Install full MFC toolchain with smart wrapper for read-only Cellar

Reinstates the full MFC functionality including the mfc command-line tool
by creating a smart wrapper that works around Homebrew's read-only Cellar.

Changes to formula:
- Install mfc.sh script and full Python toolchain
- Create wrapper that uses temporary working directory
- Wrapper symlinks toolchain, mfc.sh, and examples into temp dir
- Automatically cleans up temp directory on exit
- Sets proper environment variables for Homebrew installation

Changes to CI:
- Test mfc wrapper functionality (--help, count)
- Run actual test case (1D Sod shock tube) with all CPU cores
- Verify full installation structure including toolchain

This allows users to use the full mfc CLI: mfc run, mfc test, mfc count, etc.

Author: sbryngelson

.github/workflows/homebrew.yml

@@ -61,20 +61,43 @@ jobs:
       - name: Test MFC binaries
         run: |
           echo "Verifying binaries are in PATH and executable..."
+          which mfc
           which pre_process
           which simulation
           which post_process
+          test -x $(which mfc)
           test -x $(which pre_process)
           test -x $(which simulation)
           test -x $(which post_process)
           echo "All binaries are accessible and executable!"
       
+      - name: Test MFC wrapper functionality
+        run: |
+          echo "Testing mfc command..."
+          mfc --help
+          
+          echo "Counting example cases..."
+          mfc count $(brew --prefix)/share/mfc/examples/1D_sodshocktube/case.py
+      
+      - name: Run MFC test case
+        run: |
+          echo "Running a simple test case (1D Sod shock tube)..."
+          cd $(mktemp -d)
+          cp $(brew --prefix)/share/mfc/examples/1D_sodshocktube/case.py .
+          
+          echo "Running with $(sysctl -n hw.ncpu) processors..."
+          mfc run case.py -j $(sysctl -n hw.ncpu)
+          
+          echo "Test case completed successfully!"
+      
       - name: Verify installation structure
         run: |
           echo "Checking installed files..."
+          ls -la $(brew --prefix)/bin/mfc
           ls -la $(brew --prefix)/bin/pre_process
           ls -la $(brew --prefix)/bin/simulation
           ls -la $(brew --prefix)/bin/post_process
+          ls -la $(brew --prefix)/libexec/mfc.sh
           ls -la $(brew --prefix)/share/mfc/examples/
           
           echo "Installation verified successfully!"

packaging/homebrew/mfc.rb

@@ -36,38 +36,88 @@ def install
       bin.install binary_paths.first
     end
 
+    # Install mfc.sh script to libexec
+    libexec.install "mfc.sh"
+
+    # Install Python toolchain
+    # The entire toolchain directory is required for mfc.sh functionality
+    prefix.install "toolchain"
+
     # Install examples
     pkgshare.install "examples"
+
+    # Create a wrapper that sets up a working environment for mfc.sh
+    # The wrapper uses a temporary directory since Cellar is read-only
+    (bin/"mfc").write <<~EOS
+      #!/bin/bash
+      set -e
+
+      # Create a working directory for MFC in user's cache
+      MFC_WORK_DIR="${TMPDIR:-/tmp}/mfc-homebrew-$$"
+      mkdir -p "$MFC_WORK_DIR"
+
+      # Function to clean up on exit
+      cleanup() {
+        rm -rf "$MFC_WORK_DIR"
+      }
+      trap cleanup EXIT
+
+      # Create minimal directory structure that mfc.sh expects
+      cd "$MFC_WORK_DIR"
+      ln -sf "#{prefix}/toolchain" toolchain
+      ln -sf "#{libexec}/mfc.sh" mfc.sh
+      ln -sf "#{pkgshare}/examples" examples
+
+      # Set up environment variables
+      export MFC_INSTALL_DIR="#{prefix}"
+      export MFC_BIN_DIR="#{bin}"
+      export BOOST_INCLUDE="#{Formula["boost"].opt_include}"
+
+      # Run mfc.sh with all arguments
+      exec ./mfc.sh "$@"
+    EOS
+    chmod 0755, bin/"mfc"
   end
 
   def caveats
     <<~EOS
-      MFC has been installed with the following binaries:
+      MFC has been installed with:
+        - mfc command-line tool: #{bin}/mfc
         - pre_process: #{bin}/pre_process
         - simulation:  #{bin}/simulation
         - post_process: #{bin}/post_process
 
       Examples are available in:
         #{pkgshare}/examples
 
-      For full development functionality (build, test, etc.),
-      clone the repository from: https://github.com/MFlowCode/MFC
+      To run an example:
+        cd #{pkgshare}/examples/1D_sodshocktube
+        mfc run case.py
 
       Documentation: https://mflowcode.github.io/
     EOS
   end
 
   test do
     # Test that the binaries exist and are executable
+    assert_path_exists bin/"mfc"
+    assert_predicate bin/"mfc", :executable?
     assert_path_exists bin/"pre_process"
     assert_predicate bin/"pre_process", :executable?
     assert_path_exists bin/"simulation"
     assert_predicate bin/"simulation", :executable?
     assert_path_exists bin/"post_process"
     assert_predicate bin/"post_process", :executable?
 
+    # Verify toolchain and mfc.sh were installed
+    assert_path_exists libexec/"mfc.sh"
+    assert_path_exists prefix/"toolchain"
+
     # Verify examples were installed
     assert_path_exists pkgshare/"examples"
     assert_path_exists pkgshare/"examples/1D_sodshocktube/case.py"
+
+    # Test mfc wrapper basic functionality
+    system bin/"mfc", "--help"
   end
 end