-- string.lua

local string_ext = {}

-- ======================================================================
-- STRING UTILITY FUNCTIONS
-- ======================================================================

-- Trim whitespace from both ends
function string_ext.trim(s)
	if type(s) ~= "string" then return s end
	return s:match("^%s*(.-)%s*$")
end

-- Split string by delimiter
function string_ext.split(s, delimiter)
	if type(s) ~= "string" then return {} end

	delimiter = delimiter or ","
	local result = {}
	for match in (s..delimiter):gmatch("(.-)"..delimiter) do
		table.insert(result, match)
	end
	return result
end

-- Check if string starts with prefix
function string_ext.starts_with(s, prefix)
	if type(s) ~= "string" or type(prefix) ~= "string" then return false end
	return s:sub(1, #prefix) == prefix
end

-- Check if string ends with suffix
function string_ext.ends_with(s, suffix)
	if type(s) ~= "string" or type(suffix) ~= "string" then return false end
	return suffix == "" or s:sub(-#suffix) == suffix
end

-- Left pad a string
function string_ext.pad_left(s, len, char)
	if type(s) ~= "string" or type(len) ~= "number" then return s end

	char = char or " "
	if #s >= len then return s end

	return string.rep(char:sub(1,1), len - #s) .. s
end

-- Right pad a string
function string_ext.pad_right(s, len, char)
	if type(s) ~= "string" or type(len) ~= "number" then return s end

	char = char or " "
	if #s >= len then return s end

	return s .. string.rep(char:sub(1,1), len - #s)
end

-- Center a string
function string_ext.center(s, width, char)
	if type(s) ~= "string" or width <= #s then return s end

	char = char or " "
	local pad_len = width - #s
	local left_pad = math.floor(pad_len / 2)
	local right_pad = pad_len - left_pad

	return string.rep(char:sub(1,1), left_pad) .. s .. string.rep(char:sub(1,1), right_pad)
end

-- Count occurrences of substring
function string_ext.count(s, substr)
	if type(s) ~= "string" or type(substr) ~= "string" or #substr == 0 then return 0 end

	local count, pos = 0, 1
	while true do
		pos = s:find(substr, pos, true)
		if not pos then break end
		count = count + 1
		pos = pos + 1
	end
	return count
end

-- Capitalize first letter
function string_ext.capitalize(s)
	if type(s) ~= "string" or #s == 0 then return s end
	return s:sub(1,1):upper() .. s:sub(2)
end

-- Capitalize all words
function string_ext.title(s)
	if type(s) ~= "string" then return s end

	return s:gsub("(%w)([%w]*)", function(first, rest)
		return first:upper() .. rest:lower()
	end)
end

-- Insert string at position
function string_ext.insert(s, pos, insert_str)
	if type(s) ~= "string" or type(insert_str) ~= "string" then return s end

	pos = math.max(1, math.min(pos, #s + 1))
	return s:sub(1, pos - 1) .. insert_str .. s:sub(pos)
end

-- Remove substring
function string_ext.remove(s, start, length)
	if type(s) ~= "string" then return s end

	length = length or 1
	if start < 1 or start > #s then return s end

	return s:sub(1, start - 1) .. s:sub(start + length)
end

-- Replace substring once
function string_ext.replace(s, old, new, n)
	if type(s) ~= "string" or type(old) ~= "string" or #old == 0 then return s end

	new = new or ""
	n = n or 1

	return s:gsub(old:gsub("[%-%^%$%(%)%%%.%[%]%*%+%-%?]", "%%%1"), new, n)
end

-- Check if string contains substring
function string_ext.contains(s, substr)
	if type(s) ~= "string" or type(substr) ~= "string" then return false end
	return s:find(substr, 1, true) ~= nil
end

-- Escape pattern magic characters
function string_ext.escape_pattern(s)
	if type(s) ~= "string" then return s end
	return s:gsub("[%-%^%$%(%)%%%.%[%]%*%+%-%?]", "%%%1")
end

-- Wrap text at specified width
function string_ext.wrap(s, width, indent_first, indent_rest)
	if type(s) ~= "string" or type(width) ~= "number" then return s end

	width = math.max(1, width)
	indent_first = indent_first or ""
	indent_rest = indent_rest or indent_first

	local result = {}
	local line_prefix = indent_first
	local pos = 1

	while pos <= #s do
		local line_width = width - #line_prefix
		local end_pos = math.min(pos + line_width - 1, #s)

		if end_pos < #s then
			local last_space = s:sub(pos, end_pos):match(".*%s()")
			if last_space then
				end_pos = pos + last_space - 2
			end
		end

		table.insert(result, line_prefix .. s:sub(pos, end_pos))
		pos = end_pos + 1

		-- Skip leading spaces on next line
		while s:sub(pos, pos) == " " do
			pos = pos + 1
		end

		line_prefix = indent_rest
	end

	return table.concat(result, "\n")
end

-- Limit string length with ellipsis
function string_ext.truncate(s, length, ellipsis)
	if type(s) ~= "string" then return s end

	ellipsis = ellipsis or "..."
	if #s <= length then return s end

	return s:sub(1, length - #ellipsis) .. ellipsis
end

-- ======================================================================
-- INSTALL EXTENSIONS INTO STRING LIBRARY
-- ======================================================================

for name, func in pairs(string) do
	string_ext[name] = func
end

return string_ext