import {
    defineJourney,
    journeyStep,
    type JourneyDef,
    type JourneyHandle,
    type JourneyStepOptions,
    type JourneyStepTarget,
    type StepHandle,
} from '../../core';
import { moduleRuntime } from '../../core/runtime';

/**
 * Knockout / desktop-legacy bridge on `window.App.Journey`.
 * Prefer `defineJourney` handles; `journeyStep` / `firstOpenJourneyName` cover multi-journey steps.
 * Use `getJourneyHandle(name)` when you need the handle from another module.
 */
interface AppJourneyApi {
    defineJourney(config: JourneyDef): JourneyHandle;
    journeyStep<T>(
        journey: JourneyStepTarget,
        stepName: string,
        fn: (step: StepHandle) => T | Promise<T>,
        opts?: JourneyStepOptions
    ): Promise<T>;
    /** First open journey **name** among candidates, or null. */
    firstOpenJourneyName(names: readonly string[]): string | null;
    /** `defineJourney` handle for an open name, or null. */
    getJourneyHandle(name: string): JourneyHandle | null;
}

export type WindowWithAppJourney = Window & {
    App?: { Journey?: AppJourneyApi } & Record<string, unknown>;
};

let journeyExposed = false;
let windowJourneyApi: AppJourneyApi | undefined;

function handleForOpenJourney(name: string): JourneyHandle | null {
    const open = moduleRuntime.getOpenJourney(name);
    if (!open) {
        return null;
    }
    return defineJourney(open.config);
}

/**
 * Publish the Knockout bridge on window.App.Journey. Idempotent for the real window.
 * Optional `target` is for tests. Never throws — logs and returns a usable API if publish fails.
 */
export function exposeAppJourney(target: WindowWithAppJourney = window): AppJourneyApi {
    if (journeyExposed && target === window && windowJourneyApi) {
        return windowJourneyApi;
    }

    const api: AppJourneyApi = {
        defineJourney,
        journeyStep,
        firstOpenJourneyName: names => moduleRuntime.firstOpenJourneyName(names),
        getJourneyHandle: handleForOpenJourney,
    };

    try {
        if (target == null || (typeof target !== 'object' && typeof target !== 'function')) {
            // eslint-disable-next-line no-console -- soft-skip missing host window
            console.warn('[journey] exposeAppJourney: skipped — missing');
            return api;
        }
        target.App = target.App ?? {};
        target.App.Journey = Object.freeze(api);
        if (target === window) {
            journeyExposed = true;
            windowJourneyApi = api;
        }
    } catch (err) {
        // eslint-disable-next-line no-console -- soft-fail host wiring
        console.error('[journey] exposeAppJourney failed', err);
    }
    return api;
}

export { instrumentJquery, type JqueryStatic } from './instrument';