#!/bin/bash
# Reproduces every factual claim in
# https://www.heatware.net/macos/brew-install-specific-version/
#
# Safe by default. It installs exactly one tiny formula (lua@5.4, ~766KB, zero dependencies)
# and uninstalls it again, and only if you don't already have lua or lua@5.4 — otherwise it
# SKIPs rather than touching your Cellar. Nothing else is mutated.
#
# The homebrew/core clone (1.4GB, ~2 minutes) is OPT-IN:
#     HW_ALLOW_BIG_TAP=1 bash verify-brew-install-specific-version.sh
# Without it, the brew extract claims report SKIP.
#
# Usage:   bash verify-brew-install-specific-version.sh
# Runtime: ~30s default, ~6 minutes with HW_ALLOW_BIG_TAP=1

set -u

PASSES=0; FAILS=0; SKIPS=0
pass() { PASSES=$((PASSES+1)); printf '  \033[32mPASS\033[0m %s\n' "$1"; }
fail() { FAILS=$((FAILS+1));  printf '  \033[31mFAIL\033[0m %s\n' "$1"
         printf '       expected: %s\n       actual:   %s\n' "$2" "$3"; }
skip() { SKIPS=$((SKIPS+1));  printf '  \033[33mSKIP\033[0m %s (needs %s)\n' "$1" "$2"; }
hdr()  { printf '\n\033[1m%s\033[0m\n' "$*"; }
contains() { case "$3" in *"$2"*) pass "$1";; *) fail "$1" "output containing: $2" "$(echo "$3" | head -3)";; esac; }
check()    { [ "$2" = "$3" ] && pass "$1" || fail "$1" "$2" "$3"; }

W="$(mktemp -d -t hwbrew)"
CLEAN_LUA=0
cleanup() {
  if [ "$CLEAN_LUA" = "1" ]; then
    printf '\n  restoring: uninstalling lua@5.4\n'
    brew unpin lua@5.4 >/dev/null 2>&1
    brew uninstall --formula lua@5.4 >/dev/null 2>&1
  fi
  rm -rf "$W"
}
trap cleanup EXIT

echo "Platform: $(sw_vers -productName) $(sw_vers -productVersion) $(uname -m)"

if ! command -v brew >/dev/null 2>&1; then
  echo "Homebrew not installed - nothing to verify."; exit 0
fi
echo "Homebrew: $(brew --version | head -1)"
PREFIX="$(brew --prefix)"

# ------------------------------------------------------------------ claim 1
hdr "Claim: 'brew switch' no longer exists and exits 1 like an unknown command"
SW_OUT="$(brew switch node 22 2>&1)"; SW_RC=$?
UNK_OUT="$(brew definitely-not-a-real-brew-command 2>&1)"; UNK_RC=$?
check "brew switch exits non-zero" "1" "$SW_RC"
check "an unknown brew command exits the same way" "$UNK_RC" "$SW_RC"
if [ "$(echo "$SW_OUT" | head -1)" = "$(echo "$UNK_OUT" | head -1)" ]; then
  pass "brew switch prints the same generic help as an unknown command"
else
  fail "brew switch prints the generic unknown-command help" "$(echo "$UNK_OUT" | head -1)" "$(echo "$SW_OUT" | head -1)"
fi

# ------------------------------------------------------------------ claim 2
hdr "Claim: versioned formulae are discoverable with an anchored regex search"
for fam in php postgresql node python openjdk; do
  OUT="$(brew search "/^${fam}@/" 2>/dev/null | tr '\n' ' ')"
  case "$OUT" in
    *"${fam}@"*) pass "brew search /^${fam}@/ returns versioned formulae: ${OUT}";;
    *)           fail "brew search /^${fam}@/ returns versioned formulae" "at least one ${fam}@N" "${OUT:-<empty>}";;
  esac
done

# ------------------------------------------------------------------ claim 3
hdr "Claim: Homebrew auto-links a keg-only versioned formula installed on request"
SRC="$PREFIX/Library/Homebrew/formula_installer.rb"
if [ -f "$SRC" ]; then
  contains "formula_installer.rb defines auto_link_versioned_keg_only?" \
           "def auto_link_versioned_keg_only?" "$(cat "$SRC")"
  contains "  ...and it bails out if any version is already installed" \
           "return false if formula.any_version_installed?" "$(sed -n '/def auto_link_versioned_keg_only?/,/^  end/p' "$SRC")"
else
  skip "formula_installer.rb source checks" "a source Homebrew install"
fi

if brew list --formula --versions lua 2>/dev/null | grep -q . || \
   brew list --formula --versions lua@5.4 2>/dev/null | grep -q .; then
  skip "live install of lua@5.4" "a machine without lua already installed"
else
  contains "brew install lua@5.4 reports it is keg-only" "keg-only" "$(brew info lua@5.4 2>&1)"
  if brew install lua@5.4 >"$W/install.log" 2>&1; then
    CLEAN_LUA=1
    contains "lua@5.4 lands in the Cellar" "Cellar/lua@5.4" "$(cat "$W/install.log")"
    if [ -L "$PREFIX/bin/lua" ]; then
      pass "the keg-only versioned formula was auto-linked: $(ls -l "$PREFIX/bin/lua" | sed 's/.*-> //')"
    else
      fail "the keg-only versioned formula was auto-linked" "$PREFIX/bin/lua is a symlink" "no symlink"
    fi
    V="$("$PREFIX/opt/lua@5.4/bin/lua" -v 2>&1)"
    contains "the installed binary reports a 5.4 version" "Lua 5.4" "$V"

    # ---------------------------------------------------------- claim 4
    hdr "Claim: brew pin records the pin as a symlink and brew upgrade skips pinned formulae"
    brew pin lua@5.4 >/dev/null 2>&1
    contains "brew list --pinned reports it" "lua@5.4" "$(brew list --pinned 2>&1)"
    if [ -L "$PREFIX/var/homebrew/pinned/lua@5.4" ]; then
      pass "the pin is a symlink under var/homebrew/pinned"
    else
      fail "the pin is a symlink under var/homebrew/pinned" "symlink present" "absent"
    fi
    contains "brew pin --help warns dependents may break" \
             "might not install or run correctly" "$(brew pin --help 2>&1)"
    UP="$PREFIX/Library/Homebrew/cmd/upgrade.rb"
    if [ -f "$UP" ]; then
      contains "upgrade.rb subtracts pinned formulae from the work list" "outdated -= pinned" "$(cat "$UP")"
    else
      skip "upgrade.rb source check" "a source Homebrew install"
    fi
    brew unpin lua@5.4 >/dev/null 2>&1
  else
    fail "brew install lua@5.4 succeeds" "exit 0" "$(tail -3 "$W/install.log")"
  fi
fi

# ------------------------------------------------------------------ claim 5
hdr "Claim: a version with no versioned formula simply is not installable"
OUT="$(brew install lua@5.3 2>&1)"
contains "brew install lua@5.3 reports no available formula" "No available formula" "$OUT"

# ------------------------------------------------------------------ claim 6
hdr "Claim: brew install of a .rb file by path is rejected"
cat > "$W/hwtest-formula.rb" <<'RB'
class HwtestFormula < Formula
  desc "Test"
  homepage "https://example.com"
  url "https://www.lua.org/ftp/lua-5.4.6.tar.gz"
  sha256 "7d5ea1b9cb6aa0b59ca3dde1c6adcb57ef83a1ba8e5432c0ecd06bf439b3ad88"
end
RB
OUT="$(brew install "$W/hwtest-formula.rb" 2>&1)"
contains "Homebrew requires formulae to be in a tap" "requires formulae to be in a tap" "$OUT"

# ------------------------------------------------------------------ claim 7
hdr "Claim: brew extract needs the homebrew/core tap, which brew itself refuses to add"
CORE_DIR="$PREFIX/Library/Taps/homebrew/homebrew-core"
if [ -d "$CORE_DIR" ]; then
  skip "the 'extract without the tap' error" "a machine WITHOUT homebrew/core already tapped"
else
  OUT="$(brew extract --version=5.3.6 lua homebrew/core 2>&1)"
  contains "brew extract says it requires the tap homebrew/core" "requires the tap homebrew/core" "$OUT"
  OUT="$(brew tap homebrew/core 2>&1)"
  contains "brew tap homebrew/core refuses without --force" "no longer typically necessary" "$OUT"
fi

# ------------------------------------------------------------------ claim 8
hdr "Claim: with the tap present, extract works - into YOUR tap, not homebrew/core"
DID_TAP=0
if [ ! -d "$CORE_DIR" ]; then
  if [ "${HW_ALLOW_BIG_TAP:-0}" = "1" ]; then
    echo "  cloning homebrew/core (1.4GB, ~2 min)..."
    if brew tap --force homebrew/core >"$W/tap.log" 2>&1; then
      DID_TAP=1
      contains "brew tap --force homebrew/core succeeds" "Tapped" "$(cat "$W/tap.log")"
      SIZE="$(du -sh "$CORE_DIR" 2>/dev/null | cut -f1)"
      COMMITS="$(git -C "$CORE_DIR" rev-list --count HEAD 2>/dev/null)"
      echo "       tap size: $SIZE   commits: $COMMITS"
      [ "${COMMITS:-0}" -gt 100000 ] && pass "the tap carries the full formula history (>100k commits)" \
        || fail "the tap carries the full formula history" ">100000 commits" "${COMMITS:-unknown}"
    else
      fail "brew tap --force homebrew/core succeeds" "exit 0" "$(tail -3 "$W/tap.log")"
    fi
  else
    skip "brew extract end-to-end" "HW_ALLOW_BIG_TAP=1 (clones 1.4GB)"
  fi
fi

if [ -d "$CORE_DIR" ]; then
  OUT="$(brew extract --version=5.4.6 lua homebrew/core 2>&1)"
  contains "extracting INTO homebrew/core is refused" "Cannot extract formula to homebrew/core" "$OUT"

  TAPNAME="hwverify/oldversions"
  TAPDIR="$PREFIX/Library/Taps/hwverify/homebrew-oldversions"
  if [ -d "$TAPDIR" ]; then
    skip "brew extract into a fresh tap" "no pre-existing $TAPNAME tap"
  else
    brew tap-new "$TAPNAME" --no-git >/dev/null 2>&1
    OUT="$(brew extract --version=5.4.6 lua "$TAPNAME" 2>&1)"
    contains "brew extract writes lua@5.4.6.rb into your tap" "lua@5.4.6.rb" "$OUT"
    if [ -f "$TAPDIR/Formula/lua@5.4.6.rb" ]; then
      pass "the extracted formula exists on disk"
      contains "  ...and it pins the 5.4.6 tarball" "lua-5.4.6.tar.gz" "$(cat "$TAPDIR/Formula/lua@5.4.6.rb")"
    else
      fail "the extracted formula exists on disk" "$TAPDIR/Formula/lua@5.4.6.rb" "missing"
    fi
    OUT="$(brew extract --version=5.3.6 lua "$TAPNAME" 2>&1)"
    contains "asking for a version that never existed fails after the history walk" \
             "Could not find lua" "$OUT"
    brew untap "$TAPNAME" >/dev/null 2>&1
    echo "  restoring: untapped $TAPNAME"
  fi
fi

if [ "$DID_TAP" = "1" ]; then
  brew untap homebrew/core >/dev/null 2>&1
  echo "  restoring: untapped homebrew/core"
fi

# ------------------------------------------------------------------ summary
printf '\n\033[1mSummary\033[0m  PASS=%d  FAIL=%d  SKIP=%d\n' "$PASSES" "$FAILS" "$SKIPS"
[ "$FAILS" -eq 0 ]