module Postspec
  class Environment
    attr_reader :postspec
    forward_to :postspec, :conn, :render

    def uids() table_sequence_ids end # FIXME: What is this? And why not using @uids?

    def initialize(postspec)
      @postspec = postspec
    end

    def table_sequence_ids(all: false)
      conn.map \
        "select table_uid, record_id from postspec.table_sequence_ids()" +
        (all ? "" : " where record_id is not null")
    end

    def table_seed_ids
      conn.map "select table_uid, record_id from postspec.seeds"
    end

    def table_max_ids
      result = table_sequence_ids(all: true)
      postspec.type.tables.select(&:subtable?).each { |table| 
        result[table.uid] = result[table.supertable.uid] or raise "Oops"
      }
      result
    end

    # Returns map from table UID to record ID of the last record to be kept so
    # that 'delete from table_uid where id > record_id' does the right thing.
    # Note: This assumes that the change triggers has been installed beforehand
    def dirty_tables
      seed_ids = table_seed_ids
      table_max_ids.map { |table_uid, record_id|
        (seed_id = seed_ids[table_uid]) ? [table_uid, seed_id] : [table_uid, record_id]
      }.compact.to_h
    end

    def create()
#     puts "Environment#create"
      conn.execute IO.read(Postspec::SHARE_DIR + "/postspec_schema.sql")
      conn.execute render.change_triggers(:create)
    end

    def drop()
#     puts "Environment#drop"
      conn.execute "drop schema if exists postspec cascade"
    end

    def exist?()
      conn.exist? "select 1 from pg_namespace where nspname = 'postspec'"
    end

    # Removes excess data and meta data, and resets sequences. It doens't change any triggers
    def clean
#     puts "Environment#clean"
      @uids = {}
      user_tables = dirty_tables
      postspec_tables = CHANGE_TABLE_UIDS
      sql = render.delete_tables(user_tables) +
            render.delete_tables(postspec_tables)
      conn.execute render.execution_unit(user_tables.keys, sql)
    end

    def setup(mode) 
#     puts "Environment#setup"
      sql = 
          case mode
            when :seed
              @uids = table_max_ids
              render.seed_triggers(:create, @uids)
            when :empty
              @uids = {}
              []
          else
            raise ArgumentError
          end
      conn.execute sql
    end

    def teardown(mode)
#     puts "Environment#teardown"
      @uids = nil
      tables, reset_sql = reset_data
      sql =
          case mode
            when :seed; render.seed_triggers(:drop) + render.delete_tables(SEED_TABLE_UIDS)
            when :empty; []
          else
            raise ArgumentError
          end + reset_sql
      conn.execute render.execution_unit(tables, sql)
    end

    def reset() 
#     puts "Environment#reset"
      conn.execute render.execution_unit(*reset_data)
    end

  private
    # Generate SQL to delete data using the postspec.inserts table
    def reset_data
      uids = conn.map "select table_uid, min(record_id) from postspec.inserts group by table_uid"
      sql = render.delete_tables(uids) + render.delete_tables(CHANGE_TABLE_UIDS)
      [uids.keys, sql]
    end

    CHANGE_TABLE_UIDS = %w(postspec.inserts postspec.updates postspec.deletes)
    SEED_TABLE_UIDS = %w(postspec.seeds)
    RUN_TABLE_UIDS = %w(postspec.runs)
    TABLE_UIDS = CHANGE_TABLE_UIDS + SEED_TABLE_UIDS + RUN_TABLE_UIDS
  end
end

__END__




  class Environment
    attr_reader :postspec
    forward_to :postspec, :conn, :render

    attr_reader :uids # UID to ID map. Only used by the seed environment

    def user_tables() @tables ||= postspec.tables.map(&:uid) end

    CHANGE_TABLE_UIDS = %w(postspec.inserts postspec.updates postspec.deletes)
    SEED_TABLE_UIDS = %w(postspec.seeds)
    RUN_TABLE_UIDS = %w(postspec.runs)
    TABLE_UIDS = CHANGE_TABLE_UIDS + SEED_TABLE_UIDS + RUN_TABLE_UIDS

    def initialize(postspec)
      @postspec = postspec
      @uids = nil
      setup_schema if !exist_schema?
    end



    # setup(mode); teardown(mode) is a NOP

    def setup(mode) self.send :"setup_#{mode}_environment" end
    def teardown(mode) self.send :"teardown_#{mode}_environment" end
    def reset(mode, *type) self.send :"reset_#{mode}_environment", *type.compact end

    def setup_schema
      conn.execute(IO.read(SHARE_DIR + "/postspec_schema.sql"))
    end

    def teardown_schema
      conn.execute "drop schema if exists postspec cascade"
    end

    def reset_schema
      teardown_seed_environment
      teardown_empty_environment
    end

    def exist_schema?
      conn.exist? "select 1 from pg_namespace where nspname = 'postspec'"
    end

    def setup_change_environment
      conn.exec render.change_triggers(:create)
    end

    def teardown_change_environment
      sql = 
          render.change_triggers(:drop) +
          render.delete_tables(CHANGE_TABLE_UIDS)
      conn.exec render.execution_unit(CHANGE_TABLE_UIDS, sql)
    end

    # Not used - should be delegated to seed or empty environment
    # def reset_change_environment
    # end



    def setup_seed_environment()
      @uids = conn.map("select name, id from postspec.sequence_ids()")
      sql = render.seed_triggers(:create, uids)
      conn.exec sql
    end

    def teardown_seed_environment()
      @uids = nil
      uids = conn.map "select table_uid, min(record_id) from postspec.inserts"
      sql = 
          render.seed_triggers(:drop) +
          render.delete_tables(uids) + 
          render.delete_tables(CHANGE_TABLE_UIDS) +
          render.delete_tables(SEED_TABLE_UIDS)
      conn.exec render.execution_unit(uids.keys, sql)
    end

    def reset_seed_environment
      uids = conn.map "select table_uid, min(record_id) from postspec.inserts"
      sql = 
          render.delete_tables(uids) + 
          render.delete_tables(CHANGE_TABLE_UIDS)
      conn.exec render.execution_unit(uids.keys, sql)
    end


    def setup_empty_environment
      @uids = {}
      sql = render.delete_tables(user_tables + CHANGE_TABLE_UIDS)
      conn.exec render.execution_unit(tables, sql)
    end

    def teardown_empty_environment
      @uids = nil
    end

    def reset_empty_environment
      # Because we know the initial environment was empty we only need to
      # inspect the postspect.inserts tables to find records to delete
      changed_tables = conn.values "select distinct table_uid from inserts"
      sql = render.delete_tables(changed_tables + CHANGE_TABLE_UIDS)
      conn.exec render.execution_unit(tables, sql)
    end
  end
end

__END__

    end

    def drop

  class PostspecEnvironment
    attr_reader :postspec
    forward_to :postspec, :conn, :render

    def initialize(postspec)
      @postspec = postspec
      self.ensure
    end

    def self.instance(postspec)
      @instance ||= PostspecEnvironment.new(postspec)
    end

    def create
    end

    def drop
    end

    def reset
      State.reset(postspec)
    end

    def ensure
      if !postspec.meta.schemas.key?("postspec")
        create
      else
        # meta knows about the postspec schema so we hide it
        postspec.meta.schemas["postspec"].hidden = true
        reset
      end
    end

  private
    @instance = nil
  end

  class Environment
    attr_reader :postspec_environment
    attr_reader :state

    forward_to :postspec_environment, :postspec, :conn, :render

    # :call-seq:
    #   ::new(postspec, state)
    #   ::new(postspec, mode)
    def self.new(postspec, arg)
      klass = 
          case mode
            when :seed; SeedEnvironment
            when :empty; EmptyEnvironment
          else
            KeepEnvironment
          end
      object = klass.allocate
      state = arg.is_state? ? arg : State.create(postspec, arg)
      object.send(:initialize, PostspecEnvironment.instance(postspec), state)
      object
    end

    def terminate
      state.write
    end

    def create() raise NotThis end
    def drop() raise NotThis end
    def reset() postspec_environment.reset end

  protected
    def initialize(postspec_environment, state)
      @postspec_environment = postspec_environment
      @state = state
    end
  end

  class SeedEnvironment < Environment
    def create
      uids = @conn.map("select name, id from postspec.sequence_ids()", :name)
      conn.exec render.seed_triggers(:create, uids)
      conn.exec "delete from postspec.seeds"
    end

    def drop
      conn.exec render.seed_triggers(:drop)
      conn.exec "delete from postspec.seeds"
    end

    def reset # TODO: Merge with PgGraph::Data::SqlRender
    end
  end

  class EmptyEnvironment < Environment
    def create() end
    def drop() end

    def reset
      super
      conn.exec state.inserts.keys.map { |uid| "delete from #{uid}" }
    end
  end

  class KeepEnvironment < Environment
  end
end

__END__

  class Environment
    attr_reader :postspec
    attr_reader :id
    attr_reader :mode
    attr_accessor :status
    def duration() @duraction ||= Time.now - created_at end
    attr_reader :created_at

    forward_to :postspec, :conn

    def initialize(postspec, id, mode, status, duration, created_at)
      @postspec = postspec
      @id = id
      @mode = mode
      @status = status
      @duration = duration
      @created_at = created_at
    end

    def update
      sql = %(
        update postspec.runs 
            set status = #{status}, 
                duration = #{duration}
            where id = #{id}
      )
      conn.exec(sql)
    end

    def self.create(conn, mode)
      sql = %(
        insert into postspec.runs (mode) values ('#{mode}') returning id, created_at
      )
      id, created_at = @conn.tuple(sql)
      State.new(conn, id, mode, nil, nil, created_at)
    end

    def self.read_last(conn)
      sql = %(
        select id, mode, status, duration, created_at
        from postspec.runs
        order by desc id
        limit 1
      )
      tuple = @conn.tuples(sql).first
      tuple && State.new(conn, *tuple)
    end
  end

  class SeedEnvironment < Environment
    def initialize(postspec, id, mode, status, duration, created_at)
    end
    def create
      super
      conn.execute(render.readonly_triggers(:create, ids)
    end

    def update
    end

    def drop
      conn.execute(render.readonly_triggers(:drop, ids)
    end
  end

  class EmptyEnvironment < Environment
    def create
      super
      conn.execute(render.delete_tables(postspec.tables.map(&:uid))
    end

    def update
    end

    def drop
    end
  end

  class KeepEnvironment < Environment
  end





  class Environment
    attr_reader :postspec
    attr_reader :state
    forward_to :postspec, :conn, :meta, :render

    def initialize(postspec, mode) 
      @postspec = postspec
      @state = State.create(postspec.conn, mode)

      last_state 

    end

    def create()
      if meta.schemas.key?("postspec")
        # meta knows about the postspec schema so we hide it
        meta.schemas["postspec"].hidden = true
#       @conn.execute render.delete_postspec_tables
      else
        # meta doesn't know about the postspec schema
        conn.execute(IO.read(SHARE_DIR + "/postspec_schema.sql"))
      end
      conn.execute(render.change_triggers(:create))
    end

    def reset()
      conn.execute(render.reset_postspec_tables)
    end
      
    def drop()
      conn.execute(render.change_triggers(:drop))
      conn.execute("drop schema postspec cascade")
    end
  end

  class SeedEnvironment < Environment
    def create
      super
      conn.execute(render.readonly_triggers(:create, ids)
    end

    def update
    end

    def drop
      conn.execute(render.readonly_triggers(:drop, ids)
    end
  end

  class EmptyEnvironment < Environment
    def create
      super
      conn.execute(render.delete_tables(postspec.tables.map(&:uid))
    end

    def update
    end

    def drop
    end
  end

  class KeepEnvironment < Environment
  end
end