replace custom command line arguments parsing with argparse, use exception message

1 files changed, 31 insertions, 45 deletions

diff --git a/blog_generator.py b/blog_generator.py
index 4dceb45..b1ffb86 100755
--- a/blog_generator.py
+++ b/blog_generator.py
@@ -9,9 +9,9 @@ import datetime # Created, modified date
 import jinja2 # HTML Templates
 import shutil # Copy files and directories
 import time # Sleep
-import sys # Command line arguments
 import livereload # Generate on content source file change and reload browser
 import datetime # Read article dates metadata
+import argparse # Command line arguments
 
 logging.basicConfig()
 logger = logging.getLogger('blog_generator')
@@ -20,9 +20,6 @@ logger.setLevel(level=logging.INFO)
 class BlogGeneratorException(Exception):
     pass
 
-class WrongCLIArgsPassedException(BlogGeneratorException):
-    pass
-
 class FoundMoreThanOneSourceFileException(BlogGeneratorException):
     pass
 
@@ -66,11 +63,9 @@ def generate_article(jinja_env: jinja2.environment.Environment, paths: dict, art
     article_dir_path = os.path.join(paths['articles'], article_name)
     sources = glob.glob(os.path.join(article_dir_path, '*.md'))
     if len(sources) > 1:
-        logger.error(f'Found more than one source file for article: {article_name}')
-        raise FoundMoreThanOneSourceFileException()
+        raise FoundMoreThanOneSourceFileException(f'Found more than one source file for article: {article_name}')
     if len(sources) == 0:
-        logger.error(f'No source file found for article: {article_name}')
-        raise ArticleSourceFileNotFoundException()
+        raise ArticleSourceFileNotFoundException(f'No source file found for article: {article_name}')
 
     article_source_path = sources[0]
     article_source_file_name = os.path.basename(article_source_path)
@@ -183,51 +178,42 @@ def main():
     source_content_root = None
     paths = {}
 
+    parser = argparse.ArgumentParser(description='Static blog site generator')
+    parser.add_argument('--action', choices=['live_reload', 'generate'], default='live_reload', nargs='?',
+                        help='serve the page to live preview changes, or just generate once')
+    parser.add_argument('--directory', default=".", nargs='?',
+                        help='the directory containing the site source files, defaults to current working directory')
     # Parse arguments
-    try:
-        if len(sys.argv) < 3:
-            logger.error('Too few arguments passed')
-            raise WrongCLIArgsPassedException()
-        paths['source_content_root'] = sys.argv[1]
-        if not os.path.exists(paths['source_content_root']):
-            logger.error(f'Source directory not found: {paths["source_content_root"]}')
-            raise SourceDirectoryNotFoundException()
+    args = parser.parse_args()
 
-        if os.path.isdir(paths['source_content_root']):
-            for directory in ['articles', 'templates', 'static']:
-                path = os.path.join(paths['source_content_root'], directory)
-                if not os.path.exists(path):
-                    logger.error(f'Source directory not found: {path}')
-                    raise SourceDirectoryNotFoundException()
-                paths[directory] = path
-            paths['output'] = os.path.join(paths['source_content_root'], 'output')
-        if sys.argv[2] not in ['generate', 'live_reload']:
-            logger.error('Action not found')
-            raise WrongCLIArgsPassedException()
+    paths['source_content_root'] = args.directory
+    if not os.path.exists(paths['source_content_root']):
+        raise SourceDirectoryNotFoundException(f'Source directory not found: {paths["source_content_root"]}')
 
-        # Setup jinja enviroment
-        # Dict values globally accesible in templates e.g. root title
-        # Get name of directory, in case it's relative
-        jinja_global = {'title': os.path.basename(os.path.realpath(sys.argv[1]))}
-        jinja_env = jinja2.Environment(loader=jinja2.FileSystemLoader(paths['templates']))
-        jinja_env.globals.update(jinja_global)
+    if os.path.isdir(paths['source_content_root']):
+        for directory in ['articles', 'templates', 'static']:
+            path = os.path.join(paths['source_content_root'], directory)
+            if not os.path.exists(path):
+                raise SourceDirectoryNotFoundException(f'Source directory not found: {path}')
+            paths[directory] = path
+        paths['output'] = os.path.join(paths['source_content_root'], 'output')
 
-        match sys.argv[2]: # Switch statement
+    # Setup jinja enviroment
+    # Dict values globally accesible in templates e.g. root title
+    # Get name of directory, in case it's relative
+    jinja_global = {'title': os.path.basename(os.path.realpath(args.directory))}
+    jinja_env = jinja2.Environment(loader=jinja2.FileSystemLoader(paths['templates']))
+    jinja_env.globals.update(jinja_global)
+    
+    try: 
+        match args.action: # Switch statement
             case 'generate':
                 generate_all(jinja_env, paths)
             case 'live_reload':
                 live_reload(jinja_env, paths)
-            case _: # Default
-                logger.error('No action specified')
-                raise WrongCLIArgsPassedException()
-
-    except WrongCLIArgsPassedException:
-        # Wrong CLI args passed
-        print("\nUsage: generate_blog [CONTENT ROOT] [ACTION]\n"
-              " [CONTENT ROOT] being the root of your content e.g. default_page\n"
-              " [ACTION] being either generate or live_reload")
-        exit(2) # Exit code 2: Incorrect command (or argument) usage
-    except BlogGeneratorException: # Other known custom error
+    # Known custom error, avoid stack trace, merely print the pretty exception message
+    except BlogGeneratorException as exception:
+        logger.error(exception)
         exit(1) # Exit code 1: Code for generic errors
 
 if __name__ == "__main__":