Module:Sandbox/Szqecs/Adjacent stations

--
-- This module implements {{Adjacent stations}}
--

local p = {}

local navbar = require('Module:Navbar')._navbar

local args = {}
local origArgs
local root

local function renderHeader()
	root
		:tag('tr')
			:tag('th')
				:addClass('hcA')
				:wikitext('Previous station')
			:tag('th')
				:addClass('hmA')
				:attr('colspan', 3)
				:wikitext('Title')
			:tag('th')
				:addClass('hcA')
				:wikitext('Following station')
end
			

local function _main()
    -- Specify the overall layout of the succession box, with special settings
        root = mw.html.create('table')
        root
        	:addClass('wikitable adjacent-stations')
        	
        renderHeader()
 
    return tostring(root)
end

local function preprocessSingleArg(argName)
    -- If the argument exists and isn't blank, add it to the argument table.
    -- Blank arguments are treated as nil to match the behaviour of ParserFunctions.
    if origArgs[argName] and origArgs[argName] ~= '' then
        args[argName] = origArgs[argName]
    end
end

local function preprocessArgs(prefixTable, step)
    -- Assign the parameters with the given prefixes to the args table, in order, in batches
    -- of the step size specified. This is to prevent references etc. from appearing in the
    -- wrong order. The prefixTable should be an array containing tables, each of which has
    -- two possible fields, a "prefix" string and a "depend" table. The function always parses
    -- parameters containing the "prefix" string, but only parses parameters in the "depend"
    -- table if the prefix parameter is present and non-blank.
    if type(prefixTable) ~= 'table' then
        error("Non-table value detected for the prefix table", 2)
    end
    if type(step) ~= 'number' then
        error("Invalid step value detected", 2)
    end
    
    -- Get arguments without a number suffix, and check for bad input.
    for i,v in ipairs(prefixTable) do
        if type(v) ~= 'table' or type(v.prefix) ~= "string" or (v.depend and type(v.depend) ~= 'table') then
            error('Invalid input detected to preprocessArgs prefix table', 2)
        end
        preprocessSingleArg(v.prefix)
        -- Only parse the depend parameter if the prefix parameter is present and not blank.
        if args[v.prefix] and v.depend then
            for j, dependValue in ipairs(v.depend) do
                if type(dependValue) ~= 'string' then
                    error('Invalid "depend" parameter value detected in preprocessArgs')
                end
                preprocessSingleArg(dependValue)
            end
        end
    end

    -- Get arguments with number suffixes.
    local a = 1 -- Counter variable.
    local moreArgumentsExist = true
    while moreArgumentsExist == true do
        moreArgumentsExist = false
        for i = a, a + step - 1 do
            for j,v in ipairs(prefixTable) do
                local prefixArgName = v.prefix .. tostring(i)
                if origArgs[prefixArgName] then
                    moreArgumentsExist = true -- Do another loop if any arguments are found, even blank ones.
                    preprocessSingleArg(prefixArgName)
                end
                -- Process the depend table if the prefix argument is present and not blank, or
                -- we are processing "prefix1" and "prefix" is present and not blank, and
                -- if the depend table is present.
                if v.depend and (args[prefixArgName] or (i == 1 and args[v.prefix])) then
                    for j,dependValue in ipairs(v.depend) do
                        local dependArgName = dependValue .. tostring(i)
                        preprocessSingleArg(dependArgName)
                    end
                end
            end
        end
        a = a + step
    end
end
 
function p.main(frame)
    -- If called via #invoke, use the args passed into the invoking template.
    -- Otherwise, for testing purposes, assume args are being passed directly in.
    if frame == mw.getCurrentFrame() then
        origArgs = frame:getParent().args
    else
        origArgs = frame
    end
    
    return _main()
end
 
return p