add regression workflow

.github/workflows/regression.yml

@@ -0,0 +1,84 @@
+on:
+  pull_request:
+    branches: [ "master" ]
+
+name: "Regression"
+
+jobs:
+  compare-results:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout PR branch
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 2
+
+    - uses: dtolnay/rust-toolchain@stable
+
+    - name: Download LAZ file
+      env:
+        REGRESSION_LAZ_FILE_URL: ${{ secrets.REGRESSION_LAZ_FILE_URL }}
+      run: curl -L "$REGRESSION_LAZ_FILE_URL" -o test_file.laz
+
+    - name: Run code on PR branch
+      id: run_pr_branch
+      run: |
+        echo "Running code on PR branch"
+        compare -list resource
+        cargo run --release -- test_file.laz
+        mv pullautus.png pullautus_pr.png
+        mv pullautus_depr.png pullautus_depr_pr.png
+        rm -rf temp/
+
+    - name: Download, extract and run latest release
+      run: |
+        # in a new folder to make sure we have a clean environment
+        mkdir latest_release && cd latest_release
+        curl -L https://github.com/rphlo/karttapullautin/releases/latest/download/karttapullautin-x86_64-linux.tar.gz | tar xvz
+        ./pullauta ../test_file.laz
+        mv pullautus.png ../pullautus_main.png
+        mv pullautus_depr.png ../pullautus_depr_main.png
+
+    - name: Compare results (pngcomp)
+      id: compare
+      run: |
+        # Compare the results from both branches, output results as step summary
+        sudo apt install pngnq 
+        printf "\n\n##### Comparing without depressions:\n" | tee -a $GITHUB_STEP_SUMMARY
+        pngcomp pullautus_main.png pullautus_pr.png | tee -a pngcomp.txt $GITHUB_STEP_SUMMARY
+        printf "\n\n##### Comparing with depressions:\n" | tee -a $GITHUB_STEP_SUMMARY
+        pngcomp pullautus_depr_main.png pullautus_depr_pr.png | tee -a pngcomp_depr.txt $GITHUB_STEP_SUMMARY
+
+    - name: Upload results
+      uses: actions/upload-artifact@v4
+      with:
+        name: regression-results
+        path: |
+          pullautus_main.png
+          pullautus_pr.png
+          pngcomp.txt
+          pullautus_depr_main.png
+          pullautus_depr_pr.png
+          pngcomp_depr.txt
+        overwrite: true # we need subsequent runs to overwrite the result
+
+    - name: Check for differences
+      run: |
+        # Analyze metrics: if there is a change this step should fail!
+
+        # Here we could check any of the metrics output by pngcomp. for now we check the
+        # percentage of overlapping/correct pixels and fail the job if it is less than 100%
+        value=$(sed -rn 's/Percentage correct pixels: ([0-9]+\.[0-9]+)$/\1/p' pngcomp.txt)
+        value_depr=$(sed -rn 's/Percentage correct pixels: ([0-9]+\.[0-9]+)$/\1/p' pngcomp_depr.txt)
+
+        if (( $(echo "$value < 100.0" | bc -l) )); then
+          echo "Percentage of correct pixels (without depressions) is $value < 100%. Output has changed!" | tee -a $GITHUB_STEP_SUMMARY
+          exit 1
+        fi
+
+        if (( $(echo "$value_depr < 100.0" | bc -l) )); then
+          echo "Percentage of correct pixels (with depressions) is $value_depr < 100%. Output has changed!" | tee -a $GITHUB_STEP_SUMMARY
+          exit 1
+        fi
+