#* pre_post_conditions:
#*   attr:
#*     fillcolor: '2'
#*   desc: Summary visualization of pre and post epochs.
#*   ext: R
#*   inputs:
#*   - person_all_facts
#* 

pre_post_conditions <- function(person_all_facts) {
    library(ggplot2)
    library(dplyr)
    library(tidyr)

    epoch_stats_by_person <- SparkR::collect(SparkR::select(person_all_facts, c("pre_num_condition_eras", "post_num_condition_eras", "cohort"))) %>%
        mutate(pre_num_condition_eras = as.numeric(pre_num_condition_eras), post_num_condition_eras = as.numeric(post_num_condition_eras)) %>%
        filter(complete.cases(.))
    print(str(epoch_stats_by_person))

    p <- ggplot(epoch_stats_by_person) +
        stat_summary_hex(aes(x = pre_num_condition_eras, y = post_num_condition_eras, z = pre_num_condition_eras), fun = length, bins = 60) +
        scale_x_continuous(trans = "log10") + 
        scale_y_continuous(trans = "log10") +
        scale_fill_continuous(trans = "log10") +
        annotation_logticks(sides = "bl") +
        facet_wrap(~ cohort) +
        coord_equal()

    plot(p)

    return(epoch_stats_by_person)

}