# frozen_string_literal: true

ArJdbc.load_java_part :MySQL

require 'bigdecimal'
require 'active_record/connection_adapters/abstract_mysql_adapter'
require 'active_record/connection_adapters/abstract/schema_definitions'
require 'arjdbc/abstract/core'
require 'arjdbc/abstract/connection_management'
require 'arjdbc/abstract/database_statements'
require 'arjdbc/abstract/statement_cache'
require 'arjdbc/abstract/transaction_support'

module ActiveRecord
  module ConnectionAdapters
    AbstractMysqlAdapter.class_eval do
      include ArJdbc::Abstract::Core # to have correct initialize() super
    end

    # Remove any vestiges of core/Ruby MySQL adapter
    remove_const(:Mysql2Adapter) if const_defined?(:Mysql2Adapter)

    class Mysql2Adapter < AbstractMysqlAdapter
      ADAPTER_NAME = 'Mysql2'

      include Jdbc::ConnectionPoolCallbacks

      include ArJdbc::Abstract::ConnectionManagement
      include ArJdbc::Abstract::DatabaseStatements
      # NOTE: do not include MySQL::DatabaseStatements
      include ArJdbc::Abstract::StatementCache
      include ArJdbc::Abstract::TransactionSupport

      include ArJdbc::MySQL

      def initialize(connection, logger, connection_options, config)
        superclass_config = config.reverse_merge(prepared_statements: false)
        super(connection, logger, connection_options, superclass_config)

        # configure_connection taken care of at ArJdbc::Abstract::Core
      end

      def self.database_exists?(config)
        conn = ActiveRecord::Base.mysql2_connection(config)
        conn && conn.really_valid?
      rescue ActiveRecord::NoDatabaseError
        false
      ensure
        conn.disconnect! if conn
      end

      def check_version
        # for JNDI, don't check version as the whole connection should be lazy
        return if ::ActiveRecord::ConnectionAdapters::JdbcConnection.jndi_config?(config)

        super
      end

      def supports_json?
        !mariadb? && database_version >= '5.7.8'
      end

      def supports_comments?
        true
      end

      def supports_comments_in_create?
        true
      end

      def supports_savepoints?
        true
      end

      def supports_lazy_transactions?
        true
      end

      def supports_transaction_isolation?
        true
      end

      def supports_set_server_option?
        false
      end

      # HELPER METHODS ===========================================

      # from MySQL::DatabaseStatements
      READ_QUERY = ActiveRecord::ConnectionAdapters::AbstractAdapter.build_read_query_regexp(
        :desc, :describe, :set, :show, :use
      ) # :nodoc:
      private_constant :READ_QUERY

      def write_query?(sql) # :nodoc:
        !READ_QUERY.match?(sql)
      end

      def explain(arel, binds = [])
        sql     = "EXPLAIN #{to_sql(arel, binds)}"
        start   = Concurrent.monotonic_time
        result  = exec_query(sql, "EXPLAIN", binds)
        elapsed = Concurrent.monotonic_time - start

        MySQL::ExplainPrettyPrinter.new.pp(result, elapsed)
      end

      # Reloading the type map in abstract/statement_cache.rb blows up postgres
      def clear_cache!
        # FIXME: This seems to have disappeared in Rails 7?
        # reload_type_map
        super
      end

      def each_hash(result) # :nodoc:
        if block_given?
          # FIXME: This is C in mysql2 gem and I just made simplest Ruby
          result.each do |row|
            new_hash = {}
            row.each { |k, v| new_hash[k.to_sym] = v }
            yield new_hash
          end
        else
          to_enum(:each_hash, result)
        end
      end

      def error_number(exception)
        exception.error_code if exception.is_a?(JDBCError)
      end

      #--
      # QUOTING ==================================================
      #+

      # FIXME: 5.1 crashes without this.  I think this is Arel hitting a fallback path in to_sql.rb.
      # So maybe an untested code path in their source.  Still means we are doing something wrong to
      # even hit it.
      def quote(value, comment=nil)
        super(value)
      end

      # NOTE: quote_string(string) provided by ArJdbc::MySQL (native code),
      # this piece is also native (mysql2) under MRI: `@connection.escape(string)`

      def quoted_date(value)
        if supports_datetime_with_precision?
          super
        else
          super.sub(/\.\d{6}\z/, '')
        end
      end

      def _quote(value)
        if value.is_a?(Type::Binary::Data)
          "x'#{value.hex}'"
        else
          super
        end
      end
      private :_quote

      #--
      # CONNECTION MANAGEMENT ====================================
      #++

      alias :reset! :reconnect!

      #

      private

      # e.g. "5.7.20-0ubuntu0.16.04.1"
      def full_version
        schema_cache.database_version.full_version_string
      end

      def get_full_version
        @full_version ||= @connection.full_version
      end

      def jdbc_connection_class(spec)
        ::ActiveRecord::ConnectionAdapters::MySQLJdbcConnection
      end

      def jdbc_column_class
        ::ActiveRecord::ConnectionAdapters::MySQL::Column
      end

      # defined in MySQL::DatabaseStatements which is not included
      def default_insert_value(column)
        super unless column.auto_increment?
      end

      # FIXME: optimize insert_fixtures_set by using JDBC Statement.addBatch()/executeBatch()

      def combine_multi_statements(total_sql)
        if total_sql.length == 1
          total_sql.first
        else
          total_sql
        end
      end
    end
  end
end