-- modules/string.lua - Enhanced string manipulation utilities

local str = {}

-- Helper function to handle errors from Go functions
local function safe_call(func, ...)
	local success, result = pcall(func, ...)
	if not success then
		error(result, 2)
	end
	return result
end

-- Helper to validate arguments
local function validate_string(s, func_name, arg_num)
	if type(s) ~= "string" then
		error(string.format("%s: argument %d must be a string, got %s", 
			func_name, arg_num or 1, type(s)), 3)
	end
end

local function validate_number(n, func_name, arg_num)
	if type(n) ~= "number" then
		error(string.format("%s: argument %d must be a number, got %s", 
			func_name, arg_num or 1, type(n)), 3)
	end
end

local function validate_table(t, func_name, arg_num)
	if type(t) ~= "table" then
		error(string.format("%s: argument %d must be a table, got %s", 
			func_name, arg_num or 1, type(t)), 3)
	end
end

-- ======================================================================
-- BASIC STRING OPERATIONS
-- ======================================================================

function str.split(s, delimiter)
	validate_string(s, "str.split", 1)
	validate_string(delimiter, "str.split", 2)
	return safe_call(moonshark.string_split, s, delimiter)
end

function str.join(arr, separator)
	validate_table(arr, "str.join", 1)
	validate_string(separator, "str.join", 2)
	return safe_call(moonshark.string_join, arr, separator)
end

function str.trim(s)
	validate_string(s, "str.trim")
	return safe_call(moonshark.string_trim, s)
end

function str.trim_left(s, cutset)
	validate_string(s, "str.trim_left", 1)
	if cutset ~= nil then
		validate_string(cutset, "str.trim_left", 2)
	end
	return safe_call(moonshark.string_trim_left, s, cutset)
end

function str.trim_right(s, cutset)
	validate_string(s, "str.trim_right", 1)
	if cutset ~= nil then
		validate_string(cutset, "str.trim_right", 2)
	end
	return safe_call(moonshark.string_trim_right, s, cutset)
end

function str.upper(s)
	validate_string(s, "str.upper")
	return safe_call(moonshark.string_upper, s)
end

function str.lower(s)
	validate_string(s, "str.lower")
	return safe_call(moonshark.string_lower, s)
end

function str.title(s)
	validate_string(s, "str.title")
	return safe_call(moonshark.string_title, s)
end

function str.contains(s, substr)
	validate_string(s, "str.contains", 1)
	validate_string(substr, "str.contains", 2)
	return safe_call(moonshark.string_contains, s, substr)
end

function str.starts_with(s, prefix)
	validate_string(s, "str.starts_with", 1)
	validate_string(prefix, "str.starts_with", 2)
	return safe_call(moonshark.string_starts_with, s, prefix)
end

function str.ends_with(s, suffix)
	validate_string(s, "str.ends_with", 1)
	validate_string(suffix, "str.ends_with", 2)
	return safe_call(moonshark.string_ends_with, s, suffix)
end

function str.replace(s, old, new)
	validate_string(s, "str.replace", 1)
	validate_string(old, "str.replace", 2)
	validate_string(new, "str.replace", 3)
	return safe_call(moonshark.string_replace, s, old, new)
end

function str.replace_n(s, old, new, n)
	validate_string(s, "str.replace_n", 1)
	validate_string(old, "str.replace_n", 2)
	validate_string(new, "str.replace_n", 3)
	validate_number(n, "str.replace_n", 4)
	if n < 0 or n ~= math.floor(n) then
		error("str.replace_n: count must be a non-negative integer", 2)
	end
	return safe_call(moonshark.string_replace_n, s, old, new, n)
end

function str.index(s, substr)
	validate_string(s, "str.index", 1)
	validate_string(substr, "str.index", 2)
	local idx = safe_call(moonshark.string_index, s, substr)
	return idx > 0 and idx or nil
end

function str.last_index(s, substr)
	validate_string(s, "str.last_index", 1)
	validate_string(substr, "str.last_index", 2)
	local idx = safe_call(moonshark.string_last_index, s, substr)
	return idx > 0 and idx or nil
end

function str.count(s, substr)
	validate_string(s, "str.count", 1)
	validate_string(substr, "str.count", 2)
	return safe_call(moonshark.string_count, s, substr)
end

function str.repeat_(s, n)
	validate_string(s, "str.repeat_", 1)
	validate_number(n, "str.repeat_", 2)
	if n < 0 or n ~= math.floor(n) then
		error("str.repeat_: count must be a non-negative integer", 2)
	end
	return safe_call(moonshark.string_repeat, s, n)
end

function str.reverse(s)
	validate_string(s, "str.reverse")
	return safe_call(moonshark.string_reverse, s)
end

function str.length(s)
	validate_string(s, "str.length")
	return safe_call(moonshark.string_length, s)
end

function str.byte_length(s)
	validate_string(s, "str.byte_length")
	return safe_call(moonshark.string_byte_length, s)
end

function str.lines(s)
	validate_string(s, "str.lines")
	return safe_call(moonshark.string_lines, s)
end

function str.words(s)
	validate_string(s, "str.words")
	return safe_call(moonshark.string_words, s)
end

function str.pad_left(s, width, pad_char)
	validate_string(s, "str.pad_left", 1)
	validate_number(width, "str.pad_left", 2)
	if width < 0 or width ~= math.floor(width) then
		error("str.pad_left: width must be a non-negative integer", 2)
	end
	if pad_char ~= nil then
		validate_string(pad_char, "str.pad_left", 3)
	end
	return safe_call(moonshark.string_pad_left, s, width, pad_char)
end

function str.pad_right(s, width, pad_char)
	validate_string(s, "str.pad_right", 1)
	validate_number(width, "str.pad_right", 2)
	if width < 0 or width ~= math.floor(width) then
		error("str.pad_right: width must be a non-negative integer", 2)
	end
	if pad_char ~= nil then
		validate_string(pad_char, "str.pad_right", 3)
	end
	return safe_call(moonshark.string_pad_right, s, width, pad_char)
end

function str.slice(s, start, end_pos)
	validate_string(s, "str.slice", 1)
	validate_number(start, "str.slice", 2)
	if start ~= math.floor(start) then
		error("str.slice: start must be an integer", 2)
	end
	if end_pos ~= nil then
		validate_number(end_pos, "str.slice", 3)
		if end_pos ~= math.floor(end_pos) then
			error("str.slice: end position must be an integer", 2)
		end
	end
	return safe_call(moonshark.string_slice, s, start, end_pos)
end

-- ======================================================================
-- REGULAR EXPRESSIONS
-- ======================================================================

function str.match(pattern, s)
	validate_string(pattern, "str.match", 1)
	validate_string(s, "str.match", 2)
	return safe_call(moonshark.regex_match, pattern, s)
end

function str.find(pattern, s)
	validate_string(pattern, "str.find", 1)
	validate_string(s, "str.find", 2)
	return safe_call(moonshark.regex_find, pattern, s)
end

function str.find_all(pattern, s)
	validate_string(pattern, "str.find_all", 1)
	validate_string(s, "str.find_all", 2)
	return safe_call(moonshark.regex_find_all, pattern, s)
end

function str.gsub(pattern, s, replacement)
	validate_string(pattern, "str.gsub", 1)
	validate_string(s, "str.gsub", 2)
	validate_string(replacement, "str.gsub", 3)
	return safe_call(moonshark.regex_replace, pattern, s, replacement)
end

-- ======================================================================
-- TYPE CONVERSION & VALIDATION
-- ======================================================================

function str.to_number(s)
	validate_string(s, "str.to_number")
	return safe_call(moonshark.string_to_number, s)
end

function str.is_numeric(s)
	validate_string(s, "str.is_numeric")
	return safe_call(moonshark.string_is_numeric, s)
end

function str.is_alpha(s)
	validate_string(s, "str.is_alpha")
	return safe_call(moonshark.string_is_alpha, s)
end

function str.is_alphanumeric(s)
	validate_string(s, "str.is_alphanumeric")
	return safe_call(moonshark.string_is_alphanumeric, s)
end

function str.is_empty(s)
	return s == nil or s == ""
end

function str.is_blank(s)
	return str.is_empty(s) or str.trim(s) == ""
end

function str.is_utf8(s)
	validate_string(s, "str.is_utf8")
	return safe_call(moonshark.string_is_valid_utf8, s)
end

function str.is_valid_utf8(s)
	validate_string(s, "str.is_valid_utf8")
	return safe_call(moonshark.string_is_valid_utf8, s)
end

-- ======================================================================
-- ADVANCED STRING OPERATIONS
-- ======================================================================

-- Capitalize first letter of each word (Pure Lua - faster)
function str.capitalize(s)
	validate_string(s, "str.capitalize")
	return s:gsub("(%a)([%w_']*)", function(first, rest)
		return first:upper() .. rest:lower()
	end)
end

-- Convert string to camelCase (Pure Lua - faster)
function str.camel_case(s)
	validate_string(s, "str.camel_case")
	local words = {}
	for word in s:gmatch("%S+") do
		table.insert(words, word:lower())
	end
	if #words == 0 then return s end
	
	local result = words[1]
	for i = 2, #words do
		result = result .. words[i]:gsub("^%l", string.upper)
	end
	return result
end

-- Convert string to PascalCase (Pure Lua - faster)
function str.pascal_case(s)
	validate_string(s, "str.pascal_case")
	local words = {}
	for word in s:gmatch("%S+") do
		table.insert(words, word:lower())
	end
	local result = ""
	for _, word in ipairs(words) do
		result = result .. word:gsub("^%l", string.upper)
	end
	return result
end

-- Convert string to snake_case (Pure Lua - faster)
function str.snake_case(s)
	validate_string(s, "str.snake_case")
	local words = {}
	for word in s:gmatch("%S+") do
		table.insert(words, word:lower())
	end
	return table.concat(words, "_")
end

-- Convert string to kebab-case (Pure Lua - faster)
function str.kebab_case(s)
	validate_string(s, "str.kebab_case")
	local words = {}
	for word in s:gmatch("%S+") do
		table.insert(words, word:lower())
	end
	return table.concat(words, "-")
end

-- Convert string to SCREAMING_SNAKE_CASE (Pure Lua - faster)
function str.screaming_snake_case(s)
	validate_string(s, "str.screaming_snake_case")
	local words = {}
	for word in s:gmatch("%S+") do
		table.insert(words, word:upper())
	end
	return table.concat(words, "_")
end

-- Center text within given width (Pure Lua - faster)
function str.center(s, width, fill_char)
	validate_string(s, "str.center", 1)
	validate_number(width, "str.center", 2)
	if width < 0 or width ~= math.floor(width) then
		error("str.center: width must be a non-negative integer", 2)
	end
	
	fill_char = fill_char or " "
	if fill_char ~= nil then
		validate_string(fill_char, "str.center", 3)
		if #fill_char == 0 then
			error("str.center: fill character cannot be empty", 2)
		end
		fill_char = fill_char:sub(1,1) -- Use only first character
	end
	
	local len = #s
	if len >= width then return s end
	
	local pad_total = width - len
	local pad_left = math.floor(pad_total / 2)
	local pad_right = pad_total - pad_left
	
	return string.rep(fill_char, pad_left) .. s .. string.rep(fill_char, pad_right)
end

-- Truncate string to maximum length (Pure Lua - faster)
function str.truncate(s, max_length, suffix)
	validate_string(s, "str.truncate", 1)
	validate_number(max_length, "str.truncate", 2)
	if max_length < 0 or max_length ~= math.floor(max_length) then
		error("str.truncate: max_length must be a non-negative integer", 2)
	end
	
	suffix = suffix or "..."
	validate_string(suffix, "str.truncate", 3)
	
	if #s <= max_length then
		return s
	end
	
	local suffix_len = #suffix
	if max_length <= suffix_len then
		return suffix:sub(1, max_length)
	end
	
	local main_part = s:sub(1, max_length - suffix_len)
	main_part = main_part:gsub("%s+$", "") -- trim right
	return main_part .. suffix
end

-- Wrap text to specified width (Pure Lua - much faster)
function str.wrap(s, width)
	validate_string(s, "str.wrap", 1)
	validate_number(width, "str.wrap", 2)
	if width <= 0 or width ~= math.floor(width) then
		error("str.wrap: width must be a positive integer", 2)
	end
	
	local words = {}
	for word in s:gmatch("%S+") do
		table.insert(words, word)
	end
	
	local lines = {}
	local current_line = ""
	
	for _, word in ipairs(words) do
		local word_len = #word
		local current_len = #current_line
		
		-- Handle words longer than width
		if word_len > width then
			if current_line ~= "" then
				table.insert(lines, current_line)
				current_line = ""
			end
			-- Break long word
			while #word > width do
				table.insert(lines, word:sub(1, width))
				word = word:sub(width + 1)
			end
			if #word > 0 then
				current_line = word
			end
		elseif current_len + word_len + 1 <= width then
			if current_line == "" then
				current_line = word
			else
				current_line = current_line .. " " .. word
			end
		else
			if current_line ~= "" then
				table.insert(lines, current_line)
			end
			current_line = word
		end
	end
	
	if current_line ~= "" then
		table.insert(lines, current_line)
	end
	
	return lines
end

-- Remove common leading whitespace (Pure Lua - faster)
function str.dedent(s)
	validate_string(s, "str.dedent")
	local lines = {}
	for line in (s.."\n"):gmatch("([^\n]*)\n") do
		table.insert(lines, line)
	end
	if #lines <= 1 then return s end
	
	-- Find minimum indentation (excluding empty lines)
	local min_indent = math.huge
	for _, line in ipairs(lines) do
		local trimmed = line:gsub("%s", "")
		if trimmed ~= "" then
			local indent = line:match("^%s*")
			if indent then
				min_indent = math.min(min_indent, #indent)
			end
		end
	end
	
	if min_indent == math.huge or min_indent == 0 then
		return s
	end
	
	-- Remove common indentation
	for i, line in ipairs(lines) do
		local trimmed = line:gsub("%s", "")
		if trimmed ~= "" then
			lines[i] = line:sub(min_indent + 1)
		end
	end
	
	return table.concat(lines, "\n")
end

-- Escape special characters for regex
function str.escape_regex(s)
	validate_string(s, "str.escape_regex")
	return s:gsub("([%.%+%*%?%[%]%^%$%(%)%{%}%|%\\])", "\\%1")
end

-- Quote string for shell usage
function str.shell_quote(s)
	validate_string(s, "str.shell_quote")
	return "'" .. s:gsub("'", "'\"'\"'") .. "'"
end

-- URL encode string
function str.url_encode(s)
	validate_string(s, "str.url_encode")
	return s:gsub("([^%w%-%.%_%~])", function(c)
		return string.format("%%%02X", string.byte(c))
	end)
end

-- URL decode string
function str.url_decode(s)
	validate_string(s, "str.url_decode")
	local result = s:gsub("%%(%x%x)", function(hex)
		local byte = tonumber(hex, 16)
		if byte then
			return string.char(byte)
		else
			return "%" .. hex -- Invalid hex, keep original
		end
	end):gsub("+", " ")
	
	-- Validate result is UTF-8
	if not str.is_valid_utf8(result) then
		error("str.url_decode: result is not valid UTF-8", 2)
	end
	
	return result
end

-- ======================================================================
-- STRING COMPARISON
-- ======================================================================

-- Case-insensitive comparison
function str.iequals(a, b)
	validate_string(a, "str.iequals", 1)
	validate_string(b, "str.iequals", 2)
	return str.lower(a) == str.lower(b)
end

-- Levenshtein distance (Pure Lua - much faster)
function str.distance(a, b)
	validate_string(a, "str.distance", 1)
	validate_string(b, "str.distance", 2)
	
	local len_a, len_b = #a, #b
	
	-- Handle empty strings
	if len_a == 0 then return len_b end
	if len_b == 0 then return len_a end
	
	-- Limit computation for very long strings
	if len_a > 1000 or len_b > 1000 then
		error("str.distance: strings too long for distance calculation", 2)
	end
	
	local matrix = {}
	
	-- Initialize matrix
	for i = 0, len_a do
		matrix[i] = {[0] = i}
	end
	for j = 0, len_b do
		matrix[0][j] = j
	end
	
	-- Fill matrix
	for i = 1, len_a do
		for j = 1, len_b do
			local cost = (a:sub(i,i) == b:sub(j,j)) and 0 or 1
			matrix[i][j] = math.min(
				matrix[i-1][j] + 1,      -- deletion
				matrix[i][j-1] + 1,      -- insertion
				matrix[i-1][j-1] + cost  -- substitution
			)
		end
	end
	
	return matrix[len_a][len_b]
end

-- String similarity (0-1) (Pure Lua - faster)
function str.similarity(a, b)
	validate_string(a, "str.similarity", 1)
	validate_string(b, "str.similarity", 2)
	
	local max_len = math.max(#a, #b)
	if max_len == 0 then return 1.0 end
	
	local dist = str.distance(a, b)
	return 1.0 - (dist / max_len)
end

-- ======================================================================
-- TEMPLATE FUNCTIONS
-- ======================================================================

-- Simple template substitution (Pure Lua - faster)
function str.template(template, vars)
	validate_string(template, "str.template", 1)
	if vars ~= nil then
		validate_table(vars, "str.template", 2)
	else
		vars = {}
	end
	
	return template:gsub("%${([%w_]+)}", function(var)
		local value = vars[var]
		if value == nil then
			return ""
		else
			return tostring(value)
		end
	end)
end

-- Advanced template with functions (Pure Lua - faster)
function str.template_advanced(template, context)
	validate_string(template, "str.template_advanced", 1)
	if context ~= nil then
		validate_table(context, "str.template_advanced", 2)
	else
		context = {}
	end
	
	return template:gsub("%${([^}]+)}", function(expr)
		-- Simple variable substitution
		if context[expr] then
			return tostring(context[expr])
		end
		
		-- Handle simple expressions like ${var.prop}
		local parts = {}
		for part in expr:gmatch("[^%.]+") do
			table.insert(parts, part)
		end
		
		local value = context
		for _, part in ipairs(parts) do
			if type(value) == "table" and value[part] ~= nil then
				value = value[part]
			else
				return ""
			end
		end
		
		return tostring(value)
	end)
end

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

-- Check if string contains only whitespace
function str.is_whitespace(s)
	validate_string(s, "str.is_whitespace")
	return s:match("^%s*$") ~= nil
end

-- Remove all whitespace
function str.strip_whitespace(s)
	validate_string(s, "str.strip_whitespace")
	return s:gsub("%s", "")
end

-- Normalize whitespace (replace multiple spaces with single space)
function str.normalize_whitespace(s)
	validate_string(s, "str.normalize_whitespace")
	return str.trim(s:gsub("%s+", " "))
end

-- Extract numbers from string
function str.extract_numbers(s)
	validate_string(s, "str.extract_numbers")
	local numbers = {}
	for num in s:gmatch("%-?%d+%.?%d*") do
		local n = tonumber(num)
		if n then table.insert(numbers, n) end
	end
	return numbers
end

-- Remove diacritics/accents
function str.remove_accents(s)
	validate_string(s, "str.remove_accents")
	local accents = {
		["à"] = "a", ["á"] = "a", ["â"] = "a", ["ã"] = "a", ["ä"] = "a", ["å"] = "a",
		["è"] = "e", ["é"] = "e", ["ê"] = "e", ["ë"] = "e",
		["ì"] = "i", ["í"] = "i", ["î"] = "i", ["ï"] = "i",
		["ò"] = "o", ["ó"] = "o", ["ô"] = "o", ["õ"] = "o", ["ö"] = "o",
		["ù"] = "u", ["ú"] = "u", ["û"] = "u", ["ü"] = "u",
		["ñ"] = "n", ["ç"] = "c", ["ý"] = "y", ["ÿ"] = "y",
		-- Uppercase versions
		["À"] = "A", ["Á"] = "A", ["Â"] = "A", ["Ã"] = "A", ["Ä"] = "A", ["Å"] = "A",
		["È"] = "E", ["É"] = "E", ["Ê"] = "E", ["Ë"] = "E",
		["Ì"] = "I", ["Í"] = "I", ["Î"] = "I", ["Ï"] = "I",
		["Ò"] = "O", ["Ó"] = "O", ["Ô"] = "O", ["Õ"] = "O", ["Ö"] = "O",
		["Ù"] = "U", ["Ú"] = "U", ["Û"] = "U", ["Ü"] = "U",
		["Ñ"] = "N", ["Ç"] = "C", ["Ý"] = "Y", ["Ÿ"] = "Y"
	}
	
	local result = s
	for accented, plain in pairs(accents) do
		result = result:gsub(accented, plain)
	end
	return result
end

-- Generate random string
function str.random(length, charset)
	validate_number(length, "str.random", 1)
	if length < 0 or length ~= math.floor(length) then
		error("str.random: length must be a non-negative integer", 2)
	end
	if charset ~= nil then
		validate_string(charset, "str.random", 2)
	end
	return safe_call(moonshark.random_string, length, charset)
end

-- Generate slug from string (Pure Lua - faster)
function str.slug(s)
	validate_string(s, "str.slug")
	
	-- Remove accents (simplified but faster)
	local accents = {
		["à"] = "a", ["á"] = "a", ["â"] = "a", ["ã"] = "a", ["ä"] = "a", ["å"] = "a",
		["è"] = "e", ["é"] = "e", ["ê"] = "e", ["ë"] = "e",
		["ì"] = "i", ["í"] = "i", ["î"] = "i", ["ï"] = "i",
		["ò"] = "o", ["ó"] = "o", ["ô"] = "o", ["õ"] = "o", ["ö"] = "o",
		["ù"] = "u", ["ú"] = "u", ["û"] = "u", ["ü"] = "u",
		["ñ"] = "n", ["ç"] = "c", ["ý"] = "y", ["ÿ"] = "y",
		-- Uppercase versions
		["À"] = "A", ["Á"] = "A", ["Â"] = "A", ["Ã"] = "A", ["Ä"] = "A", ["Å"] = "A",
		["È"] = "E", ["É"] = "E", ["Ê"] = "E", ["Ë"] = "E",
		["Ì"] = "I", ["Í"] = "I", ["Î"] = "I", ["Ï"] = "I",
		["Ò"] = "O", ["Ó"] = "O", ["Ô"] = "O", ["Õ"] = "O", ["Ö"] = "O",
		["Ù"] = "U", ["Ú"] = "U", ["Û"] = "U", ["Ü"] = "U",
		["Ñ"] = "N", ["Ç"] = "C", ["Ý"] = "Y", ["Ÿ"] = "Y"
	}
	
	local result = s:lower()
	for accented, plain in pairs(accents) do
		result = result:gsub(accented:lower(), plain:lower())
	end
	
	-- Keep only alphanumeric characters and spaces, then convert spaces to hyphens
	result = result:gsub("[^%w%s]", "")
	result = result:gsub("%s+", "-")
	result = result:gsub("^%-+", ""):gsub("%-+$", "")
	
	return result
end

return str