from __future__ import annotations

from typing import Any, Dict, List, Literal, Optional, Tuple, Type
from pathlib import Path
import tempfile
import uuid
import json

import numpy as np
from huggingface_hub import hf_hub_download

try:
    import cv2  # type: ignore
except Exception as e:  # pragma: no cover
    cv2 = None  # lazy import error handled in _ensure_dependencies

import torch
from pydantic import BaseModel, Field, validator

from langchain_core.callbacks import (
    AsyncCallbackManagerForToolRun,
    CallbackManagerForToolRun,
)
from langchain_core.tools import BaseTool


class EchoSegmentationInput(BaseModel):
    """Input schema for the Echo (ultrasound) segmentation tool.

    Supports MP4/AVI/GIF and single image (PNG/JPG). For DICOM cine, please
    convert to a standard video first or extend this tool to read DICOM directly.
    """

    video_path: str = Field(
        ..., description="Path to echo video (mp4/avi/gif) or single image (png/jpg)"
    )
    prompt_mode: Literal["auto", "points", "box", "mask"] = Field(
        "auto", description="Segmentation prompt mode: auto, points, box, or mask"
    )
    # Normalized coordinates in [0,1], labels: 1=foreground, 0=background
    points: Optional[List[Tuple[float, float, int]]] = Field(
        None, description="List of (x,y,label) in normalized coords for the first frame"
    )
    # Normalized box [x1,y1,x2,y2] in [0,1]
    box: Optional[Tuple[float, float, float, float]] = Field(
        None, description="Normalized box (x1,y1,x2,y2) for the first frame"
    )
    mask_path: Optional[str] = Field(
        None, description="Path to an initial segmentation mask for the first frame (for 'mask' mode)"
    )
    mask_label: Optional[int] = Field(
        None,
        description="Palette label to extract from the provided mask when using dataset annotations",
    )
    mask_frame_index: Optional[int] = Field(
        0,
        ge=0,
        description="Frame index to pick when mask_path points to an annotation directory",
    )
    mask_label_map: Optional[Dict[int, int]] = Field(
        None,
        description="Mapping from palette pixel values to object IDs (e.g. {1:1,2:2,3:3,4:4})",
    )
    mask_palette: Optional[Dict[int, List[int]]] = Field(
        None,
        description="Mapping from object IDs to RGB colors for overlays (each value is [R,G,B])",
    )
    target_name: Optional[str] = Field(
        "LV", description="Optional target label used in metadata/filenames"
    )
    sample_rate: int = Field(
        1,
        description="Process every Nth frame for speed (1 = every frame)",
        ge=1,
    )
    output_fps: Optional[int] = Field(
        None, description="FPS for output video. Defaults to source FPS"
    )
    save_mask_video: bool = Field(True, description="Save binary mask-only video")
    save_overlay_video: bool = Field(True, description="Save overlay video")

    @validator("points")
    def _validate_points(cls, v):
        if v is not None:
            for p in v:
                if len(p) != 3:
                    raise ValueError("Each point must be (x,y,label)")
        return v

    @validator("box")
    def _validate_box(cls, v):
        if v is not None and len(v) != 4:
            raise ValueError("box must be (x1,y1,x2,y2)")
        return v

    @validator("mask_palette")
    def _validate_palette(cls, v):
        if v is not None:
            for obj_id, color in v.items():
                if len(color) != 3:
                    raise ValueError("mask_palette colors must be RGB triplets")
                if any(c < 0 or c > 255 for c in color):
                    raise ValueError("mask_palette colors must be 0-255 integers")
        return v


class EchoSegmentationTool(BaseTool):
    """Segments cardiac chambers in echocardiography videos using MedSAM2 (HF) with SAM2 video predictor.

    - Downloads MedSAM2 checkpoint from Hugging Face by default (wanglab/MedSAM2) and builds a SAM2 video predictor.
    - Supports auto or prompted segmentation (points/box on first frame) with propagation.
    - Returns paths to generated videos (overlay and/or mask) and basic per-frame metrics.

    Note: You must supply a valid SAM2 model config YAML via `model_cfg` (from the SAM2 repo). The tool will
    auto-download the MedSAM2 checkpoint unless you provide a local `checkpoint` path. Pass the CONFIG NAME
    (e.g., 'sam2.1_hiera_t.yaml'), not a filesystem path.
    """

    name: str = "echo_segmentation"
    description: str = (
        "Segments echocardiography videos/images with MedSAM2 (SAM2-based). "
        "Downloads MedSAM2 weights from Hugging Face if needed. "
        "Input: video_path and optional prompt (points/box). "
        "Output: paths to generated videos and per-frame metrics."
    )
    args_schema: Type[BaseModel] = EchoSegmentationInput

    # Runtime
    device: Optional[str] = "cuda"
    temp_dir: Path = Path("temp")

    # Model config
    model_cfg: Optional[str] = None
    checkpoint: Optional[str] = None
    cache_dir: Optional[str] = None
    # Hugging Face model info (used if checkpoint not provided)
    model_id: Optional[str] = "wanglab/MedSAM2"
    model_filename: Optional[str] = "MedSAM2_US_Heart.pt"

    # Internal predictor (SAM2/MedSAM2 video predictor)
    _predictor: Any = None

    def __init__(
        self,
        device: Optional[str] = "cuda",
        temp_dir: Optional[str] = "temp",
        model_cfg: Optional[str] = None,
        checkpoint: Optional[str] = None,
        cache_dir: Optional[str] = None,
        model_id: Optional[str] = "wanglab/MedSAM2",
        model_filename: Optional[str] = "MedSAM2_US_Heart.pt",
    ):
        super().__init__()
        self.device = device or ("cuda" if torch.cuda.is_available() else "cpu")
        self.temp_dir = Path(temp_dir or tempfile.mkdtemp())
        self.temp_dir.mkdir(exist_ok=True, parents=True)
        self.model_cfg = model_cfg
        self.checkpoint = checkpoint
        self.cache_dir = cache_dir
        self.model_id = model_id
        self.model_filename = model_filename

        # Lazy-load predictor on first run to avoid heavy startup if unused
        self._predictor = None

    # ------------- SAM2/MedSAM2 predictor helpers -------------
    def _ensure_dependencies(self):
        if cv2 is None:
            raise RuntimeError(
                "OpenCV (cv2) is required. Install with: pip install opencv-python"
            )
        # Torch is imported already; SAM2/MedSAM2 imports happen in _load_predictor

    def _resolve_default_model_cfg(self) -> Optional[str]:
        """Resolve a default SAM2 YAML CONFIG NAME if none provided.

        We rely on the configs packaged inside the installed `sam2` module.
        Returns a config NAME like 'sam2.1_hiera_t' if found, else None.
        """
        if self.model_cfg:
            return self.model_cfg

        try:
            import importlib.resources as pkg_resources
            import sam2  # type: ignore

            candidates = [
                "sam2.1_hiera_t512.yaml",
                "sam2.1_hiera_t.yaml", 
                "sam2_hiera_s.yaml",
            ]
            for name in candidates:
                try:
                    cfg_path = pkg_resources.files(sam2) / "configs" / name
                    if cfg_path and cfg_path.is_file():
                        # Return the NAME without .yaml extension for Hydra
                        return name[:-5] if name.endswith('.yaml') else name
                except Exception:
                    continue
        except Exception:
            pass

        # If not found, return None and let caller raise a clear error.
        return None

    def _normalize_model_cfg_name(self, cfg: str) -> str:
        """Normalize user-provided model_cfg to a config NAME for Hydra.

        - If a filesystem path is provided, reduce to basename.
        - Fix common typos: 'sam2.1.hiera' -> 'sam2.1_hiera'.
        - Remove .yaml extension as Hydra expects just the config name.
        """
        try:
            p = Path(cfg)
            if p.exists():
                cfg = p.name
        except Exception:
            pass
        if "sam2.1.hiera" in cfg:
            cfg = cfg.replace("sam2.1.hiera", "sam2.1_hiera")
        
        # Remove .yaml extension - Hydra expects just the config name
        if cfg.endswith('.yaml'):
            cfg = cfg[:-5]
        
        return cfg

    def _load_predictor(self):
        """Load the SAM2 video predictor with MedSAM2 weights.

        If `checkpoint` is not provided, attempt to download from Hugging Face using
        `model_id` and `model_filename` (defaults target the ultrasound heart model).
        A valid SAM2 YAML config NAME is required; if not provided, we try to resolve a default.
        """
        if self._predictor is not None:
            return

        # Ensure checkpoint (local or download)
        if not self.checkpoint:
            if not self.model_id or not self.model_filename:
                raise RuntimeError(
                    "Either provide `checkpoint` or set (`model_id`, `model_filename`) to download MedSAM2."
                )
            try:
                ckpt_path = hf_hub_download(
                    repo_id=self.model_id,
                    filename=self.model_filename,
                    local_dir=self.cache_dir or str(self.temp_dir / "hf_cache"),
                    local_dir_use_symlinks=False,
                )
                self.checkpoint = ckpt_path
            except Exception as e:
                raise RuntimeError(
                    f"Failed to download MedSAM2 checkpoint from Hugging Face ({self.model_id}/{self.model_filename}): {e}"
                )

        # Ensure a model config NAME
        if not self.model_cfg:
            self.model_cfg = self._resolve_default_model_cfg()
        if not self.model_cfg:
            raise RuntimeError(
                "Could not resolve a SAM2 config automatically. Install `sam2` and pass a config NAME, e.g., --model-cfg sam2.1_hiera_t.yaml"
            )

        cfg_name = self._normalize_model_cfg_name(self.model_cfg)

        try:
            # Build SAM2 video predictor with MedSAM2 weights
            from sam2.build_sam import build_sam2_video_predictor  # type: ignore
            from hydra.core.global_hydra import GlobalHydra
            from hydra import initialize_config_dir
            import os
            
            # Clear any existing Hydra configuration to avoid conflicts
            GlobalHydra.instance().clear()
            
            # Get SAM2 configs directory path
            import sam2
            sam2_configs_dir = os.path.join(os.path.dirname(sam2.__file__), "configs")
            
            # Initialize Hydra with SAM2 configs directory
            with initialize_config_dir(config_dir=sam2_configs_dir, version_base=None):
                predictor = build_sam2_video_predictor(
                    cfg_name, self.checkpoint, device=self.device
                )
        except Exception as e:
            raise RuntimeError(
                f"Failed to build predictor with MedSAM2 weights. Config: '{cfg_name}', "
                f"Checkpoint: '{self.checkpoint}'. Error: {e}"
            )

        self._predictor = predictor

    # ------------- Video IO helpers -------------
    def _read_video(self, path: str) -> Tuple[List[np.ndarray], float]:
        """Read video into list of RGB frames and return frames + fps.
        If it's an image, return single frame and default fps=25.
        """
        p = Path(path)
        if not p.exists():
            raise FileNotFoundError(f"Video/image not found: {path}")

        if p.suffix.lower() in {".png", ".jpg", ".jpeg", ".bmp"}:
            img = cv2.imread(str(p), cv2.IMREAD_COLOR)
            if img is None:
                raise RuntimeError("Failed to read image.")
            img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
            return [img], 25.0

        cap = cv2.VideoCapture(str(p))
        if not cap.isOpened():
            raise RuntimeError("Failed to open video.")

        fps = cap.get(cv2.CAP_PROP_FPS) or 25.0
        frames: List[np.ndarray] = []
        while True:
            ret, frame = cap.read()
            if not ret:
                break
            frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            frames.append(frame)
        cap.release()
        if not frames:
            raise RuntimeError("No frames read from video.")
        return frames, float(fps)

    def _write_video(self, frames: List[np.ndarray], fps: float, out_path: Path):
        out_path.parent.mkdir(exist_ok=True, parents=True)
        h, w = frames[0].shape[:2]
        fourcc = cv2.VideoWriter_fourcc(*"H264")
        writer = cv2.VideoWriter(str(out_path), fourcc, fps, (w, h))
        for fr in frames:
            bgr = cv2.cvtColor(fr, cv2.COLOR_RGB2BGR)
            writer.write(bgr)
        writer.release()

    # ------------- Segmentation core -------------
    def _normalized_to_abs_points(self, points: List[Tuple[float, float, int]], w: int, h: int):
        coords = np.array([[int(x * w), int(y * h)] for x, y, _ in points], dtype=np.int32)
        labels = np.array([int(lbl) for _, _, lbl in points], dtype=np.int32)
        return coords, labels

    def _normalized_to_abs_box(self, box: Tuple[float, float, float, float], w: int, h: int):
        x1, y1, x2, y2 = box
        return np.array([int(x1 * w), int(y1 * h), int(x2 * w), int(y2 * h)], dtype=np.int32)

    def _compose_color_layer(
        self,
        masks: Dict[int, np.ndarray],
        palette: Dict[int, Tuple[int, int, int]],
        fallback: Tuple[Tuple[int, int, int], ...],
    ) -> np.ndarray:
        """Create an RGB layer where each object mask is painted with its palette color."""

        # Determine output spatial size from first mask
        sample_mask = next(iter(masks.values()))
        height, width = sample_mask.shape[:2]
        color_layer = np.zeros((height, width, 3), dtype=np.uint8)

        for obj_id, mask in masks.items():
            if mask.shape != (height, width):
                mask = cv2.resize(mask.astype(np.uint8), (width, height), interpolation=cv2.INTER_NEAREST)
            mask_bool = mask.astype(bool)
            color = palette.get(obj_id)
            if color is None:
                color = fallback[obj_id % len(fallback)]
            color_layer[mask_bool] = color

        return color_layer

    def _render_overlay(
        self,
        frame: np.ndarray,
        masks: Dict[int, np.ndarray],
        palette: Dict[int, Tuple[int, int, int]],
        fallback: Tuple[Tuple[int, int, int], ...],
        alpha: float = 0.5,
    ) -> np.ndarray:
        """Alpha blend colorized masks onto the frame."""

        color_layer = self._compose_color_layer(masks, palette, fallback)
        overlay = cv2.addWeighted(frame, 1 - alpha, color_layer, alpha, 0)
        return overlay

    def _load_mask_prompt(
        self,
        mask_path: str,
        frame_shape: Tuple[int, int],
        mask_label: Optional[int] = None,
        mask_frame_index: Optional[int] = 0,
        mask_label_map: Optional[Dict[int, int]] = None,
    ) -> Dict[int, np.ndarray]:
        """Load prompt masks (object_id -> binary mask) from annotation."""

        if mask_path is None:
            raise ValueError("mask_path must be provided for mask prompts")

        candidate = Path(mask_path)
        if candidate.is_dir():
            if mask_frame_index is None:
                mask_frame_index = 0
            frame_name = f"{int(mask_frame_index):04d}.png"
            candidate = candidate / frame_name

        if not candidate.exists():
            raise FileNotFoundError(f"Mask prompt not found at {candidate}")

        mask = cv2.imread(str(candidate), cv2.IMREAD_GRAYSCALE)
        if mask is None:
            raise RuntimeError(f"Failed to read mask prompt: {candidate}")

        height, width = frame_shape
        if mask.shape != frame_shape:
            mask = cv2.resize(mask, (width, height), interpolation=cv2.INTER_NEAREST)

        prompt_masks: Dict[int, np.ndarray] = {}

        if mask_label_map:
            for pixel_value, obj_id in mask_label_map.items():
                prompt_masks[int(obj_id)] = (mask == pixel_value).astype(np.uint8)
        elif mask_label is not None:
            prompt_masks[1] = (mask == mask_label).astype(np.uint8)
        else:
            prompt_masks[1] = (mask > 0).astype(np.uint8)

        if not prompt_masks:
            raise RuntimeError("No foreground objects extracted from mask prompt")

        return prompt_masks

    def _run(
        self,
        video_path: str,
        prompt_mode: Literal["auto", "points", "box", "mask"] = "auto",
        points: Optional[List[Tuple[float, float, int]]] = None,
        box: Optional[Tuple[float, float, float, float]] = None,
        mask_path: Optional[str] = None,
        mask_label: Optional[int] = None,
        mask_frame_index: Optional[int] = 0,
        mask_label_map: Optional[Dict[int, int]] = None,
        mask_palette: Optional[Dict[int, List[int]]] = None,
        target_name: Optional[str] = "LV",
        sample_rate: int = 1,
        output_fps: Optional[int] = None,
        save_mask_video: bool = True,
        save_overlay_video: bool = True,
        run_manager: Optional[CallbackManagerForToolRun] = None,
    ) -> Tuple[Dict[str, Any], Dict]:
        """Run MedSAM2/SAM2 video segmentation on an echo video or image.

        Returns (output, metadata), where output contains file paths;
        metadata contains additional info and basic per-frame metrics.
        """
        self._ensure_dependencies()
        
        # Load predictor lazily
        self._load_predictor()
        predictor = self._predictor

        # Get video info for output formatting
        frames, src_fps = self._read_video(video_path)
        fps = float(output_fps) if output_fps else src_fps
        h, w = frames[0].shape[:2]

        default_palette = {
            1: (0, 255, 0),  # LV - green
            2: (255, 0, 0),  # RV - red
            3: (255, 255, 0),  # LA - yellow
            4: (0, 0, 255),  # RA - blue
            5: (255, 0, 255),  # myocardium/other
        }
        palette_rgb: Dict[int, Tuple[int, int, int]] = dict(default_palette)
        if mask_palette:
            palette_rgb.update(
                {
                    int(obj_id): tuple(int(c) for c in color)
                    for obj_id, color in mask_palette.items()
                }
            )
        fallback_colors: Tuple[Tuple[int, int, int], ...] = (
            (0, 255, 0),
            (255, 0, 0),
            (0, 0, 255),
            (255, 255, 0),
            (255, 0, 255),
            (0, 255, 255),
        )
        active_object_ids: List[int] = []

        # Initialize video state (SAM2 expects video path directly)
        try:
            # SAM2 wants the video file path, not processed frames
            state = predictor.init_state(video_path)
        except Exception as e:
            raise RuntimeError(
                f"Failed to initialize SAM2 state with video: {video_path}. "
                f"SAM2 may only support MP4 videos and JPEG folders. Error: {e}"
            )

        # Feed prompt to predictor on first frame
        try:
            if state is None:
                raise RuntimeError("SAM2 state initialization failed")

            if prompt_mode == "mask" and mask_path:
                prompt_masks = self._load_mask_prompt(
                    mask_path,
                    (h, w),
                    mask_label=mask_label,
                    mask_frame_index=mask_frame_index,
                    mask_label_map=mask_label_map,
                )
                for obj_id, obj_mask in prompt_masks.items():
                    predictor.add_new_mask(
                        state,
                        frame_idx=0,
                        obj_id=int(obj_id),
                        mask=obj_mask.astype(bool),
                    )
                    active_object_ids.append(int(obj_id))
            elif prompt_mode == "points" and points:
                abs_points, point_labels = self._normalized_to_abs_points(points, w, h)
                predictor.add_new_points(
                    state,
                    frame_idx=0,
                    obj_id=1,
                    points=abs_points,
                    labels=point_labels,
                )
                active_object_ids.append(1)
            elif prompt_mode == "box" and box:
                abs_box = self._normalized_to_abs_box(box, w, h)
                predictor.add_new_points_or_box(
                    state,
                    frame_idx=0,
                    obj_id=1,
                    box=abs_box,
                )
                active_object_ids.append(1)
            else:
                # Default: use center point as prompt
                center_x, center_y = w // 2, h // 2
                center_points = np.array([[center_x, center_y]])
                center_labels = np.array([1])
                predictor.add_new_points(
                    state,
                    frame_idx=0,
                    obj_id=1,
                    points=center_points,
                    labels=center_labels,
                )
                active_object_ids.append(1)
        except Exception as e:
            raise RuntimeError(
                f"Prompting API mismatch. Please adapt the add_new_points calls "
                f"to your installed SAM2/MedSAM2 version. Error: {e}"
            )

        # Propagate segmentation across frames
        mask_frames: List[Dict[int, np.ndarray]] = []
        overlay_frames: List[np.ndarray] = []
        per_frame_metrics: List[Dict[str, Any]] = []

        try:
            for out in predictor.propagate_in_video(state):
                if not (isinstance(out, tuple) and len(out) == 3):
                    continue

                frame_idx, obj_ids, mask_logits = out
                if len(mask_logits) == 0:
                    continue

                frame_masks: Dict[int, np.ndarray] = {}
                for idx, obj_id in enumerate(obj_ids):
                    logits = mask_logits[idx]
                    mask = (torch.sigmoid(logits).cpu().numpy() > 0.5).astype(np.uint8)
                    frame_masks[int(obj_id)] = mask

                if not frame_masks:
                    continue

                mask_frames.append(frame_masks)

                if save_overlay_video and frame_idx < len(frames):
                    overlay = self._render_overlay(
                        frames[frame_idx], frame_masks, palette_rgb, fallback_colors
                    )
                    overlay_frames.append(overlay)

                per_frame_metrics.append(
                    {
                        "frame_index": int(frame_idx),
                        "object_areas": {
                            int(obj_id): int(mask.sum()) for obj_id, mask in frame_masks.items()
                        },
                    }
                )
        except Exception as e:
            raise RuntimeError(f"Error during propagation: {e}")

        # Write outputs
        out_base = f"echo_seg_{target_name}_{uuid.uuid4().hex[:8]}"
        outputs: Dict[str, Any] = {}

        if save_overlay_video and overlay_frames:
            overlay_path = self.temp_dir / f"{out_base}_overlay.mp4"
            self._write_video(overlay_frames, fps, overlay_path)
            outputs["overlay_video_path"] = str(overlay_path)

        if save_mask_video and mask_frames:
            mask_rgb_frames: List[np.ndarray] = []
            for frame_masks in mask_frames:
                color_layer = self._compose_color_layer(frame_masks, palette_rgb, fallback_colors)
                mask_rgb_frames.append(color_layer)
            mask_path = self.temp_dir / f"{out_base}_mask.mp4"
            self._write_video(mask_rgb_frames, fps, mask_path)
            outputs["mask_video_path"] = str(mask_path)

        metadata: Dict[str, Any] = {
            "video_path": video_path,
            "frames_processed": len(mask_frames),
            "source_frames": len(frames),
            "sample_rate": sample_rate,
            "fps_out": fps,
            "resolution": [h, w],
            "target_name": target_name,
            "active_object_ids": sorted(set(active_object_ids) or {1}),
            "per_frame_metrics": per_frame_metrics,
            "analysis_status": "completed",
        }

        return outputs, metadata

    async def _arun(
        self,
        video_path: str,
        prompt_mode: Literal["auto", "points", "box", "mask"] = "auto",
        points: Optional[List[Tuple[float, float, int]]] = None,
        box: Optional[Tuple[float, float, float, float]] = None,
        mask_path: Optional[str] = None,
        mask_label: Optional[int] = None,
        mask_frame_index: Optional[int] = 0,
        mask_label_map: Optional[Dict[int, int]] = None,
        mask_palette: Optional[Dict[int, List[int]]] = None,
        target_name: Optional[str] = "LV",
        sample_rate: int = 1,
        output_fps: Optional[int] = None,
        save_mask_video: bool = True,
        save_overlay_video: bool = True,
        run_manager: Optional[AsyncCallbackManagerForToolRun] = None,
    ) -> Tuple[Dict[str, Any], Dict]:
        return self._run(
            video_path,
            prompt_mode,
            points,
            box,
            mask_path,
            mask_label,
            mask_frame_index,
            mask_label_map,
            mask_palette,
            target_name,
            sample_rate,
            output_fps,
            save_mask_video,
            save_overlay_video,
        )