Mô đun:Check isxn

--
This code is derived from the ISXN validation code at Module:Citation/CS1.  It allows validating ISBN,
ISMN, and ISSN without invoking a citation template.
local p = {}
------------------------------------------------------------------------------
error message supplements for check_isbn(); adapted from a similarly named table at Module:Citation/CS1/Configuration
local err_msg_supl_t = {
	'char' = 'invalid character',
	'check' = 'checksum',
	'form' = 'invalid form',
	'group' = 'invalid group id',
	'length' = 'length',
	'prefix' = 'invalid prefix',
	}
---------------------------------------------------------------------------------
ISBN-10 and ISSN validator code calculates checksum across all isbn/issn digits including the check digit. ISBN-13 is checked in check_isbn().
If the number is valid the result will be 0. Before calling this function, issbn/issn must be checked for length and stripped of dashes,
spaces and other non-isxn characters.
local function is_valid_isxn (isxn_str, len)
	local temp = 0;
	isxn_str = { isxn_str:byte(1, len) };	-- make a table of byte values '0' → 0x30 .. '9'  → 0x39, 'X' → 0x58
	len = len+1;							-- adjust to be a loop counter
	for i, v in ipairs( isxn_str ) do		-- loop through all of the bytes and calculate the checksum
		if v == string.byte( "X" ) then		-- if checkdigit is X (compares the byte value of 'X' which is 0x58)
			temp = temp + 10*( len - i );	-- it represents 10 decimal
		else
			temp = temp + tonumber( string.char(v) )*(len-i);
		end
	end
	return temp % 11 == 0;					-- returns true if calculation result is zero
end
--------------------------------------------------------------------------
ISBN-13 and ISMN validator code calculates checksum across all 13 isbn/ismn digits including the check digit.
If the number is valid, the result will be 0. Before calling this function, isbn-13/ismn must be checked for length
and stripped of dashes, spaces and other non-isxn-13 characters.
local function is_valid_isxn_13 (isxn_str)
	local temp=0;
	
	isxn_str = { isxn_str:byte(1, 13) };										-- make a table of byte values '0' → 0x30 .. '9'  → 0x39
	for i, v in ipairs( isxn_str ) do
		temp = temp + (3 - 2*(i % 2)) * tonumber( string.char(v) );				-- multiply odd index digits by 1, even index digits by 3 and sum; includes check digit
	end
	return temp % 10 == 0;														-- sum modulo 10 is zero when isbn-13/ismn is correct
end
----------------------------------------------------------------------------------------
Determines whether an ISBN string is valid.  Implements an ISBN validity check for , , , and
.
local function check_isbn (isbn_str, frame)
	local function return_result (check, err_type)								-- local function to render the various error returns
		if not check then														--  false when there is an error
			local template = ((frame.args.template_name and  ~= frame.args.template_name) and frame.args.template_name) or nil;	-- get template name
			if not template then
				return ' calling template requires template_name parameter';
			end
			local out_t = {};		-- open the error message span
			table.insert (out_t, ' Parameter error in : ');								-- close wikilink; close 'template' markup
			table.insert (out_t, err_type);										-- type of isbn error
			table.insert (out_t, )										-- close the error message span
			if 0 == mw.title.getCurrentTitle().namespace then					-- categorize only when this template is used in mainspace
				local category = table.concat ({});
				table.insert (out_t, category);
			end
			return table.concat (out_t);										-- make a big string and done
		end
	return ;																	-- no error, return an empty string
	end
	if nil ~= isbn_str:match ('^%s-0-9X') then
		return return_result (false, err_msg_supl_t.char);						-- fail if isbn_str contains anything but digits, hyphens, or the uppercase X
	end
	local id = isbn_str:gsub ('%s-', );										-- remove hyphens and whitespace
	local len = id:len();

	if len ~= 10 and len ~= 13 then
		return return_result (false, err_msg_supl_t.length);					-- fail if incorrect length
	end
	if len == 10 then
		if id:match ('^%d*X?$') == nil then										-- fail if isbn_str has 'X' anywhere but last position
			return return_result (false, err_msg_supl_t.form);									
		end
		if id:find ('^6301') then												-- 630xxxxxxx and 631xxxxxxx are (apparently) not valid isbn group ids but are used by amazon as numeric identifiers (asin)
			return return_result (false, err_msg_supl_t.group);					-- fail if isbn-10 begins with 630/1
		end
		return return_result (is_valid_isxn (id, 10), err_msg_supl_t.check);	-- pass if isbn-10 is numerically valid (checksum)
	else
		if id:match ('^%d+$') == nil then
			return return_result (false, err_msg_supl_t.char);					-- fail if ISBN-13 is not all digits
		end
		if id:match ('^9789%d*$') == nil then
			return return_result (false, err_msg_supl_t.prefix);				-- fail when ISBN-13 does not begin with 978 or 979
		end
		if id:match ('^9790') then
			return return_result (false, err_msg_supl_t.group);					-- group identifier '0' is reserved to ISMN
		end
		return return_result (is_valid_isxn_13 (id), err_msg_supl_t.check);		-- pass if isbn-10 is numerically valid (checksum)
	end
end
----------------------------------------------------------------------------------------
Determines whether an ISMN string is valid.  Similar to isbn-13, ismn is 13 digits begining 979-0-... and uses the
same check digit calculations.  See http://www.ismn-international.org/download/Web_ISMN_Users_Manual_2008-6.pdf
section 2, pages 9–12.
local function check_ismn (id, error_string)
	local text;
	local valid_ismn = true;
	id=id:gsub( "%s-–", "" );													-- strip spaces, hyphens, and endashes from the ismn
	if 13 ~= id:len() or id:match( "^9790%d*$" ) == nil then					-- ismn must be 13 digits and begin 9790
		valid_ismn = false;
	else
		valid_ismn=is_valid_isxn_13 (id);										-- validate ismn
	end
	return valid_ismn and  or error_string
end
--issn=0819 4327 gives:  4327 0819 4327  -- can't have spaces in an external link
	
This code now prevents that by inserting a hyphen at the issn midpoint.  It also validates the issn for length and makes sure that the checkdigit agrees
with the calculated value.  Incorrect length (8 digits), characters other than 0-9 and X, or checkdigit / calculated value mismatch will all cause a check issn
error message.
local function check_issn(id, error_string)
	local issn_copy = id;		-- save a copy of unadulterated issn; use this version for display if issn does not validate
	local text;
	local valid_issn = true;
	if not id:match ('^%d%d%d%d%-%d%d%d%dX$') then
		return error_string;
	end
	
	id=id:gsub( "%s-–", "" );									-- strip spaces, hyphens, and endashes from the issn
	if 8 ~= id:len() or nil == id:match( "^%d*X?$" ) then		-- validate the issn: 8 digits long, containing only 0-9 or X in the last position
		valid_issn=false;										-- wrong length or improper character
	else
		valid_issn=is_valid_isxn(id, 8);						-- validate issn
	end
	return valid_issn and  or error_string
end
--------------------------------------------------------------------------------**
function p.check_isbn(frame)
	return check_isbn(frame.args1 or frame:getParent().args1, frame)
end
function p.check_ismn(frame)
	return check_ismn(frame.args1 or frame:getParent().args1, frame.args'error' or frame:getParent().args'error' or 'error')
end
function p.check_issn(frame)
	return check_issn(frame.args1 or frame:getParent().args1, frame.args'error' or frame:getParent().args'error' or 'error')
end
return p