local HF = {}

function HF.explode( sep, text )
	local sep, fields = sep or "::", {}
	local pattern = string.format("([^%s]+)", sep)

	text:gsub( pattern, function( c ) fields[#fields+1] = c end )

	return fields
end

function HF.isempty(s)
	local result = false

	if type( s ) == "nil" then
		result = true
	elseif type( s ) == "string" then
		if s == "" then
			result = true
		end
	elseif type( s ) == "table" then
		if next( s ) == nil then
			result = true
		end
	end

	return result
end

function HF.firstToUpper( str )
	return ( str:gsub( "^%l", string.upper ) )
end

function HF.round(num, idp)
	local mult = 10^(idp or 0)
	return math.floor( num * mult + 0.5 ) / mult
end

-- eliminates whitespace from the front and back of a string
function HF.trim(s)
  if type(s) == 'string' then
    return (s:gsub("^%s*(.-)%s*$", '%1'))
  else
    return false
  end
end

-- This creates an external link.
function HF.ExternalLink( target, label, plain )
  local output = string.format('[%s %s]', target, label)

  if plain == true then
    output = string.format('<span class="plainlinks">%s</span>', output)
  end

  return output
end

-- This creates a link to a category, as well as placing it in that category.
-- `sortkey` and `label` are optional
-- If there's no `label` given, it will only place it in the category,
-- which is what HF.Category is for.
function HF.CategoryLink( category, sortkey, label )
  if not HF.isempty( label ) then
    return HF.LinkToCategory( category, label ) ..
        HF.Category( category, sortkey )
  else
    return HF.Category( category, sortkey )
  end
end

-- Adds a Category
-- `sortkey` is optional
function HF.Category( category, sortkey )
    if sortkey == nil then sortkey = '' else sortkey = '|' .. sortkey end

    return string.format('%s' .. mw.site.namespaces[14].canonicalName .. ':%s%s]]', '[[', category, sortkey)
end

-- Adds a link to a Category
function HF.LinkToCategory( category, label )
    local category_namespace_name = mw.site.namespaces[14].canonicalName
    return string.format('%s'..category_namespace_name..':%s|%s]]', '[[:', category,
        label or category_namespace_name..':' .. category )
end

-- Adds an internal link
-- `label` is optional
function HF.Link( link, text )
    if not HF.isempty( text ) then
        return string.format('%s'..'%s|%s]]', '[[', link, text)
    else
        return string.format('%s'..'%s]]', '[[', link)
    end
end

-- Checks to see if there's an existing article at the target.
-- If there is, creates a link.
-- If there's not, only write the target's name as text.
-- If it is passed a link, it will not perform this check and will only write the link.
function HF.Link_safe( object )
    if object:match("^%[%[(.*)%]%]$") then
        return object
    elseif mw.title.new( object ).exists == true then
        return HF.Link( object )
    else
        return object
    end
end

-- Checks to see if there's an existing category at the target.
-- If there is, creates a link.
-- If there's not, only write the target's name as text.
function HF.LinkToCategory_safe( object )
    if mw.title.new( object, 14 ).exists == true then
        return HF.Link( ':'..mw.site.namespaces[14].canonicalName..':'..object, object )
    else
        return object
    end
end

-- Checks to see if there's an existing category at the target.
-- If there is, creates a link.
-- If there's not, only write the target's name as text.
function HF.KillNewCategories( object )
    if mw.title.new( object, 14 ).exists == true then
        return HF.Category( object, object, object)
    else
        return object
    end
end

-- Unique table items
function HF.unique( raw_table )
    local hash = {}
    local unique_results = {}

    for _,v in ipairs( raw_table ) do
       if (not hash[v] and v ~= '') then
           table.insert( unique_results, mw.text.trim(v) )
           hash[v] = true
       end
    end

    return unique_results
end