feat: add mermaid

Refs #14

DESCRIPTION

 Package: fairify
 Title: Produce FAIR reports with Rmarkdown and data in the cloud
 Version: 0.0.0.9000
-Authors@R: 
+Authors@R:
     person("David", "Dorchies", role = c("aut", "cre"), comment = c(ORCID = "0000-0002-6595-7984"), email = "david.dorchies@inrae.fr")
 Description: R-package proposing a framework to apply FAIR principles based on reports created using the bookdown R-package and published as a website (e.g. gitlab pages) and data located on a owncloud/nextcloud server.
 License: AGPL (>= 3)
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
 RoxygenNote: 7.2.3
-Imports: 
+Imports:
     bookdown,
     gert,
     magrittr,
+    rlang,
     usethis,
-    yaml
-Suggests: 
+    yaml,
+    zlib
+Suggests:
     testthat (>= 3.0.0),
     tinytex
 Config/testthat/edition: 3

NAMESPACE

@@ -6,6 +6,8 @@ export(add_report)
 export(create_fairify)
 export(create_reports)
 export(iconv_filename)
+export(mermaid)
+export(mermaid_gen_link)
 export(pkg_sys)
 export(purge_string)
 export(render_report)

R/mermaid.R

+#' Generate a file from a mermaid diagram
+#'
+#' This function download the file from https://mermaid.ink which generates the image.
+#' The file is downloaded only if it does not already exist.
+#'
+#' @details
+#' Use this function with [knitr::include_graphics] to display a mermaid diagram
+#' in a Rmarkdown document. Compared to the `diagrammeR::mermaid` function, the
+#' generated image is not a HTMLwidget and can be knit in pdf through latex and
+#' moreover, its size can be controlled with `fig.width` and `fig.height`.
+#'
+#' @param diagram Diagram in mermaid markdown-like language or file (as a connection or file name) containing a diagram specification
+#' @param theme Mermaid theme (See https://mermaid.js.org/config/theming.html#available-themes)
+#' @param format Image format (either `"jpg"`, or `"png"`, or `"svg"`)
+#' @param file Path to the downloaded image
+#'
+#' @return The path to the downloaded image.
+#' @export
+#' @rdname mermaid
+#'
+#' @examples
+#' diagram <- "flowchart LR\n  A --> B"
+#' mermaid_gen_link(diagram)
+#' f <- mermaid(diagram)
+#' f
+#' \dontrun{
+#' # For displaying the diagram in Rmarkdown document
+#' knitr::include_graphics(mermaid(diagram))
+#' }
+#'
+#' # Clean temporary folder
+#' unlink(f)
+mermaid <- function(diagram,
+                    format = "png",
+                    theme = "default",
+                    file = file.path(tempdir(), paste0(rlang::hash(diagram), ".", format))) {
+  if (!file.exists(file)) {
+    link <- mermaid_gen_link(diagram, theme = theme, format = format)
+    download.file(link, file, quiet = TRUE, mode = "wb")
+  }
+  return(file)
+}
+
+#' Compress data in pako format
+#'
+#' @param data [character] data to compress
+#'
+#' @return Raw compresses data.
+#' @source Translated from python script
+#' https://github.com/mermaid-js/mermaid-live-editor/discussions/1291#discussioncomment-6837936
+#' @noRd
+pako_deflate <- function(data) {
+  # compress = zlib.compressobj(9, zlib.DEFLATED, 15, 8,zlib.Z_DEFAULT_STRATEGY)
+  compress <- zlib::compressobj(
+    level = 9,
+    method = zlib::zlib$DEFLATED,
+    wbits = 15,
+    memLevel = 8,
+    strategy = zlib::zlib$Z_DEFAULT_STRATEGY
+  )
+  compressed_data <- compress$compress(charToRaw(data))
+  compressed_data <- c(compressed_data, compress$flush())
+return(compressed_data)
+}
+
+#' @rdname mermaid
+#' @export
+mermaid_gen_link <- function(diagram, theme = "default", format = "png") {
+  is_connection_or_file <- inherits(diagram[1], "connection") ||
+    file.exists(diagram[1])
+  if (is_connection_or_file) {
+    diagram <- readLines(diagram, encoding = "UTF-8", warn = FALSE)
+  }
+  if (length(diagram) > 1) {
+    diagram <- paste(diagram, collapse = "\n")
+  }
+  jGraph <-
+    list(code = diagram,
+         mermaid = list(theme = theme)) |> jsonlite::toJSON(auto_unbox = TRUE)
+  deflated <- pako_deflate(jGraph)
+  dEncode = gsub("\n", "", jsonlite::base64url_enc(deflated))
+  mode <- ifelse(format != "svg", "img", "svg")
+  link = sprintf('https://mermaid.ink/%s/pako:%s', mode, dEncode)
+  if (format != "svg") {
+    link <- paste0(link, "?type=", format)
+  }
+  return(link)
+}

man/mermaid.Rd

+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/mermaid.R
+\name{mermaid}
+\alias{mermaid}
+\alias{mermaid_gen_link}
+\title{Generate a file from a mermaid diagram}
+\usage{
+mermaid(
+  diagram,
+  format = "png",
+  theme = "default",
+  file = file.path(tempdir(), paste0(rlang::hash(diagram), ".", format))
+)
+
+mermaid_gen_link(diagram, theme = "default", format = "png")
+}
+\arguments{
+\item{diagram}{Diagram in mermaid markdown-like language or file (as a connection or file name) containing a diagram specification}
+
+\item{format}{Image format (either \code{"jpg"}, or \code{"png"}, or \code{"svg"})}
+
+\item{theme}{Mermaid theme (See https://mermaid.js.org/config/theming.html#available-themes)}
+
+\item{file}{Path to the downloaded image}
+}
+\value{
+The path to the downloaded image.
+}
+\description{
+This function download the file from https://mermaid.ink which generates the image.
+The file is downloaded only if it does not already exist.
+}
+\details{
+Use this function with \link[knitr:include_graphics]{knitr::include_graphics} to display a mermaid diagram
+in a Rmarkdown document. Compared to the \code{diagrammeR::mermaid} function, the
+generated image is not a HTMLwidget and can be knit in pdf through latex and
+moreover, its size can be controlled with \code{fig.width} and \code{fig.height}.
+}
+\examples{
+diagram <- "flowchart LR\n  A --> B"
+mermaid_gen_link(diagram)
+f <- mermaid(diagram)
+f
+\dontrun{
+# For displaying the diagram in Rmarkdown document
+knitr::include_graphics(mermaid(diagram))
+}
+
+# Clean temporary folder
+unlink(f)
+}

tests/testthat/test-mermaid.R

+test_that("Conversion of mmd to pako works", {
+  diagram <- "flowchart LR\n  A --> B"
+  pako <- "https://mermaid.ink/img/pako:eNqrVkrOT0lVslJKy8kvT85ILCpR8AmKyVNQcFTQ1bVTcFLSUcpNLcpNzExRsqpWKslIzQUpTklNSyzNKVGqrQUAjIcUfg?type=png"
+  expect_equal(mermaid_gen_link(diagram), pako)
+  diagram <- strsplit(diagram, "\n")[[1]]
+  expect_equal(mermaid_gen_link(diagram), pako)
+})