Split string into chunks that have max size and use new line as seperator

split_at_newline.py

def split_at_newline(text, max_chars=4300):
    rows = text.split('\n')
    char_count = 0
    messages = []
    current_msg = ''

    for text in rows:
        new_char_count = char_count + len(text)
        current_msg += text + '\n'

        if new_char_count > max_chars:
            messages.append(current_msg)
            current_msg = ''
            char_count = 0
            continue

        char_count = new_char_count

    return messages