1 files changed, 161 insertions, 0 deletions
diff --git a/paper/lua-filters/scrlttr2/scrlttr2.lua b/paper/lua-filters/scrlttr2/scrlttr2.lua
new file mode 100644
index 0000000..78f38fd
--- /dev/null
+++ b/paper/lua-filters/scrlttr2/scrlttr2.lua
@@ -0,0 +1,161 @@
+-- Ensure unpack also works if pandoc was compiled against Lua 5.1
+local unpack = unpack or table.unpack
+local List = require 'pandoc.List'
+local stringify = (require 'pandoc.utils')['stringify']
+
+--- Set some default options
+local default = {
+  opening = 'Dear Sir/Madam,',
+  closing = 'Sincerely,',
+  address = 'no address given'
+}
+
+--- Return a list of inlines representing a call to a latex command.
+local function latex_command (command, ...)
+  local entry = {
+    pandoc.RawInline('latex', '\\' .. command),
+  }
+  for _, arg in ipairs{...} do
+    entry[#entry + 1] = pandoc.RawInline('latex', '{')
+    if type(arg) ~= 'table' then
+      entry[#entry + 1] = pandoc.RawInline('latex', tostring(arg))
+    else
+      List.extend(entry, arg)
+    end
+    entry[#entry + 1] = pandoc.RawInline('latex', '}')
+  end
+  return entry
+end
+
+--- Convert the given meta-value to a list of inlines
+local function ensure_inlines (val)
+  if not val or type(val) == 'string' or type(val) == 'boolean' then
+    return pandoc.MetaInlines{pandoc.Str(tostring(val))}
+  elseif type(val) == 'table' and val.t == 'MetaInlines' then
+      return val
+  elseif type(val) == 'table' then
+    local res = List:new{}
+    for i = 1, #val do
+      res:extend(val[i])
+      res[#res + 1] = pandoc.RawInline('latex', '\\\\ ')
+    end
+    res[#res] = nil -- drop last linebreak
+    return pandoc.MetaInlines(res)
+  else
+    return pandoc.MetaInlines{pandoc.Str(pandoc.utils.stringify(val))}
+  end
+end
+
+--- Convert the given value to a MetaList
+local function ensure_meta_list (val)
+  if not val or val.t ~= 'MetaList'  then
+    return pandoc.MetaList{}
+  else
+    return val
+  end
+end
+
+--- Set supported variables as KOMA variables.
+function setkomavar_commands (meta)
+  local set_vars = {}
+  local res = {}
+  local function set_koma_var (name, value, enable)
+    if value ~= nil then
+      res[#res + 1] = latex_command('setkomavar', name, ensure_inlines(value))
+      if enable then
+        set_vars[#set_vars + 1] = name
+      end
+    end
+  end
+
+  set_koma_var('fromname', meta.fromname or meta.author)
+  set_koma_var('fromaddress', meta.fromaddress or meta['return-address'])
+  set_koma_var('subject', meta.subject)
+  set_koma_var('title', meta.title)
+  set_koma_var('signature', meta.signature)
+  set_koma_var('customer', meta.customer)
+  set_koma_var('yourref', meta.yourref)
+  set_koma_var('myref', meta.myref)
+  set_koma_var('invoice', meta.invoice)
+  set_koma_var('place', meta.place)
+
+  set_koma_var('fromfax', meta.fromfax or meta.fax, true)
+  set_koma_var('fromurl', meta.fromurl or meta.url, true)
+  set_koma_var('fromlogo', meta.fromlogo or meta.logo, true)
+  set_koma_var('fromemail', meta.fromemail or meta.email, true)
+  set_koma_var('fromphone', meta.fromphone or meta.phone, true)
+
+  -- don't set date if date is set to `false`
+  if meta.date == nil or meta.date == true then
+    if meta['date-format'] then
+      set_koma_var('date', os.date(stringify(date_format)))
+    else
+      set_koma_var('date', pandoc.MetaInlines{pandoc.RawInline('latex', '\\today')})
+    end
+  elseif meta.date then
+    set_koma_var('date', meta.date)
+  end
+
+  if meta['KOMAoptions'] or #set_vars >= 1 then
+    res[#res + 1] = latex_command(
+      'KOMAoptions',
+      meta['KOMAoptions']
+        or table.concat(set_vars, '=true,') .. '=true'
+    )
+  end
+
+  return res
+end
+
+--- Bring Metadata in a form suitable for the scrlttr KOMA class
+local function make_koma_metadata(meta)
+  local header_includes = ensure_meta_list(meta['header-includes'])
+  List.extend(header_includes, setkomavar_commands(meta))
+
+  local include_before = ensure_meta_list(meta['include-before'])
+  List.extend(
+    include_before,
+    {
+      pandoc.MetaInlines(
+        latex_command(
+          'begin',
+          'letter',
+          ensure_inlines(meta.address or default.address)
+        )
+      ),
+
+      pandoc.MetaInlines(
+        latex_command('opening', meta.opening or default.opening)
+      ),
+    }
+  )
+
+  local include_after = ensure_meta_list(meta['include-after'])
+  List.extend(
+    include_after,
+    {
+      pandoc.MetaInlines(
+        latex_command('closing', meta.closing or default.closing)
+      ),
+      pandoc.MetaInlines(latex_command('end', 'letter')),
+    }
+  )
+
+  -- unset or reset some unwanted vars
+  meta.data   = nil  -- set via komavar 'date'
+  meta.title  = nil  -- set via komavar 'subject'
+  meta.indent = true -- disable parskib
+  -- set documentclass to scrlttr2 if it's unset
+  meta.documentclass = meta.documentclass or pandoc.MetaString'scrlttr2'
+
+
+  meta['header-includes'] = header_includes
+  meta['include-before'] = include_before
+  meta['include-after'] = include_after
+
+  return meta
+end
+
+return {
+  {Meta = make_koma_metadata}
+}