Add automated PR checks

.github/workflows/pr-checks.yml

@@ -0,0 +1,98 @@
+name: pr-checks
+
+on:
+  pull_request:
+    branches: [ "main" ]
+
+  workflow_dispatch:
+
+permissions:
+  pull-requests: write
+
+jobs:
+  changed_files:
+    runs-on: ubuntu-latest
+    name: PR automated checks
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@v42
+      - name: Process changed files
+        id: changes-errors
+        env:
+          ALL_CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
+        run: |
+          echo 'errorsStr<<EOF' >> $GITHUB_OUTPUT
+
+          for file in $ALL_CHANGED_FILES; do
+            echo "Processing file: $file"
+
+            if [[ $file != images/* ]] && [[ $file != platforms/* ]] ;
+            then
+              errorText="Only additions of token icons (in the /images folder) or platform logos (in the /platforms folder) are permitted"
+              errorOutputText="- Error with \`$file\`: $errorText"
+              echo "::error file=$file::$errorText"
+              echo "$errorOutputText" >> $GITHUB_OUTPUT
+            fi
+
+            # Only check token icon additions, not platform icons which don't have anything automated
+            if [[ $file == images/assets* ]] ;
+            then
+              if [[ $file != *.png ]] ;
+              then
+                errorText="The new icon must be a PNG file"
+                errorOutputText="- Error with \`$file\`: $errorText"
+                echo "::error file=$file::$errorText"
+                echo "$errorOutputText" >> $GITHUB_OUTPUT
+              elif [[ ! $file =~ ^images/assets(-[a-z]+)?/[a-z0-9]+\.png$ ]] ;
+              then
+                errorText="The new icon's filename must be entirely lowercase"
+                errorOutputText="- Error with \`$file\`: $errorText"
+                echo "::error file=$file::$errorText"
+                echo "$errorOutputText" >> $GITHUB_OUTPUT
+              fi
+            fi
+          done
+
+          echo 'EOF' >> $GITHUB_OUTPUT
+      - name: Check if errors
+        id: check-if-errors
+        env:
+          ERRORS: ${{ steps.changes-errors.outputs.errorsStr }}
+        run: |
+          errorsStrLength=${#ERRORS}
+          echo "prev output : $ERRORS $errorsStrLength"
+
+          if (( errorsStrLength == 0 ));
+          then
+            echo 'hasErrors=false'
+            echo "hasErrors=false" >> "$GITHUB_OUTPUT"
+          else
+            echo 'hasErrors=true'
+            echo "hasErrors=true" >> "$GITHUB_OUTPUT"
+          fi
+      - name: Comment on PR if error
+        env:
+          ERRORS: ${{ steps.changes-errors.outputs.errorsStr }}
+          HAS_ERRORS: ${{ steps.check-if-errors.outputs.hasErrors }}
+        uses: thollander/actions-comment-pull-request@v2
+        if: ${{ env.HAS_ERRORS == 'true' }}
+        with:
+          message: |
+            Changes are required before your pull request can be reviewed:
+
+            ${{ env.ERRORS }}
+      - name: Exit with error
+        env:
+          ERRORS: ${{ steps.changes-errors.outputs.errorsStr }}
+          HAS_ERRORS: ${{ steps.check-if-errors.outputs.hasErrors }}
+        if: ${{ env.HAS_ERRORS == 'true' }}
+        run: |
+          mapfile myarray <<< $ERRORS
+          for ((i = 0; i < ${#myarray[@]}; ++i)); do
+            echo "::error::${myarray[i]}"
+          done
+          exit 1