module PgsqlStats
  class Table
    include PgsqlStats::Parsing
    include ActionView::Helpers::NumberHelper
    
    attr_accessor :oid, :schema_name, :name, :sequential_scans, :rows_fetched,
      :index_scans, :index_rows_fetched, :inserts, :updates, :deletes,
      :vacuumed_at, :autovacuumed_at, :analyzed_at, :autoanalyzed_at,
      :blocks_read, :cache_hits, :index_blocks_read, :index_cache_hits,
      :toast_blocks_read, :toast_cache_hits, :toast_index_blocks_read, :toast_index_cache_hits

    attr_accessor :analysis

    def initialize(connection, row, io_row)
      @connection = connection
      @analysis = nil
      load(row)
      load_io(io_row)
    end
    
    def refresh
      @connection.transaction do
        load(@connection.select_one("SELECT * FROM pg_stat_all_tables WHERE relid = #{oid}"))
        load_io(@connection.select_one("SELECT * FROM pg_statio_all_tables WHERE relid = #{oid}"))
      end
      @analysis = nil
      @pages = nil
      @indexes = nil
    end
    
    def indexes
      unless @indexes
        old_conn, Collector.connection = Collector.connection, @connection
        @indexes = Collector.all_indexes(oid)
        Collector.connection = old_conn
      end
      @indexes
    end
    
    def cache_hit_rate
      cache_hits.to_f / (blocks_read + cache_hits) * 100
    end
    
    def index_cache_hit_rate
      index_cache_hits.to_f / (index_blocks_read + index_cache_hits) * 100
    end
    
    def toast_cache_hit_rate
      toast_cache_hits.to_f / (toast_blocks_read + toast_cache_hits) * 100
    end
    
    def toast_index_cache_hit_rate
      toast_index_cache_hits.to_f / (toast_index_blocks_read + toast_index_cache_hits) * 100
    end
    
    def pages
      @pages ||= @connection.select_one("SELECT SUM(relpages) FROM pg_class WHERE relname = '#{name}'")["sum"].to_i
    end
    
    private
    
    def load(row)
      self.oid = row["relid"].to_i
      self.schema_name = row["schemaname"]
      self.name = row["relname"]
      self.sequential_scans = row["seq_scan"].to_i
      self.rows_fetched = row["seq_tup_read"].to_i
      self.index_scans = row["idx_scan"].to_i
      self.index_rows_fetched = row["idx_tup_fetch"].to_i
      self.inserts = row["n_tup_ins"].to_i
      self.updates = row["n_tup_upd"].to_i
      self.deletes = row["n_tup_del"].to_i
      self.vacuumed_at = parse_time(row["last_vacuum"])
      self.autovacuumed_at = parse_time(row["last_autovacuum"])
      self.analyzed_at = parse_time(row["last_analyze"])
      self.autoanalyzed_at = parse_time(row["last_autoanalyze"])
    end
    
    def load_io(row)
      self.blocks_read = row["heap_blks_read"].to_i
      self.cache_hits = row["heap_blks_hit"].to_i
      self.index_blocks_read = row["idx_blks_read"].to_i
      self.index_cache_hits = row["idx_blks_hit"].to_i
      self.toast_blocks_read = row["toast_blks_read"].to_i
      self.toast_cache_hits = row["toast_blks_hit"].to_i
      self.toast_index_blocks_read = row["tidx_blks_read"].to_i
      self.toast_index_cache_hits = row["tidx_blks_hit"].to_i
    end
  end
end