import type {
    AgentEvent,
    AgentStartOptions,
} from '../shared/agent-protocol'

/* ─────────────────────────────────────────────────────────────────────────
 * agent-bridge — renderer-side handle to a worker-hosted Agent SDK session.
 *
 * One `AgentSession` per chat. The session id is a UUID generated by the
 * caller (see chat/store.ts) and round-trips through the SDK as its own
 * session id, so resuming after a process restart is just `start({ resume:
 * true })` with the same id.
 *
 * Events arrive on a dedicated IPC channel; the bridge fans them out to a
 * single callback so the chat runner can update its store without tracking
 * subscribers itself.
 * ──────────────────────────────────────────────────────────────────────── */

export interface AgentSession {
    readonly id: string
    /** Send a follow-up user message into a live session. Queues if the
     *  assistant is mid-turn. */
    send(text: string): void
    /** Interrupt the current assistant turn; the session stays alive. */
    interrupt(): void
    /** End the session and release the worker-side state. Once stopped,
     *  any future messages must `start()` again with `resume: true`. */
    stop(): void
}

export interface OpenSessionArgs {
    sessionId: string
    /** First user message to send. */
    prompt: string
    /** When true, load history for `sessionId` from the SDK's session store
     *  before sending `prompt`. */
    resume: boolean
    options: AgentStartOptions
    onEvent(ev: AgentEvent): void
    /** Fired once the worker has cleaned up the session (after `stop()` or
     *  when the SDK exits naturally). */
    onClosed?: () => void
}

export function openAgentSession(args: OpenSessionArgs): AgentSession {
    const offEvent = window.agent.onEvent(args.sessionId, args.onEvent)
    const offClosed = window.agent.onClosed(args.sessionId, () => {
        try {
            args.onClosed?.()
        } finally {
            offEvent()
            offClosed()
        }
    })

    window.agent.start({
        sessionId: args.sessionId,
        prompt: args.prompt,
        resume: args.resume,
        options: args.options,
    })

    return {
        id: args.sessionId,
        send: (text) => window.agent.send(args.sessionId, text),
        interrupt: () => window.agent.interrupt(args.sessionId),
        stop: () => window.agent.stop(args.sessionId),
    }
}