# Copyright 2023-2024 SGLang Team
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================

# Source: https://github.com/LLaVA-VL/LLaVA-NeXT/blob/main/llava/mm_utils.py
"""
Utilities for multi-modal models.

This python file mainly contains utilities that were used in the
image processing logic of llava-next including operations such as
anyres and anyres_max

Currently supports the anyres and anyres_max operation for CLIP and
SigLip. For more information, you may refer to the paper or the blog

LLaVA-NeXT : https://llava-vl.github.io/blog/2024-01-30-llava-next/
LLaVA-Onevision : https://arxiv.org/pdf/2408.03326

"""
import ast
import base64
import math
import re
from io import BytesIO

import numpy as np
from PIL import Image


def select_best_resolution(original_size, possible_resolutions):
    """
    Selects the best resolution from a list of possible resolutions based on the original size.

    Args:
        original_size (tuple): The original size of the image in the format (width, height).
        possible_resolutions (list): A list of possible resolutions in the format [(width1, height1), (width2, height2), ...].

    Returns:
        tuple: The best fit resolution in the format (width, height).
    """
    original_width, original_height = original_size
    best_fit = None
    max_effective_resolution = 0
    min_wasted_resolution = float("inf")

    for width, height in possible_resolutions:
        # Calculate the downscaled size to keep the aspect ratio
        scale = min(width / original_width, height / original_height)
        downscaled_width, downscaled_height = int(original_width * scale), int(
            original_height * scale
        )

        # Calculate effective and wasted resolutions
        effective_resolution = min(
            downscaled_width * downscaled_height, original_width * original_height
        )
        wasted_resolution = (width * height) - effective_resolution

        if effective_resolution > max_effective_resolution or (
            effective_resolution == max_effective_resolution
            and wasted_resolution < min_wasted_resolution
        ):
            max_effective_resolution = effective_resolution
            min_wasted_resolution = wasted_resolution
            best_fit = (width, height)

    return best_fit


def resize_and_pad_image(image, target_resolution):
    """
    Resize and pad an image to a target resolution while maintaining aspect ratio.

    Args:
        image (PIL.Image.Image): The input image.
        target_resolution (tuple): The target resolution (width, height) of the image.

    Returns:
        PIL.Image.Image: The resized and padded image.
    """
    original_width, original_height = image.size
    target_width, target_height = target_resolution

    scale_w = target_width / original_width
    scale_h = target_height / original_height

    if scale_w < scale_h:
        new_width = target_width
        new_height = min(math.ceil(original_height * scale_w), target_height)
    else:
        new_height = target_height
        new_width = min(math.ceil(original_width * scale_h), target_width)

    # Resize the image
    resized_image = image.resize((new_width, new_height))

    new_image = Image.new("RGB", (target_width, target_height), (0, 0, 0))
    paste_x = (target_width - new_width) // 2
    paste_y = (target_height - new_height) // 2
    new_image.paste(resized_image, (paste_x, paste_y))

    return new_image


def divide_to_patches(image, patch_size):
    """
    Divides an image into patches of a specified size.

    Args:
        image (PIL.Image.Image): The input image.
        patch_size (int): The size of each patch.

    Returns:
        list: A list of PIL.Image.Image objects representing the patches.
    """
    patches = []
    width, height = image.size
    for i in range(0, height, patch_size):
        for j in range(0, width, patch_size):
            box = (j, i, j + patch_size, i + patch_size)
            patch = image.crop(box)
            patches.append(patch)

    return patches


def get_anyres_image_grid_shape(image_size, grid_pinpoints, patch_size):
    """
    Calculate the shape of the image patch grid after the preprocessing for images of any resolution.

    Args:
        image_size (tuple): The size of the input image in the format (width, height).
        grid_pinpoints (str): A string representation of a list of possible resolutions.
        patch_size (int): The size of each image patch.

    Returns:
        tuple: The shape of the image patch grid in the format (width, height).
    """
    if isinstance(grid_pinpoints, str) and "x" in grid_pinpoints:
        assert patch_size in [
            224,
            336,
            384,
            448,
            512,
        ], "patch_size should be in [224, 336, 384, 448, 512]"
        # Use regex to extract the range from the input string
        matches = re.findall(r"\((\d+)x(\d+)\)", grid_pinpoints)
        range_start = tuple(map(int, matches[0]))
        range_end = tuple(map(int, matches[-1]))
        # Generate a matrix of tuples from (range_start[0], range_start[1]) to (range_end[0], range_end[1])
        grid_pinpoints = [
            (i, j)
            for i in range(range_start[0], range_end[0] + 1)
            for j in range(range_start[1], range_end[1] + 1)
        ]
        # Multiply all elements by patch_size
        grid_pinpoints = [[dim * patch_size for dim in pair] for pair in grid_pinpoints]
    if type(grid_pinpoints) is list:
        possible_resolutions = grid_pinpoints
    else:
        possible_resolutions = ast.literal_eval(grid_pinpoints)
    width, height = select_best_resolution(image_size, possible_resolutions)
    return width // patch_size, height // patch_size


def process_anyres_image(image, processor, grid_pinpoints):
    """
    Process an image with variable resolutions.

    Args:
        image (PIL.Image.Image): The input image to be processed.
        processor: The image processor object.
        grid_pinpoints (str): A string representation of a list of possible resolutions.

    Returns:
        np.array: An np array containing the processed image patches.
    """
    if isinstance(grid_pinpoints, str) and "x" in grid_pinpoints:
        try:
            patch_size = processor.size[0]
        except Exception as e:
            patch_size = processor.size["shortest_edge"]
        assert patch_size in [
            224,
            336,
            384,
            448,
            512,
        ], "patch_size should be in [224, 336, 384, 448, 512]"
        # Use regex to extract the range from the input string
        matches = re.findall(r"\((\d+)x(\d+)\)", grid_pinpoints)
        range_start = tuple(map(int, matches[0]))
        range_end = tuple(map(int, matches[-1]))
        # Generate a matrix of tuples from (range_start[0], range_start[1]) to (range_end[0], range_end[1])
        grid_pinpoints = [
            (i, j)
            for i in range(range_start[0], range_end[0] + 1)
            for j in range(range_start[1], range_end[1] + 1)
        ]
        # Multiply all elements by patch_size
        grid_pinpoints = [[dim * patch_size for dim in pair] for pair in grid_pinpoints]

    if type(grid_pinpoints) is list:
        possible_resolutions = grid_pinpoints
    else:
        possible_resolutions = ast.literal_eval(grid_pinpoints)
    best_resolution = select_best_resolution(image.size, possible_resolutions)
    image_padded = resize_and_pad_image(image, best_resolution)

    # For Siglip processor, only have size but no crop size
    crop_size = (
        processor.crop_size["height"]
        if "crop_size" in processor.__dict__
        else processor.size["height"]
    )
    shortest_edge = (
        processor.size["shortest_edge"]
        if "shortest_edge" in processor.size
        else processor.size["height"]
    )
    patches = divide_to_patches(image_padded, crop_size)

    image_original_resize = image.resize((shortest_edge, shortest_edge))

    image_patches = [image_original_resize] + patches
    image_patches = [
        processor.preprocess(image_patch.convert("RGB"))["pixel_values"][0]
        for image_patch in image_patches
    ]
    return np.stack(image_patches, axis=0)


def load_image_from_base64(image):
    return Image.open(BytesIO(base64.b64decode(image)))


def expand2square(pil_img, background_color):
    width, height = pil_img.size
    if width == height:
        return pil_img
    if pil_img.mode == "L":
        pil_img = pil_img.convert("RGB")
    if width > height:
        result = Image.new(pil_img.mode, (width, width), background_color)
        result.paste(pil_img, (0, (width - height) // 2))
        return result
    else:
        result = Image.new(pil_img.mode, (height, height), background_color)
        result.paste(pil_img, ((height - width) // 2, 0))
        return result


def unpad_image(tensor, original_size):
    """
    Unpads a PyTorch tensor of a padded and resized image.

    Args:
    tensor (torch.Tensor): The image tensor, assumed to be in CxHxW format.
    original_size (tuple): The original size of the image (height, width).

    Returns:
    torch.Tensor: The unpadded image tensor.
    """
    original_width, original_height = original_size
    current_height, current_width = tensor.shape[1:]

    original_aspect_ratio = original_width / original_height
    current_aspect_ratio = current_width / current_height

    if original_aspect_ratio > current_aspect_ratio:
        scale_factor = current_width / original_width
        new_height = int(original_height * scale_factor)
        padding = (current_height - new_height) // 2
        unpadded_tensor = tensor[:, padding : current_height - padding, :]
    else:
        scale_factor = current_height / original_height
        new_width = int(original_width * scale_factor)
        padding = (current_width - new_width) // 2
        unpadded_tensor = tensor[:, :, padding : current_width - padding]

    return unpadded_tensor


def unpad_image_shape(current_height, current_width, original_size):
    """
    Unpads a PyTorch tensor of a padded and resized image
    and returns the new shape.
    """
    original_width, original_height = original_size

    original_aspect_ratio = original_width / original_height
    current_aspect_ratio = current_width / current_height

    if original_aspect_ratio > current_aspect_ratio:
        scale_factor = current_width / original_width
        new_height = int(original_height * scale_factor)
        padding = (current_height - new_height) // 2
        new_shape = (current_height - 2 * padding, current_width)
    else:
        scale_factor = current_height / original_height
        new_width = int(original_width * scale_factor)
        padding = (current_width - new_width) // 2
        new_shape = (current_height, current_width - 2 * padding)

    return new_shape


def process_images(images, image_processor, model_cfg):
    image_aspect_ratio = getattr(model_cfg, "image_aspect_ratio", None)
    new_images = []
    if image_aspect_ratio == "pad":
        for image in images:
            image = expand2square(
                image, tuple(int(x * 255) for x in image_processor.image_mean)
            )
            image = image_processor.preprocess(image)["pixel_values"][0]
            new_images.append(image)
    elif "anyres" in image_aspect_ratio:
        for image in images:
            image = process_anyres_image(
                image, image_processor, model_cfg.image_grid_pinpoints
            )
            new_images.append(image)
    else:
        return image_processor(images)["pixel_values"]
    if all(x.shape == new_images[0].shape for x in new_images):
        new_images = np.stack(new_images, axis=0)
    return new_images