library(latticeExtra)
require(gridExtra)
require(grid)

# set error messages test to english
Sys.setenv(LANG = "en")

drawDiagramSingle <- function(samples) {

    # date column should be type of date, not string, so parse it
    png(filename = paste0("results-", format(Sys.time(), "%d_%b_%Y_%H_%M"), ".png"), 
        width = 800, height = 900, bg = "white")

    samples$Time = as.POSIXct(samples$Time, format="%Y-%m-%d %H:%M:%S.%OS")

    # create graphs
    plotValueVsTime <- xyplot(Counter ~ Time, 
                    data = samples, 
                    type = "l", 
                    grid = TRUE, 
                    col.line = "black",
                    ylab = "counts per minute",
                    ylim=c(min(samples$Counter), max(samples$Counter)),
                    xlim=c(min(samples$Time), max(samples$Time)),
                    main = "Change over time")

    plotHistogram <- histogram(samples$Counter, 
                               color = "white", 
                               col = "grey", 
                               xlab = "counts", 
                               ylab = "percentage", 
                               main = "Histogram")

    # show graphs
    grid.arrange(plotValueVsTime, plotHistogram, nrow = 2)

    # add timestamp
    trellis.focus("toplevel")
    pictureCreationTimestamp <- as.POSIXlt(Sys.time())
    panel.text(0.85, 0.03, pictureCreationTimestamp, cex = 1.2, font = 2)
    trellis.unfocus()
}