local _module = {}

_module.create = function(frame)
    
    ------------- Functions -------------
    local strFind = string.find
    local strMatch = string.match
    local strSplit = mw.text.split
    local strFormat = string.format
    local strTrim = mw.text.trim
    local strSub = string.sub
    local strUpper = string.upper
    
    ------------- Arguments -------------
    local args = frame.args
    local matchesPerTeam = tonumber(args.matchesPerTeam) or error("Invalid or missing parameter 'matchesPerTeam'")
    local teams = strSplit(args.teams or error("Invalid or missing parameter 'teams'"), ',', true)
    
    local playoffLabels = {}
    if args.playoffLabels and args.playoffLabels ~= "" then
        playoffLabels = strSplit(args.playoffLabels, ',', true)
    end
    local numPlayoffs = #playoffLabels
    
    local matchReportArticle = args.matchReportArticle or ''
    local caption = args.caption

    local colours_win           = "#99FF99"
    local colours_loss          = "#FFDDDD"
    local colours_tie           = "#FFFFCC"
    local colours_noResult      = "#DFDFFF"
    local colours_eliminated    = "#DCDCDC"
    
    local classes_win       = "yes table-yes2"
    local classes_loss      = "no table-no2"
    local classes_tie       = "table-partial"
    local classes_noResult  = "noresult"
    
    local output = {}
    local function print(s)
        table.insert(output, s)
    end
    
    -- Header
    print(strFormat([[
{| class="wikitable" style="text-align: center; font-size: 100%%"
%s
! scope="col" rowspan="2" | Team
! colspan="%d" style="border-left: 4px solid #454545" | Group matches
]], caption and '|+ ' .. caption or '', matchesPerTeam))

    if numPlayoffs > 0 then
        print(strFormat('! colspan="%d" style="border-left: 4px solid #454545" | Play-offs\n', numPlayoffs))
    end

    print('|-\n')
    
    for i = 1, matchesPerTeam do
        print(strFormat('! scope="col" style="width: 45px;%s" | %d\n', i == 1 and " border-left: 4px solid #454545" or "", i))
    end
    
    for i = 1, numPlayoffs do
        print(strFormat('! scope="col" style="width: 40px;%s" | %s\n', i == 1 and " border-left: 4px solid #454545" or "", strTrim(playoffLabels[i])))
    end
        
    local argCounter = 1
    
    -- Rows
    for i = 1, #teams do
        local team = strTrim(teams[i])
        print('\n|-\n! scope="row" style="text-align: left; padding-right: 10px" | ' .. team .. '\n')
        
        local groupResultsRaw = args[argCounter] or ''
        local playoffResultsRaw = args[argCounter + 1] or ''
        argCounter = argCounter + 2
        
        local g_results = strSplit(groupResultsRaw, ',', true)
        local p_results = strSplit(playoffResultsRaw, ',', true)
        
        local runningScore = 0
        
        -- 1. Group Stage
        for j = 1, matchesPerTeam do
            local resultData = strTrim(g_results[j] or "")
            local cellStart = (j == 1) and '| style="border-left: 4px solid #454545; ' or '|| style="'
            
            if resultData ~= "" then
                local res = strUpper(strSub(resultData, 1, 1))
                if not strFind("WLTN", res) then
                    error(strFormat("Invalid Result '%s' for %s. Use W, L, T, or N.", res, team))
                end

                local match_id = strMatch(resultData, '%d+%a?')
                local bonus = tonumber(strMatch(resultData, '%+(%d+)')) or 0
                
                if res == 'W' then runningScore = runningScore + 2
                elseif res == 'T' or res == 'N' then runningScore = runningScore + 1 end
                runningScore = runningScore + bonus
                
                local color = (res == 'W' and colours_win) or (res == 'L' and colours_loss) or (res == 'T' and colours_tie) or colours_noResult
                local class = (res == 'W' and classes_win) or (res == 'L' and classes_loss) or (res == 'T' and classes_tie) or classes_noResult
                
                print(strFormat('%sbackground-color: %s" class="%s" | [[%s#match%s|%d]] ', cellStart, color, class, matchReportArticle, match_id or '', runningScore))
            else
                print(cellStart .. '" | ')
            end
        end

        -- 2. Play-offs 
        if numPlayoffs > 0 then
            for k = 1, numPlayoffs do
                local pData = strTrim(p_results[k] or "")
                local cellStart = (k == 1) and '|| style="border-left: 4px solid #454545; ' or '|| style="'
                
                if pData ~= "" then
                    local res = strUpper(strSub(pData, 1, 1))
                    if not strFind("WLTNE", res) then
                        error(strFormat("Invalid Play-off Result '%s' for %s. Use W, L, T, N, or E.", res, team))
                    end

                    local match_id = strMatch(pData, '%d+%a?')
                    local color = (res == 'W' and colours_win) or (res == 'L' and colours_loss) or (res == 'T' and colours_tie) or (res == 'E' and colours_eliminated) or colours_noResult
                    
                    if res == 'E' then
                        print(strFormat('%sbackground-color: %s" | — ', cellStart, color))
                    else
                        print(strFormat('%sbackground-color: %s" | [[%s#match%s|%s]] ', cellStart, color, matchReportArticle, match_id or '', res))
                    end
                else
                    -- Check if there is a result in ANY future column for this team
                    local hasFutureResult = false
                    for future = k + 1, #p_results do
                        if strTrim(p_results[future] or "") ~= "" then
                            hasFutureResult = true
                            break
                        end
                    end

                    if hasFutureResult then
                        print(cellStart .. '" | → ')
                    else
                        print(cellStart .. '" | ')
                    end
                end
            end
        end
    end
    
    -- Footer Legend
    print(strFormat([[

|}
{| class="wikitable" style="text-align: center; font-size: 90%%"
| class="%s" style="background-color: %s" | Win
| class="%s" style="background-color: %s" | Loss
| class="%s" style="background-color: %s" | Tie
| class="%s" style="background-color: %s" | No result
| style="background-color: %s" | Eliminated
|}
<ul style="font-size: 85%%">
<li>'''Note''': The total points at the end of each group match are listed.</li>
<li>'''Note''': Click on the points or results to see the match summary.</li>
</ul>
]], classes_win, colours_win, classes_loss, colours_loss, classes_tie, colours_tie, classes_noResult, colours_noResult, colours_eliminated))

    return table.concat(output)
end

return _module