Fixes 5445: Add checks for feature flags (oppia#5464)

<!-- READ ME FIRST: Please fill in the explanation section below and
check off every point from the Essential Checklist! -->
## Explanation
Fixes oppia#5445: When merged, this PR will;
- Introduce a check to ensure new feature flags are added into the
FeatureFlagsLogger
- Add any existing flags that are currently not being logged
- Add the feature_flags_check.sh file to static_checks.sh so that it can
be run locally
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- Explain what your PR does. If this PR fixes an existing bug, please
include
- "Fixes #bugnum:" in the explanation so that GitHub can auto-close the
issue
  - when this PR is merged.
  -->

## Essential Checklist
<!-- Please tick the relevant boxes by putting an "x" in them. -->
- [x] The PR title and explanation each start with "Fix #bugnum: " (If
this PR fixes part of an issue, prefix the title with "Fix part of
#bugnum: ...".)
- [x] Any changes to
[scripts/assets](https://github.com/oppia/oppia-android/tree/develop/scripts/assets)
files have their rationale included in the PR explanation.
- [x] The PR follows the [style
guide](https://github.com/oppia/oppia-android/wiki/Coding-style-guide).
- [x] The PR does not contain any unnecessary code changes from Android
Studio
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#undo-unnecessary-changes)).
- [x] The PR is made from a branch that's **not** called "develop" and
is up-to-date with "develop".
- [x] The PR is **assigned** to the appropriate reviewers
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#clarification-regarding-assignees-and-reviewers-section)).

---------

Co-authored-by: Kenneth Murerwa <[email protected]>

.github/workflows/static_checks.yml

@@ -84,6 +84,10 @@ jobs:
         run: |
           bash /home/runner/work/oppia-android/oppia-android/scripts/ktlint_lint_check.sh $HOME
 
+      - name: Feature flag checks
+        run: |
+          bash /home/runner/work/oppia-android/oppia-android/scripts/feature_flags_check.sh $HOME
+
       - name: Protobuf lint check
         run: |
           bash /home/runner/work/oppia-android/oppia-android/scripts/buf_lint_check.sh $HOME

scripts/assets/todo_open_exemptions.textproto

@@ -336,7 +336,7 @@ todo_open_exemption {
 }
 todo_open_exemption {
   exempted_file_path: "scripts/static_checks.sh"
-  line_number: 110
+  line_number: 114
 }
 todo_open_exemption {
   exempted_file_path: "wiki/Coding-style-guide.md"

scripts/feature_flags_check.sh

@@ -0,0 +1,147 @@
+#!/bin/bash
+
+echo "********************************"
+echo "Running feature flag checks"
+echo "********************************"
+
+failed_checks=0
+
+function item_in_array() {
+  local item="$1"
+  shift
+  local array=("$@")
+
+  for element in "${array[@]}"; do
+    if [[ "$element" == "$item" ]]; then
+      echo 1
+      return
+    fi
+  done
+
+  echo 0
+}
+
+function get_classes_from_constants_file() {
+  # Get the file path of the FeatureFlagConstants File
+  file_path=$(find . -name FeatureFlagConstants.kt)
+
+  # Get a list of feature flag annotation classes
+  annotation_classes=$(grep -E '[\s\w]*annotation\s*class' "$file_path")
+
+  # Convert the string into an array, splitting by newline
+  IFS=$'\n' read -rd '' -a array <<<"$annotation_classes"
+
+  # Create an empty array to hold individual class names
+  class_names=()
+
+  # Iterate through each line and take the last word of the list
+  for line in "${array[@]}"; do
+      # Convert each line into an array of words, splitting by space
+      IFS=' ' read -ra words <<<"$line"
+
+      # Get last element of the list
+      last_element="${words[${#words[@]}-1]}"
+
+      # Add the element into class_names
+      class_names+=("$last_element")
+  done
+
+  echo "${class_names[@]}"
+}
+
+function get_imported_classes_in_logger() {
+  # File path containing the block of text
+  file_path=$(find . -name FeatureFlagsLogger.kt)
+
+  # Use sed to extract the block based on a starting pattern and an ending pattern
+  extracted_block=$(sed -n '/class FeatureFlagsLogger @Inject constructor(/,/^)/p' "$file_path")
+
+  # Get annotation classes
+  logged_classes=$(grep -E '@Enable[A-Za-z0-9_]+' "$file_path")
+
+  # Replace the @ symbol and spaces within each element of the list
+  for i in "${!logged_classes[@]}"; do
+    logged_classes[$i]=$(echo "${logged_classes[$i]}" | tr -d '@' | tr -d ' ')
+  done
+
+  # Print the logged classes
+  echo "$logged_classes"
+}
+
+function get_flags_added_into_the_logging_map() {
+  # File path containing the block of text
+  file_path=$(find . -name FeatureFlagsLogger.kt)
+
+  # Use sed to extract the block based on a starting pattern and an ending pattern
+  extracted_block=$(sed -n '/Map<String, PlatformParameterValue<Boolean>> = mapOf(/,/)$/p' "$file_path")
+
+  # Get any word beginning with enable from the extracted block
+  enable_flags=$(grep -E 'enable[A-Za-z0-9_]+' <<<"$extracted_block")
+
+  added_flags=()
+
+  # Convert the string into an array, splitting by newline
+  IFS=$'\n' read -rd '' -a added_flags <<<"$enable_flags"
+
+  # Create an empty array to hold individual class names
+  class_names=()
+
+  # Iterate through each line and take the last word of the list
+  for line in "${added_flags[@]}"; do
+      # Remove the comma at the end of the line
+      line=$(echo "$line" | awk '{sub(/,$/, ""); print}')
+
+      # Convert each line into an array of words, splitting by space
+      IFS=' ' read -ra words <<<"$line"
+
+      # Get last element of the list
+      last_element="${words[${#words[@]}-1]}"
+
+      # Capitalize last element using sed
+      last_element=$(echo "$last_element" | awk '{for(i=1;i<=NF;i++) $i=toupper(substr($i,1,1)) substr($i,2)}1')
+
+      # Add the element into class_names
+      class_names+=("$last_element")
+  done
+
+  echo "${class_names[@]}"
+}
+
+function perform_checks_on_feature_flags() {
+  feature_flags=($(get_classes_from_constants_file))
+  imported_classes=($(get_imported_classes_in_logger))
+  flags_added_to_map=($(get_flags_added_into_the_logging_map))
+
+  file_path=$(find . -name FeatureFlagsLogger.kt)
+  imports_line_number=$(grep -n 'class FeatureFlagsLogger @Inject constructor(' "$file_path" | head -n 1 | awk -F: '{print $1}')
+  flags_map_line_number=$(grep -n 'Map<String, PlatformParameterValue<Boolean>> = mapOf(' "$file_path" | head -n 1 | awk -F: '{print $1}')
+
+  for element in "${feature_flags[@]}"; do
+    in_array=$(item_in_array "$element" "${imported_classes[@]}")
+    if [[ $in_array -ne 1 ]]; then
+      failed_checks=$((failed_checks + 1))
+      echo "$element is not imported in the constructor argument in $file_path at line $imports_line_number"
+    fi
+  done
+
+  for element in "${feature_flags[@]}"; do
+    in_array=$(item_in_array "$element" "${flags_added_to_map[@]}")
+    if [[ $in_array -ne 1 ]]; then
+      failed_checks=$((failed_checks + 1))
+      echo "$element is not added to the logging map in $file_path at line $flags_map_line_number"
+    fi
+  done
+
+  if [[ $failed_checks -eq 0 ]]; then
+    echo "Feature flag checks completed successfully"
+    exit 0
+  else
+    echo "********************************"
+    echo "Feature flag issues found."
+    echo "Please fix the above issues."
+    echo "********************************"
+    exit 1
+  fi
+}
+
+perform_checks_on_feature_flags

scripts/static_checks.sh

@@ -19,6 +19,10 @@ echo ""
 bash scripts/ktlint_lint_check.sh
 echo ""
 
+# Run feature flag checks
+bash scripts/feature_flags_check.sh
+echo ""
+
 # Run protobuf lint checks
 bash scripts/buf_lint_check.sh
 echo ""

utility/src/main/java/org/oppia/android/util/platformparameter/FeatureFlagConstants.kt

@@ -24,13 +24,6 @@ const val DOWNLOADS_SUPPORT = "android_enable_downloads_support"
 /** Default value for feature flag corresponding to [EnableDownloadsSupport]. */
 const val ENABLE_DOWNLOADS_SUPPORT_DEFAULT_VALUE = false
 
-/** Qualifier for the feature flag corresponding to enabling the language selection UI. */
-@Qualifier
-annotation class EnableLanguageSelectionUi
-
-/** Default value for the feature flag corresponding to [EnableLanguageSelectionUi]. */
-const val ENABLE_LANGUAGE_SELECTION_UI_DEFAULT_VALUE = true
-
 /**
  * Qualifier for the feature flag corresponding to enabling the extra topic tabs: practice and info.
  */