library(ggplot2)
library(readr)
library(latex2exp)

data_t1 <- read_csv(
  "m1,m2,a_measured
  0.055,0.060,0.380
  0.060,0.065,0.354
  0.065,0.070,0.323
  0.070,0.075,0.310
  0.075,0.080,0.303
  0.080,0.085,0.279
  0.065,0.075,0.649
  0.080,0.095,0.780"
)

data_t1$cat <- rep("Theoretical", 8)
colnames(data_t1) <- c("m1", "m2", "a_measured", "Theoretical")

a_theoretical <- function(m) {
  9.81 * m
}

m_from_masses <- function(m1, m2) {
  (m2 - m1) / (m1 + m2)
}

x_lab <- function() {
  TeX(r"($M$)")
}

y_lab <- function() {
  TeX(r"($a \ \small{m \cdot s^{-2}}$)")
}

lm_eqn <- function(df) {
  m <- lm(df)
  eq <- substitute(
    italic(y) == a + b %.% italic(x),
    list(a = format(unname(coef(m)[1]), digits = 3),
         b = format(unname(coef(m)[2]), digits = 3))
  )
  as.character(as.expression(eq))
}

th_eqn <- function() {
  eq <- substitute(
    italic(y) == b %.% italic(x),
    list(b = format(unname(9.81), digits = 3))
  )
  as.character(as.expression(eq))
}

data_t1["M"] <- m_from_masses(data_t1["m1"], data_t1["m2"])

data_t1["a"] <- data_t1$M * 9.8

plt <- ggplot(
  data = data_t1,
  mapping = aes(x = M, y = a_measured)
) +
  geom_point(
    aes(color = "D55E00"),
    size = 8,
  ) +
  geom_smooth(
    se = FALSE,
    method = "lm",
    linewidth = 2.6,
    col = "#D55E00",
  ) +
  geom_segment(aes(x = min(data_t1$M),
                   y = a_theoretical(min(data_t1$M)),
                   xend = max(data_t1$M),
                   yend = a_theoretical(max(data_t1$M)),
                   linetype = "Theoretical"),
    size = 2.2,
    color = "#0072B2"
  ) +
  theme(
    axis.text = element_text(size = 32),
    axis.title = element_text(size = 50),
    panel.grid.minor = element_line(size = 1.5),
    panel.grid.major = element_line(size = 2),
    legend.title = element_blank(),
    legend.text = element_text(size = 36),
    legend.key.size = unit(8, "line")
  ) +
  labs(
    x = x_lab(),
    y = y_lab(),
  ) +
  annotate("text",
    label = lm_eqn(data_t1[, c("a_measured", "M")]),
    x = 0.076,
    y = 0.58,
    size = 18,
    col = "#D55E00",
    parse = TRUE,
  ) +
  annotate("text",
    label = th_eqn(),
    x = 0.068,
    y = 0.74,
    col = "#0072B2",
    size = 18,
    parse = TRUE,
  ) +
  scale_color_manual(name = "", values = c("#D55E00"), labels = "Measured") +
  scale_linewidth_manual("Theoretical", values = c("Theoretical" = 2))

plt

ggsave("plot.svg",
  plot = plt,
  width = 30,
  height = 25,
)