library(Seurat)
library(ggplot2)
library(ggthemes)
library(ggpubr)

make_expression_plots <- function(seuset, feature, reduction = NULL) {
  stopifnot(length(feature) == 1)

  if (!feature %in% rownames(seuset)) {
    warning(paste("Feature", feature, "not found"), call. = FALSE)
    return(NULL)
  }

  # define base theme
  base_theme <- theme(
    aspect.ratio = 1,
    plot.margin = unit(c(5, 5, 5, 5), "mm"),
    plot.title = element_blank()
  )

  dr_idents <- DimPlot(seuset, group.by = "ident", reduction = reduction) +
    scale_color_tableau(palette = "Tableau 20") +
    theme_void() +
    base_theme

  dr_feature <- FeaturePlot(seuset, features = feature, reduction = reduction, min.cutoff = "q10") +
    scale_color_viridis_c(option = "inferno") +
    theme_void() +
    base_theme

  vln <- VlnPlot(seuset, features = feature, pt.size = 0.3, sort = TRUE) +
    scale_fill_viridis_d(direction = -1) +
    base_theme +
    theme(
      legend.position = "none",
      axis.title.x = element_blank(),
      panel.grid.major.y = element_line(colour = "grey75")
      )

  ridge <- RidgePlot(seuset, features = feature, sort = TRUE) +
    scale_fill_viridis_d(direction = -1) +
    base_theme +
    theme(
      legend.position = "none",
      axis.title.y = element_blank(),
      axis.title.x = element_text(hjust = 0.5),
      panel.grid.major.y = element_line(colour = "grey75")
      )

  # combine plots and add global title
  CombinePlots(
    list(dr_idents, dr_feature, vln, ridge),
    ncol = 2, axis = "tb"
  ) %>%
    ggpubr::annotate_figure(
      top = text_grob(feature, face = "bold", size = 18)
    )
}