/**
 * March Agent SDK - Structural Streaming Base
 * Port of Python march_agent/structural/base.py
 *
 * Base class for structural streaming objects.
 */

import type { Streamer } from '../streamer.js'

/**
 * Abstract base class for structural streaming objects.
 *
 * Structural streamers generate events but don't hold streaming state.
 * The Streamer binds to them via streamBy() to enable streaming.
 */
export abstract class StructuralStreamer {
    readonly id: string
    protected _streamer?: Streamer

    constructor(id?: string) {
        this.id = id ?? this._generateId()
    }

    /**
     * Generate a unique ID for this streamer type.
     */
    protected abstract _generateId(): string

    /**
     * Get the event type prefix (e.g., 'artifact', 'text_block').
     */
    abstract getEventTypePrefix(): string

    /**
     * Bind this structural streamer to a Streamer instance.
     * Called by Streamer.streamBy(). Returns self for chaining.
     */
    _bindStreamer(streamer: Streamer): this {
        this._streamer = streamer
        return this
    }

    /**
     * Send an event through the bound streamer.
     *
     * Creates event payload and sends via streamer._send().
     * Returns self for method chaining.
     */
    protected _sendEvent(action: string, data: Record<string, unknown> = {}): this {
        if (!this._streamer) {
            throw new Error(
                `${this.constructor.name} not bound to a Streamer. ` +
                `Call streamer.streamBy() first.`
            )
        }

        // Build event body
        const body = { id: this.id, ...data }

        // Build event type
        const eventType = `${this.getEventTypePrefix()}:${action}`

        // Send through streamer using existing _send() method
        // content = stringified JSON body
        // eventType = structural event type
        // persist = false (structural events not persisted as content)
        this._streamer._send(
            JSON.stringify(body),
            false, // done
            false, // persist
            eventType
        )

        return this
    }
}

/**
 * Generate a short random hex string for IDs.
 */
export function generateShortId(): string {
    return Math.random().toString(16).slice(2, 10)
}