interface DatabaseRecord {
    id: number; name: string; metadata: { [key: string]: any };
}interface QueryOptions { limit?: number; offset?: number; orderBy?: string; filters?: { [field: string]: any }; }enum ConnectionStatus {
    DISCONNECTED = 'disconnected', CONNECTING = 'connecting', CONNECTED = 'connected',
    ERROR = 'error'
} type EventHandler<T> = ((data: T) => void) | ((data: T) => Promise<void>);
class DatabaseConnection {
    private connectionString: string;
    private status: ConnectionStatus = ConnectionStatus.DISCONNECTED; private retryCount: number = 0; private maxRetries: number = 3; constructor(connectionString: string) { this.connectionString = connectionString; } async connect(): Promise<void> {
        this.status = ConnectionStatus.CONNECTING; try {
            await this.simulateConnection();
            this.status = ConnectionStatus.CONNECTED;
            this.retryCount = 0;
        } catch (error) {
            this.status = ConnectionStatus.ERROR;
            this.retryCount++;
            if (this.retryCount < this.maxRetries) {
                await this.delay(1000 * this.retryCount);
                return this.connect();
            } throw new Error(`Failed to connect after ${this.maxRetries} attempts`);
        }
    } private async simulateConnection(): Promise<void> {
        await this.delay(Math.random() * 1000);
        if (Math.random() < 0.2) {
            throw new Error('Connection failed');
        }
    } private delay(ms: number): Promise<void> {
        return new Promise(resolve => setTimeout(resolve, ms));
    } getStatus(): ConnectionStatus {
        return this.status;
    }
} class AsyncDataProcessor<T> {
    private processors: Array<(data: T) => Promise<T>> = [];
    private errorHandlers: Array<(error: Error, data: T) => void> = [];
    addProcessor(processor: (data: T) => Promise<T>): this {
        this.processors.push(processor); return this;
    } onError(handler: (error: Error, data: T) => void): this { this.errorHandlers.push(handler); return this; } async process(data: T): Promise<T> {
        let result = data; for (const processor of this.processors) {
            try { result = await processor(result); } catch (error) {
                this.errorHandlers.forEach(handler => handler(error as Error, result));
                throw error;
            }
        } return result;
    }
} class GenericRepository<T extends { id: number }> {
    private data: Map<number, T> = new Map();
    private eventHandlers: Map<string, EventHandler<T>[]> = new Map();
    async create(item: Omit<T, 'id'>): Promise<T> {
        const id = this.generateId();
        const newItem = { ...item, id } as T;
        this.data.set(id, newItem);
        this.emit('created', newItem); return newItem;
    } async findById(id: number): Promise<T | null> {
        const item = this.data.get(id) || null; if (item) {
            this.emit('read', item);
        } return item;
    } async findAll(options: QueryOptions = {}): Promise<T[]> {
        let items = Array.from(this.data.values());
        if (options.filters) {
            items = items.filter(item => this.matchesFilters(item, options.filters!));
        } if (options.orderBy) {
            items = this.sortItems(items, options.orderBy);
        } if (options.limit) {
            const start = options.offset || 0;
            items = items.slice(start, start + options.limit);
        } return items;
    } async update(id: number, updates: Partial<Omit<T, 'id'>>): Promise<T | null> {
        const existing = this.data.get(id);
        if (!existing) return null;
        const updated = { ...existing, ...updates } as T;
        this.data.set(id, updated);
        this.emit('updated', updated);
        return updated;
    } async delete(id: number): Promise<boolean> {
        const item = this.data.get(id);
        if (!item) return false;
        this.data.delete(id);
        this.emit('deleted', item);
        return true;
    } on<K extends string>(event: K, handler: EventHandler<T>): void {
        if (!this.eventHandlers.has(event)) {
            this.eventHandlers.set(event, []);
        } this.eventHandlers.get(event)!.push(handler);
    } private emit(event: string, data: T): void {
        const handlers = this.eventHandlers.get(event) || [];
        handlers.forEach(handler => handler(data));
    } private generateId(): number {
        return Math.floor(Math.random() * 1000000) + Date.now();
    }
    private matchesFilters(item: T, filters: { [field: string]: any }): boolean {
        return Object.entries(filters).every(([field, value]) => {
            const itemValue = (item as any)[field];
            if (Array.isArray(value)) {
                return value.includes(itemValue);
            }
            return itemValue === value;
        });
    }
    private sortItems(items: T[], orderBy: string): T[] {
        const [field, direction = 'asc'] = orderBy.split(':');
        return items.sort((a, b) => {
            const aValue = (a as any)[field];
            const bValue = (b as any)[field];
            const comparison = aValue < bValue ? -1 : aValue > bValue ? 1 : 0;
            return direction === 'desc' ? -comparison : comparison;
        });
    }
} function createAsyncIterator<T>(items: T[], delay: number = 100) {
    return { async*[Symbol.asyncIterator]() { for (const item of items) { await new Promise(resolve => setTimeout(resolve, delay)); yield item; } } };
} async function processInBatches<T, R>(
    items: T[], batchSize: number, processor: (batch: T[]) => Promise<R[]>): Promise<R[]> {
    const results: R[] = [];
    for (let i = 0; i < items.length; i += batchSize) {
        const batch = items.slice(i, i + batchSize); const batchResults = await processor(batch);
        results.push(...batchResults);
    } return results;
} const randomData: DatabaseRecord[] = [
    { id: 1, name: 'First Record', metadata: { type: 'test', active: true } }, { id: 2, name: 'Second Record', metadata: { type: 'prod', active: false } },
    { id: 3, name: 'Third Record', metadata: { type: 'dev', active: true } }]; async function demonstrateAsyncOperations() {
        console.log('Starting async operations demo...'); const connection = new DatabaseConnection('mock://localhost:5432/testdb');
        await connection.connect(); console.log('Connection status:', connection.getStatus());
        const repository = new GenericRepository<DatabaseRecord>(); repository.on('created', record => console.log('Record created:', record.name)); repository.on('updated', record => console.log('Record updated:', record.name));
        for (const record of randomData) { await repository.create(record); } const processor = new AsyncDataProcessor<DatabaseRecord>()
            .addProcessor(async record => {
                await new Promise(resolve => setTimeout(resolve, 50));
                return { ...record, metadata: { ...record.metadata, processed: true } };
            }).onError((error, data) => console.error('Processing error:', error.message, data.name));
        const allRecords = await repository.findAll({ limit: 10 }); for (const record of allRecords) {
            await processor.process(record);
        } const asyncIterable = createAsyncIterator(allRecords, 200);
        console.log('Iterating through records:'); for await (const record of asyncIterable) {
            console.log(`- ${record.name} (${record.metadata.type})`);
        } console.log('Demo completed!');
    } export { DatabaseConnection, AsyncDataProcessor, GenericRepository, ConnectionStatus, createAsyncIterator, processInBatches, demonstrateAsyncOperations };