import datetime
import logging
import mimetypes
import os
import PIL.Image
import re
import shutil
import subprocess

def walk_media_files(dir_path):
    for root, dirs, files in os.walk(dir_path):
        for f in files:
            file_path = os.path.join(root, f)
            if is_media_file(file_path):
                yield (f, file_path)

def extract_meta_time(file_path):
    if is_media_file(file_path, types=['image']):
        return _extract_image_timestamp(file_path)
    elif is_media_file(file_path, types=['video']):
        return _extract_video_timestamp(file_path)

def find_alt_file(base_dir, name, size, meta_time, exclude_dir):
    for root, dirs, files in os.walk(base_dir):
        if root.startswith(exclude_dir):
            continue
        for alt_name in files:
            if alt_name == name:
                full_path = os.path.join(root, alt_name)
                if os.path.getsize(full_path) == size:
                    alt_meta_time = extract_meta_time(full_path)
                    if meta_time == alt_meta_time:
                        return root
    return None

def import_file(src_file_path, dst_file_path):
    shutil.copyfile(src_file_path, dst_file_path)
    src_stat = os.stat(src_file_path)
    dst_stat = os.stat(dst_file_path)
    os.utime( dst_file_path, ns=(dst_stat.st_atime_ns, src_stat.st_mtime_ns) )

def is_media_file(file_path, types=['image', 'video']):
    if not os.path.isfile(file_path):
        return False
    mime_type = mimetypes.guess_type(file_path)[0]
    if not mime_type:
        return False
    if not mime_type.split('/')[0] in types:
        return False
    return True

def _extract_image_timestamp(file_path):
    time = None
    try:
        with PIL.Image.open(file_path) as image:
            exif = image._getexif()
            if exif and 36867 in exif:
                time = datetime.datetime\
                               .strptime(exif[36867], '%Y:%m:%d %H:%M:%S')\
                               .timestamp()
    except Exception as e:
        logging.warn("Error extracting exif for %s: %s", file_path, str(e))
    return time

def _extract_video_timestamp(file_path):
    p = subprocess.run(['ffmpeg', '-i', file_path],
                       capture_output=True, encoding='UTF-8')
    for line in p.stderr.splitlines():
        m = re.search('^.*creation_time.*: ([^ ]+)$', line)
        if m:
            return datetime.datetime\
                           .strptime(m.group(1), '%Y-%m-%dT%H:%M:%S.%fZ')\
                           .timestamp()
    return None