name: LaTeX Diff

on:
  workflow_dispatch:
    inputs:
      base_branch:
        description: 'Base branch (older version)'
        required: true
      compare_branch:
        description: 'Compare branch (new version)'
        required: true

jobs:
  latexdiff:
    runs-on: ubuntu-latest
    container:
      image: ghcr.io/xu-cheng/texlive-full:latest
      options: --user root

    steps:
      - name: Install latexpand (Perl script)
        run: |
          tlmgr init-usertree
          tlmgr install latexpand
        
      - name: Checkout base branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.inputs.base_branch }}
          path: base

      - name: Checkout compare branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.inputs.compare_branch }}
          path: compare


      - name: Create output folder
        run: mkdir -p diff_output

      - name: Flatten base/main.tex (with latexpand)
        run: |
          cd base/latex
          echo "📂 Listing files in base/latex:"
          ls -R
          echo "🔄 Flattening with latexpand..."
          latexpand --verbose --keep-comments --output=../../diff_output/base_flat.tex main.tex
          echo "✅ Preview of base_flat.tex:"
          head -n 50 ../../diff_output/base_flat.tex


      - name: Flatten compare/main.tex (with latexpand)
        run: |
          cd compare/latex
          echo "📂 Listing files in compare/latex:"
          ls -R
          echo "🔄 Flattening with latexpand..."
          latexpand --verbose --keep-comments --output=../../diff_output/compare_flat.tex main.tex
          echo "✅ Preview of compare_flat.tex:"
          head -n 50 ../../diff_output/compare_flat.tex

      - name: Generate diff.tex using latexdiff
        run: |
          latexdiff diff_output/base_flat.tex diff_output/compare_flat.tex > diff_output/diff.tex
          
      - name: Upload flattened .tex and diff.tex early
        uses: actions/upload-artifact@v4
        with:
          name: latex-diff-tex
          path: |
            diff_output/base_flat.tex
            diff_output/compare_flat.tex
            diff_output/diff.tex
            
      - name: Copy thesis.cls to diff_output
        run: cp compare/latex/thesis.cls diff_output/
        
      - name: Override “\input{preamble/fonts}” in diff.tex
        run: |
          sed -i '/\\input{preamble\/fonts}/c\
          % — replaced by CI: use TeX Gyre fonts instead of Times New Roman/Arial       \
          \setmainfont{TeX Gyre Termes}                                                   \
          \setsansfont{TeX Gyre Heros}                                                    \
          \setmonofont{TeX Gyre Cursor}\
          ' diff_output/diff.tex
          
      - name: Print preview of diff.tex (after font override)
        run: |
          echo "📄 Preview of diff_output/diff.tex after font override:"
          head -n 50 diff_output/diff.tex
          
      - name: Compile diff.tex to PDF
        working-directory: diff_output
        continue-on-error: true
        run: |
          xelatex -interaction=nonstopmode diff.tex
          xelatex -interaction=nonstopmode diff.tex

        
      - name: Compile diff.tex to PDF
        working-directory: diff_output
        run: |
          xelatex -interaction=nonstopmode diff.tex
          xelatex -interaction=nonstopmode diff.tex

      - name: Upload diff output files
        uses: actions/upload-artifact@v4
        with:
          name: latex-diff-output
          path: diff_output/