RED-9149 - Address comments

layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/utils/HeaderFooterDetection.java

@@ -17,6 +17,11 @@ import lombok.experimental.UtilityClass;
 public class HeaderFooterDetection {
 
     private final Map<Integer, ClassificationPage> pagesCache = new HashMap<>();
+    private static final double THRESHOLD = 0.5;
+    // Weight will go from 1.0 to 0.5 because the first element is the most likely to be the header on the page.
+    private static final double[] headerWeights = {1.0, 0.75, 0.5};
+    // Weight will go from 0.5 to 1.0 because the last element is the most likely to be the footer on the page.
+    private static final double[] footerWeights = {0.5, 0.75, 1.0};
 
 
     public boolean isLikelyFooter(TextPageBlock textPageBlock, ClassificationDocument document, ClassificationPage classificationPage) {
@@ -32,8 +37,6 @@ public class HeaderFooterDetection {
         List<ClassificationPage> nearestPages = findNearestPages(classificationPage, document.getPages(), window);
         List<List<AbstractPageBlock>> footerCandidates = getFooterCandidates(nearestPages);
 
-        // Weight will go from 0.5 to 1.0 because the last element is the most likely to be the footer on the page.
-        double[] footerWeights = {0.5, 0.75, 1.0};
         return detectHeadersOrFootersByPageAssociation(textPageBlock.getText(), footerCandidates, window, footerWeights);
     }
 
@@ -51,8 +54,6 @@ public class HeaderFooterDetection {
         List<ClassificationPage> nearestPages = findNearestPages(classificationPage, document.getPages(), window);
         List<List<AbstractPageBlock>> headerCandidates = getHeaderCandidates(nearestPages);
 
-        // Weight will go from 1.0 to 0.5 because the first element is the most likely to be the header on the page.
-        double[] headerWeights = {1.0, 0.75, 0.5};
         return detectHeadersOrFootersByPageAssociation(textPageBlock.getText(), headerCandidates, window, headerWeights);
     }
 
@@ -62,19 +63,19 @@ public class HeaderFooterDetection {
         double highestScore = 0.0;
 
         for (int i = 0; i < candidates.size(); i++) {
-            List<List<String>> temp = new ArrayList<>();
+            List<List<String>> candidateStrings = new ArrayList<>();
             for (int k = Math.max(i - window, 0); k < Math.min(i + window, candidates.size()); k++) {
-                temp.add(candidates.get(k)
+                candidateStrings.add(candidates.get(k)
-                                 .stream()
+                                             .stream()
-                                 .map(AbstractPageBlock::getText)
+                                             .map(AbstractPageBlock::getText)
-                                 .collect(Collectors.toList()));
+                                             .collect(Collectors.toList()));
             }
 
-            int maxLen = temp.stream()
+            int maxLen = candidateStrings.stream()
                     .mapToInt(List::size)
                     .max()
                     .orElse(0);
-            for (List<String> sublist : temp) {
+            for (List<String> sublist : candidateStrings) {
                 while (sublist.size() < maxLen) {
                     sublist.add(0, "");
                 }
@@ -85,13 +86,13 @@ public class HeaderFooterDetection {
                 double score = 0.0;
                 try {
                     int finalJ = j;
-                    List<String> cmp = temp.stream()
+                    List<String> paddedCandidateStrings = candidateStrings.stream()
                             .map(sublist -> sublist.size() > finalJ ? sublist.get(finalJ) : "")
                             .toList();
-                    for (String cm : cmp) {
+                    for (String cm : paddedCandidateStrings) {
                         score += compare(testString, cm) * (j < weights.length ? weights[j] : 1);
                     }
-                    score /= cmp.size();
+                    score /= paddedCandidateStrings.size();
                 } catch (IndexOutOfBoundsException e) {
                     continue;
                 }
@@ -99,7 +100,7 @@ public class HeaderFooterDetection {
             }
         }
 
-        return highestScore > 0.5;
+        return highestScore > THRESHOLD;
     }
 
 
@@ -155,10 +156,11 @@ public class HeaderFooterDetection {
         List<List<AbstractPageBlock>> footerCandidates = new ArrayList<>();
         for (ClassificationPage page : pages) {
             List<AbstractPageBlock> textBlocks = page.getTextBlocks();
-            int blockCount = textBlocks.size();
+            List<TextPageBlock> textPageBlocks = textBlocks.stream().filter(textBlock -> textBlock instanceof TextPageBlock).map(textBlock -> (TextPageBlock) textBlock).toList();
+            int blockCount = textPageBlocks.size();
             if (blockCount > 0) {
                 int start = Math.max(0, blockCount - 3);
-                footerCandidates.add(new ArrayList<>(textBlocks.subList(start, blockCount)));
+                footerCandidates.add(new ArrayList<>(textPageBlocks.subList(start, blockCount)));
             }
         }
         return footerCandidates;
@@ -171,8 +173,9 @@ public class HeaderFooterDetection {
         List<List<AbstractPageBlock>> headerCandidates = new ArrayList<>();
         for (ClassificationPage page : pages) {
             List<AbstractPageBlock> textBlocks = page.getTextBlocks();
-            int count = Math.min(3, textBlocks.size());
+            List<TextPageBlock> textPageBlocks = textBlocks.stream().filter(textBlock -> textBlock instanceof TextPageBlock).map(textBlock -> (TextPageBlock) textBlock).toList();
-            headerCandidates.add(new ArrayList<>(textBlocks.subList(0, count)));
+            int count = Math.min(3, textPageBlocks.size());
+            headerCandidates.add(new ArrayList<>(textPageBlocks.subList(0, count)));
         }
         return headerCandidates;
     }