1 files changed, 143 insertions, 0 deletions
diff --git a/gems/gitlab-schema-validation/lib/gitlab/schema/validation/sources/structure_sql.rb b/gems/gitlab-schema-validation/lib/gitlab/schema/validation/sources/structure_sql.rb
new file mode 100644
index 00000000000..b2e3fcd63c5
--- /dev/null
+++ b/gems/gitlab-schema-validation/lib/gitlab/schema/validation/sources/structure_sql.rb
@@ -0,0 +1,143 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Schema
+    module Validation
+      module Sources
+        class StructureSql
+          DEFAULT_SCHEMA = 'public'
+
+          def initialize(structure_file_path, schema_name = DEFAULT_SCHEMA)
+            @structure_file_path = structure_file_path
+            @schema_name = schema_name
+          end
+
+          def index_exists?(index_name)
+            index = indexes.find { |index| index.name == index_name }
+
+            return false if index.nil?
+
+            true
+          end
+
+          def trigger_exists?(trigger_name)
+            trigger = triggers.find { |trigger| trigger.name == trigger_name }
+
+            return false if trigger.nil?
+
+            true
+          end
+
+          def foreign_key_exists?(foreign_key_name)
+            foreign_key = foreign_keys.find { |fk| fk.name == foreign_key_name }
+
+            return false if foreign_key.nil?
+
+            true
+          end
+
+          def table_exists?(table_name)
+            table = fetch_table_by_name(table_name)
+
+            return false if table.nil?
+
+            true
+          end
+
+          def fetch_table_by_name(table_name)
+            tables.find { |table| table.name == table_name }
+          end
+
+          def indexes
+            @indexes ||= map_with_default_schema(index_statements, SchemaObjects::Index)
+          end
+
+          def triggers
+            @triggers ||= map_with_default_schema(trigger_statements, SchemaObjects::Trigger)
+          end
+
+          def foreign_keys
+            @foreign_keys ||= foreign_key_statements.map do |stmt|
+              stmt.relation.schemaname = schema_name if stmt.relation.schemaname == ''
+
+              SchemaObjects::ForeignKey.new(Adapters::ForeignKeyStructureSqlAdapter.new(stmt))
+            end
+          end
+
+          def tables
+            @tables ||= table_statements.map do |stmt|
+              table_name = stmt.relation.relname
+              partition_stmt = stmt.partspec
+
+              columns = stmt.table_elts.select { |n| n.node == :column_def }.map do |column|
+                adapter = Adapters::ColumnStructureSqlAdapter.new(table_name, column.column_def, partition_stmt)
+                SchemaObjects::Column.new(adapter)
+              end
+
+              SchemaObjects::Table.new(table_name, columns)
+            end
+          end
+
+          private
+
+          attr_reader :structure_file_path, :schema_name
+
+          def index_statements
+            statements.filter_map { |s| s.stmt.index_stmt }
+          end
+
+          def trigger_statements
+            statements.filter_map { |s| s.stmt.create_trig_stmt }
+          end
+
+          def table_statements
+            statements.filter_map { |s| s.stmt.create_stmt }
+          end
+
+          def foreign_key_statements
+            constraint_statements(:CONSTR_FOREIGN)
+          end
+
+          # Filter constraint statement nodes
+          #
+          # @param constraint_type [Symbol] node type. One of CONSTR_PRIMARY, CONSTR_CHECK, CONSTR_EXCLUSION,
+          #        CONSTR_UNIQUE or CONSTR_FOREIGN.
+          def constraint_statements(constraint_type)
+            alter_table_statements(:AT_AddConstraint).filter do |stmt|
+              stmt.cmds.first.alter_table_cmd.def.constraint.contype == constraint_type
+            end
+          end
+
+          # Filter alter table statement nodes
+          #
+          # @param subtype [Symbol] node subtype +AT_AttachPartition+, +AT_ColumnDefault+ or +AT_AddConstraint+
+          def alter_table_statements(subtype)
+            statements.filter_map do |statement|
+              node = statement.stmt.alter_table_stmt
+
+              next unless node
+
+              node if node.cmds.first.alter_table_cmd.subtype == subtype
+            end
+          end
+
+          def statements
+            @statements ||= parsed_structure_file.tree.stmts
+          end
+
+          def parsed_structure_file
+            PgQuery.parse(File.read(structure_file_path))
+          end
+
+          def map_with_default_schema(statements, validation_class)
+            statements.map do |statement|
+              statement.relation.schemaname = schema_name if statement.relation.schemaname == ''
+
+              validation_class.new(statement)
+            end
+          end
+        end
+      end
+    end
+  end
+end