##' download phylopic and convert to grob object
 ##'
 ##' 
 ##' @title get.phylopic
 ##' @param id phylopic id
 ##' @param size size of the phylopic
 ##' @param color color
 ##' @param alpha alpha
 ##' @return grob object
 ##' @importFrom grid rasterGrob
 ##' @export
 ##' @author Guangchuang Yu
 get.phylopic <- function(id, size=512, color="black", alpha=1) {

     download.phylopic(id, size, color, alpha) %>% rasterGrob
 }

 ##' download phylopic
 ##'
 ##' @title download.phylopic
 ##' @param id phyopic id
 ##' @param size size of phylopic
 ##' @param color color
 ##' @param alpha alpha
 ##' @return matrix
 ##' @importFrom grDevices rgb
 ##' @importFrom grDevices col2rgb

 ## @importFrom EBImage readImage
 ## @importFrom EBImage channel

 ##' @export
 ##' @author Guangchuang Yu
 download.phylopic <- function(id, size=512, color="black", alpha=1) {

     imgfile <- tempfile(fileext = ".png")
     download.phylopic_internal(id, size, imgfile)

     channel <- get_fun_from_pkg("EBImage", "channel")
     readImage <- get_fun_from_pkg("EBImage", "readImage")
     

     img <- readImage(imgfile)
        
     color <- col2rgb(color) / 255
 
     img <- channel(img, 'rgb')
     img[,,1] <- color[1]
     img[,,2] <- color[2]
     img[,,3] <- color[3]
     img[,,4] <- img[,,4]*alpha

     return(img)

 }

 ##' @importFrom utils download.file
 ##' @importFrom utils modifyList

 download.phylopic_internal <- function(id, size=512, outfile=NULL) {
     size %<>% as.character %>%
         match.arg(c("64", "128", "256", "512", "1024"))
 
     imgurl <- paste0("http://phylopic.org/assets/images/submissions/", id, ".", size, ".png")
     if (is.null(outfile)) {
         outfile <- sub(".*/", "", imgurl)
     }
     ## mode = "wb" for Windows platform
     download.file(imgurl, outfile, mode="wb", quiet = TRUE) 
 }
 
 

 ##' add phylopic layer
 ##'
 ##' 
 ##' @title phylopic
 ##' @param tree_view tree view
 ##' @param phylopic_id phylopic id
 ##' @param size size of phylopic to download
 ##' @param color color
 ##' @param alpha alpha
 ##' @param node selected node
 ##' @param x x position
 ##' @param y y position
 ##' @param width width of phylopic
 ##' @return phylopic layer
 ##' @export
 ##' @importFrom ggplot2 annotation_custom
 ##' @importFrom grid rasterGrob
 ##' @author Guangchuang Yu
 phylopic <- function(tree_view, phylopic_id,
                      size=512, color="black", alpha=0.5,

                      node=NULL, x=NULL, y=NULL, width=.1) {
     width <- diff(range(tree_view$data$x)) * width

     img <- download.phylopic(phylopic_id, size, color, alpha)
     if ( is.null(node) ) {
         xmin <- ymin <- -Inf
         xmax <- ymax <- Inf
     } else {
         if (is.null(x) || is.null(y)) {
             if (is.null(node)) {
                 stop("node or x and y should not be NULL...")
             }

             df <- tree_view$data
             x <- df[match(node, df$node), "x"]
             y <- df[match(node, df$node), "y"]

         }

         AR <- getAR(img)

         xmin <- x - width/2
         xmax <- x + width/2
         ymin <- y - AR * width/2
         ymax <- y + AR * width/2
     }
     
     tree_view + annotation_custom(xmin=xmin, ymin=ymin,
                                   xmax=xmax, ymax=ymax,
                                   rasterGrob(img))
 }
 

 getAR <- function(img) {
     dims <- dim(img)[1:2]
     dims[1]/dims[2]
 }
 
 
 ##' annotation taxa with images
 ##'
 ##' 
 ##' @title annotation_image
 ##' @param tree_view tree view
 ##' @param img_info data.frame with first column of taxa name and second column of image names
 ##' @param width width of the image to be plotted in image
 ##' @param align logical
 ##' @param linetype line type if align = TRUE
 ##' @param linesize line size if align = TRUE
 ##' @param offset offset of image from the tree view
 ##' @return tree view
 ##' @export
 ##' @author Guangchuang Yu
 annotation_image <- function(tree_view, img_info, width=0.1, align=TRUE, linetype="dotted", linesize =1, offset=0) {
     df <- tree_view$data
     idx <- match(img_info[,1], df$label)
     x <- df[idx, "x"]
     y <- df[idx, "y"]
 

     readImage <- get_fun_from_pkg("EBImage", "readImage")

     images <- lapply(img_info[,2], readImage)
 
     ARs <- sapply(images, getAR)
 
     width <- width * diff(range(df$x))
     if (align) {
         xmin <- max(df$x) + offset
         xmin <- rep(xmin, length(x))
     } else {

         xmin <- x - width/2 + offset

     }

     xmax <- xmin + width
     

     ymin <- y - ARs * width/2
     ymax <- y + ARs * width/2
     image_layers <- lapply(1:length(xmin), function(i) {
         annotation_custom(xmin=xmin[i], ymin=ymin[i],
                           xmax=xmax[i], ymax=ymax[i],
                           rasterGrob(images[[i]]))
     })
 
     tree_view <- tree_view + image_layers
 
     if (align && (!is.null(linetype) && !is.na(linetype))) {
         tree_view <- tree_view + geom_segment(data=df[idx,],
                                               x=xmin, xend = x*1.01,
                                               y = y, yend = y,
                                               linetype=linetype, size=linesize)
     }
     tree_view
 }