libgenbulk

added more stuff to the lua script

diff --git a/gen_list_of_URLs.lua b/gen_list_of_URLs.lua
index 45d79ef..61abbcc 100644
--- a/gen_list_of_URLs.lua
+++ b/gen_list_of_URLs.lua
@@ -1,36 +1,126 @@
--- for a more selective approach, a small helper script to parse the linksfile and select each Link containing
--- these keywords and save them in a file.
--- the result is a output.txt file containing Links of URLs matching these Words for filtered Downloading
-local strarr = {"Biology", "Computer"}
-
-local file = io.open("links.txt", "r")
-if not file then
-    error("error opening file ... ")
+local function show_help()
+    print([[
+Usage: lua gen_list_of_URLs.lua [options]
+Options:
+  -i, --input FILE     Input file containing URLs (default: links.txt)
+  -o, --output FILE    Output file for selected URLs (default: selected_links.txt)
+  -k, --keywords FILE  File containing keywords to match, one per line
+  -e, --extension EXT  Filter by file extension (e.g., epub, pdf)
+  -h, --help           Show this help message
+]])
 end
 
-local matches = {}
-for line in file:lines() do
-    for _, target in ipairs(strarr) do
-        -- Escape any special pattern characters in the target string
-        local escaped_target = string.gsub(target, "([%^%$%(%)%%%.%[%]%*%+%-%?])", "%%%1")
-        
-        -- Use plain text matching (third parameter as true) to avoid pattern matching
-        if string.find(line, escaped_target, 1, true) then
-            table.insert(matches, line)
-            break
+local function parse_args(args)
+    local options = {
+        input = "links.txt",
+        output = "selected_links.txt",
+        keywords = nil,
+        extension = nil
+    }
+    
+    local i = 1
+    while i <= #args do
+        local arg = args[i]
+        if arg == "-i" or arg == "--input" then
+            options.input = args[i + 1]
+            i = i + 2
+        elseif arg == "-o" or arg == "--output" then
+            options.output = args[i + 1]
+            i = i + 2
+        elseif arg == "-k" or arg == "--keywords" then
+            options.keywords = args[i + 1]
+            i = i + 2
+        elseif arg == "-e" or arg == "--extension" then
+            options.extension = args[i + 1]
+            i = i + 2
+        elseif arg == "-h" or arg == "--help" then
+            show_help()
+            os.exit(0)
+        else
+            print("Unknown option: " .. arg)
+            show_help()
+            os.exit(1)
         end
     end
+    
+    return options
 end
 
-file:close()
+local function load_keywords(filename)
+    local keywords = {}
+    local file = io.open(filename, "r")
+    if not file then
+        error("Error opening keywords file: " .. filename)
+    end
+    
+    for line in file:lines() do
+        if line ~= "" then
+            table.insert(keywords, line)
+        end
+    end
+    file:close()
+    return keywords
+end
 
-local outfile = io.open("output.txt", "w")
-if not outfile then
-    error("error opening output file ... ")
+local function has_extension(url, extension)
+    if not extension then
+        return true  -- No extension filter
+    end
+    
+    local escaped_ext = string.gsub(extension, "([%^%$%(%)%%%.%[%]%*%+%-%?])", "%%%1")
+    return string.match(url, "%." .. escaped_ext .. "$") ~= nil
 end
 
-for _, line in ipairs(matches) do
-    outfile:write(line .. "\n")
+local default_keywords = {
+    "Discrete Mathematics",
+    "Algorithms",
+    "Assembly",
+    "x86"
+}
+
+local function main(args)
+    local options = parse_args(args)
+    
+    local keywords = default_keywords
+    if options.keywords then
+        keywords = load_keywords(options.keywords)
+    end
+    
+    print("Opening input file: " .. options.input)
+    local file = io.open(options.input, "r")
+    if not file then
+        error("Error opening input file: " .. options.input)
+    end
+    
+    print("Processing: finding links...")
+    local matches = {}
+    for line in file:lines() do
+        if has_extension(line, options.extension) then
+            for _, target in ipairs(keywords) do
+                local escaped_target = string.gsub(target, "([%^%$%(%)%%%.%[%]%*%+%-%?])", "%%%1")
+                if string.find(line, escaped_target, 1, true) then
+                    table.insert(matches, line)
+                    break
+                end
+            end
+        end
+    end
+    file:close()
+    
+    print("Writing matched links to: " .. options.output)
+    local outfile = io.open(options.output, "w")
+    if not outfile then
+        error("Error opening output file: " .. options.output)
+    end
+    
+    local count = 0
+    for _, line in ipairs(matches) do
+        count = count + 1
+        outfile:write(line .. "\n")
+    end
+    outfile:close()
+    
+    print("Done! Found " .. count .. " matching links.")
 end
-outfile:close()
-print("done...")
+
+main(arg)