local path = pandoc.path
local MetaList = pandoc.MetaList
local Link = pandoc.Link

INPUT_FILES = (function(prog)
  local insert = table.insert
  local input_files = {}
  local pfile = io.popen(prog)
  for filename in pfile:lines() do
    insert(input_files, filename)
  end
  pfile:close()
  return input_files
end)("ls -t *.md")

OUTPUT_FILES = (function(pattern)
  local insert = table.insert
  local output_files = {}
  for _,filename in ipairs(INPUT_FILES) do
    local basename = path.split_extension(filename)
    insert(output_files, (pattern):format(basename))
  end
  return output_files
end)("public_html/%s.html")

print("[INFO] bavbavhaus.net:")
do
  for i,input_file in ipairs(INPUT_FILES) do
    print("    " .. INPUT_FILES[i] .. " -> " .. OUTPUT_FILES[i])
  end
end

print("[INFO] bavbavhaus.net: reading pages")
PAGES = (function()
  local input_format = "markdown+wikilinks_title_before_pipe"
  local reader_options = pandoc.ReaderOptions({})
  local pages = MetaList({})
  function pages:get(input_file)
    return self:find_if(function(page)
      return page["meta"]["input_file"] == input_file
    end)
  end
  for i,input_file in ipairs(INPUT_FILES) do
    local f = io.open(input_file)
    if not f then goto continue end
    local page = pandoc.read(f:read("*a"), input_format, reader_options)
    f:close()
    pages:insert(page)
    ::continue::
  end
  return pages
end)()

print("[INFO] bavbavhaus.net: updating metadata (initial)")
do
  for i,page in ipairs(PAGES) do
    local input_file = INPUT_FILES[i]
    local output_file = OUTPUT_FILES[i]
    PAGES[i] = page:walk({
      Meta = function(meta)
        meta["input_file"] = input_file
        meta["output_file"] = output_file
        meta["url"] = input_file
        meta["title"] = meta["title"] or pandoc.Inlines(pandoc.Str(input_file))
        return meta
      end,
    })
  end
end

print("[INFO] bavbavhaus.net: scanning pages for internal links")
BACKLINKS, FORELINKS = (function(pages)
  local MetaMap = pandoc.MetaMap
  local backlinks = MetaMap({})
  local forelinks = MetaMap({})
  for i,page in ipairs(pages) do
    local input_file = page["meta"]["input_file"]
    page:walk({
      Link = function(link)
        if not PAGES:get(link.target) then return end
        if input_file == link.target then return end
        if not backlinks[link.target] then
          backlinks[link.target] = MetaList({})
        end
        if not forelinks[input_file] then
          forelinks[input_file] = MetaList({})
        end
        if not backlinks[link.target]:includes(input_file) then
          backlinks[link.target]:insert(input_file)
        end
        if not forelinks[input_file]:includes(link.target) then
          forelinks[input_file]:insert(link.target)
        end
      end
    })
  end
  return backlinks, forelinks
end)(PAGES)

print("[INFO] bavbavhaus.net: updating index page")
do
  local index = "index.md"
  FORELINKS[index] = MetaList({})
  for i,page in ipairs(PAGES) do
    if PAGES[i]["meta"]["input_file"] == index then goto continue end
    FORELINKS[index]:insert(page["meta"]["input_file"])
    ::continue::
  end
end

print("[INFO] bavbavhaus.net: updating link targets")
do
  function update_target(target)
    return ("%s.html#start"):format(path.split_extension(target))
  end
  for i,page in ipairs(PAGES) do
    PAGES[i] = page:walk({
      Meta = function(meta)
        meta["url"] = update_target(meta["url"])
        return meta
      end,
      Link = function(link)
        if not PAGES:get(link.target) then return end
        link.target = update_target(link.target)
        return Link(link.content, link.target)
      end
    })
  end
end

print("[INFO] bavbavhaus.net: generating sitemap")
SITEMAP = (function()
  local sitemap = MetaList({})
  for _,page in ipairs(PAGES) do
    local meta = page["meta"]
    sitemap:insert(Link(meta["title"], meta["url"]))
  end
  return sitemap
end)()


print("[INFO] bavbavhaus.net: processing citations")
do
  local csl = "pandoc/csl/chicago-fullnote-sl"
  for i,page in ipairs(PAGES) do
    PAGES[i] = page:walk({
      Meta = function(meta)
        meta["csl"] = csl
        return meta
      end,
      Pandoc = function(doc)
        return pandoc.utils.citeproc(doc)
      end
    })
  end
end

print("[INFO] bavbavhaus.net: updating metadata (sitemap)")
do
  for i,page in ipairs(PAGES) do
    PAGES[i] = page:walk({
      Meta = function(meta)
        meta["sitemap"] = SITEMAP
        return meta
      end
    })
  end
end

do
  print("[INFO] bavbavhaus.net: writing partial pages")
  function get_template(path)
    local f = io.open(path)
    if not f then return end
    local template = f:read("*a")
    f:close()
    return pandoc.template.compile(template)
  end
  local write = pandoc.write
  local output_format = "html5"
  local WriterOptions = pandoc.WriterOptions
  local template = get_template("pandoc/templates/bavbavhaus.net.partial.html5")
  local RawBlock = pandoc.RawBlock
  for i,page in ipairs(PAGES) do
    local input_file = page["meta"]["input_file"]
    if not BACKLINKS[input_file] then goto continue end
    local backlinks = MetaList({})
    for _,backlink in ipairs(BACKLINKS[input_file]) do
      local backlink_page = PAGES:get(backlink)
      local writer_options = WriterOptions({
        identifier_prefix = "back/" .. backlink,
        template = template
      })
      local text = pandoc.write(backlink_page, output_format, writer_options)
      backlinks:insert(RawBlock("html5", text))
    end
    PAGES[i] = page:walk({
      Meta = function(meta)
        meta["backlinks"] = backlinks
        return meta
      end
    })
    ::continue::
  end
  for i,page in ipairs(PAGES) do
    local input_file = page["meta"]["input_file"]
    if not FORELINKS[input_file] then goto continue end
    local forelinks = MetaList({})
    for _,forelink in ipairs(FORELINKS[input_file]) do
      local forelink_page = PAGES:get(forelink)
      local writer_options = WriterOptions({
        identifier_prefix = "fore/" .. forelink,
        template = template
      })
      local text = pandoc.write(forelink_page, output_format, writer_options)
      forelinks:insert(RawBlock("html5", text))
    end
    PAGES[i] = page:walk({
      Meta = function(meta)
        meta["forelinks"] = forelinks
        return meta
      end
    })
    ::continue::
  end
  print("[INFO] bavbavhaus.net: writing pages")
  for _,page in ipairs(PAGES) do
    local f = io.open(page["meta"]["output_file"], "w")
    f:write(pandoc.write(page, output_format, WriterOptions({
      template = get_template("pandoc/templates/bavbavhaus.net.html5")
    })))
    f:close()
  end
end