#!/bin/sh
# Installs the latest iyi release into ~/.local (bin/, lib/, share/iyi/):
#
#   curl -fsSL https://raw.githubusercontent.com/iyilang/iyi/master/install.sh | sh
#
# IYI_PREFIX       where to unpack, default ~/.local; the tarball is relocatable
# IYI_VERSION      a release to pin, e.g. 0.20.0; default is the latest release
# IYI_RELEASE_URL  where the release's files are, default the GitHub release;
#                  CI points it at a directory (file://) to install a tarball
#                  before it is released, which is how this script is gated
#
# POSIX sh, curl and tar are all it needs. The release is resolved by
# following GitHub's /releases/latest redirect, not the API, so there is
# no token and no rate limit in the way. The tarball is checked against
# the SHA256SUMS the release publishes beside it before anything is
# unpacked: what comes out of it reaches the linker, so a byte that is
# not the byte the release job wrote is refused rather than run.
set -eu

repo="iyilang/iyi"
prefix="${IYI_PREFIX:-$HOME/.local}"
version="${IYI_VERSION:-}"

say() { printf '%s\n' "$*" >&2; }
die() { say "install.sh: $*"; exit 1; }

for tool in curl tar; do
  command -v "$tool" >/dev/null 2>&1 || die "$tool is required"
done

os="$(uname -s)"
arch="$(uname -m)"
case "$os-$arch" in
  Linux-x86_64) target=linux-x86_64 ;;
  Darwin-arm64) target=darwin-arm64 ;;
  *) die "no release for $os $arch: releases ship linux-x86_64 and darwin-arm64, see README.md (Getting it) to build from source" ;;
esac

if [ -z "$version" ]; then
  tag_url="$(curl -fsSLI -o /dev/null -w '%{url_effective}' "https://github.com/$repo/releases/latest")" ||
    die "could not resolve the latest release of $repo"
  version="${tag_url##*/tag/v}"
  [ "$version" != "$tag_url" ] || die "unexpected redirect for the latest release: $tag_url"
fi
version="${version#v}"

asset="iyi-$version-$target.tar.gz"
base="${IYI_RELEASE_URL:-https://github.com/$repo/releases/download/v$version}"

mkdir -p "$prefix" 2>/dev/null && [ -w "$prefix" ] ||
  die "$prefix is not writable; set IYI_PREFIX to a directory that is"

tmp="$(mktemp -d)"
trap 'rm -rf "$tmp"' EXIT

say "iyi $version for $target"
curl -fSL --progress-bar -o "$tmp/$asset" "$base/$asset" || die "download failed: $base/$asset"

# The checksum line for this tarball, out of the release's SHA256SUMS.
# Releases before 0.12.0 published none, and that is said rather than
# passed over: an install that was not verified should know it was not.
if curl -fsSL -o "$tmp/SHA256SUMS" "$base/SHA256SUMS" 2>/dev/null; then
  expected="$(awk -v name="$asset" '$2 == name || $2 == "*" name { print $1; exit }' "$tmp/SHA256SUMS")"
  [ -n "$expected" ] || die "the release's SHA256SUMS has no line for $asset"
  if command -v sha256sum >/dev/null 2>&1; then
    actual="$(sha256sum "$tmp/$asset" | awk '{ print $1 }')"
  elif command -v shasum >/dev/null 2>&1; then
    actual="$(shasum -a 256 "$tmp/$asset" | awk '{ print $1 }')"
  else
    die "the release publishes a checksum and neither sha256sum nor shasum is here to check it"
  fi
  [ "$actual" = "$expected" ] ||
    die "$asset does not match the release's SHA256SUMS: expected $expected, got $actual. Nothing was unpacked; try again, and if it repeats, say so at https://github.com/$repo/issues"
  say "verified: sha256 $actual"
else
  say "note: release $version publishes no SHA256SUMS; the tarball was not verified"
fi

# What a previous install left, removed before this one is unpacked.
#
# `tar` overwrites the files it carries and knows nothing about the ones
# it no longer carries, so an upgrade used to leave every file the
# release had deleted lying in the prefix. That is not tidy-versus-untidy:
# `share/iyi/crystal` is a *library*, `crystal/dwarf.cr` requires
# `./dwarf/**`, and a file a release removed is still required by the
# glob. One real case, found on a machine that had upgraded in place:
# `crystal/dwarf/line_numbers.cr` from an older release stayed behind and
# every `--crystal` build died with `undefined constant FORM`, naming a
# file the person never wrote and cannot find in the repository.
#
# So each install writes down what it unpacked, and the next one removes
# exactly that - no more, since `bin/` and `lib/` are shared with whatever
# else lives under the prefix. An install from before this manifest
# existed leaves no list, and for it the two directories iyi owns whole
# are cleared instead, which is where the library that poisons a build
# lives.
manifest="$prefix/share/iyi/installed-files"
if [ -f "$manifest" ]; then
  while IFS= read -r path; do
    case "$path" in
      /*|*..*) continue ;;  # a manifest is this script's own writing; refuse anything that climbs out
    esac
    [ -n "$path" ] || continue
    [ -d "$prefix/$path" ] || rm -f "$prefix/$path"
  done < "$manifest"
  # Directories after their contents, and only the ones that emptied.
  sort -r "$manifest" | while IFS= read -r path; do
    case "$path" in
      /*|*..*|"") continue ;;
    esac
    [ -d "$prefix/$path" ] && rmdir "$prefix/$path" 2>/dev/null || true
  done
elif [ -d "$prefix/share/iyi" ]; then
  say "replacing the install at $prefix (no file list: it predates one)"
  rm -rf "$prefix/share/iyi" "$prefix/share/licenses/iyi"
fi

tar -xzf "$tmp/$asset" -C "$prefix"

# And what this install owns, for the next one to remove. Paths as the
# archive names them, `./` stripped, so they read as prefix-relative.
tar -tzf "$tmp/$asset" | sed 's|^\./||' | grep -v '^$' > "$manifest"

"$prefix/bin/iyi" version >/dev/null || die "$prefix/bin/iyi does not start"

say "installed $prefix/bin/iyi"
command -v cc >/dev/null 2>&1 ||
  say "note: no C compiler on PATH; iyi links through cc, so install gcc or clang before building"

case ":$PATH:" in
  *":$prefix/bin:"*) ;;
  *) say "note: add $prefix/bin to PATH, e.g. export PATH=\"$prefix/bin:\$PATH\"" ;;
esac
say "try: $prefix/bin/iyi run $prefix/share/iyi/samples/hello.iyi"