import os
import re
import copy
import torch
import numpy as np
# import matplotlib
# matplotlib.use("Agg")
# import matplotlib.pyplot as plt
from shutil import copyfile


def get_proper_cuda_device(device, verbose=True):
    if not isinstance(device, list):
        device = [device]
    count = torch.cuda.device_count()
    if verbose:
        print("[Builder]: Found {} gpu".format(count))
    for i in range(len(device)):
        d = device[i]
        did = None
        if isinstance(d, str):
            if re.search("cuda:[\d]+", d):
                did = int(d[5:])
        elif isinstance(d, int):
            did = d
        if did is None:
            raise ValueError("[Builder]: Wrong cuda id {}".format(d))
        if did < 0 or did >= count:
            if verbose:
                print("[Builder]: {} is not found, ignore.".format(d))
            device[i] = None
        else:
            device[i] = did
    device = [d for d in device if d is not None]
    return device


def get_proper_device(devices, verbose=True):
    origin = copy.copy(devices)
    devices = copy.copy(devices)
    if not isinstance(devices, list):
        devices = [devices]
    use_cpu = any([d.find("cpu")>=0 for d in devices])
    use_gpu = any([(d.find("cuda")>=0 or isinstance(d, int)) for d in devices])
    assert not (use_cpu and use_gpu), "{} contains cpu and cuda device.".format(devices)
    if use_gpu:
        devices = get_proper_cuda_device(devices, verbose)
        if len(devices) == 0:
            if verbose:
                print("[Builder]: Failed to find any valid gpu in {}, use `cpu`.".format(origin))
            devices = ["cpu"]
    return devices


def _file_at_step(step):
    return "save_{}k{}.pkg".format(int(step // 1000), int(step % 1000))


def _file_best():
    return "trained.pkg"


def save(global_step, graph, optim, criterion_dict=None, pkg_dir="", is_best=False, max_checkpoints=None):
    if optim is None:
        raise ValueError("cannot save without optimzier")
    state = {
        "global_step": global_step,
        # DataParallel wrap model in attr `module`.
        "graph": graph.module.state_dict() if hasattr(graph, "module") else graph.state_dict(),
        "optim": optim.state_dict(),
        "criterion": {}
    }
    if criterion_dict is not None:
        for k in criterion_dict:
            state["criterion"][k] = criterion_dict[k].state_dict()
    save_path = os.path.join(pkg_dir, _file_at_step(global_step))
    best_path = os.path.join(pkg_dir, _file_best())
    torch.save(state, save_path)
    if is_best:
        copyfile(save_path, best_path)
    if max_checkpoints is not None:
        history = []
        for file_name in os.listdir(pkg_dir):
            if re.search("save_\d*k\d*\.pkg", file_name):
                digits = file_name.replace("save_", "").replace(".pkg", "").split("k")
                number = int(digits[0]) * 1000 + int(digits[1])
                history.append(number)
        history.sort()
        while len(history) > max_checkpoints:
            path = os.path.join(pkg_dir, _file_at_step(history[0]))
            print("[Checkpoint]: remove {} to keep {} checkpoints".format(path, max_checkpoints))
            if os.path.exists(path):
                os.remove(path)
            history.pop(0)


def load(step_or_path, graph, optim=None, criterion_dict=None, pkg_dir="", device=None):
    step = step_or_path
    save_path = None
    if isinstance(step, int):
        save_path = os.path.join(pkg_dir, _file_at_step(step))
    if isinstance(step, str):
        if pkg_dir is not None:
            if step == "best":
                save_path = os.path.join(pkg_dir, _file_best())
            else:
                save_path = os.path.join(pkg_dir, step)
        else:
            save_path = step
    if save_path is not None and not os.path.exists(save_path):
        print("[Checkpoint]: Failed to find {}".format(save_path))
        return
    if save_path is None:
        print("[Checkpoint]: Cannot load the checkpoint with given step or filename or `best`")
        return

    # begin to load
    state = torch.load(save_path, map_location=device)
    global_step = state["global_step"]
    graph.load_state_dict(state["graph"])
    if optim is not None:
        optim.load_state_dict(state["optim"])
    if criterion_dict is not None:
        for k in criterion_dict:
            criterion_dict[k].load_state_dict(state["criterion"][k])

    graph.set_actnorm_init(inited=True)

    print("[Checkpoint]: Load {} successfully".format(save_path))
    return global_step


def __save_figure_to_numpy(fig):
    # save it to a numpy array.
    data = np.fromstring(fig.canvas.tostring_rgb(), dtype=np.uint8, sep='')
    data = data.reshape(fig.canvas.get_width_height()[::-1] + (3,))
    return data


def __to_ndarray_list(tensors, titles):
    if not isinstance(tensors, list):
        tensors = [tensors]
        titles = [titles]
    assert len(titles) == len(tensors),\
        "[visualizer]: {} titles are not enough for {} tensors".format(
            len(titles), len(tensors))
    for i in range(len(tensors)):
        if torch.is_tensor(tensors[i]):
            tensors[i] = tensors[i].cpu().detach().numpy()
    return tensors, titles


def __get_figures(num_tensors, figsize):
    fig, axes = plt.subplots(num_tensors, 1, figsize=figsize)
    if not isinstance(axes, np.ndarray):
        axes = np.asarray([axes])
    return fig, axes


def __make_dir(file_name, plot_dir):
    if file_name is not None and not os.path.exists(plot_dir):
        os.makedirs(plot_dir)


def __draw(fig, file_name, plot_dir):
    if file_name is not None:
        plt.savefig('{}/{}.png'.format(plot_dir, file_name), format='png')
        plt.close(fig)
        return None
    else:
        fig.tight_layout()
        fig.canvas.draw()
        data = __save_figure_to_numpy(fig)
        plt.close(fig)
        return data


def __get_size_for_spec(tensors):
    spectrogram = tensors[0]
    fig_w = np.min([int(np.ceil(spectrogram.shape[1] / 10.0)), 10])
    fig_w = np.max([fig_w, 3])
    fig_h = np.max([3 * len(tensors), 3])
    return (fig_w, fig_h)


def __get_aspect(spectrogram):
    fig_w = np.min([int(np.ceil(spectrogram.shape[1] / 10.0)), 10])
    fig_w = np.max([fig_w, 3])
    aspect = 3.0 / fig_w
    if spectrogram.shape[1] > 50:
        aspect = aspect * spectrogram.shape[1] / spectrogram.shape[0]
    else:
        aspect = aspect * spectrogram.shape[1] / (spectrogram.shape[0])
    return aspect


def plot_prob(done, title="", file_name=None, plot_dir=None):
    __make_dir(file_name, plot_dir)

    done, title = __to_ndarray_list(done, title)
    for i in range(len(done)):
        done[i] = np.reshape(done[i], (-1, done[i].shape[-1]))
    figsize = (5, 5 * len(done))
    fig, axes = __get_figures(len(done), figsize)
    for ax, d, t in zip(axes, done, title):
        im = ax.imshow(d, vmin=0, vmax=1, cmap="Blues", aspect=d.shape[1]/d.shape[0])
        ax.set_title(t)
        ax.set_yticks(np.arange(d.shape[0]))
        lables = ["Frame{}".format(i+1) for i in range(d.shape[0])]
        ax.set_yticklabels(lables)
        ax.set_yticks(np.arange(d.shape[0])-.5, minor=True)
        ax.grid(which="minor", color="g", linestyle='-.', linewidth=1)
        ax.invert_yaxis()
    return __draw(fig, file_name, plot_dir)
