import json, os, re
from typing import List

from million.model.fb_export import FacebookExport


def is_file_valid(file_name: str) -> bool:
    return os.path.splitext(file_name)[-1].lower() == '.json'

def valid_dirfiles(file_dir: str) -> List[str]:
    return [os.path.join(file_dir, file_name)
            for file_name in os.listdir(file_dir)
            if is_file_valid(file_name)]

def parse_file(file_name: str) -> FacebookExport:
    if not is_file_valid(file_name): return None

    with open(file_name, 'rb') as f:
        fixed_json = __read_broken_fb_json(f.read())
        json_data = json.loads(fixed_json)
        return (FacebookExport(**json_data))

def parse_dirfiles(file_dir: str) -> FacebookExport:
    exports = [parse_file(f) for f in valid_dirfiles(file_dir)]
    if len(exports) == 0: return

    for other in exports[1:]:
        exports[0].messages.extend(other.messages)
        exports[0].participants.extend(other.participants)

    exports[0].messages.sort(key = lambda m: m.timestamp_ms)
    exports[0].participants = set(exports[0].participants)
    return exports[0]

def __read_broken_fb_json(binary_data):
    repaired = re.sub(
        rb'\\u00([\da-f]{2})',
        lambda m: bytes.fromhex(m.group(1).decode()),
        binary_data
    )

    return repaired.decode('utf8')