# frozen_string_literal: true

module ActiveRecord
  module ConnectionAdapters
    module SQLite3
      module SchemaStatements # :nodoc:
        # Returns an array of indexes for the given table.
        def indexes(table_name)
          exec_query("PRAGMA index_list(#{quote_table_name(table_name)})", "SCHEMA").map do |row|
            # Indexes SQLite creates implicitly for internal use start with "sqlite_".
            # See https://www.sqlite.org/fileformat2.html#intschema
            next if row["name"].starts_with?("sqlite_")

            index_sql = query_value(<<~SQL, "SCHEMA")
              SELECT sql
              FROM sqlite_master
              WHERE name = #{quote(row['name'])} AND type = 'index'
              UNION ALL
              SELECT sql
              FROM sqlite_temp_master
              WHERE name = #{quote(row['name'])} AND type = 'index'
            SQL

            /\bON\b\s*"?(\w+?)"?\s*\((?<expressions>.+?)\)(?:\s*WHERE\b\s*(?<where>.+))?\z/i =~ index_sql

            columns = exec_query("PRAGMA index_info(#{quote(row['name'])})", "SCHEMA").map do |col|
              col["name"]
            end

            orders = {}

            if columns.any?(&:nil?) # index created with an expression
              columns = expressions
            else
              # Add info on sort order for columns (only desc order is explicitly specified,
              # asc is the default)
              if index_sql # index_sql can be null in case of primary key indexes
                index_sql.scan(/"(\w+)" DESC/).flatten.each { |order_column|
                  orders[order_column] = :desc
                }
              end
            end

            IndexDefinition.new(
              table_name,
              row["name"],
              row["unique"] != 0,
              columns,
              where: where,
              orders: orders
            )
          end.compact
        end

        def create_schema_dumper(options)
          SQLite3::SchemaDumper.create(self, options)
        end

        private
          def schema_creation
            SQLite3::SchemaCreation.new(self)
          end

          def create_table_definition(*args)
            SQLite3::TableDefinition.new(*args)
          end

          def new_column_from_field(table_name, field)
            default = \
              case field["dflt_value"]
              when /^null$/i
                nil
              when /^'(.*)'$/m
                $1.gsub("''", "'")
              when /^"(.*)"$/m
                $1.gsub('""', '"')
              else
                field["dflt_value"]
              end

            type_metadata = fetch_type_metadata(field["type"])
            Column.new(field["name"], default, type_metadata, field["notnull"].to_i == 0, table_name, nil, field["collation"])
          end

          def data_source_sql(name = nil, type: nil)
            scope = quoted_scope(name, type: type)
            scope[:type] ||= "'table','view'"

            sql = +"SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'"
            sql << " AND name = #{scope[:name]}" if scope[:name]
            sql << " AND type IN (#{scope[:type]})"
            sql
          end

          def quoted_scope(name = nil, type: nil)
            type = \
              case type
              when "BASE TABLE"
                "'table'"
              when "VIEW"
                "'view'"
              end
            scope = {}
            scope[:name] = quote(name) if name
            scope[:type] = type if type
            scope
          end
      end
    end
  end
end
