#!/bin/sh
# Installs Sill:
#
#   curl -fsSL https://sill.burakbuilds.dev/install.sh | sh
#
# What it does, in order (nothing is installed until every check passes):
#   1. reads latest.json from the download host (version, archive, SHA-256,
#      minimum macOS) and checks this Mac meets the minimum
#   2. downloads the archive and checks its SHA-256
#   3. unpacks it and checks the app's code signature: valid, made by team
#      UV5582B9AL, identifier app.sill.Sill — so a file swapped on the
#      host cannot install anybody else's app
#   4. puts Sill.app in /Applications (or ~/Applications if that isn't
#      writable) and opens it
# To update later, run the same command again.
#
# Environment, all optional: SILL_INSTALL_DIR (where to install),
# SILL_NO_OPEN=1 (don't launch it), SILL_DOWNLOADS_URL (download host).
#
# Written for /bin/sh, and wrapped in main() so that a download cut short
# runs nothing at all.

main() {
    set -eu

    base="${SILL_DOWNLOADS_URL:-https://sill.burakbuilds.dev}"
    base="${base%/}"
    team="UV5582B9AL"
    identifier="${SILL_EXPECT_IDENTIFIER:-app.sill.Sill}"

    say() { printf '\033[1m==>\033[0m %s\n' "$*"; }
    fail() { printf '\033[31mSill install: %s\033[0m\n' "$*" >&2; exit 1; }

    [ "$(uname -s)" = "Darwin" ] || fail "Sill is a Mac app."
    for tool in curl shasum ditto codesign plutil; do
        command -v "$tool" >/dev/null 2>&1 || fail "missing $tool"
    done

    tmp="$(mktemp -d "${TMPDIR:-/tmp}/sill-install.XXXXXX")"
    trap 'rm -rf "$tmp"' EXIT INT TERM

    fetch() { curl -fsSL --proto '=https' --tlsv1.2 --retry 2 -o "$2" "$1"; }
    # Tests may point at a local http server; anything else must be https.
    case "$base" in
        https://*) ;;
        http://127.0.0.1:*) fetch() { curl -fsSL --retry 2 -o "$2" "$1"; } ;;
        *) fail "download host must be https: $base" ;;
    esac

    say "Checking the latest Sill"
    fetch "$base/latest.json" "$tmp/latest.json" || fail "could not reach $base"
    field() { plutil -extract "$1" raw -o - "$tmp/latest.json" 2>/dev/null; }
    version="$(field version)" || fail "latest.json has no version"
    archive="$(field archive)" || fail "latest.json has no archive"
    sha="$(field sha256)" || fail "latest.json has no sha256"
    minimum="$(field minimumSystemVersion)" || fail "latest.json has no minimumSystemVersion"
    printf '%s' "$version" | grep -Eq '^[0-9]+\.[0-9]+\.[0-9]+$' || fail "odd version in latest.json"
    printf '%s' "$archive" | grep -Eq '^updates/Sill-[0-9]+\.[0-9]+\.[0-9]+\.zip$' || fail "odd archive path in latest.json"
    printf '%s' "$sha" | grep -Eq '^[0-9a-f]{64}$' || fail "odd checksum in latest.json"

    macos="$(sw_vers -productVersion)"
    at_least() { # $1 >= $2, dotted versions
        awk -v a="$1" -v b="$2" 'BEGIN {
            n = split(a, x, "."); m = split(b, y, "."); k = n > m ? n : m
            for (i = 1; i <= k; i++) { p = (i <= n) ? x[i] + 0 : 0; q = (i <= m) ? y[i] + 0 : 0
                if (p > q) exit 0; if (p < q) exit 1 }
            exit 0 }'
    }
    at_least "$macos" "$minimum" || fail "Sill $version needs macOS $minimum or later (this Mac has $macos)."

    say "Downloading Sill $version"
    fetch "$base/$archive" "$tmp/Sill.zip" || fail "download failed"
    [ "$(shasum -a 256 "$tmp/Sill.zip" | cut -d' ' -f1)" = "$sha" ] || fail "checksum mismatch — download corrupted or tampered with"

    mkdir "$tmp/x"
    ditto -x -k "$tmp/Sill.zip" "$tmp/x" || fail "could not unpack"
    app="$tmp/x/Sill.app"
    [ -d "$app" ] || fail "the archive holds no Sill.app"

    say "Verifying the signature"
    codesign --verify --deep --strict "$app" 2>/dev/null || fail "Sill.app's code signature is invalid"
    details="$(codesign -dv "$app" 2>&1)"
    printf '%s\n' "$details" | grep -qx "TeamIdentifier=$team" || fail "Sill.app is not signed by team $team"
    printf '%s\n' "$details" | grep -qx "Identifier=$identifier" || fail "this is not Sill ($identifier)"

    dir="${SILL_INSTALL_DIR:-/Applications}"
    if [ -z "${SILL_INSTALL_DIR:-}" ] && [ ! -w "$dir" ]; then
        dir="$HOME/Applications"
    fi
    mkdir -p "$dir" || fail "cannot create $dir"
    dest="$dir/Sill.app"
    if pgrep -f "^$dest/Contents/MacOS/Sill\$" >/dev/null 2>&1; then
        fail "Sill is running from $dest. Quit it (Sill ▸ Settings ▸ Quit), then run this again."
    fi

    say "Installing to $dest"
    staged="$dir/.Sill.app.installing.$$"
    rm -rf "$staged"
    ditto "$app" "$staged" || { rm -rf "$staged"; fail "cannot write to $dir"; }
    if [ -e "$dest" ]; then
        mv "$dest" "$tmp/previous.app" || { rm -rf "$staged"; fail "cannot replace $dest (is it yours? try: sudo rm -rf \"$dest\")"; }
    fi
    if ! mv "$staged" "$dest"; then
        [ -e "$tmp/previous.app" ] && mv "$tmp/previous.app" "$dest"
        rm -rf "$staged"
        fail "could not move Sill.app into $dir"
    fi

    printf '\n\033[1mSill %s is installed\033[0m in %s. Move the pointer to the notch.\n' "$version" "$dir"
    if [ "${SILL_NO_OPEN:-}" != "1" ]; then
        open "$dest" || true
    fi
}

main "$@"