if(NOT DEFINED INPUTS OR NOT DEFINED OUTPUT)
	message(FATAL_ERROR "embed_localization.cmake requires INPUTS and OUTPUT")
endif()

set(contents "// Generated from assets/localization; do not edit.\n#pragma once\n#include <span>\n#include <string_view>\n\nnamespace {\n")
set(lookup "std::span<const unsigned char> EmbeddedCatalog(std::string_view locale) {\n")
set(continuation "[89ab][0-9a-f]")
string(CONCAT utf8_character
	"[0-7][0-9a-f]|(c[2-9a-f]|d[0-9a-f])${continuation}"
	"|e0[ab][0-9a-f]${continuation}|e[1-9abcef]${continuation}${continuation}"
	"|ed[89][0-9a-f]${continuation}|f0[9ab][0-9a-f]${continuation}${continuation}"
	"|f[123]${continuation}${continuation}${continuation}|f48[0-9a-f]${continuation}${continuation}")
foreach(catalog IN LISTS INPUTS)
	file(READ "${catalog}" bytes HEX)
	# Validate UTF-8, excluding overlong sequences, surrogates, and values above U+10FFFF.
	if(NOT bytes MATCHES "^(${utf8_character})*$")
		message(FATAL_ERROR "Localization must be UTF-8: ${catalog}")
	endif()
	file(READ "${catalog}" json)
	string(JSON type ERROR_VARIABLE error TYPE "${json}")
	if(error OR NOT type STREQUAL "OBJECT")
		message(FATAL_ERROR "Invalid localization object in ${catalog}: ${error}")
	endif()
	string(JSON count LENGTH "${json}")
	if(count GREATER 0)
		math(EXPR last "${count} - 1")
		foreach(index RANGE ${last})
			string(JSON key MEMBER "${json}" ${index})
			string(JSON type TYPE "${json}" "${key}")
			if(NOT type STREQUAL "STRING")
				message(FATAL_ERROR "Localization value '${key}' must be a string: ${catalog}")
			endif()
			string(JSON text GET "${json}" "${key}")
			if(key STREQUAL "" OR text STREQUAL "")
				message(FATAL_ERROR "Localization keys and values must not be empty: ${catalog}")
			endif()
		endforeach()
	endif()
	get_filename_component(locale "${catalog}" NAME_WE)
	if(locale STREQUAL "en-US")
		string(JSON earned ERROR_VARIABLE error GET "${json}" "trophy.toast.earned")
		if(error OR earned STREQUAL "")
			message(FATAL_ERROR "English localization requires trophy.toast.earned: ${catalog}")
		endif()
		set(english_found TRUE)
	endif()
	string(MAKE_C_IDENTIFIER "${locale}" symbol)
	string(REGEX REPLACE "(..)" "0x\\1," bytes "${bytes}")
	string(APPEND contents "constexpr unsigned char catalog_${symbol}[] = {${bytes}};\n")
	string(APPEND lookup "\tif (locale == \"${locale}\") return catalog_${symbol};\n")
endforeach()
if(NOT english_found)
	message(FATAL_ERROR "Localization requires an en-US.json fallback")
endif()
string(APPEND contents "\n${lookup}\treturn {};\n}\n} // namespace\n")

get_filename_component(output_dir "${OUTPUT}" DIRECTORY)
file(MAKE_DIRECTORY "${output_dir}")
file(WRITE "${OUTPUT}.tmp" "${contents}")
execute_process(COMMAND "${CMAKE_COMMAND}" -E copy_if_different "${OUTPUT}.tmp" "${OUTPUT}"
	COMMAND_ERROR_IS_FATAL ANY)
file(REMOVE "${OUTPUT}.tmp")