#meta

Implements useful template functions

-- priority: 50
-- Template API root table
template = template or {}
-- Template storage table
templates = {}

-- Iterates over a table/array and applies a function to each element,
-- concatenating the results. The last, optional argument is output for empty table
function template.each(tbl, fn, empty)
  local empty = empty or ""
  
  local result = {}
  for _, item in ipairs(tbl) do
      table.insert(result, fn(item))
  end

  if #result == 0 then
    return empty
  else
    return table.concat(result)
  end
end

-- Creates a new template function from a string template
function template.new(templateStr)
  -- Preprocess: strip indentation
  local lines = {}
  local splitLines = string.split(templateStr, "\n")
  for _, line in ipairs(splitLines) do
    line = string.gsub(line, "^    ", "")
    table.insert(lines, line)
  end
  templateStr = table.concat(lines, "\n")
  return function(obj)
    return spacelua.interpolate(templateStr, obj)
  end
end

-- Reads a template from a page
-- Return value:
-- * The template itself
-- * The extracted frontmatter
function template.fromPage(name, raw)
  local fm = index.extractFrontmatter(space.readPage(name),  {
    removeFrontmatterSection = true,
    removeTags = true
  })

  local templateText = string.trimStart(fm.text)
  if raw then
    -- Don't actually parse this as a template, just pass it along
    return function()
      return templateText
    end, fm.frontmatter
  end
  return template.new(templateText), fm.frontmatter
end