#!/usr/bin/env bash
# Offline simulation of rustup installation/selection; no Rust or network required.
set -Eeuo pipefail
ROOT=$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)
WORK=$(mktemp -d)
trap 'rm -rf "$WORK"' EXIT
mkdir -p "$WORK/bin" "$WORK/source" "$WORK/state"
cat > "$WORK/bin/rustup" <<'MOCK'
#!/usr/bin/env bash
set -Eeuo pipefail
state=${MOCK_RUSTUP_STATE:?}
case "$1" in
  run)
    channel=$2
    [[ -r "$state/$channel.version" ]] || exit 1
    printf 'rustc %s (mock)\n' "$(cat "$state/$channel.version")"
    ;;
  toolchain)
    [[ "$2" == install ]] || exit 7
    channel=$3
    [[ ${MOCK_INSTALL_FAIL:-0} != 1 ]] || exit 9
    case "$channel" in
      stable) version=${MOCK_NEW_STABLE:-1.100.0} ;;
      *) case "$channel" in *.*.*) version=$channel ;; *) version=${channel}.0 ;; esac ;;
    esac
    echo "$version" > "$state/$channel.version"
    printf 'install %s\n' "$channel" >> "$state/calls"
    ;;
  target)
    action=$2
    if [[ "$action" == list ]]; then
      [[ "$3" == --toolchain && "$5" == --installed ]] || exit 7
      [[ -f "$state/$4.target" ]] && cat "$state/$4.target"
    elif [[ "$action" == add ]]; then
      [[ "$4" == --toolchain ]] || exit 7
      echo "$3" > "$state/$5.target"
      printf 'target %s %s\n' "$5" "$3" >> "$state/calls"
    else exit 7
    fi
    ;;
  *) printf 'Unexpected rustup arguments: %s\n' "$*" >&2; exit 7 ;;
esac
MOCK
chmod +x "$WORK/bin/rustup"
export PATH="$WORK/bin:$PATH" MOCK_RUSTUP_STATE="$WORK/state" TOML_PYTHON=python3
TOOL="$ROOT/scripts/ensure-rust-toolchain.sh"
reset_state() { rm -f "$WORK/state/"*; }
manifest() { printf '[package]\nname = "rust-proxy"\nversion = "0.31.2"\nrust-version = "%s"\n' "$1" > "$WORK/source/Cargo.toml"; rm -f "$WORK/source/rust-toolchain" "$WORK/source/rust-toolchain.toml"; }

# No update or download when installed stable already satisfies the manifest.
reset_state
manifest 1.99
printf '1.100.0\n' > "$WORK/state/stable.version"
result=$($TOOL "$WORK/source" linux)
[[ "$result" == stable ]]
[[ ! -e "$WORK/state/calls" ]]

# Upgrade stable only when too old, then reuse it on subsequent checks.
reset_state
printf '1.98.1\n' > "$WORK/state/stable.version"
result=$($TOOL "$WORK/source" linux)
[[ "$result" == stable ]]
grep -Fqx 'install stable' "$WORK/state/calls"
[[ $($TOOL "$WORK/source" linux) == stable ]]
[[ $(wc -l < "$WORK/state/calls") == 1 ]]

# FreeBSD default 1.88 is auto raised to the project's 1.99 MSRV with its own target.
reset_state
result=$(FREEBSD_RUST_TOOLCHAIN=1.88.0 "$TOOL" "$WORK/source" freebsd)
[[ "$result" == 1.99 ]]
grep -Fqx 'install 1.99' "$WORK/state/calls"
grep -Fqx 'target 1.99 x86_64-unknown-freebsd' "$WORK/state/calls"
[[ $(FREEBSD_RUST_TOOLCHAIN=1.88.0 "$TOOL" "$WORK/source" freebsd) == 1.99 ]]
[[ $(wc -l < "$WORK/state/calls") == 2 ]]

# A deliberate rust-toolchain.toml pin is respected; do not silently override it.
reset_state
cat > "$WORK/source/rust-toolchain.toml" <<'PIN'
[toolchain]
channel = "1.98.0"
PIN
if "$TOOL" "$WORK/source" linux >/dev/null 2>&1; then
  printf 'An incompatible explicit pin should have failed\n' >&2
  exit 1
fi
[[ ! -e "$WORK/state/calls" ]] || { echo 'Should not install an incompatible pin' >&2; exit 1; }
rm "$WORK/source/rust-toolchain.toml"

# Pin that meets the project requirement is installed without changing stable.
reset_state
cat > "$WORK/source/rust-toolchain.toml" <<'PIN'
[toolchain]
channel = "1.99.0"
PIN
[[ $($TOOL "$WORK/source" linux) == 1.99.0 ]]
grep -Fqx 'install 1.99.0' "$WORK/state/calls"
rm "$WORK/source/rust-toolchain.toml"

# RustProxy-like rust-toolchain.toml (stable) also upgrades stale stable for FreeBSD.
reset_state
manifest 1.99
cat > "$WORK/source/rust-toolchain.toml" <<'PIN'
[toolchain]
channel = "stable"
profile = "minimal"
components = ["rustfmt", "clippy"]
PIN
printf '1.98.1\n' > "$WORK/state/stable.version"
[[ $(FREEBSD_RUST_TOOLCHAIN=1.88.0 "$TOOL" "$WORK/source" freebsd) == stable ]]
grep -Fqx 'install stable' "$WORK/state/calls"
grep -Fqx 'target stable x86_64-unknown-freebsd' "$WORK/state/calls"
rm "$WORK/source/rust-toolchain.toml"

# Workspace-inherited rust-version is resolved through TOML, not grep.
reset_state
cat > "$WORK/source/Cargo.toml" <<'MANIFEST'
[workspace.package]
rust-version = "1.99"
[package]
name = "rust-proxy"
version = "0.31.2"
rust-version = { workspace = true }
MANIFEST
printf '1.100.0\n' > "$WORK/state/stable.version"
[[ $($TOOL "$WORK/source" linux) == stable ]]

# An unavailable upgrade must be a hard failure.
reset_state
manifest 1.99
printf '1.98.1\n' > "$WORK/state/stable.version"
if MOCK_INSTALL_FAIL=1 "$TOOL" "$WORK/source" linux >/dev/null 2>&1; then
  printf 'A failed rustup update should abort the build\n' >&2
  exit 1
fi

echo 'Rust toolchain selection: 8 offline scenarios OK'