#!/bin/sh
# Install Zetlyn.
#
#   curl -fsSL https://get.zetlyn.com | sh
#
# It fetches one binary, checks it against the checksums published beside it, and puts it somewhere
# on your path. It installs nothing else: adapters are separate programs and the models a build needs
# are fetched by `zetlyn model install`, both only when you ask for them.
#
#   ZETLYN_VERSION=0.1.0 sh    a version other than the current one
#   ZETLYN_TO=~/.local/bin sh  somewhere other than the first writable place below
set -eu

FROM=${ZETLYN_FROM:-https://download.zetlyn.com/zetlyn}

case "$(uname -s)" in
	Linux) OS=linux ;;
	Darwin) OS=macos ;;
	*) echo "zetlyn: this installs on Linux and macOS. On anything else, build it from source." >&2; exit 1 ;;
esac
case "$(uname -m)" in
	x86_64 | amd64) ARCH=x86_64 ;;
	arm64 | aarch64) ARCH=aarch64 ;;
	*) echo "zetlyn: $(uname -m) is not a platform binaries are published for." >&2; exit 1 ;;
esac
TARGET="$OS-$ARCH"

fetch() {
	if command -v curl >/dev/null 2>&1; then curl -fsSL "$1"
	elif command -v wget >/dev/null 2>&1; then wget -qO- "$1"
	else echo "zetlyn: neither curl nor wget is here" >&2; exit 1
	fi
}

VERSION=${ZETLYN_VERSION:-$(fetch "$FROM/latest" | tr -d ' \n\r')}
[ -n "$VERSION" ] || { echo "zetlyn: $FROM/latest says nothing" >&2; exit 1; }

TMP=$(mktemp -d)
trap 'rm -rf "$TMP"' EXIT INT TERM

echo "zetlyn $VERSION for $TARGET"
fetch "$FROM/$VERSION/$TARGET/zetlyn" > "$TMP/zetlyn" || {
	echo "zetlyn: there is no binary for $TARGET in $VERSION." >&2
	echo "        What is published is listed at $FROM/$VERSION/" >&2
	exit 1
}

# Checked before it is run, and not afterwards. A downloaded program that is verified by the person
# who remembers to is not verified.
fetch "$FROM/$VERSION/SHA256SUMS" > "$TMP/SHA256SUMS"
WANT=$(grep " $TARGET/zetlyn\$" "$TMP/SHA256SUMS" | cut -d' ' -f1)
if command -v sha256sum >/dev/null 2>&1; then GOT=$(sha256sum "$TMP/zetlyn" | cut -d' ' -f1)
elif command -v shasum >/dev/null 2>&1; then GOT=$(shasum -a 256 "$TMP/zetlyn" | cut -d' ' -f1)
else echo "zetlyn: no sha256sum and no shasum, so the bytes cannot be checked" >&2; exit 1
fi
[ -n "$WANT" ] || { echo "zetlyn: SHA256SUMS names no $TARGET/zetlyn" >&2; exit 1; }
[ "$WANT" = "$GOT" ] || {
	echo "zetlyn: the bytes are not the ones published." >&2
	echo "        published $WANT" >&2
	echo "        fetched   $GOT" >&2
	exit 1
}
chmod +x "$TMP/zetlyn"

if [ -n "${ZETLYN_TO:-}" ]; then
	TO=$ZETLYN_TO
else
	TO=""
	for candidate in /usr/local/bin "$HOME/.local/bin"; do
		[ -d "$candidate" ] && [ -w "$candidate" ] && { TO=$candidate; break; }
	done
	[ -n "$TO" ] || TO="$HOME/.local/bin"
fi
mkdir -p "$TO"
mv "$TMP/zetlyn" "$TO/zetlyn"

echo "installed $TO/zetlyn"
case ":$PATH:" in
	*":$TO:"*) ;;
	*) echo "$TO is not on your PATH" ;;
esac
echo
echo "  zetlyn init"
echo "  zetlyn corpus subscribe zetlyn/docs"
echo "  zetlyn serve"