local SWS_ADDON_NAME, StatWeightScore = ...;
local XmlModule = StatWeightScore:NewModule(SWS_ADDON_NAME.."Xml");

local function parseargs(s)
    local arg = {}
    string.gsub(s, "([%-%w]+)=([\"'])(.-)%2", function (w, _, a)
        arg[w] = a
    end)
    return arg
end

local function collect(s)
    local stack = {}
    local top = {}
    table.insert(stack, top)
    local ni,c,label,xarg, empty
    local i, j = 1, 1
    while true do
        ni,j,c,label,xarg, empty = string.find(s, "<(%/?)([%w:]+)(.-)(%/?)>", i)
        if not ni then break end
        local text = string.sub(s, i, ni-1)
        if not string.find(text, "^%s*$") then
            table.insert(top, text)
        end
        if empty == "/" then  -- empty element tag
        table.insert(top, {label=label, xarg=parseargs(xarg), empty=1})
        elseif c == "" then   -- start tag
        top = {label=label, xarg=parseargs(xarg)}
        table.insert(stack, top)   -- new level
        else  -- end tag
        local toclose = table.remove(stack)  -- remove top
        top = stack[#stack]
        if #stack < 1 then
            error("nothing to close with "..label)
        end
        if toclose.label ~= label then
            error("trying to close "..toclose.label.." with "..label)
        end
        table.insert(top, toclose)
        end
        i = j+1
    end
    local text = string.sub(s, i)
    if not string.find(text, "^%s*$") then
        table.insert(stack[#stack], text)
    end
    if #stack > 1 then
        error("unclosed "..stack[#stack].label)
    end
    return stack[1]
end

function XmlModule:Parse(input)
    return collect(input);
end