import importlib
import numpy as np
import io
import os
import posixpath
import random
import re
import subprocess
import time
import torch
import torchaudio
import webdataset as wds

from aeiou.core import is_silence
from os import path
from pedalboard.io import AudioFile
from torchaudio import transforms as T
from typing import Optional, Callable, List

from .utils import Stereo, Mono, PhaseFlipper, PadCrop_Normalized_T

AUDIO_KEYS = ("flac", "wav", "mp3", "m4a", "ogg", "opus")

# fast_scandir implementation by Scott Hawley originally in https://github.com/zqevans/audio-diffusion/blob/main/dataset/dataset.py

def fast_scandir(
    dir:str,  # top-level directory at which to begin scanning
    ext:list,  # list of allowed file extensions,
    #max_size = 1 * 1000 * 1000 * 1000 # Only files < 1 GB
    ):
    "very fast `glob` alternative. from https://stackoverflow.com/a/59803793/4259243"
    subfolders, files = [], []
    ext = ['.'+x if x[0]!='.' else x for x in ext]  # add starting period to extensions if needed
    try: # hope to avoid 'permission denied' by this try
        for f in os.scandir(dir):
            try: # 'hope to avoid too many levels of symbolic links' error
                if f.is_dir():
                    subfolders.append(f.path)
                elif f.is_file():
                    file_ext = os.path.splitext(f.name)[1].lower()
                    is_hidden = os.path.basename(f.path).startswith(".")

                    if file_ext in ext and not is_hidden:
                        files.append(f.path)
            except:
                pass 
    except:
        pass

    for dir in list(subfolders):
        sf, f = fast_scandir(dir, ext)
        subfolders.extend(sf)
        files.extend(f)
    return subfolders, files

def keyword_scandir(
    dir: str,  # top-level directory at which to begin scanning
    ext: list,  # list of allowed file extensions
    keywords: list,  # list of keywords to search for in the file name
):
    "very fast `glob` alternative. from https://stackoverflow.com/a/59803793/4259243"
    subfolders, files = [], []
    # make keywords case insensitive
    keywords = [keyword.lower() for keyword in keywords]
    # add starting period to extensions if needed
    ext = ['.'+x if x[0] != '.' else x for x in ext]
    banned_words = ["paxheader", "__macosx"]
    try:  # hope to avoid 'permission denied' by this try
        for f in os.scandir(dir):
            try:  # 'hope to avoid too many levels of symbolic links' error
                if f.is_dir():
                    subfolders.append(f.path)
                elif f.is_file():
                    is_hidden = f.name.split("/")[-1][0] == '.'
                    has_ext = os.path.splitext(f.name)[1].lower() in ext
                    name_lower = f.name.lower()
                    has_keyword = any(
                        [keyword in name_lower for keyword in keywords])
                    has_banned = any(
                        [banned_word in name_lower for banned_word in banned_words])
                    if has_ext and has_keyword and not has_banned and not is_hidden and not os.path.basename(f.path).startswith("._"):
                        files.append(f.path)
            except:
                pass
    except:
        pass

    for dir in list(subfolders):
        sf, f = keyword_scandir(dir, ext, keywords)
        subfolders.extend(sf)
        files.extend(f)
    return subfolders, files

def get_audio_filenames(
    paths: list,  # directories in which to search
    keywords=None,
    exts=['.wav', '.mp3', '.flac', '.ogg', '.aif', '.opus']
):
    "recursively get a list of audio filenames"
    filenames = []
    if type(paths) is str:
        paths = [paths]
    for path in paths:               # get a list of relevant filenames
        if keywords is not None:
            subfolders, files = keyword_scandir(path, exts, keywords)
        else:
            subfolders, files = fast_scandir(path, exts)
        filenames.extend(files)
    return filenames

class SampleDataset(torch.utils.data.Dataset):
    def __init__(
        self, 
        paths, 
        sample_size=65536, 
        sample_rate=48000, 
        keywords=None, 
        relpath=None, 
        random_crop=True,
        force_channels="stereo",
        custom_metadata_fn: Optional[Callable[[str], str]] = None
    ):
        super().__init__()
        self.filenames = []
        self.relpath = relpath

        self.augs = torch.nn.Sequential(
            PhaseFlipper(),
        )

        self.pad_crop = PadCrop_Normalized_T(sample_size, sample_rate, randomize=random_crop)

        self.force_channels = force_channels

        self.encoding = torch.nn.Sequential(
            Stereo() if self.force_channels == "stereo" else torch.nn.Identity(),
            Mono() if self.force_channels == "mono" else torch.nn.Identity(),
        )

        self.filenames = get_audio_filenames(paths, keywords)

        print(f'Found {len(self.filenames)} files')

        self.sr = sample_rate

        self.custom_metadata_fn = custom_metadata_fn

    def load_file(self, filename):
        ext = filename.split(".")[-1]

        if ext == "mp3":
            with AudioFile(filename) as f:
                audio = f.read(f.frames)
                audio = torch.from_numpy(audio)
                in_sr = f.samplerate
        else:
            audio, in_sr = torchaudio.load(filename, format=ext)

        if in_sr != self.sr:
            resample_tf = T.Resample(in_sr, self.sr)
            audio = resample_tf(audio)

        return audio

    def __len__(self):
        return len(self.filenames)

    def __getitem__(self, idx):
        audio_filename = self.filenames[idx]
        try:
            start_time = time.time()
            audio = self.load_file(audio_filename)

            audio, t_start, t_end, seconds_start, seconds_total, padding_mask = self.pad_crop(audio)

            # Run augmentations on this sample (including random crop)
            if self.augs is not None:
                audio = self.augs(audio)

            audio = audio.clamp(-1, 1)

            # Encode the file to assist in prediction
            if self.encoding is not None:
                audio = self.encoding(audio)

            info = {}

            info["path"] = audio_filename

            if self.relpath is not None:
                info["relpath"] = path.relpath(audio_filename, self.relpath)

            info["timestamps"] = (t_start, t_end)
            info["seconds_start"] = seconds_start
            info["seconds_total"] = seconds_total
            info["padding_mask"] = padding_mask

            end_time = time.time()

            info["load_time"] = end_time - start_time

            if self.custom_metadata_fn is not None:
                custom_metadata = self.custom_metadata_fn(info, audio)
                info.update(custom_metadata)

                if "__reject__" in info and info["__reject__"]:
                    return self[random.randrange(len(self))]

            return (audio, info)
        except Exception as e:
            print(f'Couldn\'t load file {audio_filename}: {e}')
            return self[random.randrange(len(self))]

def group_by_keys(data, keys=wds.tariterators.base_plus_ext, lcase=True, suffixes=None, handler=None):
    """Return function over iterator that groups key, value pairs into samples.
    :param keys: function that splits the key into key and extension (base_plus_ext)
    :param lcase: convert suffixes to lower case (Default value = True)
    """
    current_sample = None
    for filesample in data:
        assert isinstance(filesample, dict)
        fname, value = filesample["fname"], filesample["data"]
        prefix, suffix = keys(fname)
        if wds.tariterators.trace:
            print(
                prefix,
                suffix,
                current_sample.keys() if isinstance(current_sample, dict) else None,
            )
        if prefix is None:
            continue
        if lcase:
            suffix = suffix.lower()
        if current_sample is None or prefix != current_sample["__key__"]:
            if wds.tariterators.valid_sample(current_sample):
                yield current_sample
            current_sample = dict(__key__=prefix, __url__=filesample["__url__"])
        if suffix in current_sample:
            print(f"{fname}: duplicate file name in tar file {suffix} {current_sample.keys()}")
        if suffixes is None or suffix in suffixes:
            current_sample[suffix] = value
    if wds.tariterators.valid_sample(current_sample):
        yield current_sample

wds.tariterators.group_by_keys = group_by_keys

# S3 code and WDS preprocessing code based on implementation by Scott Hawley originally in https://github.com/zqevans/audio-diffusion/blob/main/dataset/dataset.py

def get_s3_contents(dataset_path, s3_url_prefix=None, filter='', recursive=True, debug=False, profile=None):
    """
    Returns a list of full S3 paths to files in a given S3 bucket and directory path.
    """
    # Ensure dataset_path ends with a trailing slash
    if dataset_path != '' and not dataset_path.endswith('/'):
        dataset_path += '/'
    # Use posixpath to construct the S3 URL path
    bucket_path = posixpath.join(s3_url_prefix or '', dataset_path)
    # Construct the `aws s3 ls` command
    cmd = ['aws', 's3', 'ls', bucket_path]

    if profile is not None:
        cmd.extend(['--profile', profile])

    if recursive:
        # Add the --recursive flag if requested
        cmd.append('--recursive')
    
    # Run the `aws s3 ls` command and capture the output
    run_ls = subprocess.run(cmd, capture_output=True, check=True)
    # Split the output into lines and strip whitespace from each line
    contents = run_ls.stdout.decode('utf-8').split('\n')
    contents = [x.strip() for x in contents if x]
    # Remove the timestamp from lines that begin with a timestamp
    contents = [re.sub(r'^\S+\s+\S+\s+\d+\s+', '', x)
                if re.match(r'^\S+\s+\S+\s+\d+\s+', x) else x for x in contents]
    # Construct a full S3 path for each file in the contents list
    contents = [posixpath.join(s3_url_prefix or '', x)
                for x in contents if not x.endswith('/')]
    # Apply the filter, if specified
    if filter:
        contents = [x for x in contents if filter in x]
    # Remove redundant directory names in the S3 URL
    if recursive:
        # Get the main directory name from the S3 URL
        main_dir = "/".join(bucket_path.split('/')[3:])
        # Remove the redundant directory names from each file path
        contents = [x.replace(f'{main_dir}', '').replace(
            '//', '/') for x in contents]
    # Print debugging information, if requested
    if debug:
        print("contents = \n", contents)
    # Return the list of S3 paths to files
    return contents


def get_all_s3_urls(
    names=[],           # list of all valid [LAION AudioDataset] dataset names
    # list of subsets you want from those datasets, e.g. ['train','valid']
    subsets=[''],
    s3_url_prefix=None,  # prefix for those dataset names
    recursive=True,     # recursively list all tar files in all subdirs
    filter_str='tar',   # only grab files with this substring
    # print debugging info -- note: info displayed likely to change at dev's whims
    debug=False,
    profiles={},        # dictionary of profiles for each item in names, e.g. {'dataset1': 'profile1', 'dataset2': 'profile2'}
):
    "get urls of shards (tar files) for multiple datasets in one s3 bucket"
    urls = []
    for name in names:
        # If s3_url_prefix is not specified, assume the full S3 path is included in each element of the names list
        if s3_url_prefix is None:
            contents_str = name
        else:
            # Construct the S3 path using the s3_url_prefix and the current name value
            contents_str = posixpath.join(s3_url_prefix, name)
        if debug:
            print(f"get_all_s3_urls: {contents_str}:")
        for subset in subsets:
            subset_str = posixpath.join(contents_str, subset)
            if debug:
                print(f"subset_str = {subset_str}")
            # Get the list of tar files in the current subset directory
            profile = profiles.get(name, None)
            tar_list = get_s3_contents(
                subset_str, s3_url_prefix=None, recursive=recursive, filter=filter_str, debug=debug, profile=profile)
            for tar in tar_list:
                # Escape spaces and parentheses in the tar filename for use in the shell command
                tar = tar.replace(" ", "\ ").replace(
                    "(", "\(").replace(")", "\)")
                # Construct the S3 path to the current tar file
                s3_path = posixpath.join(name, subset, tar) + " -"
                # Construct the AWS CLI command to download the current tar file
                if s3_url_prefix is None:
                    request_str = f"pipe:aws s3 --cli-connect-timeout 0 cp {s3_path}"
                else:
                    request_str = f"pipe:aws s3 --cli-connect-timeout 0 cp {posixpath.join(s3_url_prefix, s3_path)}"
                if profiles.get(name):
                    request_str += f" --profile {profiles.get(name)}"
                if debug:
                    print("request_str = ", request_str)
                # Add the constructed URL to the list of URLs
                urls.append(request_str)
    return urls


def log_and_continue(exn):
    """Call in an exception handler to ignore any exception, isssue a warning, and continue."""
    print(f"Handling webdataset error ({repr(exn)}). Ignoring.")
    return True


def is_valid_sample(sample):
    has_json = "json" in sample
    has_audio = "audio" in sample
    is_silent = is_silence(sample["audio"])
    is_rejected = "__reject__" in sample["json"] and sample["json"]["__reject__"]

    return has_json and has_audio and not is_silent and not is_rejected

class S3DatasetConfig:
    def __init__(
        self,
        id: str,
        s3_path: str,
        custom_metadata_fn: Optional[Callable[[str], str]] = None,
        profile: Optional[str] = None,
    ):
        self.id = id
        self.s3_path = s3_path
        self.custom_metadata_fn = custom_metadata_fn
        self.profile = profile
        self.urls = []

    def load_data_urls(self):
        self.urls = get_all_s3_urls(
            names=[self.s3_path],
            s3_url_prefix=None,
            recursive=True,
            profiles={self.s3_path: self.profile} if self.profile else {},
        )

        return self.urls

def audio_decoder(key, value):
    # Get file extension from key
    ext = key.split(".")[-1]

    if ext in AUDIO_KEYS:
        return torchaudio.load(io.BytesIO(value))
    else:
        return None

def collation_fn(samples):
        batched = list(zip(*samples))
        result = []
        for b in batched:
            if isinstance(b[0], (int, float)):
                b = np.array(b)
            elif isinstance(b[0], torch.Tensor):
                b = torch.stack(b)
            elif isinstance(b[0], np.ndarray):
                b = np.array(b)
            else:
                b = b
            result.append(b)
        return result

class S3WebDataLoader():
    def __init__(
        self,
        datasets: List[S3DatasetConfig],
        batch_size,
        sample_size,
        sample_rate=48000,
        num_workers=8,
        epoch_steps=1000,
        random_crop=True,
        force_channels="stereo",
        augment_phase=True,
        **data_loader_kwargs
    ):

        self.datasets = datasets

        self.sample_size = sample_size
        self.sample_rate = sample_rate
        self.random_crop = random_crop
        self.force_channels = force_channels
        self.augment_phase = augment_phase

        urls = [dataset.load_data_urls() for dataset in datasets]

        # Flatten the list of lists of URLs
        urls = [url for dataset_urls in urls for url in dataset_urls]

        self.dataset = wds.DataPipeline(
            wds.ResampledShards(urls),
            wds.tarfile_to_samples(handler=log_and_continue),
            wds.decode(audio_decoder, handler=log_and_continue),
            wds.map(self.wds_preprocess, handler=log_and_continue),
            wds.select(is_valid_sample),
            wds.to_tuple("audio", "json", handler=log_and_continue),
            wds.batched(batch_size, partial=False, collation_fn=collation_fn),
        ).with_epoch(epoch_steps//num_workers if num_workers > 0 else epoch_steps)

        self.data_loader = wds.WebLoader(self.dataset, num_workers=num_workers, **data_loader_kwargs)

    def wds_preprocess(self, sample):

        found_key, rewrite_key = '', ''
        for k, v in sample.items():  # print the all entries in dict
            for akey in AUDIO_KEYS:
                if k.endswith(akey):
                    # to rename long/weird key with its simpler counterpart
                    found_key, rewrite_key = k, akey
                    break
            if '' != found_key:
                break
        if '' == found_key:  # got no audio!
            return None  # try returning None to tell WebDataset to skip this one

        audio, in_sr = sample[found_key]
        if in_sr != self.sample_rate:
            resample_tf = T.Resample(in_sr, self.sample_rate)
            audio = resample_tf(audio)

        if self.sample_size is not None:
            # Pad/crop and get the relative timestamp
            pad_crop = PadCrop_Normalized_T(
                self.sample_size, randomize=self.random_crop, sample_rate=self.sample_rate)
            audio, t_start, t_end, seconds_start, seconds_total, padding_mask = pad_crop(
                audio)
            sample["json"]["seconds_start"] = seconds_start
            sample["json"]["seconds_total"] = seconds_total
            sample["json"]["padding_mask"] = padding_mask
        else:
            t_start, t_end = 0, 1

        # Check if audio is length zero, initialize to a single zero if so
        if audio.shape[-1] == 0:
            audio = torch.zeros(1, 1)

        # Make the audio stereo and augment by randomly inverting phase
        augs = torch.nn.Sequential(
            Stereo() if self.force_channels == "stereo" else torch.nn.Identity(),
            Mono() if self.force_channels == "mono" else torch.nn.Identity(),
            PhaseFlipper() if self.augment_phase else torch.nn.Identity()
        )

        audio = augs(audio)

        sample["json"]["timestamps"] = (t_start, t_end)

        if "text" in sample["json"]:
            sample["json"]["prompt"] = sample["json"]["text"]

        # Check for custom metadata functions
        for dataset in self.datasets:
            if dataset.custom_metadata_fn is None:
                continue
        
            if dataset.s3_path in sample["__url__"]:
                custom_metadata = dataset.custom_metadata_fn(sample["json"], audio)
                sample["json"].update(custom_metadata)

        if found_key != rewrite_key:   # rename long/weird key with its simpler counterpart
            del sample[found_key]

        sample["audio"] = audio

        # Add audio to the metadata as well for conditioning
        sample["json"]["audio"] = audio
        
        return sample

def create_dataloader_from_config(dataset_config, batch_size, sample_size, sample_rate, audio_channels=2, num_workers=4):

    dataset_type = dataset_config.get("dataset_type", None)

    assert dataset_type is not None, "Dataset type must be specified in dataset config"

    if audio_channels == 1:
        force_channels = "mono"
    else:
        force_channels = "stereo"

    if dataset_type == "audio_dir":

        audio_dir_configs = dataset_config.get("datasets", None)

        assert audio_dir_configs is not None, "Directory configuration must be specified in datasets[\"dataset\"]"

        training_dirs = []

        custom_metadata_fn = None
        custom_metadata_module_path = dataset_config.get("custom_metadata_module", None)

        if custom_metadata_module_path is not None:
            spec = importlib.util.spec_from_file_location("metadata_module", custom_metadata_module_path)
            metadata_module = importlib.util.module_from_spec(spec)
            spec.loader.exec_module(metadata_module)                

            custom_metadata_fn = metadata_module.get_custom_metadata

        for audio_dir_config in audio_dir_configs:
            audio_dir_path = audio_dir_config.get("path", None)
            assert audio_dir_path is not None, "Path must be set for local audio directory configuration"
            training_dirs.append(audio_dir_path)

        train_set = SampleDataset(
            training_dirs,
            sample_rate=sample_rate,
            sample_size=sample_size,
            random_crop=dataset_config.get("random_crop", True),
            force_channels=force_channels,
            custom_metadata_fn=custom_metadata_fn,
            relpath=training_dirs[0] #TODO: Make relpath relative to each training dir
        )

        return torch.utils.data.DataLoader(train_set, batch_size, shuffle=True,
                                num_workers=num_workers, persistent_workers=True, pin_memory=True, drop_last=True, collate_fn=collation_fn)

    elif dataset_type == "s3":
        dataset_configs = []

        for s3_config in dataset_config["datasets"]:

            custom_metadata_fn = None
            custom_metadata_module_path = s3_config.get("custom_metadata_module", None)

            if custom_metadata_module_path is not None:
                spec = importlib.util.spec_from_file_location("metadata_module", custom_metadata_module_path)
                metadata_module = importlib.util.module_from_spec(spec)
                spec.loader.exec_module(metadata_module)                

                custom_metadata_fn = metadata_module.get_custom_metadata

            dataset_configs.append(
                S3DatasetConfig(
                    id=s3_config["id"],
                    s3_path=s3_config["s3_path"],
                    custom_metadata_fn=custom_metadata_fn,
                    profile=s3_config.get("profile", None),
                )
            )

        return S3WebDataLoader(
            dataset_configs,
            sample_rate=sample_rate,
            sample_size=sample_size,
            batch_size=batch_size,
            random_crop=dataset_config.get("random_crop", True),
            num_workers=num_workers,
            persistent_workers=True,
            force_channels=force_channels,
            epoch_steps=dataset_config.get("epoch_steps", 2000),
        ).data_loader