#!/bin/sh
# Installs horizon-server (docs/server.md) on Linux or macOS: the latest Horizon release for this computer,
# downloaded from GitHub Releases and checked against the SHA-256 GitHub publishes for it.
#
#   curl -fsSL https://raw.githubusercontent.com/ludovic111/horizon/main/packaging/server/install.sh | sh
#   curl -fsSL .../install.sh | sh -s -- --version v0.5.0 --dir /opt/horizon --bin /usr/local/bin
#
# It needs curl, tar or unzip, and sha256sum or shasum; it never asks for sudo (pick folders you can write).
# Releases go to <dir>/releases/<version>, <dir>/current points at the one in use, and <bin>/horizon-server
# runs it. The game files you prepare from your own Minecraft stay in <dir>/game-files across updates.
# Nothing of Mojang's is downloaded.
set -eu

REPO=ludovic111/horizon
VERSION=latest
DIR="${XDG_DATA_HOME:-$HOME/.local/share}/horizon"
BIN="$HOME/.local/bin"

die() { echo "horizon install: $*" >&2; exit 1; }

while [ $# -gt 0 ]; do
  case "$1" in
    --version) [ $# -ge 2 ] || die "--version needs a tag"; VERSION=$2; shift 2 ;;
    --dir) [ $# -ge 2 ] || die "--dir needs a folder"; DIR=$2; shift 2 ;;
    --bin) [ $# -ge 2 ] || die "--bin needs a folder"; BIN=$2; shift 2 ;;
    -h|--help) sed -n '2,12p' "$0" 2>/dev/null || true; exit 0 ;;
    *) die "unknown option $1" ;;
  esac
done

case "$(uname -s)-$(uname -m)" in
  Linux-x86_64) ASSET=horizon-linux-x86_64.tar.gz ;;
  Darwin-arm64) ASSET=horizon-macos-arm64.zip ;;
  *) die "no Horizon release for $(uname -s) $(uname -m) yet: build it from source (docs/server.md)" ;;
esac

command -v curl >/dev/null || die "curl is needed"
if command -v sha256sum >/dev/null; then SHA="sha256sum"
elif command -v shasum >/dev/null; then SHA="shasum -a 256"
else die "sha256sum or shasum is needed"; fi

if [ "$VERSION" = latest ]; then API="https://api.github.com/repos/$REPO/releases/latest"
else API="https://api.github.com/repos/$REPO/releases/tags/$VERSION"; fi
JSON=$(curl -fsSL -H "Accept: application/vnd.github+json" "$API") || die "no release $VERSION on GitHub"

TAG=$(printf '%s\n' "$JSON" | sed -n 's/^  "tag_name": "\([^"]*\)".*/\1/p' | head -n 1)
[ -n "$TAG" ] || die "could not read the release's tag"
# The asset's download address and digest, from its block in the release's JSON.
FIELDS=$(printf '%s\n' "$JSON" | awk -v asset="$ASSET" '
  /"name": / { line = $0; sub(/.*"name": "/, "", line); sub(/".*/, "", line); current = line }
  current == asset && /"digest": / { line = $0; sub(/.*"digest": "sha256:/, "", line); sub(/".*/, "", line); digest = line }
  current == asset && /"browser_download_url": / { line = $0; sub(/.*"browser_download_url": "/, "", line); sub(/".*/, "", line); url = line }
  END { print url; print digest }')
URL=$(printf '%s\n' "$FIELDS" | sed -n 1p)
DIGEST=$(printf '%s\n' "$FIELDS" | sed -n 2p)
[ -n "$URL" ] || die "release $TAG has no $ASSET"
[ -n "$DIGEST" ] || die "release $TAG publishes no SHA-256 for $ASSET"

TMP=$(mktemp -d)
trap 'rm -rf "$TMP"' EXIT
echo "Downloading Horizon $TAG ($ASSET)..."
curl -fL --progress-bar -o "$TMP/$ASSET" "$URL"
GOT=$($SHA "$TMP/$ASSET" | cut -d' ' -f1)
[ "$GOT" = "$DIGEST" ] || die "$ASSET doesn't match its SHA-256 (got $GOT, expected $DIGEST): not installed"

mkdir -p "$TMP/x"
case "$ASSET" in
  *.tar.gz) tar -xzf "$TMP/$ASSET" -C "$TMP/x" ;;
  *.zip) command -v unzip >/dev/null || die "unzip is needed"; unzip -q "$TMP/$ASSET" -d "$TMP/x" ;;
esac
SOURCE=$(dirname "$(find "$TMP/x" -name horizon-server -type f | head -n 1)")
[ -x "$SOURCE/horizon-server" ] || die "$ASSET holds no horizon-server (a release from before it existed?)"

RELEASE="$DIR/releases/$TAG"
mkdir -p "$DIR/releases" "$DIR/game-files/horizon-client" "$BIN"
rm -rf "$RELEASE"
mv "$SOURCE" "$RELEASE"
# Prepared game files live outside the release, so updates and rollbacks keep them.
mkdir -p "$RELEASE/.local"
ln -sfn "$DIR/game-files/horizon-client" "$RELEASE/.local/horizon-client"
ln -sfn "$RELEASE" "$DIR/current"
# Small launchers rather than links: the programs find their release folder from where they run.
for tool in horizon-server horizon-prepare; do
  printf '#!/bin/sh\nexec "%s/current/%s" "$@"\n' "$DIR" "$tool" > "$BIN/$tool"
  chmod +x "$BIN/$tool"
done

echo "Installed Horizon $TAG in $RELEASE; horizon-server and horizon-prepare are in $BIN."
case ":$PATH:" in
  *":$BIN:"*) ;;
  *) echo "Add $BIN to your PATH, for example: echo 'export PATH=\"$BIN:\$PATH\"' >> ~/.profile" ;;
esac
if [ -z "$(ls -A "$DIR/game-files/horizon-client" 2>/dev/null)" ]; then
  echo "Next, prepare the game files from your own Minecraft 26.3 (it needs Java 25 and the game installed once"
  echo "by the official launcher; see docs/server.md):"
  echo "  horizon-prepare --prepare --server-jar /path/to/server.jar"
fi
echo "Then set up a server: mkdir my-server && cd my-server && horizon-server init"