# Copyright Niantic 2019. Patent Pending. All rights reserved.
#
# This software is licensed under the terms of the Monodepth2 licence
# which allows for non-commercial use only, the full terms of which are made
# available in the LICENSE file.

from __future__ import absolute_import, division, print_function
import os
import hashlib
import zipfile
from six.moves import urllib
import numpy as np
import cv2

def visualize_depth(depth, mask=None, depth_min=None, depth_max=None, direct=False):
    """Visualize the depth map with colormap.
       Rescales the values so that depth_min and depth_max map to 0 and 1,
       respectively.
    """
    if not direct:
        depth = 1.0 / (depth + 1e-6)
    invalid_mask = np.logical_or(np.isnan(depth), np.logical_not(np.isfinite(depth)))
    if mask is not None:
        invalid_mask += np.logical_not(mask)
    if depth_min is None:
        depth_min = np.percentile(depth[np.logical_not(invalid_mask)], 5)
    if depth_max is None:
        depth_max = np.percentile(depth[np.logical_not(invalid_mask)], 95)
    depth[depth < depth_min] = depth_min
    depth[depth > depth_max] = depth_max
    depth[invalid_mask] = depth_max

    depth_scaled = (depth - depth_min) / (depth_max - depth_min)
    depth_scaled_uint8 = np.uint8(depth_scaled * 255)
    depth_color = cv2.applyColorMap(depth_scaled_uint8, cv2.COLORMAP_MAGMA)
    depth_color[invalid_mask, :] = 0

    return depth_color

def compute_errors(gt, pred):
    """Computation of error metrics between predicted and ground truth depths
    """
    thresh = np.maximum((gt / pred), (pred / gt))
    a1 = (thresh < 1.25     ).mean()
    a2 = (thresh < 1.25 ** 2).mean()
    a3 = (thresh < 1.25 ** 3).mean()

    rmse = (gt - pred) ** 2
    rmse = np.sqrt(rmse.mean())

    rmse_log = (np.log(gt) - np.log(pred)) ** 2
    rmse_log = np.sqrt(rmse_log.mean())

    abs_rel = np.mean(np.abs(gt - pred) / gt)

    sq_rel = np.mean(((gt - pred) ** 2) / gt)

    return abs_rel, sq_rel, rmse, rmse_log, a1, a2, a3
    
def readlines(filename):
    """Read all the lines in a text file and return as a list
    """
    with open(filename, 'r') as f:
        lines = f.read().splitlines()
    return lines


def normalize_image(x):
    """Rescale image pixels to span range [0, 1]
    """
    ma = float(x.max().cpu().data)
    mi = float(x.min().cpu().data)
    d = ma - mi if ma != mi else 1e5
    return (x - mi) / d


def sec_to_hm(t):
    """Convert time in seconds to time in hours, minutes and seconds
    e.g. 10239 -> (2, 50, 39)
    """
    t = int(t)
    s = t % 60
    t //= 60
    m = t % 60
    t //= 60
    return t, m, s


def sec_to_hm_str(t):
    """Convert time in seconds to a nice string
    e.g. 10239 -> '02h50m39s'
    """
    h, m, s = sec_to_hm(t)
    return "{:02d}h{:02d}m{:02d}s".format(h, m, s)


def download_model_if_doesnt_exist(model_name):
    """If pretrained kitti model doesn't exist, download and unzip it
    """
    # values are tuples of (<google cloud URL>, <md5 checksum>)
    download_paths = {
        "mono_640x192":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/mono_640x192.zip",
             "a964b8356e08a02d009609d9e3928f7c"),
        "stereo_640x192":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/stereo_640x192.zip",
             "3dfb76bcff0786e4ec07ac00f658dd07"),
        "mono+stereo_640x192":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/mono%2Bstereo_640x192.zip",
             "c024d69012485ed05d7eaa9617a96b81"),
        "mono_no_pt_640x192":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/mono_no_pt_640x192.zip",
             "9c2f071e35027c895a4728358ffc913a"),
        "stereo_no_pt_640x192":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/stereo_no_pt_640x192.zip",
             "41ec2de112905f85541ac33a854742d1"),
        "mono+stereo_no_pt_640x192":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/mono%2Bstereo_no_pt_640x192.zip",
             "46c3b824f541d143a45c37df65fbab0a"),
        "mono_1024x320":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/mono_1024x320.zip",
             "0ab0766efdfeea89a0d9ea8ba90e1e63"),
        "stereo_1024x320":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/stereo_1024x320.zip",
             "afc2f2126d70cf3fdf26b550898b501a"),
        "mono+stereo_1024x320":
            ("https://storage.googleapis.com/niantic-lon-static/research/monodepth2/mono%2Bstereo_1024x320.zip",
             "cdc5fc9b23513c07d5b19235d9ef08f7"),
        }

    if not os.path.exists("models"):
        os.makedirs("models")

    model_path = os.path.join("models", model_name)

    def check_file_matches_md5(checksum, fpath):
        if not os.path.exists(fpath):
            return False
        with open(fpath, 'rb') as f:
            current_md5checksum = hashlib.md5(f.read()).hexdigest()
        return current_md5checksum == checksum

    # see if we have the model already downloaded...
    if not os.path.exists(os.path.join(model_path, "encoder.pth")):

        model_url, required_md5checksum = download_paths[model_name]

        if not check_file_matches_md5(required_md5checksum, model_path + ".zip"):
            print("-> Downloading pretrained model to {}".format(model_path + ".zip"))
            urllib.request.urlretrieve(model_url, model_path + ".zip")

        if not check_file_matches_md5(required_md5checksum, model_path + ".zip"):
            print("   Failed to download a file which matches the checksum - quitting")
            quit()

        print("   Unzipping model...")
        with zipfile.ZipFile(model_path + ".zip", 'r') as f:
            f.extractall(model_path)

        print("   Model unzipped to {}".format(model_path))