1 files changed, 166 insertions, 0 deletions
diff --git a/_extensions/js/multicol-nohead/multicol-nohead.lua b/_extensions/js/multicol-nohead/multicol-nohead.lua
new file mode 100644
index 0000000..f190db8
--- /dev/null
+++ b/_extensions/js/multicol-nohead/multicol-nohead.lua
@@ -0,0 +1,166 @@
+-- Render content below header in three columns
+
+local multicol_begin = pandoc.RawBlock('latex', [[
+\begin{multicols}{3}\raggedcolumns
+]])
+local multicol_end = pandoc.RawBlock('latex', [[
+\end{multicols}
+]])
+
+local ad_template = [[
+\begin{minipage}[%s][%s\textheight][c]{\textwidth}
+\centering
+\includegraphics[width=\linewidth,height=%s\textheight,keepaspectratio]{%s}
+\end{minipage}
+]]
+
+local function has_class(elem, class)
+  local classes = elem.classes
+  if not classes then
+    return false
+  end
+  for _, c in ipairs(classes) do
+    if c == class then
+      return true
+    end
+  end
+  return false
+end
+
+local function is_columnar_header(elem)
+  return elem.t == "Header" and elem.level == 1
+end
+
+local function is_multicols_begin(elem)
+  return elem.t == "RawBlock" and elem.text == "\\begin{multicols}{3}\\raggedcolumns"
+end
+
+local function is_multicols_end(elem)
+  return elem.t == "RawBlock" and elem.text == "\\end{multicols}"
+end
+
+-- a standalone image with optional caption that has class .wide
+-- TODO: detect pre-quarto-filter pattern too
+local function is_wide(elem)
+  return ((elem.t == "Para" and has_class(elem.content[1], "wide"))
+  or (elem.t == "Figure" and has_class(elem.content[1].content[1], "wide")))
+end
+
+-- TODO: detect pre-quarto-filter pattern too
+local function is_newpage_command(elem)
+  return (elem.t == "RawBlock" and elem.text == "\\newpage{}")
+    or (elem.t == "Para" and #elem.content == 5 and elem.content[3] == "pagebreak")
+end
+
+-- a paragraph where initial element has class .ad is an advertising
+local function is_advertising(elem)
+  if elem.t == "Para" then
+    local elem1 = elem.content[1]
+    if elem1.t == "Image" and has_class(elem1, "ad") then
+      return true
+    end
+  end
+  return false
+end
+
+-- wrap images with class .ad to span half or full page
+local function ad(elem)
+  local amount = #elem.content
+
+  -- 1 ad, spanning full page except with class .top or .bottom
+  if amount == 1 then
+    local elem1 = elem.content[1]
+    if elem1.t ~= "Image" or not elem1.src then
+      error("failed to parse advertisement")
+      return elem
+    end
+    if has_class(elem1, "top") then
+      return pandoc.RawBlock('latex', "\\noindent\n"
+        .. string.format(ad_template, "t", "0.5", "0.5", elem1.src))
+    elseif has_class(elem1, "bottom") then
+      return pandoc.RawBlock('latex', "\\vspace*{\\fill}\\noindent\n"
+        .. string.format(ad_template, "b", "0.5", "0.5", elem1.src))
+    end
+    return pandoc.RawBlock('latex',"\\noindent\n"
+      .. string.format(ad_template, "t", "1", "1", elem1.src))
+  end
+
+  -- 2 ads spanning full page
+  if amount == 3 then
+    local elem1 = elem.content[1]
+    local elem2 = elem.content[3]
+    if elem1.t ~= "Image" or not elem1.src
+      or elem2.t ~= "Image" or not elem2.src
+    then
+      error("failed to parse 2-element advertisement")
+      return elem
+    end
+    return pandoc.RawBlock('latex', "\\noindent\n"
+      .. string.format(ad_template, "t", "0.5", "0.5", elem1.src)
+      .. string.format(ad_template, "b", "0.5", "0.5", elem2.src))
+  end
+
+  error("failed to parse advertisement, wrong amount of elements: "
+    .. amount)
+  return elem
+end
+
+function Pandoc(doc)
+  if FORMAT:match 'latex' then
+
+    -- locate topmost-only elements where multicol state should change
+    local multicol_now = false
+    local multicol_places = {}
+    for i, elem in ipairs(doc.blocks) do
+      if is_columnar_header(elem) then
+        multicol_places[i] = multicol_now and "renew" or "begin"
+        multicol_now = true
+      elseif is_wide(elem) then
+        if multicol_now then
+          multicol_places[i] = "renew"
+        end
+      elseif is_advertising(elem) then
+        doc.blocks[i] = ad(elem)
+        if multicol_now then
+          multicol_places[i] = "renew"
+        end
+      elseif is_newpage_command(elem) then
+        if multicol_now then
+          multicol_places[i] = "end"
+          multicol_now = false
+        end
+      elseif elem.t == "HorizontalRule" then
+        if multicol_now then
+          multicol_places[i] = "end"
+          multicol_now = false
+        end
+      elseif is_multicols_begin(elem) then
+        multicol_now = true
+      elseif is_multicols_end(elem) then
+        multicol_now = false
+      end
+    end
+    if multicol_now then
+      multicol_places[#doc.blocks] = "end"
+    end
+
+    -- apply multicol, in reverse order since it shifts later indices
+    for i = #doc.blocks, 1, -1 do
+      local state = multicol_places[i]
+      if state ~= nil then
+        if state == "begin" then
+          doc.blocks:insert(i + 1, multicol_begin)
+        elseif state == "renew" then
+          doc.blocks:insert(i + 1, multicol_begin)
+          doc.blocks:insert(i, multicol_end)
+        elseif state == "end" then
+          doc.blocks:insert(i, multicol_end)
+        end
+      end
+    end
+
+    if #multicol_places >= 1 then
+      return doc
+    end
+  end
+end