#!/usr/bin/env Rscript
# Usage: Rscript plot_wordcounts.R [tick_days] [input.csv] [output.svg]
# By default, label every seven days, independently of the data points.

library(ggplot2)

args <- commandArgs(trailingOnly = TRUE)
if (length(args) > 3L) {
  stop("Usage: Rscript plot_wordcounts.R [tick_days] [input.csv] [output.svg]")
}
tick_days <- if (length(args) >= 1L) {
  as.numeric(args[1])
} else {
  7
}

script_arg <- grep("^--file=", commandArgs(), value = TRUE)[1]
script_dir <- dirname(normalizePath(sub("^--file=", "", script_arg)))
input <- if (length(args) >= 2L) {
  args[2]
} else {
  file.path(script_dir, "wordcounts.csv")
}
output <- if (length(args) >= 3L) {
  args[3]
} else {
  file.path(script_dir, "wordcounts.svg")
}

counts <- read.csv(input, colClasses = "character")

timezone <- Sys.getenv("TZ", unset = "Europe/Berlin")
if (!nzchar(timezone)) {
  timezone <- "Europe/Berlin"
}
normalized <- sub("([+-][0-9]{2}):([0-9]{2})$", "\\1\\2", counts$date)
counts$timestamp <- as.POSIXct(
  normalized,
  format = "%Y-%m-%dT%H:%M:%S%z",
  tz = timezone
)
date_only <- grepl("^[0-9]{4}-[0-9]{2}-[0-9]{2}$", counts$date)
counts$timestamp[date_only] <- as.POSIXct(
  counts$date[date_only],
  format = "%Y-%m-%d",
  tz = timezone
)
counts$wordcount <- as.numeric(counts$wordcount)
counts <- counts[order(counts$timestamp), ]

# Fixed time intervals
start <- as.POSIXct(
  format(min(counts$timestamp), "%Y-%m-%d", tz = timezone),
  tz = timezone
)
interval <- tick_days * 86400
span <- as.numeric(difftime(max(counts$timestamp), start, units = "secs"))
ticks <- start + seq(0, max(1, ceiling(span / interval))) * interval

plot <- ggplot(counts, aes(x = timestamp, y = wordcount)) +
  scale_x_datetime(
    breaks = ticks,
    limits = range(ticks),
    date_labels = "%Y-%m-%d",
    timezone = timezone,
    minor_breaks = NULL
  ) +
  scale_y_continuous(labels = scales::label_comma()) +
  labs(
    title = "Thesis Word Count",
    x = "Date",
    y = "Words"
  ) +
  theme_minimal(base_size = 12) +
  theme(
    axis.text.x = element_text(angle = 45, hjust = 1),
    panel.grid.minor = element_blank()
  )
if (nrow(counts) > 1L) {
  plot <- plot + geom_line(linewidth = 0.5)
}

ggsave(output, plot, width = 10, height = 5, dpi = 180, bg = "white")
message("Saved ", output)