feat: proper CLI usage in main

main.lua

@@ -1,28 +1,140 @@
 #!/bin/env lua
 
-local html = require(".html")
-local css = require(".css")
+local HTML = require(".html")
+local CSS = require(".css")
+
+local logger = require(".logging")
 
 
-local file = io.open("small.html", "r")
 
-if file == nil then
-	error("File doesn't exist")
+
+local function file_exists(name)
+   local f=io.open(name,"r")
+   if f~=nil then io.close(f) return true else return false end
 end
 
-local content = file:read("a")
-
-local doc = html.parse( content )
 
 
-print("Write a css selector:")
-local whole_selector = css.parse( io.read() )
-local current_selector = whole_selector
+local function print_usage()
+    logger.print("Usage: lua main.lua [FLAGS] <html_path_or_minus> <css_selector>")
+    logger.print("  html_path_or_minus: Path to HTML file or '-' for stdin")
+    logger.print("  css_selector: CSS selector to search for")
+		logger.print()
+		logger.print("  Flags:")
+    logger.print("  -f, --first-only: return only the first match")
+    logger.print("  -q, --quiet: Don't print warnings")
+    os.exit(1)
+end
+
+
+
+
+
+local FLAGS = {
+	FIRST_ONLY = {},
+	NO_PRINT_ERRORS = {},
+}
+
+local LONGHAND_FLAGS = {
+	["first-only"] = FLAGS.FIRST_ONLY,
+	["quiet"] = FLAGS.NO_PRINT_ERRORS
+}
+
+local SHORTHAND_FLAGS = {
+	["f"] = FLAGS.FIRST_ONLY,
+	["q"] = FLAGS.NO_PRINT_ERRORS,
+}
+
+
+
+if #arg < 2 then
+	logger.printerr("Error: Not enough arguments")
+	print_usage()
+	return 1
+end
+
+local flags = {}
+local positionals = {}
+
+for _, argument in ipairs(arg) do
+	if argument:match("^%-%w+$") then
+		for letter in argument:sub(2):gmatch("(%w)") do
+			if not SHORTHAND_FLAGS[letter] then
+				logger.printerr("Unknown flag: -"..letter..".")
+				print_usage()
+				return 1
+			end
+
+			local flag = SHORTHAND_FLAGS[letter]
+
+			if flags[flag] then
+				logger.printerr("Warning: passed -" .. letter .. " flag already !")
+			end
+
+			flags[flag] = true
+		end
+	elseif argument:match("^%-%-[%w%-]+$") then
+		local flagname = argument:sub(3)
+		if not LONGHAND_FLAGS[flagname] then
+			logger.printerr("Unknown flag: --"..flagname..".")
+			print_usage()
+			return 1
+		end
+
+		local flag = LONGHAND_FLAGS[flagname]
+
+		if flags[flag] then
+			logger.printerr("Warning: passed --" .. flagname .. " flag already !")
+		end
+
+		flags[flag] = true
+	else
+		table.insert( positionals, argument )
+	end
+end
+
+
+if not flags[ FLAGS.NO_PRINT_ERRORS ] then
+	logger.enable_printing_errors()
+end
+
+
+if #positionals > 2 then
+	logger.printerr("Error: too many arguments !")
+	print_usage()
+	return 1
+end
+
+local html_file = positionals[1]
+local html = nil
+
+if html_file ~= "-" then
+	if not( file_exists( html_file )) then
+		logger.printerr("File doesn't exist: " .. html_file)
+		return 2
+	end
+
+	local handle = io.open( html_file, "r" )
+	if not handle then
+		logger.printerr("Failed to open file " .. html_file)
+		return 2
+	end
+
+	html = handle:read("a")
+else
+	html = io.read()
+end
+
+local document = HTML.parse( html )
+local css_selector = CSS.parse( positionals[2] )
+
+
+local current_selector = css_selector
 
 
 local elements = {}
 -- start with all elements matching the first selector
-doc:foreach(function( el )
+document:foreach(function( el )
 	if el:check_simple_selector( current_selector.selector ) then
 		table.insert( elements, el )
 	end
@@ -33,7 +145,7 @@ while current_selector.combinator ~= nil do
 
 	local new_elements = {}
 
-	if current_selector.combinator == css.COMBINATORS.DESCENDANT then
+	if current_selector.combinator == CSS.COMBINATORS.DESCENDANT then
 		for _, element in ipairs( elements ) do
 			element:foreach(function( el )
 				if el:check_simple_selector( next_selector.selector ) then
@@ -45,7 +157,7 @@ while current_selector.combinator ~= nil do
 		goto continue
 	end
 
-	if current_selector.combinator == css.COMBINATORS.DIRECT_DESCENDANT then
+	if current_selector.combinator == CSS.COMBINATORS.DIRECT_DESCENDANT then
 		for _, element in ipairs( elements ) do
 			for _, child in ipairs( element.children ) do
 				if child:check_simple_selector( next_selector.selector ) then
@@ -57,7 +169,7 @@ while current_selector.combinator ~= nil do
 		goto continue
 	end
 
-	if current_selector.combinator == css.COMBINATORS.NEXT_SIBLING then
+	if current_selector.combinator == CSS.COMBINATORS.NEXT_SIBLING then
 		for _, element in ipairs( elements ) do
 			local next_sibling = element:get_next_sibling()
 			while next_sibling and next_sibling.tag_name == ":text" do
@@ -72,7 +184,7 @@ while current_selector.combinator ~= nil do
 		goto continue
 	end
 
-	if current_selector.combinator == css.COMBINATORS.SUBSEQUENT_SIBLING then
+	if current_selector.combinator == CSS.COMBINATORS.SUBSEQUENT_SIBLING then
 		for _, element in ipairs( elements ) do
 			local sibling = element:get_next_sibling()
 			while sibling ~= nil do
@@ -96,10 +208,14 @@ end
 
 
 
+if flags[FLAGS.FIRST_ONLY] then
+	if #elements > 0 then
+		logger.print( HTML.tostring( elements[1] ) )
+	end
 
-for _, el in ipairs(elements) do
-	print( html.tostring( el ) )
+	return 0
 end
 
-
-
+for _, el in ipairs(elements) do
+		logger.print( HTML.tostring(el) )
+end