f = {
    args_default = {
        bracket_left = "",
        bracket_right = "",
        bracket_year_left = "",
        bracket_year_right = "",
        postscript = "",
        page = "",
        pages = "",
        location = "",
        page_sep = ", p. ",
        pages_sep = ", pp. ",
        ref = "",
        P1 = "",
        P2 = "",
        P3 = "",
        P4 = "",
        P5 = ""
    }
}

function trim( str )
    if str == nil then
        return nil
    end
    return str:match( "^%s*(.-)%s*$")
end

function core( args )
    local result;
--TODO: evaluate to make sure that the following if correctly handles the parameter set when there is no year
    local ano

    if args.P5 ~= "" then
        result = args.P1 .. ' et al. ' .. args.bracket_year_left .. args.P5 ..
        args.bracket_year_right
    elseif args.P4 ~= "" then
        result = args.P1 .. ', ' .. args.P2 .. ' & ' .. args.P3 .. ' ' ..
        args.bracket_year_left .. args.P4 .. args.bracket_year_right
    elseif args.P3 ~= "" then
        result = args.P1 .. ' & ' .. args.P2 .. ' ' .. args.bracket_year_left ..
        args.P3 .. args.bracket_year_right
    elseif args.P2 ~= "" then
        local ano = args.P2
        -- converte possível hífen para traço
        if string.match(ano, "^[1-9]%d%d%d?[%-–][1-9]%d%d%d?%a?$") then
            ano = ("%d–%d"):format(string.match(args.P2, "(%d%d%d%d?)%-(%d%d%d%d?)%a?"))
        end
        local isDate
        for _, tmp in ipairs {'%d%d', 'Século', 'século', 'AC', 'A%.C%.', 'AD', 'A%.D%.'
            , 'aC', 'a%.C%.', 'dC', 'd%.C%.', 'DC', 'D%.C%.', 'n%.d%.', 'nd', 's%.d%.', 'sd'}
        do
            if ano:find(tmp) then
                isDate = true
                break
            end
        end

        if isDate then
            result = args.P1 .. ' ' .. args.bracket_year_left .. ano .. args.bracket_year_right
        else
            result = args.P1 .. ' & ' .. args.P2 -- for the case where the last numbered parameter is a name and not a year and not no-date
        end
        args.P2 = ano
    else
        result = trim( args.P1 .. ' ' .. args.bracket_year_left .. args.P2 ..
        args.bracket_year_right )
    end

    if ('.' == result:sub(-1)) and ('' == args.page) and ('' == args.pages) and ('' == args.location) then
        args.postscript = '' -- prevent double periods when date is 'n.d.'
    end

    if args.ref ~= 'none' then
        if args.ref ~= "" then
            result = "[[#" .. mw.uri.anchorEncode(args.ref) .. "|" .. result .. "]]"
        else
            result = "[[#CITEREF" .. mw.uri.anchorEncode(args.P1 .. (ano or args.P2)
                .. args.P3 .. args.P4 .. args.P5) .. "|" .. result .. "]]"
        end
    end

    if args.page ~= "" then
        result = result .. args.page_sep .. args.page
    elseif args.pages ~= "" then
        result = result .. args.pages_sep .. args.pages
    end

    if args.location ~= "" then
        result = result .. ", " .. args.location
    end

    result = args.bracket_left .. result .. args.bracket_right .. args.postscript
    return result
end

function f.harvard_core( frame )
    local args = {}
    local pframe = frame:getParent()

    args.bracket_left = pframe.args.BracketLeft or ""
    args.bracket_right = pframe.args.BracketRight or ""
    args.bracket_year_left = pframe.args.BracketYearLeft or ""
    args.bracket_year_right = pframe.args.BracketYearRight or ""
    args.postscript = pframe.args.Postscript or ""
    if 'none' == args.postscript then
        args.postscript = ''
    end

    args.page = pframe.args.Page or ""
    args.pages = pframe.args.Pages or ""
    args.location = pframe.args.Location or ""
    args.page_sep = pframe.args.PageSep or ""
    args.pages_sep = pframe.args.PagesSep or ""
    args.ref = pframe.args.REF or "{{{REF}}}"
    args.P1 = trim( pframe.args.P1 ) or ""
    args.P2 = trim( pframe.args.P2 ) or ""
    args.P3 = trim( pframe.args.P3 ) or ""
    args.P4 = trim( pframe.args.P4 ) or ""
    args.P5 = trim( pframe.args.P5 ) or ""

    return core( args )
end

function f.harvard_citation( frame )
    local args = f.args_default
    pframe = frame:getParent()

    args.bracket_left = "("
    args.bracket_right = ")"
    args.page = pframe.args.p or pframe.args.page or ""
    args.pages = pframe.args.pp or pframe.args.pages or ""
    args.location = pframe.args.loc or ""
    args.ref = pframe.args.ref or pframe.args.Ref or ""
    args.P1 = trim( pframe.args[1] ) or ""
    args.P2 = trim( pframe.args[2] ) or ""
    args.P3 = trim( pframe.args[3] ) or ""
    args.P4 = trim( pframe.args[4] ) or ""
    args.P5 = trim( pframe.args[5] ) or ""

    return core( args )
end

function f.harvard_citation_no_bracket( frame )
    local args = f.args_default
    pframe = frame:getParent()

    args.page = pframe.args.p or pframe.args.page or ""
    args.pages = pframe.args.pp or pframe.args.pages or ""
    args.location = pframe.args.loc or ""
    args.ref = pframe.args.ref or pframe.args.Ref or ""
    args.P1 = trim( pframe.args[1] ) or ""
    args.P2 = trim( pframe.args[2] ) or ""
    args.P3 = trim( pframe.args[3] ) or ""
    args.P4 = trim( pframe.args[4] ) or ""
    args.P5 = trim( pframe.args[5] ) or ""

    return core( args )
end

function f.sfn( frame )
    local args = f.args_default
    for k, v in pairs( frame.args ) do -- for {{sfnp}}, override default with values provided in the #invoke:
        args[k] = v
    end

    pframe = frame:getParent()

    args.postscript = pframe.args.postscript or pframe.args.ps or "."
    if 'none' == args.postscript then
        args.postscript = ''
    end
    args.page = pframe.args.p or pframe.args.page or ""
    args.pages = pframe.args.pp or pframe.args.pages or ""
    args.location = pframe.args.loc or ""
    args.ref = pframe.args.ref or pframe.args.Ref or ""
    args.P1 = trim( pframe.args[1] ) or ""
    args.P2 = trim( pframe.args[2] ) or ""
    args.P3 = trim( pframe.args[3] ) or ""
    args.P4 = trim( pframe.args[4] ) or ""
    args.P5 = trim( pframe.args[5] ) or ""

    local result = core( args );
    local name = trim(pframe.args['name']) or trim(pframe.args['nome']) or
        "FOOTNOTE" .. args.P1 .. args.P2 .. args.P3 .. args.P4 .. args.P5 ..
        args.page .. args.pages .. args.location

    local group = trim(pframe.args['group']) or trim(pframe.args['grupo'])

    result = frame:extensionTag{ name = "ref", args = { name = name,  group = group}, content=result }

    return result
end

return f