import { AxesHelper, Box3, Cache, Object3D, Vector2, Vector3 } from "three";
import type { GLTF } from "three/examples/jsm/loaders/GLTFLoader.js";

import { isDevEnvironment } from "../engine/debug/index.js";
import { AnimationUtils } from "../engine/engine_animation.js";
import { addComponent } from "../engine/engine_components.js";
import { Context } from "../engine/engine_context.js";
import { destroy } from "../engine/engine_gameobject.js";
import { Gizmos } from "../engine/engine_gizmos.js";
import { getLoader } from "../engine/engine_gltf.js";
import { BlobStorage } from "../engine/engine_networking_blob.js";
import { PreviewHelper } from "../engine/engine_networking_files.js";
import { generateSeed, InstantiateIdProvider } from "../engine/engine_networking_instantiate.js";
import { serializable } from "../engine/engine_serialization_decorator.js";
import { fitObjectIntoVolume, getBoundingBox, placeOnSurface } from "../engine/engine_three_utils.js";
import { IGameObject, Model, Vec3 } from "../engine/engine_types.js";
import { getParam, setParamWithoutReload } from "../engine/engine_utils.js";
import { Animation } from "./Animation.js";
import { Behaviour } from "./Component.js";
import { EventList } from "./EventList.js";

/**
 * Debug mode can be enabled with the URL parameter `?debugdroplistener`, which
 * logs additional information during drag and drop events and visualizes hit points.
 */
const debug = getParam("debugdroplistener");

/**
 * Events dispatched by the DropListener component
 * @enum {string}
 */
export enum DropListenerEvents {
    /**
     * Dispatched when a file is dropped into the scene. The detail of the event is the {@link File} that was dropped.
     * The event is called once for each dropped file.
     */
    FileDropped = "file-dropped",
    /**
     * Dispatched when a new object is added to the scene. The detail of the event contains {@link DropListenerOnDropArguments} for the content that was added.
     */
    ObjectAdded = "object-added",
}

/**
 * Context information for a drop operation
 */
declare type DropContext = {
    /** Position where the file was dropped in screen coordinates */
    screenposition: Vector2;
    /** URL of the dropped content, if applicable */
    url?: string,
    /** File object of the dropped content, if applicable */
    file?: File;
    /** 3D position where the content should be placed */
    point?: Vec3;
    /** Size dimensions for the content */
    size?: Vec3;
}


/**  
 * Network event arguments passed between clients when using the DropListener with networking
 */
export declare type DropListenerNetworkEventArguments = {
    /** Unique identifier of the sender */
    guid: string,
    /** Name of the dropped object */
    name: string,
    /** URL or array of URLs to the dropped content */
    url: string | string[],
    /** Worldspace point where the object was placed in the scene */
    point: Vec3;
    /** Bounding box size */
    size: Vec3;
    /** MD5 hash of the content for verification */
    contentMD5: string;
}

/**
 * Arguments provided to handlers when an object is dropped or added to the scene
 */
export declare type DropListenerOnDropArguments = {
    /** The DropListener component that processed the drop event */
    sender: DropListener,
    /** The root object added to the scene */
    object: Object3D,
    /** The complete model with all associated data */
    model: Model,
    /** MD5 hash of the content for verification */
    contentMD5: string;
    /** The original dropped URL or File object */
    dropped: URL | File | undefined;
}

/**
 * CustomEvent dispatched when an object is added to the scene via the DropListener
 */
class DropListenerAddedEvent<T extends DropListenerOnDropArguments> extends CustomEvent<T> {
    /**
     * Creates a new added event with the provided details
     * @param detail Information about the added object
     */
    constructor(detail: T) {
        super(DropListenerEvents.ObjectAdded, { detail });
    }
}

/**
 * Key name used for blob storage parameters
 */
const blobKeyName = "blob";

/** The DropListener component is used to listen for drag and drop events in the browser and add the dropped files to the scene  
 * It can be used to allow users to drag and drop glTF files into the scene to add new objects.  
 * 
 * If {@link useNetworking} is enabled, the DropListener will automatically synchronize dropped files to other connected clients.
 * Enable {@link fitIntoVolume} to automatically scale dropped objects to fit within the volume defined by {@link fitVolumeSize}.
 * 
 * The following events are dispatched by the DropListener:
 * - **object-added** - dispatched when a new object is added to the scene
 * - **file-dropped** - dispatched when a file is dropped into the scene
 * 
 * @example
 * ```typescript
 * import { DropListener, DropListenerEvents } from "@needle-tools/engine";
 * 
 * const dropListener = new DropListener();
 * 
 * gameObject.addComponent(dropListener);
 * dropListener.on(DropListenerEvents.FileDropped, (evt) => {
 *   console.log("File dropped", evt.detail);
 *   const file = evt.detail as File;
 * });
 * 
 * dropListener.on(DropListenerEvents.ObjectAdded, (evt) => {
 *    console.log("Object added", evt.detail);
 *    const gltf = evt.detail as GLTF;
 * });
 * ```
 * 
 * @category Asset Management
 * @group Components
 */
export class DropListener extends Behaviour {

    /**
     * When enabled, the DropListener will automatically synchronize dropped files to other connected clients.
     * When a file is dropped locally, it will be uploaded to blob storage and the URL will be shared with other clients.
     */
    @serializable()
    useNetworking: boolean = true;

    /**
     * When assigned, the DropListener will only accept files that are dropped on this specific object.
     * This allows creating designated drop zones in your scene.
     */
    @serializable(Object3D)
    dropArea?: Object3D;

    /**
     * When enabled, dropped objects will be automatically scaled to fit within the volume defined by fitVolumeSize.
     * Useful for ensuring dropped models appear at an appropriate scale.
     * @default false
     */
    @serializable()
    fitIntoVolume: boolean = false;

    /**
     * Defines the dimensions of the volume that dropped objects will be scaled to fit within.
     * Only used when fitIntoVolume is enabled.
     */
    @serializable(Vector3)
    fitVolumeSize = new Vector3(1, 1, 1);

    /** 
     * When enabled, dropped objects will be positioned at the point where the cursor hit the scene.
     * When disabled, objects will be placed at the origin of the DropListener.
     * @default true
     */
    @serializable()
    placeAtHitPosition: boolean = true;

    /**
     * Event list that gets invoked after a file has been successfully added to the scene.
     * Receives {@link DropListenerOnDropArguments} containing the added object and related information.
     * @event object-added
     * @example
     * ```typescript
     * dropListener.onDropped.addEventListener((evt) => {
     *  console.log("Object added", evt.model);
     * });
     */
    @serializable(EventList)
    onDropped: EventList<DropListenerOnDropArguments> = new EventList();

    /** @internal */
    onEnable(): void {
        this.context.renderer.domElement.addEventListener("dragover", this.onDrag);
        this.context.renderer.domElement.addEventListener("drop", this.onDrop);
        window.addEventListener("paste", this.handlePaste);
        this.context.connection.beginListen("droplistener", this.onNetworkEvent)
    }
    /** @internal */
    onDisable(): void {
        this.context.renderer.domElement.removeEventListener("dragover", this.onDrag);
        this.context.renderer.domElement.removeEventListener("drop", this.onDrop);
        window.removeEventListener("paste", this.handlePaste);
        this.context.connection.stopListen("droplistener", this.onNetworkEvent);
    }

    /**
     * Loads a file from the given URL and adds it to the scene.
     */
    loadFromURL(url: string, data?: { point?: Vec3, size?: Vec3 }) {
        this.addFromUrl(url, { screenposition: new Vector2(), point: data?.point, size: data?.size, }, true);
    }

    /**
     * Forgets all previously added objects.     
     * The droplistener will then not be able to remove previously added objects.
     */
    forgetObjects() {
        this.removePreviouslyAddedObjects(false);
    }

    /**
     * Handles network events received from other clients containing information about dropped objects
     * @param evt Network event data containing object information, position, and content URL
     */
    private onNetworkEvent = (evt: DropListenerNetworkEventArguments) => {
        if (!this.useNetworking) {
            if (debug) console.debug("[DropListener] Ignoring networked event because networking is disabled", evt);
            return;
        }
        if (evt.guid?.startsWith(this.guid)) {
            const url = evt.url;
            console.debug("[DropListener] Received networked event", evt);
            if (url) {
                if (Array.isArray(url)) {
                    for (const _url of url) {
                        this.addFromUrl(_url, { screenposition: new Vector2(), point: evt.point, size: evt.size, }, true);
                    }
                }
                else {
                    this.addFromUrl(url, { screenposition: new Vector2(), point: evt.point, size: evt.size }, true);
                }
            }
        }
    }

    /**
     * Handles clipboard paste events and processes them as potential URL drops
     * Only URLs are processed by this handler, and only when editing is allowed
     * @param evt The paste event
     */
    private handlePaste = (evt: Event) => {
        if (this.context.connection.allowEditing === false) return;
        if (evt.defaultPrevented) return;
        const clipboard = navigator.clipboard;
        clipboard.readText()
            .then(value => {
                if (value) {
                    const isUrl = value.startsWith("http") || value.startsWith("https") || value.startsWith("blob");
                    if (isUrl) {
                        const ctx = { screenposition: new Vector2(this.context.input.mousePosition.x, this.context.input.mousePosition.y) };
                        if (this.testIfIsInDropArea(ctx))
                            this.addFromUrl(value, ctx, false);
                    }
                }
            })
            .catch(console.warn);
    }

    /**
     * Handles drag events over the renderer's canvas
     * Prevents default behavior to enable drop events
     * @param evt The drag event
     */
    private onDrag = (evt: DragEvent) => {
        if (this.context.connection.allowEditing === false) return;
        // necessary to get drop event
        evt.preventDefault();
    }

    /**
     * Processes drop events to add files to the scene
     * Handles both file drops and text/URL drops
     * @param evt The drop event
     */
    private onDrop = async (evt: DragEvent) => {
        if (this.context.connection.allowEditing === false) return;

        if (debug) console.log(evt);
        if (!evt?.dataTransfer) return;
        // If the event is marked as handled for droplisteners then ignore it
        if (evt["droplistener:handled"]) return;
        evt.preventDefault();

        const ctx: DropContext = { screenposition: new Vector2(evt.offsetX, evt.offsetY) };

        if (this.dropArea) {
            const res = this.testIfIsInDropArea(ctx);
            if (res === false) return;
        }

        // Don't stop propagation because this will break e.g. the RemoteSkybox drop
        // evt.stopImmediatePropagation();
        // Mark the event handled for droplisteners
        evt["droplistener:handled"] = true;

        const items = evt.dataTransfer.items;
        if (!items) return;

        const files: File[] = [];
        for (const ite in items) {
            const it = items[ite];
            if (it.kind === "file") {
                const file = it.getAsFile();
                if (!file) continue;
                files.push(file);
            }
            else if (it.kind === "string" && it.type == "text/plain") {
                it.getAsString(str => {
                    this.addFromUrl(str, ctx, false);
                });
            }
        }
        if (files.length > 0) {
            await this.addDroppedFiles(files, ctx);
        }
    }

    /**
     * Processes a dropped or pasted URL and tries to load it as a 3D model
     * Handles special cases like GitHub URLs and Polyhaven asset URLs
     * @param url The URL to process
     * @param ctx Context information about where the drop occurred
     * @param isRemote Whether this URL was shared from a remote client
     * @returns The added object or null if loading failed
     */
    private async addFromUrl(url: string, ctx: DropContext, isRemote: boolean) {
        if (debug) console.log("dropped url", url);

        try {
            if (url.startsWith("https://github.com/")) {
                // make raw.githubusercontent.com url
                const parts = url.split("/");
                const user = parts[3];
                const repo = parts[4];
                const branch = parts[6];
                const path = parts.slice(7).join("/");
                url = `https://raw.githubusercontent.com/${user}/${repo}/${branch}/${path}`;
            }
            else if (url.startsWith("https://polyhaven.com/a")) {
                url = tryResolvePolyhavenAssetUrl(url);
            }
            if (!url) return null;

            // Ignore dropped images
            const lowercaseUrl = url.toLowerCase();
            if (lowercaseUrl.endsWith(".hdr") || lowercaseUrl.endsWith(".hdri") || lowercaseUrl.endsWith(".exr") || lowercaseUrl.endsWith(".png") || lowercaseUrl.endsWith(".jpg") || lowercaseUrl.endsWith(".jpeg")) {
                return null;
            }

            // TODO: if the URL is invalid this will become a problem
            this.removePreviouslyAddedObjects();
            // const binary = await fetch(url).then(res => res.arrayBuffer());
            const res = await FileHelper.loadFileFromURL(new URL(url), {
                guid: this.guid,
                context: this.context,
                parent: this.gameObject,
                point: ctx.point,
                size: ctx.size,
            });
            if (res && this._addedObjects.length <= 0) {
                ctx.url = url;
                const obj = this.addObject(res, ctx, isRemote);
                return obj;
            }
        }
        catch (_) {
            console.warn("String is not a valid URL", url);
        }

        return null;
    }

    private _abort: AbortController | null = null;

    /**
     * Processes dropped files, loads them as 3D models, and handles networking if enabled
     * Creates an abort controller to cancel previous uploads if new files are dropped
     * @param fileList Array of dropped files
     * @param ctx Context information about where the drop occurred
     */
    private async addDroppedFiles(fileList: Array<File>, ctx: DropContext) {
        if (debug) console.log("Add files", fileList)
        if (!Array.isArray(fileList)) return;
        if (!fileList.length) return;

        this.deleteDropEvent();
        this.removePreviouslyAddedObjects();
        setParamWithoutReload(blobKeyName, null);

        // Create an abort controller for the current drop operation
        this._abort?.abort("New files dropped");
        this._abort = new AbortController();

        for (const file of fileList) {
            if (!file) continue;
            console.debug("Load file " + file.name);
            const res = await FileHelper.loadFile(file, this.context, { guid: this.guid });
            if (res) {
                this.dispatchEvent(new CustomEvent(DropListenerEvents.FileDropped, { detail: file }));
                ctx.file = file;
                const obj = this.addObject(res, ctx, false);

                // handle uploading the dropped object and networking the event
                if (obj && this.context.connection.isConnected && this.useNetworking) {
                    console.debug("Uploading dropped file to blob storage");
                    BlobStorage.upload(file, { abort: this._abort?.signal, })
                        .then(upload => {
                            // check if the upload was successful and if the object should still be visible
                            if (upload?.download_url && this._addedObjects.includes(obj)) {
                                // setParamWithoutReload(blobKeyName, upload.key);
                                this.sendDropEvent(upload.download_url, obj, res.contentMD5);
                            }
                        })
                        .catch(console.warn);
                }

                // we currently only support dropping one file
                break;
            }
        }
    }

    /** Previously added objects */
    private readonly _addedObjects = new Array<Object3D>();
    private readonly _addedModels = new Array<Model>();

    /**
     * Removes all previously added objects from the scene
     * @param doDestroy When true, destroys the objects; when false, just clears the references
     */
    private removePreviouslyAddedObjects(doDestroy: boolean = true) {
        if (doDestroy) {
            for (const prev of this._addedObjects) {
                if (prev.parent === this.gameObject) {
                    destroy(prev, true, true);
                }
            }
        }
        this._addedObjects.length = 0;
        this._addedModels.length = 0;
    }

    /**
     * Adds a loaded model to the scene with proper positioning and scaling.
     * Handles placement based on component settings and raycasting.
     * If {@link fitIntoVolume} is enabled, the object will be scaled to fit within the volume defined by {@link fitVolumeSize}.
     * @param data The loaded model data and content hash
     * @param ctx Context information about where the drop occurred
     * @param isRemote Whether this object was shared from a remote client
     * @returns The added object or null if adding failed
     */
    private addObject(data: { model: Model, contentMD5: string }, ctx: DropContext, isRemote: boolean): Object3D | null {

        const { model, contentMD5 } = data;

        if (debug) console.log(`Dropped ${this.gameObject.name}`, model);
        if (!model?.scene) {
            console.warn("No object specified to add to scene", model);
            return null;
        }

        this.removePreviouslyAddedObjects();

        const obj = model.scene;

        // use attach to ignore the DropListener scale (e.g. if the parent object scale is not uniform)
        this.gameObject.attach(obj);
        obj.position.set(0, 0, 0);
        obj.quaternion.identity();

        this._addedObjects.push(obj);
        this._addedModels.push(model);

        const volume = new Box3().setFromCenterAndSize(new Vector3(0, this.fitVolumeSize.y * .5, 0).add(this.gameObject.worldPosition), this.fitVolumeSize);
        if (debug) Gizmos.DrawWireBox3(volume, 0x0000ff, 5);
        if (this.fitIntoVolume) {
            fitObjectIntoVolume(obj, volume, {
                position: !this.placeAtHitPosition
            });
        }

        if (this.placeAtHitPosition && ctx && ctx.screenposition) {
            obj.visible = false; // < don't raycast on the placed object
            const rc = this.context.physics.raycast({ screenPoint: this.context.input.convertScreenspaceToRaycastSpace(ctx.screenposition.clone()) });
            obj.visible = true;
            if (rc && rc.length > 0) {
                for (const hit of rc) {
                    const pos = hit.point.clone();
                    if (debug) console.log("Place object at hit", hit);
                    placeOnSurface(obj, pos);
                    break;
                }
            }
        }

        AnimationUtils.assignAnimationsFromFile(model, {
            createAnimationComponent: obj => addComponent(obj, Animation)
        });

        const evt = new DropListenerAddedEvent({
            sender: this,
            gltf: model,
            model: model,
            object: obj,
            contentMD5: contentMD5,
            dropped: ctx.file || (ctx.url ? new URL(ctx.url) : undefined),
        });
        this.dispatchEvent(evt);
        this.onDropped?.invoke(evt.detail);

        // send network event
        if (!isRemote && ctx.url?.startsWith("http") && this.context.connection.isConnected && obj) {
            this.sendDropEvent(ctx.url, obj, contentMD5);
        }

        return obj;
    }

    /**
     * Sends a network event to other clients about a dropped object
     * Only triggered when networking is enabled and the connection is established
     * @param url The URL to the content that was dropped
     * @param obj The object that was added to the scene
     * @param contentmd5 The content hash for verification
     */
    private async sendDropEvent(url: string, obj: Object3D, contentmd5: string) {
        if (!this.useNetworking) {
            if (debug) console.debug("[DropListener] Ignoring networked event because networking is disabled", url);
            return;
        }
        if (this.context.connection.isConnected) {
            console.debug("Sending drop event \"" + obj.name + "\"", url);
            const bounds = getBoundingBox([obj]);
            const evt: DropListenerNetworkEventArguments = {
                name: obj.name,
                guid: this.guid,
                url,
                point: obj.worldPosition.clone(),
                size: bounds.getSize(new Vector3()),
                contentMD5: contentmd5,
            };
            this.context.connection.send("droplistener", evt);
        }
    }

    /**
     * Deletes remote state for this DropListener's objects
     * Called when new files are dropped to clean up previous state
     */
    private deleteDropEvent() {
        this.context.connection.sendDeleteRemoteState(this.guid);
    }

    /**
     * Tests if a drop event occurred within the designated drop area if one is specified
     * @param ctx The drop context containing screen position information
     * @returns True if the drop is valid (either no drop area is set or the drop occurred inside it)
     */
    private testIfIsInDropArea(ctx: DropContext): boolean {
        if (this.dropArea) {
            const screenPoint = this.context.input.convertScreenspaceToRaycastSpace(ctx.screenposition.clone());
            const hits = this.context.physics.raycast({
                targets: [this.dropArea],
                screenPoint,
                recursive: true,
                testObject: obj => {
                    // Ignore hits on the already added objects, they don't count as part of the dropzone
                    if (this._addedObjects.includes(obj)) return false;
                    return true;
                }
            });
            if (!hits.length) {
                if (isDevEnvironment()) console.log(`Dropped outside of drop area for DropListener \"${this.name}\".`);
                return false;
            }
        }
        return true;
    }

}

/**
 * Attempts to convert a Polyhaven website URL to a direct glTF model download URL
 * @param urlStr The original Polyhaven URL
 * @returns The direct download URL for the glTF model if it's a valid Polyhaven asset URL, otherwise returns the original URL
 */
function tryResolvePolyhavenAssetUrl(urlStr: string) {
    if (!urlStr.startsWith("https://polyhaven.com/")) return urlStr;
    // Handle dropping polyhaven image url
    const baseUrl = "https://dl.polyhaven.org/file/ph-assets/Models/gltf/4k/";
    const url = new URL(urlStr);
    const path = url.pathname;
    const name = path.split("/").pop();
    const assetUrl = `${baseUrl}${name}/${name}_4k.gltf`;
    console.log("Resolved polyhaven asset url", urlStr, "→", assetUrl);
    // TODO: need to resolve textures properly
    return assetUrl;
}

/**
 * Helper namespace for loading files and models from various sources
 */
namespace FileHelper {

    /**
     * Loads and processes a File object into a 3D model
     * @param file The file to load (supported formats: gltf, glb, fbx, obj, usdz, vrm)
     * @param context The application context
     * @param args Additional arguments including a unique guid for instantiation
     * @returns Promise containing the loaded model and its content hash, or null if loading failed
     */
    export async function loadFile(file: File, context: Context, args: { guid: string }): Promise<{ model: Model, contentMD5: string } | null> {
        const name = file.name.toLowerCase();
        if (name.endsWith(".gltf") ||
            name.endsWith(".glb") ||
            name.endsWith(".fbx") ||
            name.endsWith(".obj") ||
            name.endsWith(".usdz") ||
            name.endsWith(".vrm") ||
            file.type === "model/gltf+json" ||
            file.type === "model/gltf-binary"
        ) {
            return new Promise((resolve, _reject) => {
                const reader = new FileReader()
                reader.readAsArrayBuffer(file);
                reader.onloadend = async (_ev: ProgressEvent<FileReader>) => {
                    const content = reader.result as ArrayBuffer;
                    // first load it locally
                    const seed = args.guid;
                    const prov = new InstantiateIdProvider(seed);
                    const model = await getLoader().parseSync(context, content, file.name, prov);
                    if (model) {
                        const hash = BlobStorage.hashMD5(content);
                        resolve({ model, contentMD5: hash });
                    }
                };
            });
        }
        else {
            console.warn("Unsupported file type: " + name, file.type)
        }

        return null;
    }

    /**
     * Loads a 3D model from a URL with progress visualization
     * @param url The URL to load the model from
     * @param args Arguments including context, parent object, and optional placement information
     * @returns Promise containing the loaded model and its content hash, or null if loading failed
     */
    export async function loadFileFromURL(url: URL, args: { guid: string, context: Context, parent: Object3D, point?: Vec3, size?: Vec3 }): Promise<{ model: Model, contentMD5: string } | null> {
        return new Promise(async (resolve, _reject) => {

            const prov = new InstantiateIdProvider(args.guid);
            const urlStr = url.toString();

            if (debug) Gizmos.DrawWireSphere(args.point!, .1, 0xff0000, 3);
            const preview = PreviewHelper.addPreview({
                guid: args.guid,
                parent: args.parent,
                position: args?.point,
                size: args?.size,
            });

            const model = await getLoader().loadSync(args.context, urlStr, urlStr, prov, prog => {
                preview.onProgress(prog.loaded / prog.total);
            }).catch(console.warn);

            if (model) {
                const binary = await fetch(urlStr).then(res => res.arrayBuffer());
                const hash = BlobStorage.hashMD5(binary);
                if (debug) setTimeout(() => PreviewHelper.removePreview(args.guid), 3000);
                else PreviewHelper.removePreview(args.guid);
                resolve({ model, contentMD5: hash });
            }
            else {
                if (debug) setTimeout(() => PreviewHelper.removePreview(args.guid), 3000);
                else PreviewHelper.removePreview(args.guid);
                console.warn("Unsupported file type: " + url.toString());
            }
        });
    }
}