import json
import os
import shutil
import warnings
from datetime import datetime
from pathlib import Path
from typing import Dict, List, Tuple
from uuid import uuid4

import gradio as gr
import numpy as np
from filelock import FileLock
from PIL.Image import Image


def setup(
    folder_path: str | Path | None = None,
    delete_button: bool = True,
    export_button: bool = True,
) -> None:
    user_history = _UserHistory()
    user_history.folder_path = _resolve_folder_path(folder_path)
    user_history.delete_button = delete_button
    user_history.export_button = export_button
    user_history.initialized = True


def render() -> None:
    user_history = _UserHistory()

    # initialize with default config
    if not user_history.initialized:
        print("Initializing user history with default config. Use `user_history.setup(...)` to customize.")
        setup()

    # deactivate if no persistent storage
    if user_history.folder_path is None:
        gr.Markdown(
            "User history is deactivated as no Persistent Storage volume has been found. Please contact the Space"
            " owner to either assign a [Persistent Storage](https://huggingface.co/docs/hub/spaces-storage) or set"
            " `folder_path` to a temporary folder."
        )
        return

    # Render user history tab
    gr.Markdown(
        "## Your past generations\n\n(Log in to keep a gallery of your previous generations."
        " Your history will be saved and available on your next visit.)"
    )
    with gr.Row():
        gr.LoginButton(min_width=250)
        gr.LogoutButton(min_width=250)
        refresh_button = gr.Button("Refresh", icon="./assets/icon_refresh.png")
        export_button = gr.Button("Export", icon="./assets/icon_download.png")
        delete_button = gr.Button("Delete history", icon="./assets/icon_delete.png")

    # "Export zip" row (hidden by default)
    with gr.Row():
        export_file = gr.File(file_count="single", file_types=[".zip"], label="Exported history", visible=False)

    # "Config deletion" row (hidden by default)
    with gr.Row():
        confirm_button = gr.Button("Confirm delete all history", variant="stop", visible=False)
        cancel_button = gr.Button("Cancel", visible=False)

    # Gallery
    gallery = gr.Gallery(
        label="Past images",
        show_label=True,
        elem_id="gallery",
        object_fit="contain",
        columns=5,
        height=600,
        preview=False,
        show_share_button=False,
        show_download_button=False,
    )
    gr.Markdown("Make sure to save your images from time to time, this gallery may be deleted in the future.")
    gallery.attach_load_event(_fetch_user_history, every=None)

    # Interactions
    refresh_button.click(fn=_fetch_user_history, inputs=[], outputs=[gallery], queue=False)
    export_button.click(fn=_export_user_history, inputs=[], outputs=[export_file], queue=False)

    # Taken from https://github.com/gradio-app/gradio/issues/3324#issuecomment-1446382045
    delete_button.click(
        lambda: [gr.update(visible=True), gr.update(visible=True)],
        outputs=[confirm_button, cancel_button],
        queue=False,
    )
    cancel_button.click(
        lambda: [gr.update(visible=False), gr.update(visible=False)],
        outputs=[confirm_button, cancel_button],
        queue=False,
    )
    confirm_button.click(_delete_user_history).then(
        lambda: [gr.update(visible=False), gr.update(visible=False)],
        outputs=[confirm_button, cancel_button],
        queue=False,
    )


def save_image(
    profile: gr.OAuthProfile | None,
    image: Image | np.ndarray | str | Path,
    label: str | None = None,
    metadata: Dict | None = None,
):
    # Ignore images from logged out users
    if profile is None:
        return
    username = profile["preferred_username"]

    # Ignore images if user history not used
    user_history = _UserHistory()
    if not user_history.initialized:
        warnings.warn(
            "User history is not set in Gradio demo. Saving image is ignored. You must use `user_history.render(...)`"
            " first."
        )
        return

    # Copy image to storage
    image_path = _copy_image(image, dst_folder=user_history._user_images_path(username))

    # Save new image + metadata
    if metadata is None:
        metadata = {}
    if "datetime" not in metadata:
        metadata["datetime"] = str(datetime.now())
    data = {"path": str(image_path), "label": label, "metadata": metadata}
    with user_history._user_lock(username):
        with user_history._user_jsonl_path(username).open("a") as f:
            f.write(json.dumps(data) + "\n")


#############
# Internals #
#############


class _UserHistory(object):
    _instance = None
    initialized: bool = False

    folder_path: Path | None
    delete_button: bool
    export_button: bool

    def __new__(cls):
        # Using singleton pattern => we don't want to expose an object (more complex to use) but still want to keep
        # state between `render` and `save_image` calls.
        if cls._instance is None:
            cls._instance = super(_UserHistory, cls).__new__(cls)
        return cls._instance

    def _user_path(self, username: str) -> Path:
        if self.folder_path is None:
            raise Exception("User history is deactivated.")
        path = self.folder_path / username
        path.mkdir(parents=True, exist_ok=True)
        return path

    def _user_lock(self, username: str) -> FileLock:
        """Ensure history is not corrupted if concurrent calls."""
        if self.folder_path is None:
            raise Exception("User history is deactivated.")
        return FileLock(self.folder_path / f"{username}.lock")  # lock outside of folder => better when exporting ZIP

    def _user_jsonl_path(self, username: str) -> Path:
        return self._user_path(username) / "history.jsonl"

    def _user_images_path(self, username: str) -> Path:
        path = self._user_path(username) / "images"
        path.mkdir(parents=True, exist_ok=True)
        return path


def _fetch_user_history(profile: gr.OAuthProfile | None) -> List[Tuple[str, str]]:
    """Return saved history for that user, if it exists."""
    # Cannot load history for logged out users
    if profile is None:
        return []
    username = profile["preferred_username"]

    user_history = _UserHistory()
    if not user_history.initialized:
        warnings.warn("User history is not set in Gradio demo. You must use `user_history.render(...)` first.")
        return []

    with user_history._user_lock(username):
        # No file => no history saved yet
        jsonl_path = user_history._user_jsonl_path(username)
        if not jsonl_path.is_file():
            return []

        # Read history
        images = []
        for line in jsonl_path.read_text().splitlines():
            data = json.loads(line)
            images.append((data["path"], data["label"] or ""))
        return list(reversed(images))


def _export_user_history(profile: gr.OAuthProfile | None) -> Dict | None:
    """Zip all history for that user, if it exists and return it as a downloadable file."""
    # Cannot load history for logged out users
    if profile is None:
        return None
    username = profile["preferred_username"]

    user_history = _UserHistory()
    if not user_history.initialized:
        warnings.warn("User history is not set in Gradio demo. You must use `user_history.render(...)` first.")
        return None

    # Zip history
    with user_history._user_lock(username):
        path = shutil.make_archive(
            str(_archives_path() / f"history_{username}"), "zip", user_history._user_path(username)
        )

    return gr.update(visible=True, value=path)


def _delete_user_history(profile: gr.OAuthProfile | None) -> None:
    """Delete all history for that user."""
    # Cannot load history for logged out users
    if profile is None:
        return
    username = profile["preferred_username"]

    user_history = _UserHistory()
    if not user_history.initialized:
        warnings.warn("User history is not set in Gradio demo. You must use `user_history.render(...)` first.")
        return

    with user_history._user_lock(username):
        shutil.rmtree(user_history._user_path(username))


####################
# Internal helpers #
####################


def _copy_image(image: Image | np.ndarray | str | Path, dst_folder: Path) -> Path:
    """Copy image to the images folder."""
    # Already a path => copy it
    if isinstance(image, str):
        image = Path(image)
    if isinstance(image, Path):
        dst = dst_folder / f"{uuid4().hex}_{Path(image).name}"  # keep file ext
        shutil.copyfile(image, dst)
        return dst

    # Still a Python object => serialize it
    if isinstance(image, np.ndarray):
        image = Image.fromarray(image)
    if isinstance(image, Image):
        dst = dst_folder / f"{uuid4().hex}.png"
        image.save(dst)
        return dst

    raise ValueError(f"Unsupported image type: {type(image)}")


def _resolve_folder_path(folder_path: str | Path | None) -> Path | None:
    if folder_path is not None:
        return Path(folder_path).expanduser().resolve()

    if os.getenv("SYSTEM") == "spaces":
        if os.path.exists("/data"):  # Persistent storage is enabled!
            return Path("/data") / "user_history"
        else:
            return None  # No persistent storage => no user history

    # Not in a Space => local folder
    return Path(__file__).parent / "user_history"


def _archives_path() -> Path:
    # Doesn't have to be on persistent storage as it's only used for download
    path = Path(__file__).parent / "_history_snapshots"
    path.mkdir(parents=True, exist_ok=True)
    return path