-- Experimental module for building complex HTML (e.g. infoboxes, navboxes) using a fluent interface

local HtmlBuilder = {}

local metatable = {}

metatable.__index = function(t, key)

   local ret = rawget(t, key)
   if ret then
       return ret
   end
   
   ret = metatable[key]
   if type(ret) == 'function' then
       return function(...) 
           return ret(t, ...) 
       end 
   else
       return ret
   end

end

metatable.__tostring = function(t)

   local ret = {}
   t._build(ret)
   return table.concat(ret, )

end

metatable._build = function(t, ret)

   if t.tagName then 
       table.insert(ret, '<' .. t.tagName)
       for i, attr in ipairs(t.attributes) do
           table.insert(ret, ' ' .. attr.name .. '="' .. attr.val .. '"') 
       end
       if #t.styles > 0 then
           table.insert(ret, ' style="')
           for i, prop in ipairs(t.styles) do
               if type(prop) == 'string' then -- added with cssText()
                   table.insert(ret, prop .. ';')
               else -- added with css()
                   table.insert(ret, prop.name .. ':' .. prop.val .. ';')
               end
           end
           table.insert(ret, '"')
       end
       table.insert(ret, '>') 
   end
   for i, node in ipairs(t.nodes) do
       if node then
           if type(node) == 'table' then
               node._build(ret)
           else
               table.insert(ret, tostring(node))
           end
       end
   end
   if t.tagName and not t.unclosed then
       table.insert(ret, '</' .. t.tagName .. '>')
   end

end

metatable.node = function(t, builder)

   if builder then
       table.insert(t.nodes, builder)
   end
   return t

end

metatable.wikitext = function(t, ...)

   local vals = {...}
   for i = 1, #vals do
       if vals[i] then
           table.insert(t.nodes, vals[i])
       end
   end
   return t

end

metatable.newline = function(t)

   table.insert(t.nodes, '\n')
   return t

end

metatable.tag = function(t, tagName, args)

   args = args or {}
   args.parent = t
   local builder = HtmlBuilder.create(tagName, args)
   table.insert(t.nodes, builder)
   return builder

end

function getAttr(t, name)

   for i, attr in ipairs(t.attributes) do
       if attr.name == name then
           return attr
       end
   end

end

metatable.attr = function(t, name, val)

   -- if caller sets the style attribute explicitly, then replace all styles previously added with css() and cssText()
   if name == 'style' then
       t.styles = {val}
       return t
   end
   
   local attr = getAttr(t, name)
   if attr then
       attr.val = val
   else
       table.insert(t.attributes, {name = name, val = val})
   end
   
   return t

end

metatable.addClass = function(t, class)

   if class then
       local attr = getAttr(t, 'class')
       if attr then
           attr.val = attr.val .. ' ' .. class
       else
           t.attr('class', class)
       end
   end

   return t

end

metatable.css = function(t, name, val)

   if type(val) == 'string' or type(val) == 'number' then
       for i, prop in ipairs(t.styles) do
           if prop.name == name then
               prop.val = val
               return t
           end
       end
       
       table.insert(t.styles, {name = name, val = val})
   end
   
   return t

end

metatable.cssText = function(t, css)

   if css then
       table.insert(t.styles, css)
   end
   return t

end

metatable.done = function(t)

   return t.parent or t

end

metatable.allDone = function(t)

   while t.parent do
       t = t.parent
   end
   return t

end

function HtmlBuilder.create(tagName, args)

   args = args or {}
   local builder = {}
   setmetatable(builder, metatable)
   builder.nodes = {}
   builder.attributes = {}
   builder.styles = {}
   builder.tagName = tagName
   builder.parent = args.parent
   builder.unclosed = args.unclosed or false
   return builder

end

return HtmlBuilder