import os
import sys

from core.parse_evaluate import parseEvaluate

def repl() -> None:
    stdlib_path = 'stdlib.lsp'
    if os.path.isfile(stdlib_path):
        with open(stdlib_path, 'r', encoding='utf‑8') as f:
            parseEvaluate(f.read(), load=True)
    else:
        print('>> Warning: standard library not found.')

    if not sys.stdin.isatty():
        parseEvaluate(sys.stdin.read(), load=True)
        print('\ninput exhausted, exiting REPL...')
        return

    prompt      = '>>> '
    exit_cmds   = {':q', ':quit', ':exit', 'exit', 'quit'}
    load_cmds   = {':l', ':load'}

    while True:
        try:
            line = input(prompt).strip()
        except (KeyboardInterrupt, EOFError):
            print("\nexiting REPL...")
            break

        if not line:
            continue

        parts = line.split(None, 1)
        if not parts:
            continue

        token = parts[0]

        if token in exit_cmds:
            print("\nexiting REPL...")
            break

        if token in load_cmds:
            filename = parts[1].strip() if len(parts) > 1 else ''
            if not filename:
                print(prompt + "Error: no filename provided.")
                continue
            if not os.path.isfile(filename):
                print(prompt + f'Error: no such file "{filename}"')
                continue
            with open(filename, 'r', encoding='utf-8') as f:
                parseEvaluate(f.read(), load=True)
            print()
            continue

        print(parseEvaluate(line))

if __name__ == '__main__':
    repl()