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library(ggplot2)
library(dplyr)
library(tidyr)
library(MBA) 


# raw data
df <- data.frame(
  y = c(3, 6, 9, 3, 6, 9, 3, 6, 9),
  z = c(2, 2, 2, 6.95, 6.95, 6.95, 10.25, 10.25, 10.25),
  Vx = c(-0.7, 25, -14, 2, 2, 3, 3, 4, 3),
  Vy = c(-0.3, 35, -4, -1, -1, -2, -1, -2, -1.8),
  Vz = c(0.1, -6, -3, 0, 0.1, -0.1, 0.5, 0.5, 0.2)
)


# Interpolation Function using MBA
interpolate_velocity_mba <- function(data, variable) {
  # formatting data for MBA
  xyz <- data.frame(x = data$y, y = data$z, z = data[[variable]])
  
  
  # we can use MBA to generate a 100x100 smooth surface. 'extend=TRUE' ensures it reaches the edges.
  surf <- mba.surf(xyz, no.X = 100, no.Y = 100, extend = TRUE)$xyz.est
  
  
  # Unpack the surface matrix into a long dataframe for ggplot
  df_interp <- expand.grid(y = surf$x, z = surf$y)
  df_interp$velocity_val <- as.vector(surf$z)
  df_interp$component <- variable
  
  return(df_interp)
}


# processing the data into a format better for plotting
plot_data <- bind_rows(
  interpolate_velocity_mba(df, "Vx"),
  interpolate_velocity_mba(df, "Vy"),
  interpolate_velocity_mba(df, "Vz")
)


# generate the Plot - comment this section out if you dont want the plot that looks like its upside down

# ggplot(plot_data, aes(x = y, y = z, fill = velocity_val)) +
#   geom_raster(interpolate = TRUE) +
#   scale_fill_distiller(palette = "Spectral",
#                        name = "cm/s",
#                        limits = c(-5, 5), # manage outliers - limits on color mapping Keeps smaller variations visible
#                        oob = scales::squish) +
#   facet_wrap(~component, ncol = 3) +
#   theme_minimal() +
#   theme(panel.background = element_rect(fill = "gray20")) + # Dark background to see edges
#   labs(title = "ADV Velocity Fields (MBA Spline Interpolation)",
#        x = "Y Position (in)",
#        y = "Z Position (in)")


# Generate the Plot with Reversed Z-Axis
ggplot(plot_data, aes(x = y, y = z, fill = velocity_val)) +
  geom_raster(interpolate = TRUE) + 
  scale_fill_distiller(palette = "Spectral", 
                       name = "cm/s", 
                       limits = c(-5, 5), 
                       oob = scales::squish) +
  scale_y_reverse() + # THIS IS THE MAGIC LINE
  facet_wrap(~component, ncol = 3) +
  theme_minimal() +
  theme(panel.background = element_rect(fill = "gray20")) + 
  labs(title = "ADV Velocity Fields (V-Notch Weir Orientation)",
       x = "Y Position (in)",
       y = "Depth Z (in)") # Updated label to reflect depth