_extensions/shafayetShafee/downloadthis/downloadthis.lua

--[[
MIT License

Copyright (c) 2023 Shafayet Khan Shafee

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
]]--



local str = pandoc.utils.stringify
--local p = quarto.log.output

local function ensureHtmlDeps()
  quarto.doc.add_html_dependency({
    name = "downloadthis",
    version = "1.9.1",
    stylesheets = {"resources/css/downloadthis.css"}
  })
end

local function optional(arg, default)
  if arg == nil or arg == ""
  then
    return default
  else
    return arg
  end
end

function import(script)
  local path = PANDOC_SCRIPT_FILE:match("(.*[/\\])") .. "resources/lua/"
  package.path = path .. script .. ";" .. package.path
  return require(script)
end

local b64 = import('base64.lua')
local puremagic = import('puremagic.lua')

return {
  ['downloadthis'] = function(args, kwargs, meta) 
    
    -- args and kwargs    
    local file_path = str(args[1])
    local extension = "." .. file_path:match("[^.]+$")
    local dname = optional(str(kwargs["dname"]), "file")
    local dfilename = dname .. extension
    local btn_label = " " .. optional(str(kwargs["label"]), "Download") .. " "
    local btn_type = optional(str(kwargs["type"]), "default")
    local icon = optional(str(kwargs["icon"]), "download")
    local class = " " .. optional(str(kwargs["class"]), "")
    local rand = "dnldts" .. str(math.random(1, 65000))
    local id = optional(str(kwargs["id"]), rand)
    -- reading files
    local fh = io.open(file_path, "rb")
    if not fh then
        io.stderr:write("Cannot open file " .. 
          file_path .. 
          " | Skipping adding buttons\n")
        return pandoc.Null()
    else
      local contents = fh:read("*all")
      fh:close()
      
      -- creating dataURI object
      local b64_encoded = b64.encode(contents)
      local mimetype = puremagic.via_path(file_path)
      local data_uri = 'data:' .. mimetype .. ";base64," .. b64_encoded
      
      -- js code taken from
      -- https://github.com/fmmattioni/downloadthis/blob/master/R/utils.R#L59
      local js = [[fetch('%s').then(res => res.blob()).then(blob => {
      const downloadURL = window.URL.createObjectURL(blob);
      const a = document.createElement('a');
      document.body.appendChild(a);
      a.href = downloadURL;
      a.download = '%s'; a.click();
      window.URL.revokeObjectURL(downloadURL);
      document.body.removeChild(a);
        });]]
      
      local clicked = js:format(data_uri, dfilename)
      
      -- creating button
      local button = 
          "<button class=\"btn btn-" .. btn_type .. " downloadthis " .. 
          class .. "\"" ..
          " id=\"" .. id .. "\"" ..
          "><i class=\"bi bi-" .. icon .. "\"" .. "></i>" ..
          btn_label .. 
          "</button>"
      if quarto.doc.is_format("html:js") and quarto.doc.has_bootstrap()
      then
        ensureHtmlDeps()
        return pandoc.RawInline('html',
        "<a href=\"#" .. id .. "\"" ..
        " onclick=\"" .. clicked .. "\">" .. button .. "</a>"
        )
      else
        return pandoc.Null()
      end
    end
  end
}