import os
import re
import argparse


MAKEFILE_INDICATOR = "# New watch faces go above this line.\n"
INCLUDE_INDICATOR = "// New includes go above this line.\n"


def replace_placeholders(contents, args):
    modified_contents = contents.replace("<#WATCH_FACE_NAME#>", args.watch_face_name.upper())
    modified_contents = modified_contents.replace("<#watch_face_name#>", args.watch_face_name)
    if args.author_name:
        modified_contents = modified_contents.replace("<#author_name#>", " ".join(args.author_name))
    if args.year:
        modified_contents = modified_contents.replace("<#year#>", args.year)

    return modified_contents


def write_output_file(args, file_type, output_dir):
    with open(f"template.{file_type}", 'r') as file_template:
        file_contents = file_template.read()
    modified_template = replace_placeholders(file_contents, args)
    file_path = f"{output_dir}{args.watch_face_name}_face.{file_type}"
    if not os.path.exists(file_path):
        with open(file_path, 'w') as output_file:
            output_file.write(modified_template)
    else:
        print(f"Generation failed: the watch face \"{args.watch_face_name}\" already exists at {file_path}. Unable to generate new files. Exiting...")
        exit(0)


def write_include_file(file_path, file_type, indicator_line, line_to_insert):
    with open(file_path, 'r+') as include_file:
        include_contents = include_file.readlines()
        if line_to_insert in include_contents:
            print(f"Generation failed: {file_path} already has an entry for {line_to_insert.strip()}. Unable to generate new files. Exiting...")
            exit(0)
        new_face_index = include_contents.index(indicator_line)
        include_contents.insert(new_face_index, line_to_insert)
        include_file.seek(0)
        include_file.writelines(include_contents)
 

def main():
    parser = argparse.ArgumentParser(description="Create a new watch face.")
    parser.add_argument("watch_face_type", metavar="face_type", type=str, choices=["complication", "clock"], help="The type of watch face to create, either \"complication\" or \"clock\"")
    parser.add_argument("watch_face_name", metavar="face_name", type=str, help="The name of the watch face")
    parser.add_argument("--author_name", metavar="author_name", type=str, nargs='*', help="The name of the author")
    parser.add_argument("--year", metavar="year", type=str, help="The copyright year")

    args = parser.parse_args()
    
    name_valid = re.fullmatch(r'[a-zA-Z_][a-zA-Z0-9_]*', args.watch_face_name)
    if name_valid == None:
        print(f"Generation failed: {args.watch_face_name} is not a valid C variable name. Exiting...")
        exit(0)
    
    line_to_insert = f"#include \"{args.watch_face_name}_face.h\"\n"
    write_include_file(f"..{os.sep}movement_faces.h", "h", INCLUDE_INDICATOR, line_to_insert)
   
    line_to_insert = f"  ..{os.sep}watch_faces{os.sep}{args.watch_face_type}{os.sep}{args.watch_face_name}_face.c \\\n"
    write_include_file(f"..{os.sep}make{os.sep}Makefile", "c", MAKEFILE_INDICATOR, line_to_insert)
    
    output_dir = f"..{os.sep}watch_faces{os.sep}{args.watch_face_type}{os.sep}"
    write_output_file(args, "h", output_dir)
    write_output_file(args, "c", output_dir)


if __name__ == "__main__":
    main()