "$@"
}

need_sudo() {
    if ! check_cmd "${SUDO}"; then
        err "\
could not find the command \`${SUDO}\` needed to get permissions for install.

If you are on Windows, please run your shell as an administrator, then rerun this script.
Otherwise, please run this script as root, or install \`sudo\`."
    fi

    if ! "${SUDO}" -v; then
        err "sudo permissions not granted, aborting installation"
    fi
}

# The below functions have been extracted with minor modifications from the
# Rustup install script:
#
#   https://github.com/rust-lang/rustup/blob/4c1289b2c3f3702783900934a38d7c5f912af787/rustup-init.sh

get_architecture() {
    local _ostype _cputype _bitness _arch _clibtype
    _ostype="$(uname -s)"
    _cputype="$(uname -m)"
    _clibtype="musl"

    if [ "${_ostype}" = Linux ]; then
        if [ "$(uname -o || true)" = Android ]; then
            _ostype=Android
        fi
    fi

    if [ "${_ostype}" = Darwin ] && [ "${_cputype}" = i386 ]; then
        # Darwin `uname -m` lies
        if sysctl hw.optional.x86_64 | grep -q ': 1'; then
            _cputype=x86_64
        fi
    fi

    if [ "${_ostype}" = SunOS ]; then
        # Both Solaris and illumos presently announce as "SunOS" in "uname -s"
        # so use "uname -o" to disambiguate.  We use the full path to the
        # system uname in case the user has coreutils uname first in PATH,
        # which has historically sometimes printed the wrong value here.
        if [ "$(/usr/bin/uname -o || true)" = illumos ]; then
            _ostype=illumos
        fi

        # illumos systems have multi-arch userlands, and "uname -m" reports the
        # machine hardware name; e.g., "i86pc" on both 32- and 64-bit x86
        # systems.  Check for the native (widest) instruction set on the
        # running kernel:
        if [ "${_cputype}" = i86pc ]; then
            _cputype="$(isainfo -n)"
        fi
    fi

    case "${_ostype}" in
    Android)
        _ostype=linux-android
        ;;
    Linux)
        check_proc
        _ostype=unknown-linux-${_clibtype}
        _bitness=$(get_bitness)
        ;;
    FreeBSD)
        _ostype=unknown-freebsd
        ;;
    NetBSD)
        _ostype=unknown-netbsd
        ;;
    DragonFly)
        _ostype=unknown-dragonfly
        ;;
    Darwin)
        _ostype=apple-darwin
        ;;
    illumos)
        _ostype=unknown-illumos
        ;;
    MINGW* | MSYS* | CYGWIN* | Windows_NT)
        _ostype=pc-windows-msvc
        ;;
    *)
        err "unrecognized OS type: ${_ostype}"
        ;;
    esac

    case "${_cputype}" in
    i386 | i486 | i686 | i786 | x86)
        _cputype=i686
        ;;
    xscale | arm)
        _cputype=arm
        if [ "${_ostype}" = "linux-android" ]; then
            _ostype=linux-androideabi
        fi
        ;;
    armv6l)
        _cputype=arm
        if [ "${_ostype}" = "linux-android" ]; then
            _ostype=linux-androideabi
        else
            _ostype="${_ostype}eabihf"
        fi
        ;;
    armv7l | armv8l)
        _cputype=armv7
        if [ "${_ostype}" = "linux-android" ]; then
            _ostype=linux-androideabi
        else
            _ostype="${_ostype}eabihf"
        fi
        ;;
    aarch64 | arm64)
        _cputype=aarch64
        ;;
    x86_64 | x86-64 | x64 | amd64)
        _cputype=x86_64
        ;;
    mips)
        _cputype=$(get_endianness mips '' el)
        ;;
    mips64)
        if [ "${_bitness}" -eq 64 ]; then
            # only n64 ABI is supported for now
            _ostype="${_ostype}abi64"
            _cputype=$(get_endianness mips64 '' el)
        fi
        ;;
    ppc)
        _cputype=powerpc
        ;;
    ppc64)
        _cputype=powerpc64
        ;;
    ppc64le)
        _cputype=powerpc64le
        ;;
    s390x)
        _cputype=s390x
        ;;
    riscv64)
        _cputype=riscv64gc
        ;;
    *)
        err "unknown CPU type: ${_cputype}"
        ;;
    esac

    # Detect 64-bit linux with 32-bit userland
    if [ "${_ostype}" = unknown-linux-musl ] && [ "${_bitness}" -eq 32 ]; then
        case ${_cputype} in
        x86_64)
            # 32-bit executable for amd64 = x32
            if is_host_amd64_elf; then {
                err "x32 userland is unsupported"
            }; else
                _cputype=i686
            fi
            ;;
        mips64)
            _cputype=$(get_endianness mips '' el)
            ;;
        powerpc64)
            _cputype=powerpc
            ;;
        aarch64)
            _cputype=armv7
            if [ "${_ostype}" = "linux-android" ]; then
                _ostype=linux-androideabi
            else
                _ostype="${_ostype}eabihf"
            fi
            ;;
        riscv64gc)
            err "riscv64 with 32-bit userland unsupported"
            ;;
        *) ;;
        esac
    fi

    # Detect armv7 but without the CPU features Rust needs in that build,
    # and fall back to arm.
    # See https://github.com/rust-lang/rustup.rs/issues/587.
    if [ "${_ostype}" = "unknown-linux-musleabihf" ] && [ "${_cputype}" = armv7 ]; then
        if ensure grep '^Features' /proc/cpuinfo | grep -q -v neon; then
            # At least one processor does not have NEON.
            _cputype=arm
        fi
    fi

    _arch="${_cputype}-${_ostype}"
    echo "${_arch}"
}

get_bitness() {
    need_cmd head
    # Architecture detection without dependencies beyond coreutils.
    # ELF files start out "\x7fELF", and the following byte is
    #   0x01 for 32-bit and
    #   0x02 for 64-bit.
    # The printf builtin on some shells like dash only supports octal
    # escape sequences, so we use those.
    local _current_exe_head
    _current_exe_head=$(head -c 5 /proc/self/exe)
    if [ "${_current_exe_head}" = "$(printf '\177ELF\001')" ]; then
        echo 32
    elif [ "${_current_exe_head}" = "$(printf '\177ELF\002')" ]; then
        echo 64
    else
        err "unknown platform bitness"
    fi
}

get_endianness() {
    local cputype="$1"
    local suffix_eb="$2"
    local suffix_el="$3"

    # detect endianness without od/hexdump, like get_bitness() does.
    need_cmd head
    need_cmd tail

    local _current_exe_endianness
    _current_exe_endianness="$(head -c 6 /proc/self/exe | tail -c 1)"
    if [ "${_current_exe_endianness}" = "$(printf '\001')" ]; then
        echo "${cputype}${suffix_el}"
    elif [ "${_current_exe_endianness}" = "$(printf '\002')" ]; then
        echo "${cputype}${suffix_eb}"
    else
        err "unknown platform endianness"
    fi
}

is_host_amd64_elf() {
    need_cmd head
    need_cmd tail
    # ELF e_machine detection without dependencies beyond coreutils.
    # Two-byte field at offset 0x12 indicates the CPU,
    # but we're interested in it being 0x3E to indicate amd64, or not that.
    local _current_exe_machine
    _current_exe_machine=$(head -c 19 /proc/self/exe | tail -c 1)
    [ "${_current_exe_machine}" = "$(printf '\076')" ]
}

check_proc() {
    # Check for /proc by looking for the /proc/self/exe link.
    # This is only run on Linux.
    if ! test -L /proc/self/exe; then
        err "unable to find /proc/self/exe. Is /proc mounted? Installation cannot proceed without /proc."
    fi
}

need_cmd() {
    if ! check_cmd "$1"; then
        err "need '$1' (command not found)"
    fi
}

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

# Run a command that should never fail. If the command fails execution
# will immediately terminate with an error showing the failing
# command.
ensure() {
    if ! "$@"; then err "command failed: $*"; fi
}

assert_nz() {
    if [ -z "$1" ]; then err "found empty string: $2"; fi
}

err() {
    echo "Error: $1" >&2
    exit 1
}

# This is put in braces to ensure that the script does not run until it is
# downloaded completely.
{
    main "$@" || exit 1
}
