# frozen-string-literal: true

Sequel::JDBC.load_driver('org.h2.Driver', :H2)

module Sequel
  module JDBC
    Sequel.synchronize do
      DATABASE_SETUP[:h2] = proc do |db|
        db.extend(Sequel::JDBC::H2::DatabaseMethods)
        db.dataset_class = Sequel::JDBC::H2::Dataset
        org.h2.Driver
      end
    end

    module H2
      module DatabaseMethods
        def commit_prepared_transaction(transaction_id, opts=OPTS)
          run("COMMIT TRANSACTION #{transaction_id}", opts)
        end

        def database_type
          :h2
        end

        def freeze
          h2_version
          super
        end

        def h2_version
          @h2_version ||= get(Sequel.function(:H2VERSION))
        end

        def rollback_prepared_transaction(transaction_id, opts=OPTS)
          run("ROLLBACK TRANSACTION #{transaction_id}", opts)
        end

        # H2 uses an IDENTITY type for primary keys
        def serial_primary_key_options
          {:primary_key => true, :type => :identity, :identity=>true}
        end

        # H2 supports CREATE TABLE IF NOT EXISTS syntax
        def supports_create_table_if_not_exists?
          true
        end
      
        # H2 supports prepared transactions
        def supports_prepared_transactions?
          true
        end
        
        # H2 supports savepoints
        def supports_savepoints?
          true
        end
        
        private
        
        # H2 does not allow adding primary key constraints to NULLable columns.
        def can_add_primary_key_constraint_on_nullable_columns?
          false
        end

        # If the :prepare option is given and we aren't in a savepoint,
        # prepare the transaction for a two-phase commit.
        def commit_transaction(conn, opts=OPTS)
          if (s = opts[:prepare]) && savepoint_level(conn) <= 1
            log_connection_execute(conn, "PREPARE COMMIT #{s}")
          else
            super
          end
        end

        def alter_table_sql(table, op)
          case op[:op]
          when :add_column
            if (pk = op.delete(:primary_key)) || (ref = op.delete(:table))
              if pk
                op[:null] = false
              end

              sqls = [super(table, op)]

              if pk && (h2_version >= '1.4' || op[:type] != :identity)
                # H2 needs to add a primary key column as a constraint in this case
                sqls << "ALTER TABLE #{quote_schema_table(table)} ADD PRIMARY KEY (#{quote_identifier(op[:name])})"
              end

              if ref
                op[:table] = ref
                constraint_name = op[:foreign_key_constraint_name]
                sqls << "ALTER TABLE #{quote_schema_table(table)} ADD#{" CONSTRAINT #{quote_identifier(constraint_name)}" if constraint_name} FOREIGN KEY (#{quote_identifier(op[:name])}) #{column_references_sql(op)}"
              end

              sqls
            else
              super(table, op)
            end
          when :rename_column
            "ALTER TABLE #{quote_schema_table(table)} ALTER COLUMN #{quote_identifier(op[:name])} RENAME TO #{quote_identifier(op[:new_name])}"
          when :set_column_null
            "ALTER TABLE #{quote_schema_table(table)} ALTER COLUMN #{quote_identifier(op[:name])} SET#{' NOT' unless op[:null]} NULL"
          when :set_column_type
            if sch = schema(table)
              if cs = sch.each{|k, v| break v if k == op[:name]; nil}
                cs = cs.dup
                cs[:default] = cs[:ruby_default]
                op = cs.merge!(op)
              end
            end
            sql = "ALTER TABLE #{quote_schema_table(table)} ALTER COLUMN #{quote_identifier(op[:name])} #{type_literal(op)}".dup
            column_definition_order.each{|m| send(:"column_definition_#{m}_sql", sql, op)}
            sql
          when :drop_constraint
            if op[:type] == :primary_key
              "ALTER TABLE #{quote_schema_table(table)} DROP PRIMARY KEY"
            else
              super(table, op)
            end
          else
            super(table, op)
          end
        end
        
        # Default to a single connection for a memory database.
        def connection_pool_default_options
          o = super
          uri == 'jdbc:h2:mem:' ? o.merge(:max_connections=>1) : o
        end
      
        DATABASE_ERROR_REGEXPS = {
          /Unique index or primary key violation/ => UniqueConstraintViolation,
          /Referential integrity constraint violation/ => ForeignKeyConstraintViolation,
          /Check constraint violation/ => CheckConstraintViolation,
          /NULL not allowed for column/ => NotNullConstraintViolation,
          /Deadlock detected\. The current transaction was rolled back\./ => SerializationFailure,
        }.freeze
        def database_error_regexps
          DATABASE_ERROR_REGEXPS
        end

        # Use IDENTITY() to get the last inserted id.
        def last_insert_id(conn, opts=OPTS)
          statement(conn) do |stmt|
            sql = 'SELECT IDENTITY();'
            rs = log_connection_yield(sql, conn){stmt.executeQuery(sql)}
            rs.next
            rs.getLong(1)
          end
        end
        
        def primary_key_index_re
          /\Aprimary_key/i
        end

        # H2 does not support named column constraints.
        def supports_named_column_constraints?
          false
        end

        # Use BIGINT IDENTITY for identity columns that use :Bignum type
        def type_literal_generic_bignum_symbol(column)
          column[:identity] ? 'BIGINT IDENTITY' : super
        end
      end
      
      class Dataset < JDBC::Dataset
        ILIKE_PLACEHOLDER = ["CAST(".freeze, " AS VARCHAR_IGNORECASE)".freeze].freeze

        # Emulate the case insensitive LIKE operator and the bitwise operators.
        def complex_expression_sql_append(sql, op, args)
          case op
          when :ILIKE, :"NOT ILIKE"
            super(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), [SQL::PlaceholderLiteralString.new(ILIKE_PLACEHOLDER, [args[0]]), args[1]])
          when :&, :|, :^, :<<, :>>, :'B~'
            complex_expression_emulate_append(sql, op, args)
          else
            super
          end
        end
        
        # H2 does not support derived column lists
        def supports_derived_column_lists?
          false
        end

        # H2 requires SQL standard datetimes
        def requires_sql_standard_datetimes?
          true
        end

        # H2 doesn't support IS TRUE
        def supports_is_true?
          false
        end
        
        # H2 doesn't support JOIN USING
        def supports_join_using?
          false
        end
        
        # H2 doesn't support multiple columns in IN/NOT IN
        def supports_multiple_column_in?
          false
        end 

        private

        # H2 expects hexadecimal strings for blob values
        def literal_blob_append(sql, v)
          sql << "'" << v.unpack("H*").first << "'"
        end
        
        # H2 handles fractional seconds in timestamps, but not in times
        def literal_sqltime(v)
          v.strftime("'%H:%M:%S'")
        end

        # H2 supports multiple rows in INSERT.
        def multi_insert_sql_strategy
          :values
        end

        def select_only_offset_sql(sql)
          sql << " LIMIT -1 OFFSET "
          literal_append(sql, @opts[:offset])
        end

        # H2 supports quoted function names.
        def supports_quoted_function_names?
          true
        end
      end
    end
  end
end