import pickle
import shutil
import subprocess
import uuid
from pathlib import Path
from typing import Optional, Sequence, Tuple

import cv2
import imageio_ffmpeg
import numpy as np

LIP_INDICES = [
    61, 146, 91, 181, 84, 17, 314, 405, 321, 375,
    291, 409, 270, 269, 267, 0, 37, 39, 40, 185,
]


def _create_face_mesh():
    # Compatible across mediapipe package variants where top-level `solutions`
    # may not be exposed (seen in some HF builds).
    try:
        from mediapipe.python.solutions.face_mesh import FaceMesh
    except Exception:
        try:
            import mediapipe as mp

            FaceMesh = mp.solutions.face_mesh.FaceMesh
        except Exception as exc:
            raise ImportError(
                "MediaPipe FaceMesh import failed. Install mediapipe==0.10.14."
            ) from exc

    return FaceMesh(
        static_image_mode=False,
        max_num_faces=1,
        refine_landmarks=True,
        min_detection_confidence=0.8,
    )


def ensure_dir(path: Path) -> Path:
    path.mkdir(parents=True, exist_ok=True)
    return path


def make_run_dir(base_dir: Path, prefix: str) -> Path:
    run_dir = ensure_dir(base_dir) / f"{prefix}_{uuid.uuid4().hex}"
    return ensure_dir(run_dir)


def copy_file_to_dir(source_path: str, target_dir: Path, target_name: Optional[str] = None) -> Path:
    source = Path(source_path)
    if not source.exists():
        raise FileNotFoundError(f"Input file not found: {source_path}")

    if target_name is None:
        target_name = source.name

    target_path = target_dir / target_name
    shutil.copy2(source, target_path)
    return target_path


def get_bbox(
    landmarks,
    indices: Sequence[int],
    iw: int,
    ih: int,
    scale_w: float = 1.5,
    scale_h: float = 1.5,
    top_padding: int = 0,
) -> Tuple[int, int, int, int]:
    coords = [(landmarks[i].x * iw, landmarks[i].y * ih) for i in indices]
    x_min, y_min = np.min(coords, axis=0)
    x_max, y_max = np.max(coords, axis=0)

    w = x_max - x_min
    h = y_max - y_min
    new_w = int(w * scale_w)
    new_h = int(h * scale_h)

    x = max(0, int(x_min - (new_w - w) // 2))
    y = max(0, int(y_min - (new_h - h) // 2) - top_padding)
    new_w = min(new_w, iw - x)
    new_h = min(new_h + top_padding, ih - y)
    return (x, y, new_w, new_h)


def _load_coords(coords_path: str) -> Tuple[int, int, int, int]:
    with open(coords_path, "rb") as handle:
        coords = pickle.load(handle)

    if len(coords) != 4:
        raise ValueError(f"Invalid coordinates in {coords_path}: expected 4 values, got {len(coords)}")

    return tuple(int(v) for v in coords)


def extract_coordinates(
    video_path: str,
    output_dir: str,
    face_name: str = "face_coords_avg.pkl",
    lip_name: str = "lip_coords_avg.pkl",
) -> Tuple[str, str, Tuple[int, int, int, int], Tuple[int, int, int, int]]:
    output_root = ensure_dir(Path(output_dir))
    face_out = output_root / face_name
    lip_out = output_root / lip_name

    cap = cv2.VideoCapture(video_path)
    if not cap.isOpened():
        raise ValueError(f"Could not open video: {video_path}")

    face_mesh = _create_face_mesh()

    face_bbox_list = []
    lip_bbox_list = []

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

        image_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        results = face_mesh.process(image_rgb)

        if results.multi_face_landmarks:
            for face_landmarks in results.multi_face_landmarks:
                ih, iw, _ = frame.shape
                face_bbox = get_bbox(
                    face_landmarks.landmark,
                    range(len(face_landmarks.landmark)),
                    iw,
                    ih,
                    scale_w=1.2,
                    scale_h=1.2,
                )
                lip_bbox_unclipped = get_bbox(
                    face_landmarks.landmark,
                    LIP_INDICES,
                    iw,
                    ih,
                    scale_w=1.5,
                    scale_h=1.5,
                    top_padding=20,
                )

                x_face, y_face, w_face, h_face = face_bbox
                x_lip, y_lip, w_lip, h_lip = lip_bbox_unclipped

                x_lip = max(x_face, x_lip)
                y_lip = max(y_face, y_lip)
                w_lip = min(w_lip, x_face + w_face - x_lip)
                h_lip = min(h_lip, y_face + h_face - y_lip)

                if w_lip > 0 and h_lip > 0:
                    face_bbox_list.append(face_bbox)
                    lip_bbox_list.append((x_lip, y_lip, w_lip, h_lip))

    cap.release()
    face_mesh.close()

    if not face_bbox_list or not lip_bbox_list:
        raise ValueError("No faces detected in the video. Check the video quality and framing.")

    avg_face_bbox = np.mean(np.array(face_bbox_list), axis=0).astype(int)
    avg_lip_bbox = np.mean(np.array(lip_bbox_list), axis=0).astype(int)

    with open(face_out, "wb") as handle:
        pickle.dump(tuple(int(v) for v in avg_face_bbox), handle)
    with open(lip_out, "wb") as handle:
        pickle.dump(tuple(int(v) for v in avg_lip_bbox), handle)

    return (
        str(face_out),
        str(lip_out),
        tuple(int(v) for v in avg_face_bbox),
        tuple(int(v) for v in avg_lip_bbox),
    )


def extract_face_video(video_path: str, face_coords_path: str, output_path: str) -> str:
    x, y, w, h = _load_coords(face_coords_path)

    cap = cv2.VideoCapture(video_path)
    if not cap.isOpened():
        raise ValueError(f"Could not open video: {video_path}")

    fps = cap.get(cv2.CAP_PROP_FPS)
    if fps <= 0:
        fps = 25.0

    frame_w = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    frame_h = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

    x = max(0, min(x, frame_w - 1))
    y = max(0, min(y, frame_h - 1))
    w = max(1, min(w, frame_w - x))
    h = max(1, min(h, frame_h - y))

    out = cv2.VideoWriter(
        output_path,
        cv2.VideoWriter_fourcc(*"mp4v"),
        fps,
        (w, h),
    )

    frame_count = 0
    while cap.isOpened():
        ret, frame = cap.read()
        if not ret:
            break
        face_img = frame[y:y + h, x:x + w]
        out.write(face_img)
        frame_count += 1

    cap.release()
    out.release()

    if frame_count == 0:
        raise ValueError("No frames were written for cropped face video.")

    return output_path


def _mux_audio(video_no_audio: str, audio_source: str, output_path: str) -> bool:
    ffmpeg_exe = imageio_ffmpeg.get_ffmpeg_exe()
    cmd = [
        ffmpeg_exe,
        "-y",
        "-i",
        video_no_audio,
        "-i",
        audio_source,
        "-map",
        "0:v:0",
        "-map",
        "1:a:0",
        "-c:v",
        "copy",
        "-c:a",
        "aac",
        "-shortest",
        output_path,
    ]
    result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
    return result.returncode == 0 and Path(output_path).exists()


def merge_lips(
    original_video_path: str,
    lip_synced_video_path: str,
    face_coords_path: str,
    lip_coords_path: str,
    final_output_path: str,
    audio_path: Optional[str] = None,
) -> Tuple[str, str]:
    x_face, y_face, w_face, h_face = _load_coords(face_coords_path)
    x_lip, y_lip, w_lip, h_lip = _load_coords(lip_coords_path)

    lip_rel_x = (x_lip - x_face) / max(1, w_face)
    lip_rel_y = (y_lip - y_face) / max(1, h_face)
    lip_rel_w = w_lip / max(1, w_face)
    lip_rel_h = h_lip / max(1, h_face)

    original_cap = cv2.VideoCapture(original_video_path)
    lip_synced_cap = cv2.VideoCapture(lip_synced_video_path)

    if not original_cap.isOpened():
        raise ValueError(f"Could not open original video: {original_video_path}")
    if not lip_synced_cap.isOpened():
        raise ValueError(f"Could not open lip-synced video: {lip_synced_video_path}")

    fps = original_cap.get(cv2.CAP_PROP_FPS)
    if fps <= 0:
        fps = 25.0

    frame_w = int(original_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    frame_h = int(original_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

    intermediate_path = str(Path(final_output_path).with_name("merged_no_audio.mp4"))
    out_final = cv2.VideoWriter(
        intermediate_path,
        cv2.VideoWriter_fourcc(*"mp4v"),
        fps,
        (frame_w, frame_h),
    )

    frames_written = 0
    while original_cap.isOpened():
        ret, original_frame = original_cap.read()
        if not ret:
            break

        ret_lip, lip_synced_frame = lip_synced_cap.read()
        if ret_lip:
            lip_x_in_face = int(lip_rel_x * w_face)
            lip_y_in_face = int(lip_rel_y * h_face)
            lip_w_in_face = int(lip_rel_w * w_face)
            lip_h_in_face = int(lip_rel_h * h_face)

            lip_x_in_face = max(0, lip_x_in_face)
            lip_y_in_face = max(0, lip_y_in_face)
            lip_w_in_face = max(1, min(lip_w_in_face, lip_synced_frame.shape[1] - lip_x_in_face))
            lip_h_in_face = max(1, min(lip_h_in_face, lip_synced_frame.shape[0] - lip_y_in_face))

            lip_synced_lip = lip_synced_frame[
                lip_y_in_face:lip_y_in_face + lip_h_in_face,
                lip_x_in_face:lip_x_in_face + lip_w_in_face,
            ]

            if lip_synced_lip.size > 0:
                target_x = max(0, min(x_lip, frame_w - 1))
                target_y = max(0, min(y_lip, frame_h - 1))
                target_w = max(1, min(w_lip, frame_w - target_x))
                target_h = max(1, min(h_lip, frame_h - target_y))
                lip_synced_lip_resized = cv2.resize(lip_synced_lip, (target_w, target_h))
                original_frame[target_y:target_y + target_h, target_x:target_x + target_w] = lip_synced_lip_resized

        out_final.write(original_frame)
        frames_written += 1

    original_cap.release()
    lip_synced_cap.release()
    out_final.release()

    if frames_written == 0:
        raise ValueError("No frames written while merging lips.")

    audio_candidates = []
    if audio_path:
        audio_candidates.append(audio_path)
    audio_candidates.extend([lip_synced_video_path, original_video_path])

    for candidate in audio_candidates:
        if candidate and Path(candidate).exists() and _mux_audio(intermediate_path, candidate, final_output_path):
            return final_output_path, candidate

    shutil.copy2(intermediate_path, final_output_path)
    return final_output_path, "none"