require 'support/matchers/base'

module ChronoTest::Matchers

  module Table
    class Base < ChronoTest::Matchers::Base

      protected
        # Database statements
        #
        def relation_exists?(options)
          schema = options[:in]
          kind   = options[:kind] == :view ? 'v' : 'r'

          select_value(<<-SQL, [ table, schema ], 'Check table exists') == 't'
            SELECT EXISTS (
              SELECT 1
                FROM pg_class c
                LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
               WHERE c.relkind = '#{kind}'
                 AND c.relname = $1
                 AND n.nspname = $2
            )
          SQL
        end
    end

    # ##################################################################
    # Checks that a table exists in the Public schema
    #
    class HavePublicBacking < Base
      def matches?(table)
        super(table)

        relation_exists? :in => public_schema
      end

      def description
        'be in the public schema'
      end

      def failure_message_for_should
        "expected #{table} to exist in the #{public_schema} schema"
      end
    end

    def have_public_backing
      HavePublicBacking.new
    end


    # ##################################################################
    # Checks that a table exists in the Temporal schema
    #
    class HaveTemporalBacking < Base
      def matches?(table)
        super(table)

        relation_exists? :in => temporal_schema
      end

      def description
        'be in the temporal schema'
      end

      def failure_message_for_should
        "expected #{table} to exist in the #{temporal_schema} schema"
      end
    end

    def have_temporal_backing
      HaveTemporalBacking.new
    end


    # ##################################################################
    # Checks that a table exists in the History schema and inherits from
    # the one in the Temporal schema
    #
    class HaveHistoryBacking < Base
      def matches?(table)
        super(table)

        table_exists?           &&
        inherits_from_temporal? &&
        has_consistency_constraint? &&
        has_history_indexes?
      end

      def description
        'be in history schema'
      end

      def failure_message_for_should
        "expected #{table} ".tap do |message|
          message << [
            ("to exist in the #{history_schema} schema"    unless @existance),
            ("to inherit from #{temporal_schema}.#{table}" unless @inheritance),
            ("to have a timeline consistency constraint"   unless @constraint),
            ("to have history indexes"                     unless @indexes)
          ].compact.to_sentence
        end
      end

      private
        def table_exists?
          @existance = relation_exists? :in => history_schema
        end

        def inherits_from_temporal?
          binds = ["#{history_schema}.#{table}", "#{temporal_schema}.#{table}"]

          @inheritance = select_value(<<-SQL, binds, 'Check inheritance') == 't'
            SELECT EXISTS (
              SELECT 1 FROM pg_catalog.pg_inherits
               WHERE inhrelid  = $1::regclass::oid
                 AND inhparent = $2::regclass::oid
            )
          SQL
        end

        def has_history_indexes?
          binds = [ history_schema, table ]

          indexes = select_values(<<-SQL, binds, 'Check history indexes')
            SELECT indexdef FROM pg_indexes
             WHERE schemaname = $1
               AND tablename  = $2
          SQL

          fqtn = [history_schema, table].join('.')

          expected = [
            "CREATE INDEX index_#{table}_temporal_on_lower_validity ON #{fqtn} USING btree (lower(validity))",
            "CREATE INDEX index_#{table}_temporal_on_upper_validity ON #{fqtn} USING btree (upper(validity))",
            "CREATE INDEX index_#{table}_temporal_on_validity ON #{fqtn} USING gist (validity)",

            "CREATE INDEX #{table}_inherit_pkey ON #{fqtn} USING btree (id)",
            "CREATE INDEX #{table}_instance_history ON #{fqtn} USING btree (id, recorded_at)",
            "CREATE UNIQUE INDEX #{table}_pkey ON #{fqtn} USING btree (hid)",
            "CREATE INDEX #{table}_recorded_at ON #{fqtn} USING btree (recorded_at)",
            "CREATE INDEX #{table}_timeline_consistency ON #{fqtn} USING gist (id, validity)"
          ]

          @indexes = (expected - indexes).empty?
        end

        def has_consistency_constraint?
          binds = [
            connection.timeline_consistency_constraint_name(table), # conname
            history_schema,                                         # connamespace
            [history_schema, table].join('.'),                      # conrelid, attrelid
            connection.primary_key(table)                           # attnum
          ]

          @constraint = select_value(<<-SQL, binds, 'Check Consistency Constraint') == 't'
            SELECT EXISTS (
              SELECT 1 FROM pg_catalog.pg_constraint
              WHERE conname = $1
                AND contype = 'x'
                AND conrelid = $3::regclass
                AND connamespace = (
                  SELECT oid FROM pg_catalog.pg_namespace WHERE nspname = $2
                )
                AND conkey = (
                  SELECT array_agg(attnum) FROM pg_catalog.pg_attribute
                  WHERE attname IN ($4, 'validity')
                    AND attrelid = $3::regclass
                )
            )
          SQL
        end
    end

    def have_history_backing
      HaveHistoryBacking.new
    end


    # ##################################################################
    # Checks that a table exists in the Public schema, is an updatable
    # view and has an INSERT, UPDATE and DELETE triggers.
    #
    class HavePublicInterface < Base
      def matches?(table)
        super(table)

        view_exists? && [ is_updatable?, has_triggers? ].all?
      end

      def description
        'be an updatable view'
      end

      def failure_message_for_should
        "expected #{table} ".tap do |message|
          message << [
            ("to exist in the #{public_schema} schema" unless @existance     ),
            ('to be an updatable view'                 unless @updatable     ),
            ('to have an INSERT trigger'               unless @insert_trigger),
            ('to have an UPDATE trigger'               unless @update_trigger),
            ('to have a DELETE trigger'                unless @delete_trigger)
          ].compact.to_sentence
        end
      end

      private
        def view_exists?
          @existance = relation_exists? :in => public_schema, :kind => :view
        end

        def is_updatable?
          binds = [ public_schema, table ]

          @updatable = select_value(<<-SQL, binds, 'Check updatable') == 'YES'
            SELECT is_updatable FROM information_schema.views
             WHERE table_schema = $1 AND table_name = $2
          SQL
        end

        def has_triggers?
          triggers = select_values(<<-SQL, [ public_schema, table ], 'Check triggers')
            SELECT t.tgname
              FROM pg_catalog.pg_trigger t, pg_catalog.pg_class c, pg_catalog.pg_namespace n
             WHERE t.tgrelid = c.relfilenode
               AND n.oid = c.relnamespace
               AND n.nspname = $1
               AND c.relname = $2;
          SQL

          @insert_trigger = triggers.include? 'chronomodel_insert'
          @update_trigger = triggers.include? 'chronomodel_update'
          @delete_trigger = triggers.include? 'chronomodel_delete'

          @insert_trigger && @update_trigger && @delete_trigger
        end
    end

    def have_public_interface
      HavePublicInterface.new
    end
  end

end