local Helpers = {}

-- ====================================
-- 1) ARG ACCESS / BARGS WIRING
-- ====================================
local _bargs = nil

function Helpers.setBargs(fn)
    _bargs = fn
end

-- If Config.init doesn't call this, Helpers installs fallbacks below.
function Helpers.installArgAccessors(fargs, pargs)
    Helpers.getFArg = function(k) return fargs[k] end
    Helpers.getPArg = function(k) return pargs[k] end
    Helpers.bargs   = function(k)
        local v = pargs[k]
        if v == nil or v == "" then v = fargs[k] end
        return v
    end
    Helpers.setBargs(Helpers.bargs)
end

-- Default bargs (so unit tests don’t explode without Config.init)
Helpers.bargs = function(key)
    if _bargs then return _bargs(key) end
    return nil
end

-- ====================================
-- 2) BASIC CHECKS & YES/NO PARSERS
-- ====================================
function Helpers.isempty(s) return s == nil or s == "" end
function Helpers.notempty(s) return s ~= nil and s ~= "" end

-- tolerant, case-insensitive
function Helpers.yes(val)
    if val == nil then return false end
    val = tostring(val):lower()
    return val == "y" or val == "yes" or val == "true" or val == "1"
end
function Helpers.no(val)
    if val == nil then return false end
    val = tostring(val):lower()
    return val == "n" or val == "no" or val == "false" or val == "0"
end

-- ====================================
-- 3) STRING HELPERS
-- ====================================
-- 1 -> 'a', 2 -> 'b', ...; wraps beyond 26; clamps nil/invalid to 'a'
function Helpers.toChar(num)
    num = tonumber(num) or 1
    if num < 1 then num = 1 end
    -- wrap to 1..26 to avoid errors if headers exceed 26
    num = ((num - 1) % 26) + 1
    return string.char(string.byte("a") + num - 1)
end

-- Escape single characters for use inside a Lua pattern character class.
local function _esc_cc(ch)
    -- dash, caret, percent, closing bracket need escaping inside [...]
    if ch == "-" or ch == "^" or ch == "]" or ch == "%" then
        return "%" .. ch
    end
    return ch
end

-- Fast split over single-char delimiters; drops empties; optional number-cast.
function Helpers.split(str, delim, tonum)
    if Helpers.isempty(str) then return {} end
    local result, buf = {}, {}
    for i = 1, #delim do buf[#buf + 1] = _esc_cc(delim[i]) end
    local patt = "[^" .. table.concat(buf) .. "]+"
    for w in string.gmatch(str, patt) do
        result[#result + 1] = (tonum == true) and tonumber(w) or w
    end
    return result
end

-- Remove bold inside (...) and [...] while preserving wikilinks [[...]]
function Helpers.unboldParenthetical(text)
    if Helpers.isempty(text) then return text end

    local STYLE_NORMAL = '<span style="font-weight:normal">%s</span>'
    local PREFIX = "__WIKILINK__"
    local counter, placeholders = 0, {}

    -- 1) Extract wikilinks to placeholders
    text = text:gsub("%[%[(.-)%]%]", function(link)
        counter = counter + 1
        local key = PREFIX .. counter .. "__"
        placeholders[key] = link
        return key
    end)

    -- 2) Wrap balanced (...) and [...]
    text = text:gsub("(%b())", function(m) return string.format(STYLE_NORMAL, m) end)
               :gsub("(%b[])", function(m) return string.format(STYLE_NORMAL, m) end)

    -- 3) Restore wikilinks
    for key, link in pairs(placeholders) do
        text = text:gsub(key, "[[" .. link .. "]]")
    end
    return text
end

-- ====================================
-- 4) STYLE & DIMENSIONS
-- ====================================
-- Border mask is {top, right, bottom, left}
function Helpers.cellBorder(b)
    -- assume well-formed input; callers always pass 4 numbers
    return b[1] .. "px " .. b[2] .. "px " .. b[3] .. "px " .. b[4] .. "px"
end

-- Normalize CSS length: numbers -> "Npx"; strings with units pass through.
function Helpers.toCssLength(v, defaultVal)
    if v == nil or v == "" then return defaultVal end
    local n = tonumber(v)
    if n then return tostring(n) .. "px" end
    return v
end

-- Resolve widths from args with normalization & default
function Helpers.getWidth(ctype, defaultVal)
    local raw = Helpers.bargs(ctype .. "-width")
    return Helpers.toCssLength(raw, defaultVal)
end

return Helpers