170476 Implementation of PR base expiration validation on specific branch only (#4862)

Implemented logic to validate PR base expiration on specific branch only

require configuration change from:
```
base_commit_allowed_days: 7
```
to:
```
base_commit_expiration:
  branch: "main"
  allowed_days: 7
```

Issue: flutter/flutter#170476

Author: ievdokdm

app_dart/integration_test/data/cocoon_config.json

@@ -160,7 +160,9 @@
     },
     {
       "name": "Linux ci_yaml roller",
-      "backfill": false,
+      "properties": {
+        "backfill": "false"
+      },
       "runIf": [
         ".ci.yaml"
       ],

auto_submit/lib/configuration/repository_configuration.dart

@@ -21,7 +21,8 @@ class RepositoryConfiguration {
   static const String supportNoReviewRevertKey = 'support_no_review_revert';
   static const String requiredCheckRunsOnRevertKey =
       'required_checkruns_on_revert';
-  static const String baseCommitAllowedDaysKey = 'base_commit_allowed_days';
+  static const String stalePrProtectionInDaysForBaseRefsKey =
+      'stale_pr_protection_in_days_for_base_refs';
 
   static const String defaultBranchStr = 'default';
 
@@ -34,7 +35,7 @@ class RepositoryConfiguration {
     bool? runCi,
     bool? supportNoReviewReverts,
     Set<String>? requiredCheckRunsOnRevert,
-    int? baseCommitAllowedDays,
+    Map<String, int>? stalePrProtectionInDaysForBaseRefs,
   }) : allowConfigOverride = allowConfigOverride ?? false,
        defaultBranch = defaultBranch ?? defaultBranchStr,
        autoApprovalAccounts = autoApprovalAccounts ?? <String>{},
@@ -43,7 +44,8 @@ class RepositoryConfiguration {
        runCi = runCi ?? true,
        supportNoReviewReverts = supportNoReviewReverts ?? true,
        requiredCheckRunsOnRevert = requiredCheckRunsOnRevert ?? <String>{},
-       baseCommitAllowedDays = baseCommitAllowedDays ?? 0;
+       stalePrProtectionInDaysForBaseRefs =
+           stalePrProtectionInDaysForBaseRefs ?? <String, int>{};
 
   /// This flag allows the repository to override the org level configuration.
   bool allowConfigOverride;
@@ -74,9 +76,9 @@ class RepositoryConfiguration {
   /// merged.
   Set<String> requiredCheckRunsOnRevert;
 
-  /// The number of days that the base commit of the pull request can not be
-  /// older than. If less than 1 then it will not be checked.
-  int baseCommitAllowedDays;
+  /// A map of [slug]/[branch] as a key and number of days to validate PR base
+  /// date is not older than on that [slug]/[branch].
+  Map<String, int> stalePrProtectionInDaysForBaseRefs;
 
   @override
   String toString() {
@@ -95,7 +97,13 @@ class RepositoryConfiguration {
     for (var checkrun in requiredCheckRunsOnRevert) {
       stringBuffer.writeln('  - $checkrun');
     }
-    stringBuffer.writeln('$baseCommitAllowedDaysKey: $baseCommitAllowedDays');
+    if (stalePrProtectionInDaysForBaseRefs.isNotEmpty) {
+      stringBuffer.writeln('$stalePrProtectionInDaysForBaseRefsKey:');
+      for (final MapEntry(key: branch, value: days)
+          in stalePrProtectionInDaysForBaseRefs.entries) {
+        stringBuffer.writeln('  $branch: $days');
+      }
+    }
     return stringBuffer.toString();
   }
 
@@ -124,6 +132,27 @@ class RepositoryConfiguration {
       }
     }
 
+    final stalePrProtectionInDaysForBaseRefs = <String, int>{};
+    final yamlstalePrProtectionInDaysForBaseRefs =
+        yamlDoc[stalePrProtectionInDaysForBaseRefsKey] as YamlMap?;
+    if (yamlstalePrProtectionInDaysForBaseRefs != null) {
+      for (var entry in yamlstalePrProtectionInDaysForBaseRefs.entries) {
+        if (entry.value is! int) {
+          throw ConfigurationException(
+            'The value for ${entry.key} must be an integer.',
+          );
+        }
+        if (entry.value as int <= 0) {
+          throw ConfigurationException(
+            'The value for ${entry.key} must be greater than zero.',
+          );
+        }
+
+        stalePrProtectionInDaysForBaseRefs[entry.key as String] =
+            entry.value as int;
+      }
+    }
+
     return RepositoryConfiguration(
       allowConfigOverride: yamlDoc[allowConfigOverrideKey] as bool?,
       defaultBranch: yamlDoc[defaultBranchKey] as String?,
@@ -133,7 +162,7 @@ class RepositoryConfiguration {
       runCi: yamlDoc[runCiKey] as bool?,
       supportNoReviewReverts: yamlDoc[supportNoReviewRevertKey] as bool?,
       requiredCheckRunsOnRevert: requiredCheckRunsOnRevert,
-      baseCommitAllowedDays: yamlDoc[baseCommitAllowedDaysKey] as int?,
+      stalePrProtectionInDaysForBaseRefs: stalePrProtectionInDaysForBaseRefs,
     );
   }
 }

auto_submit/lib/configuration/repository_configuration_manager.dart

@@ -141,7 +141,8 @@ class RepositoryConfigurationManager {
       runCi: globalConfiguration.runCi,
       supportNoReviewReverts: globalConfiguration.supportNoReviewReverts,
       requiredCheckRunsOnRevert: globalConfiguration.requiredCheckRunsOnRevert,
-      baseCommitAllowedDays: globalConfiguration.baseCommitAllowedDays,
+      stalePrProtectionInDaysForBaseRefs:
+          globalConfiguration.stalePrProtectionInDaysForBaseRefs,
     );
 
     // auto approval accounts, they should be empty if nothing was defined
@@ -187,13 +188,12 @@ class RepositoryConfigurationManager {
       );
     }
 
-    // if the local configuration is not the default value then use it.
-    // Can be setted to negative value in local configuration to turn-off
-    // base commit allowed days validation.
-    final localBaseCommitAllowedDays = localConfiguration.baseCommitAllowedDays;
-    if (localBaseCommitAllowedDays != 0) {
-      mergedRepositoryConfiguration.baseCommitAllowedDays =
-          localConfiguration.baseCommitAllowedDays;
+    // if the local configuration is not empty then use it.
+    final localstalePrProtectionInDaysForBaseRefs =
+        localConfiguration.stalePrProtectionInDaysForBaseRefs;
+    if (localstalePrProtectionInDaysForBaseRefs.isNotEmpty) {
+      mergedRepositoryConfiguration.stalePrProtectionInDaysForBaseRefs =
+          localConfiguration.stalePrProtectionInDaysForBaseRefs;
     }
 
     return mergedRepositoryConfiguration;

auto_submit/lib/validations/base_commit_date_allowed.dart

@@ -29,18 +29,31 @@ class BaseCommitDateAllowed extends Validation {
       slug,
     );
 
-    // If the base commit allowed days is less than or equal to 0 then the
-    // validation is turned off and the base commit creation date is ignored.
-    if (repositoryConfiguration.baseCommitAllowedDays <= 0) {
+    // If the base_commit_expiration is empty then the validation is turned off
+    // and the base commit creation date is ignored.
+    if (repositoryConfiguration.stalePrProtectionInDaysForBaseRefs.isEmpty) {
+      log.info('PR base commit creation date validation turned off');
+      return ValidationResult(
+        true,
+        Action.IGNORE_FAILURE,
+        'PR base commit creation date validation turned off',
+      );
+    }
+
+    // Check if PR base expiration validation is configured for this branch.
+    if (!repositoryConfiguration.stalePrProtectionInDaysForBaseRefs.containsKey(
+      '${slug.fullName}/${messagePullRequest.base!.ref}',
+    )) {
       log.info(
-        'PR base commit creation date validation turned off by setting '
-        'base_commit_allowed_days to ${repositoryConfiguration.baseCommitAllowedDays}.',
+        'PR ${slug.fullName}/${messagePullRequest.number} is for branch: '
+        '${messagePullRequest.base!.ref} which does not match any configured PR '
+        'base for stale protection',
       );
       return ValidationResult(
         true,
         Action.IGNORE_FAILURE,
-        'PR base commit creation date validation turned off by setting '
-        'base_commit_allowed_days to ${repositoryConfiguration.baseCommitAllowedDays}.',
+        'The base commit expiration validation is not configured for this '
+        'branch.',
       );
     }
 
@@ -61,23 +74,26 @@ class BaseCommitDateAllowed extends Validation {
     }
 
     log.info(
-      'PR ${slug.fullName}/${messagePullRequest.number} base creation date is: '
-      '${commit.commit?.author?.date}. Allowed age is '
-      '${repositoryConfiguration.baseCommitAllowedDays} days.',
+      'PR ${slug.fullName}/${messagePullRequest.number} requested for branch: '
+      '${messagePullRequest.base!.ref} with base creation date: '
+      '${commit.commit?.author?.date}.',
     );
 
     final isBaseRecent = commit.commit!.author!.date!.isAfter(
       DateTime.now().subtract(
-        Duration(days: repositoryConfiguration.baseCommitAllowedDays),
+        Duration(
+          days: repositoryConfiguration
+              .stalePrProtectionInDaysForBaseRefs['${slug.fullName}/${messagePullRequest.base!.ref}']!,
+        ),
       ),
     );
 
     final message = isBaseRecent
         ? 'The base commit of the PR is recent enough for merging.'
         : 'The base commit of the PR is older than '
-              '${repositoryConfiguration.baseCommitAllowedDays} days and can not '
-              'be merged. Please merge the latest changes from the main into '
-              'this branch and resubmit the PR.';
+              '${repositoryConfiguration.stalePrProtectionInDaysForBaseRefs['${slug.fullName}/${messagePullRequest.base!.ref}']} '
+              'days and can not be merged. Please merge the latest changes '
+              'from the main into this branch and resubmit the PR.';
 
     return ValidationResult(isBaseRecent, Action.REMOVE_LABEL, message);
   }

auto_submit/test/configuration/repository_configuration_data.dart

@@ -45,5 +45,7 @@ const String sampleConfigWithOverride = '''
   support_no_review_revert: true
   required_checkruns_on_revert:
     - ci.yaml validation
-  base_commit_allowed_days: 7
+  stale_pr_protection_in_days_for_base_refs:
+    flutter/flutter/main: 7
+    flutter/cocoon/main: 30
 ''';