### Execution Time
##  MJ, 2019-02-24, v0.1 
##  inspired by 'timeR' package https://cran.r-project.org/web/packages/timeR/index.html
##  github: https://github.com/mjaniec2013/ExecutionTime

library(R6)
library(glue)
library(data.table)



common_dir <- "m:/Programming/R/COMMON/"
source( paste0(common_dir, "Round2.R") )



ET <- R6Class("ET",
                         
  public = list(
    
    start = function( this_timer_keeper_name="" ) {
      
      private$time_keeper_start <- Sys.time()
      
      if (this_timer_keeper_name!="") {
        
        private$time_keeper_name <- this_timer_keeper_name
        
      }
      
      if (private$is_verbose)
      
        cat(glue("Starting timer: [{private$time_keeper_name}] @ {private$time_keeper_start}."), "\n")
      
    },
    
    elapsed = function() {
            	  
  	  if ( private$is_running() ) {
  	  
  		current_time <- Sys.time()
  			
  		  cat(glue( paste("Elapsed time for timer [{private$time_keeper_name}] started @ {private$time_keeper_start}",
  						  "- {Round2(difftime(current_time, private$time_keeper_start, units='auto'), 4)}") ), 
  			  "\n")
  	  	  
  	  } else {
  	
  		  return(NULL)
  		  
  	  }
      
    },
    
    eta = function() {
      
		  # TODO: 'eta' not implemented yet
      
    },
    
    stage = function( this_stage_name=NA ) {
          	  
	    if ( private$is_running(msg_stopped="Timer stopped. Cannot add stage.\n") ) {
      
  		  current_time <- Sys.time()
  		  
  		  stages_num   <- length(private$time_keeper_stages)
  		  
  		  if (is.na(this_stage_name)) {
  			
  			this_stage_name <- glue("Stage {as.character(stages_num+1)}")
			
		  }
		  
		  if (private$is_verbose)
		  
  			cat(glue( paste("Recording stage #{stages_num+1} [{this_stage_name}]",
  							"for [{private$time_keeper_name}] @ {current_time},",
  							"elapsed: {Round2(difftime(current_time, private$time_keeper_start, units='auto'), 4)}.") ), 
  					  "\n")
		  
		  private$time_keeper_stages[[stages_num+1]] <- 
			
			list(
			  
			  stage_time = current_time,
			  
			  stage_name = this_stage_name
			  
			)
		
	  } else {
	  
		  return(NULL)
	  
	  }
      
  },
    
    # 'short' - show recorded stages only
    stages = function( short=FALSE, time_stopped=FALSE ) {
      
      if ( private$is_running(msg_stopped=NULL) ) {
        
        stages_num   <- length(private$time_keeper_stages)
        
        if (short) {
          
          cat( glue("{stages_num} stage(s) recorded:"), "\n\n" )
          
        } else {
          
          cat( glue("{stages_num} stage(s) recorded for [{private$time_keeper_name}] started @ {private$time_keeper_start}:"), "\n\n" )
          
        }
        
        if (stages_num>0) {
          
          # stages table construction:
          
            stages_tbl <-
            
              data.table( 
                
                stage_name      = 
                  
                  sapply(private$time_keeper_stages, function(x) x$stage_name),
                
                stage_time      = 
                  
                  sapply(private$time_keeper_stages, function(x) as.character(x$stage_time)),
                
                time_from_prev =
                  
                  round(as.numeric(diff(c(private$time_keeper_start, sapply(private$time_keeper_stages, function(x) x$stage_time)), unit="secs")), 2),
                
                time_from_start = 
                  
                  round(sapply(private$time_keeper_stages, 
                         function(x) 
                           as.numeric(difftime(x$stage_time, private$time_keeper_start, unit="secs"))), 2) 
                
              )
            
            if (time_stopped) {
              
              stages_tbl[, time_to_next :=
                            
                              round(as.numeric(diff(c(sapply(private$time_keeper_stages, function(x) x$stage_time), private$time_keeper_stop), unit="secs")), 2)]
              
              stages_tbl[, time_share := round(time_to_next/sum(time_to_next)*100, 2)]
              
            }
            
            # print(stages_tbl)
            
            return(stages_tbl[])
          
        }
        
      } else {
        
        return(NULL)
        
      }
      
    },
    
    stop = function() {
      
      current_time             <- Sys.time()
      
      private$time_keeper_stop <- current_time
      
      cat( glue("Timer [{private$time_keeper_name}] started @ {private$time_keeper_start} stopped @ {private$time_keeper_stop} - time: {Round2(difftime(private$time_keeper_stop, private$time_keeper_start), 2)}"), "\n\n" )
      
      self$stages(short=TRUE, time_stopped=TRUE)
      
    },
    
    verbose = function() {
      
      private$is_verbose <- !private$is_verbose
      
    }
    
  ),                         
  
                         
  private = list(
    
    time_keeper_name   = "",
    
    time_keeper_start  = NA,
    
    time_keeper_stages = list(),
    
    time_keeper_stop   = NA,
    
    is_verbose         = TRUE,
    
    
	
	is_running = function( 
		msg_not_started = "Timer not started.\n",
		msg_stopped     = "Timer stopped.\n"
	) {
	
	  running <- TRUE
      
      if (is.na(private$time_keeper_start)) {
        
        cat(msg_not_started)
        
        running <- FALSE
        
      }
      
      if (!is.null(msg_stopped) && !is.na(private$time_keeper_stop)) {
        
        cat(msg_stopped)
		
		running <- FALSE
        
      }
      
	  return(running)
	  
    }
    
  )                     
                         
)