import cv2
import numpy as np
from scipy import signal
import matplotlib.pyplot as plt
import sys

TARGET_FPS = 30  # common reference rate

def get_video_signal(path):
    cap = cv2.VideoCapture(path)
    fps = cap.get(cv2.CAP_PROP_FPS)

    motion_signal = []
    prev_gray = None

    while True:
        ret, frame = cap.read()
        if not ret:
            break

        small_frame = cv2.resize(frame, (160, 90))
        gray = cv2.cvtColor(small_frame, cv2.COLOR_BGR2GRAY)

        if prev_gray is not None:
            diff = cv2.absdiff(gray, prev_gray)
            motion_signal.append(np.sum(diff))
        else:
            motion_signal.append(0)

        prev_gray = gray

    cap.release()

    return np.array(motion_signal), fps


def resample_signal(sig, original_fps, target_fps):
    duration = len(sig) / original_fps
    target_length = int(duration * target_fps)

    return signal.resample(sig, target_length)


def find_offset(video_a, video_b):

    sig_a, fps_a = get_video_signal(video_a)
    sig_b, fps_b = get_video_signal(video_b)

    # Resample both signals to common FPS
    sig_a = resample_signal(sig_a, fps_a, TARGET_FPS)
    sig_b = resample_signal(sig_b, fps_b, TARGET_FPS)

    # Normalize
    sig_a = (sig_a - np.mean(sig_a)) / (np.std(sig_a) + 1e-5)
    sig_b = (sig_b - np.mean(sig_b)) / (np.std(sig_b) + 1e-5)

    correlation = signal.correlate(sig_a, sig_b, mode='full')
    lags = signal.correlation_lags(len(sig_a), len(sig_b), mode='full')

    best_lag = lags[np.argmax(correlation)]

    # Convert lag to seconds
    offset_seconds = best_lag / TARGET_FPS

    return best_lag, offset_seconds

def multiple():
    # Usage
    for i in range(1, 12):
        # print(f"{i:02}")
        video_a = f"/home/honney/projects/mkv/AnoHana The Flower We Saw That Day (2011-2011) [imdbid-tt1913273]/Season 01/AnoHana The Flower We Saw That Day S01E0{i:02}.mkv"
        video_b = f"/home/honney/projects/mkv/Anohana - The Flower We Saw That Day/S01/AnoHana The Flower We Saw That Day S01E0{i:02}.mkv"

        offset_frames = find_offset(video_a, video_b)
        print(f"{i}: Video B is offset by {offset_frames} frames relative to Video A.")
        sys.exit()

def single():
    video_a = f"/home/honney/mount/Media/tmp/serien/ger_low_quality/Black Bullet/Black Bullet Season 01 E02 Die Maske des Wahnsinns.mp4"
    video_b = f"/home/honney/mount/Media/tmp/serien/high_quality/Black Bullet (Season 1)/Season 01/Black Bullet - S01E02.mkv"

    frames, seconds = find_offset(video_a, video_b)
    print(f"Video B is offset by {frames} frames or {seconds} seconds relative to Video A.")

if __name__ == '__main__':
    single()