import {DocumentCodes, SdkVerifierType, SupportedLanguages} from '../generated/zenid-enums.generated.js';
import {EncodedImage, SdkWizardStep, UploadReadyData} from '../generated/zenid-types.generated.js';
import {WorkerCallAction, WorkerInitAction, WorkerResponse, WorkerResponseType, WorkerTerminateAction} from './worker-interfaces.js';
import {LogLevel, zenidLog} from '../zenid-log.js';

// For native function names
export enum NativeFunction {
    ProcessFrame = 'nativeProcessFrame',
    SetVisualizerVersion = 'nativeSetVisualizerVersion',
    InitOrRestart = 'nativeInitOrRestart',
    RestartWithPreviousSettings = 'nativeRestartWithPreviousSettings',
    GetRenderCommands = 'nativeGetRenderCommands',
    ReadyForFrame = 'nativeReadyForFrame',
    GetStateContainerJson = 'nativeGetStateContainerJson',
    GetFrameProcessingResolution = 'nativeGetFrameProcessingResolution',    
    SubmitExternalResponse = 'nativeSubmitExternalResponse',
    GetUploadReadyData = 'nativeGetUploadReadyData',
    SetDebugVisualization = 'nativeSetDebugVisualization',
    SetLanguage = 'nativeSetLanguage',
    GetLanguageLocale = 'nativeGetLanguageLocale',
    SetupResourceLoader = 'nativeSetupResourceLoader',
    Authorize = 'nativeAuthorize',
    GetChallengeToken = 'nativeGetChallengeToken',
    SelectProfile = 'nativeSelectProfile',
    Unload = 'nativeUnload',
    GetSdkWizardSteps = 'nativeGetSdkWizardSteps',
    MeasureAvailableRAM = 'nativePrepareAndEstimateMemory',
    GetSupportedPageCount = 'nativeGetSupportedPageCount',
}

export enum DataType {
    object = 'object',
    string = 'string',
}

// Interface for callback storage
interface CallbackPair {
    resolve: (value: any) => void;
    reject: (reason: any) => void;
}


export class ZenidSDK {
    private worker: Worker | null;
    private callbackMap: Map<string | number, CallbackPair>;
    private callIdCounter: number;
    private initialized: boolean = false;
    private initPromise: Promise<void> | null;
    private useSingleThread: boolean | null = null;

    // Global debug state accessible by verifiers
    public debugVisualizationEnabled: boolean = false;

    // Transform ZenidSDK to singleton pattern
    private static instance: ZenidSDK;
    
    public static get Instance(): ZenidSDK {
        if (!ZenidSDK.instance) {
            ZenidSDK.instance = new ZenidSDK();
        }
        return ZenidSDK.instance;
    }
    private constructor() {
        this.worker = null;
        this.callbackMap = new Map();
        this.callIdCounter = 0;
        this.initPromise = null;
    }

    /**
     * Initialize the SDK
     * @returns {Promise<void>} Resolves when SDK is initialized
     */
    public setup(resourcePath: string, useSingleThreaded: boolean, assetUrls?: { wasmUrl?: string; emscriptenJsUrl?: string }): Promise<void> {
        if (this.initPromise) {
            return this.initPromise;
        }

        this.initPromise = new Promise<void>(async (resolve, reject) => {
            try {
                // Use static new URL(..., import.meta.url) pattern for bundler compatibility.
                // Both Webpack 5+ and Vite recognize this pattern and emit the referenced files
                // (worker, emscripten glue, wasm) into the customer's bundle output.
                // Branches must be static literals so bundlers can analyze them.
                const workerUrl = useSingleThreaded
                    ? new URL('./zenid-worker-st.js', import.meta.url)
                    : new URL('./zenid-worker.js', import.meta.url);
                const wasmUrl = assetUrls?.wasmUrl ?? (useSingleThreaded
                    ? new URL('./zenid-wasm-st.wasm', import.meta.url).href
                    : new URL('./zenid-wasm-mt.wasm', import.meta.url).href);
                const emscriptenJsUrl = assetUrls?.emscriptenJsUrl ?? (useSingleThreaded
                    ? new URL('./zenid-wasm-st.js', import.meta.url).href
                    : new URL('./zenid-wasm-mt.js', import.meta.url).href);
                // Pass absolute URLs to the worker via query string so it doesn't have to
                // derive them from self.location.href (which is wrong under bundling).
                workerUrl.searchParams.set('wasm', wasmUrl);
                workerUrl.searchParams.set('js', emscriptenJsUrl);
                this.worker = new Worker(workerUrl);
                this.useSingleThread = useSingleThreaded;

                // register initialized, but set initialized to true in resolve
                this.callbackMap.set(WorkerResponseType.Initialized, {
                    resolve: async () => {
                        this.initialized = true;
                        await this.callNative<boolean>(NativeFunction.SetupResourceLoader, resourcePath);
                        resolve();
                    },
                    reject: (error) => {
                        this.initialized = false;
                        reject(error);
                    }
                });

                // Set up message handling
                this.worker.onmessage = (e: MessageEvent<WorkerResponse>) => this.handleWorkerMessage(e);

                // Call init function
                this.worker.postMessage(new WorkerInitAction());                

            } catch (error) {
                reject(error);
            }
        });

        return this.initPromise;
    }

    /**
     * Generic method to call any native function
     * @param {string} functionName - Name of the native function to call
     * @param {...any} args - Arguments to pass to the function
     * @returns {Promise<any>} Resolves with the result of the function call
     */
    public callNative<T = any>(functionName: string, ...args: any[]): Promise<T> {
        if (!this.initialized) {
            return Promise.reject(new Error('SDK not initialized. Call init() first.'));
        }

        return new Promise<T>((resolve, reject) => {
            if (!this.worker) {
                reject(new Error('Worker not initialized'));
                return;
            }

            const callId = this.getNextCallId();
            const transferables = this.findTransferables(args);

            // Register callback
            this.registerCallback(callId, resolve, reject);

            // Call the function
            const callMessage = new WorkerCallAction(callId, functionName, args, transferables);
            this.worker.postMessage(callMessage, transferables);
        });
    }

    /**
     * Finds ArrayBuffers that can be transferred instead of copied
     * @param {Array} args - Arguments to search
     * @returns {Array<ArrayBuffer>} - Transferable objects
     */
    private findTransferables(args: any[]): ArrayBuffer[] {
        const transferables: ArrayBuffer[] = [];

        const findBuffer = (obj: any): void => {
            if (!obj) return;

            if (obj instanceof ArrayBuffer) {
                transferables.push(obj);
            } else if (ArrayBuffer.isView(obj) && obj.buffer) {
                transferables.push(obj.buffer as ArrayBuffer);
            } else if (typeof obj === DataType.object) {
                for (const key in obj) {
                    findBuffer(obj[key]);
                }
            }
        };

        args.forEach(findBuffer);
        return transferables;
    }

    /**
     * Handle messages from the worker
     * @param {MessageEvent<WorkerResponse>} e - Message event
     */
    private handleWorkerMessage(e: MessageEvent<WorkerResponse>): void {
        const { type, id, result, error } = e.data;

        // zenidLog.debug("ZenidSDK: Received worker message:", JSON.stringify(e.data));
        
        if (type === WorkerResponseType.Initialized) {
            const callbacks = this.callbackMap.get(WorkerResponseType.Initialized);
            if (callbacks) {
                callbacks.resolve(undefined);
                this.callbackMap.delete(WorkerResponseType.Initialized);
            }
            return;
        }
        
        if (type === WorkerResponseType.Log) {
            const logLevel = e.data.logLevel as LogLevel;
            const logMessage = e.data.logMessage as string;
            zenidLog.log(logLevel, logMessage);
            return;
        }

        if (id === undefined) {
            //console.warn('Message received with no ID');
            return;
        }

        const callbacks = this.callbackMap.get(id);
        if (!callbacks) {
            zenidLog.warn(`No callback found for message with id: ${id}`);
            return;
        }

        const { resolve, reject } = callbacks;
        this.callbackMap.delete(id);

        if (type === WorkerResponseType.Error && error) {
            reject(new Error(error));
        } else if (type === WorkerResponseType.Result) {
            resolve(result);
        }
    }

    /**
     * Register callbacks for a specific call ID
     * @param {string|number} id - Call ID
     * @param {Function} resolve - Resolve function
     * @param {Function} reject - Reject function
     */
    private registerCallback(id: string | number, 
                             resolve: (value: any) => void, 
                             reject: (reason: any) => void): void {
        this.callbackMap.set(id, { resolve, reject });
    }

    /**
     * Get a unique call ID
     * @returns {number} Unique call ID
     */
    private getNextCallId(): number {
        return this.callIdCounter++;
    }

    /**
     * Process a frame
     * @param {string} feature - Feature name
     * @param {Uint8ClampedArray} imageData - Pointer to the input image
     * @param {number} width - Image width
     * @param {number} height - Image height
     * @returns {Promise<string>} - Processing result
     */
    public processFrame(feature: SdkVerifierType, imageData: Uint8ClampedArray, width: number, height: number): Promise<string> {
        return this.callNative<string>(NativeFunction.ProcessFrame, feature, imageData, width, height);
    }

    public destroy(): void {
        zenidLog.info('Destroying ZenidSDK instance and cleaning up resources');

        try {
            // Terminate the worker
            if (this.worker) {
                this.worker.terminate();
                this.worker = null;
            }

            // Clear all pending callbacks
            this.callbackMap.clear();

            // Reset instance state
            this.initialized = false;
            this.initPromise = null;
            this.callIdCounter = 0;

            // Release any additional resources here if needed

        } catch (error) {
            zenidLog.error('Error during SDK cleanup:', error);
        }
    }

    /**
     * Kill all threads and workers
     * This is a utility method to forcefully terminate all resources
     * Especially useful for iOS WebKit memory.atomic.wait32 bug
     */
    public killAll(): void {
        zenidLog.info('Forcefully killing all threads and workers');

        this.worker?.postMessage(new WorkerTerminateAction());
        zenidLog.info('All threads and workers have been terminated');
        this.initPromise = null;
        this.worker = null;
    }

    public IsUsingSingleThreaded(): boolean {
        return this.useSingleThread === true;
    }

    // Convenience methods for common operations
    public setVisualizerVersion(
        visualizerVersion: number
    ): Promise<void> {
        return this.callNative<void>(
            NativeFunction.SetVisualizerVersion,
            visualizerVersion
        );
    }

    public initOrRestart(feature: SdkVerifierType,
            jsSettings: string): Promise<string> {
        return this.callNative<string>(NativeFunction.InitOrRestart, feature, jsSettings);
    }

    public restartWithPreviousSettings(feature: SdkVerifierType): Promise<string> {
        return this.callNative<string>(NativeFunction.RestartWithPreviousSettings, feature);
    }

    public getRenderCommands(feature: SdkVerifierType, width: number, height: number): Promise<string> {
        return this.callNative<string>(NativeFunction.GetRenderCommands, feature, width, height);
    }

    public readyForFrame(feature: SdkVerifierType): Promise<boolean> {
        return this.callNative<boolean>(NativeFunction.ReadyForFrame, feature);
    }

    public submitExternalResponse(
        feature: SdkVerifierType,
        request: string
    ): Promise<string> {
        return this.callNative<string>(NativeFunction.SubmitExternalResponse, feature, request);
    }

    public submitPhotoImage(
        feature: SdkVerifierType,
        encodedImage: EncodedImage
    ): Promise<string> {
        
        const request = JSON.stringify(encodedImage);
        return this.callNative<string>(NativeFunction.SubmitExternalResponse, feature, request);
    }

    /**
     * Get upload-ready data as a JSON string
     * @param {string} feature - Feature name
     * @returns {Promise<UploadReadyData>} - Parsed upload-ready data object
     */
    public async getUploadReadyData(feature: SdkVerifierType): Promise<UploadReadyData> {
        let jsonString = await this.callNative<string>(NativeFunction.GetUploadReadyData, feature);
        return JSON.parse(jsonString) as UploadReadyData;
    }

    public async setDebugVisualization(isEnabled: boolean): Promise<void> {
        this.debugVisualizationEnabled = isEnabled;
        return this.callNative<void>(NativeFunction.SetDebugVisualization, isEnabled);
    }

    public setLanguage(language: SupportedLanguages): Promise<void> {
        return this.callNative<void>(NativeFunction.SetLanguage, language);
    }

    public getLanguageLocale(): Promise<string> {
        return this.callNative<string>(NativeFunction.GetLanguageLocale);
    }

    public authorize(responseToken: string): Promise<boolean> {
        return this.callNative<boolean>(NativeFunction.Authorize, responseToken);
    }

    public unloadAll(): Promise<boolean> {
        return this.callNative<boolean>(NativeFunction.Unload, "");
    }

    public unloadFeature(feature: SdkVerifierType): Promise<boolean> {
        return this.callNative<boolean>(NativeFunction.Unload, feature);
    }

    public getChallengeToken(): Promise<string> {
        return this.callNative<string>(NativeFunction.GetChallengeToken);
    }

    public selectProfile(profileName: string): Promise<boolean> {
        return this.callNative<boolean>(NativeFunction.SelectProfile, profileName);
    }
    
    public getStateContainerJson(feature: SdkVerifierType): Promise<string> {
        return this.callNative<string>(NativeFunction.GetStateContainerJson, feature);
    }
    
    public async getSdkWizardSteps(): Promise<SdkWizardStep[]> {
        let wizardStepsJson = await this.callNative<string>(NativeFunction.GetSdkWizardSteps);
        return JSON.parse(wizardStepsJson) as SdkWizardStep[];
    }

    public getFrameProcessingResolution(feature: SdkVerifierType): Promise<number> {
        return this.callNative<number>(NativeFunction.GetFrameProcessingResolution, feature);
    }
    
    /**
     * Measure available RAM by attempting to allocate memory blocks
     * @returns {Promise<number>} Available RAM in bytes
     */
    public measureAvailableRAM(): Promise<string> {
        return this.callNative<string>(NativeFunction.MeasureAvailableRAM);        
    }

    /**
     * Gets the supported page count for a specific document code
     * @param documentCode - The document code value (from DocumentCodes enum)
     * @returns Number of supported pages (1 or 2)
     */
    public getSupportedPageCount(documentCode: DocumentCodes): Promise<number> {
       return this.callNative<number>(NativeFunction.GetSupportedPageCount, documentCode);
    }
}

// Export the SDK
export default ZenidSDK;