/**
 * Plot Connections - Links data sources to visualization plots
 *
 * This module manages the connection between data sources and plots,
 * handling buffering, timing, and data flow.
 *
 * Connection Types:
 * - DirectConnection: Lines from source → plot (no buffering)
 * - BufferedConnection: Points → buffer → lines → plot
 * - SynchronizedConnection: Multiple sources → synchronized output
 */

/**
 * Base connection class
 */
class PlotConnection {
    constructor(source, plot, config = {}) {
        this.source = source;
        this.plot = plot;
        this.config = config;
        this.isActive = false;
        this.subscriptions = [];
    }

    /**
     * Activate the connection - start data flow
     */
    connect() {
        if (this.isActive) return;
        this.isActive = true;
        this.setupSubscriptions();
        this.source.start();
    }

    /**
     * Deactivate the connection - stop data flow
     */
    disconnect() {
        if (!this.isActive) return;
        this.isActive = false;
        this.cleanup();
        this.source.stop();
    }

    /**
     * Setup event subscriptions (override in subclasses)
     */
    setupSubscriptions() {
        throw new Error('setupSubscriptions() must be implemented by subclass');
    }

    /**
     * Cleanup subscriptions
     */
    cleanup() {
        this.subscriptions.forEach(unsub => unsub());
        this.subscriptions = [];
    }
}

/**
 * Direct connection - passes lines directly from source to plot
 * Use when source emits complete lines of data
 */
export class DirectConnection extends PlotConnection {
    setupSubscriptions() {
        const unsubLine = this.source.on('line', (data) => {
            this.plot.addLine(data.points, data.metadata);
        });

        const unsubError = this.source.on('error', (data) => {
            console.error('[DirectConnection] Source error:', data.error);
        });

        this.subscriptions.push(unsubLine, unsubError);
    }
}

/**
 * Buffered connection - buffers individual points into lines
 * Use when source emits individual data points that need to be assembled
 */
export class BufferedConnection extends PlotConnection {
    constructor(source, plot, config = {}) {
        super(source, plot, config);
        this.buffer = [];
        this.bufferSize = config.bufferSize || 100;
        this.bufferTimeout = config.bufferTimeout || 1000; // ms
        this.lastFlush = Date.now();
        this.flushHandle = null;

        // Start auto-flush timer
        if (config.autoFlush !== false) {
            this.startAutoFlush();
        }
    }

    setupSubscriptions() {
        const unsubPoint = this.source.on('point', (data) => {
            this.addToBuffer(data);
        });

        const unsubError = this.source.on('error', (data) => {
            console.error('[BufferedConnection] Source error:', data.error);
        });

        this.subscriptions.push(unsubPoint, unsubError);
    }

    addToBuffer(data) {
        this.buffer.push(data);

        // Flush if buffer is full
        if (this.buffer.length >= this.bufferSize) {
            this.flush();
        }
    }

    flush() {
        if (this.buffer.length === 0) return;

        // Convert buffer to line points
        const points = this.buffer.map((data, idx) => {
            const x = (idx / this.buffer.length) * this.plot.width;
            return { x, y: data.value };
        });

        this.plot.addLine(points, {
            timestamp: this.lastFlush,
            pointCount: this.buffer.length,
        });

        this.buffer = [];
        this.lastFlush = Date.now();
    }

    startAutoFlush() {
        this.flushHandle = setInterval(() => {
            const timeSinceLastFlush = Date.now() - this.lastFlush;
            if (timeSinceLastFlush >= this.bufferTimeout && this.buffer.length > 0) {
                this.flush();
            }
        }, 100); // Check every 100ms
    }

    cleanup() {
        super.cleanup();
        if (this.flushHandle) {
            clearInterval(this.flushHandle);
            this.flushHandle = null;
        }
    }
}

/**
 * Synchronized connection - synchronizes multiple sources to one plot
 * Useful for combining multiple data streams
 */
export class SynchronizedConnection extends PlotConnection {
    constructor(sources, plot, config = {}) {
        super(null, plot, config); // No single source
        this.sources = sources;
        this.syncMode = config.syncMode || 'wait-for-all'; // 'wait-for-all', 'first-available'
        this.lineBuffers = new Map(); // sourceId => latest line
    }

    connect() {
        if (this.isActive) return;
        this.isActive = true;

        this.sources.forEach((source, idx) => {
            const unsubLine = source.on('line', (data) => {
                this.handleSourceLine(idx, data);
            });

            const unsubError = source.on('error', (data) => {
                console.error(`[SynchronizedConnection] Source ${idx} error:`, data.error);
            });

            this.subscriptions.push(unsubLine, unsubError);
            source.start();
        });
    }

    disconnect() {
        if (!this.isActive) return;
        this.isActive = false;
        this.cleanup();
        this.sources.forEach(source => source.stop());
    }

    handleSourceLine(sourceIdx, data) {
        this.lineBuffers.set(sourceIdx, data);

        if (this.syncMode === 'wait-for-all') {
            // Wait until we have data from all sources
            if (this.lineBuffers.size === this.sources.length) {
                this.emitSynchronized();
            }
        } else if (this.syncMode === 'first-available') {
            // Emit immediately
            this.plot.addLine(data.points, {
                ...data.metadata,
                sourceIdx,
            });
        }
    }

    emitSynchronized() {
        // For now, just emit the first source's line
        // Could implement more sophisticated merging
        const firstLine = this.lineBuffers.get(0);
        if (firstLine) {
            this.plot.addLine(firstLine.points, firstLine.metadata);
        }
        this.lineBuffers.clear();
    }
}

/**
 * Connection Manager - manages multiple connections
 */
export class ConnectionManager {
    constructor() {
        this.connections = new Map(); // connectionId => connection
        this.nextId = 0;
    }

    /**
     * Create and register a connection
     * @returns {number} connectionId
     */
    connect(source, plot, config = {}) {
        const type = config.type || 'direct';
        let connection;

        switch (type) {
            case 'direct':
                connection = new DirectConnection(source, plot, config);
                break;
            case 'buffered':
                connection = new BufferedConnection(source, plot, config);
                break;
            case 'synchronized':
                connection = new SynchronizedConnection(source, plot, config);
                break;
            default:
                throw new Error(`Unknown connection type: ${type}`);
        }

        const id = this.nextId++;
        this.connections.set(id, connection);
        connection.connect();

        return id;
    }

    /**
     * Disconnect and remove a connection
     */
    disconnect(connectionId) {
        const connection = this.connections.get(connectionId);
        if (connection) {
            connection.disconnect();
            this.connections.delete(connectionId);
        }
    }

    /**
     * Disconnect all connections
     */
    disconnectAll() {
        this.connections.forEach(connection => connection.disconnect());
        this.connections.clear();
    }

    /**
     * Get statistics about connections
     */
    getStats() {
        return {
            activeConnections: this.connections.size,
            connections: Array.from(this.connections.entries()).map(([id, conn]) => ({
                id,
                isActive: conn.isActive,
                type: conn.constructor.name,
            })),
        };
    }
}

/**
 * Helper functions for common connection patterns
 */

/**
 * Connect a synthetic data source to a plot
 * @param {DataGenerator} generator - Test data generator instance
 * @param {TimeSeriesPlot} plot - Plot to display data
 * @param {Object} config - Configuration options
 * @returns {DirectConnection} The connection instance
 */
export function connectSyntheticData(generator, plot, config = {}) {
    const { SyntheticDataSource } = require('./data-sources.js');

    const source = new SyntheticDataSource({
        generator,
        pointsPerLine: config.pointsPerLine || 100,
        width: plot.width,
        lineInterval: config.lineInterval || 100,
    });

    const connection = new DirectConnection(source, plot, config);
    connection.connect();

    return connection;
}

/**
 * Connect a function-based source to a plot
 * @param {Function} func - Function (x, t) => y
 * @param {TimeSeriesPlot} plot - Plot to display data
 * @param {Object} config - Configuration options
 * @returns {DirectConnection} The connection instance
 */
export function connectFunction(func, plot, config = {}) {
    const { FunctionDataSource } = require('./data-sources.js');

    const source = new FunctionDataSource({
        func,
        pointsPerLine: config.pointsPerLine || 100,
        width: plot.width,
        amplitude: config.amplitude || 30,
        lineInterval: config.lineInterval || 100,
    });

    const connection = new DirectConnection(source, plot, config);
    connection.connect();

    return connection;
}

/**
 * Connect a streaming source to a plot with buffering
 * @param {DataGenerator} generator - Test data generator instance
 * @param {TimeSeriesPlot} plot - Plot to display data
 * @param {Object} config - Configuration options
 * @returns {BufferedConnection} The connection instance
 */
export function connectStreamingData(generator, plot, config = {}) {
    const { StreamingDataSource } = require('./data-sources.js');

    const source = new StreamingDataSource({
        generator,
        sampleRate: config.sampleRate || 60,
    });

    const connection = new BufferedConnection(source, plot, {
        bufferSize: config.bufferSize || 100,
        bufferTimeout: config.bufferTimeout || 1000,
    });
    connection.connect();

    return connection;
}

/**
 * Quick setup: Create a plot with a data source in one call
 * @param {Application} app - PixiJS application
 * @param {Object} plotConfig - Plot configuration
 * @param {Object} sourceConfig - Source configuration
 * @returns {Object} {plot, source, connection}
 */
export function createConnectedPlot(app, plotConfig, sourceConfig) {
    const { TimeSeriesPlot } = require('./timeseries-plot.js');
    const { SyntheticDataSource } = require('./data-sources.js');

    const plot = new TimeSeriesPlot(plotConfig);
    app.stage.addChild(plot.container);

    const source = new SyntheticDataSource({
        generator: sourceConfig.generator,
        pointsPerLine: plotConfig.width / 8, // Default: ~8 pixels per point
        width: plotConfig.width,
        lineInterval: sourceConfig.lineInterval || 100,
    });

    const connection = new DirectConnection(source, plot);
    connection.connect();

    return { plot, source, connection };
}