import { assign, createMachine, send, sendParent } from 'xstate';
// import type { QueryManager } from '$lib/services/query-manager-test';

export type FetchContext = {
    id: string;
    verb: string;
    endpoint: string;
    query: any;
    body: any;
    requestTimestamp: any,
    responseTimestamp: any,
    response: any;
    errorMessage: string;
    broadcastEvent: string; 
    // manager: QueryManager
}

export const fetchMachine = createMachine (
  {
    tsTypes: {} as import("./fetch.machine.typegen").Typegen0,
    schema: {
        context: {} as FetchContext,
        events: {} as 
        { type: 'FETCH', endpoint: string, query?: string, body?: any } |
        { type: 'FETCH_SUCCESS', data: any } |
        { type: 'FETCH_ERROR', error: any } |
        { type: 'FETCH_CANCEL' }
    },
    initial: 'inFlight',
    context: {
        id: null,
        verb: null,
        endpoint: null,
        query: null,
        body: null,
        requestTimestamp: null,
        responseTimestamp: null,
        response: null,
        errorMessage: null,
        broadcastEvent: 'RECEIVE_DATA'
        // manager: null
    },
    states: {
        inFlight: {
            invoke: {
                src: 'fetchCall',
                onDone: {
                    target: 'success',
                    actions: [ 'assignDataToContext' ]   
                },
                onError: {
                    target: 'error',
                    actions: 'assignErrorToContext',
                }
            },
            on: {
                // CANCEL: {
                //     target: 'complete',
                // }
            }
        },
        success: {
            entry: [ 'notifyParent' ],
            type: 'final'
            // data: {
            //     id: (context: FetchContext, event: FetchEvent) => context.id, 
            //     endpoint: (context: FetchContext, event: FetchEvent) => context.endpoint, 
            //     data: (context: FetchContext, event: FetchEvent) => context.response,
            // }
        },
        error: {
            // work in retries and exponential backoff 
            entry: [ 
                // (c,e) => console.log("Error in fetch: ", c, e) 
            ]
        }
    },
},
{
    services: { 
        fetchCall: (context, event): Promise<any> => {
            return fetch(`${context.endpoint}`).then((response) => response.json());
            // return context.endpoint.includes('http') ? 
            //     fetch(`${context.endpoint}${context.query}`).then((response) => response.json()) :
            //     context.manager[ context.endpoint ]( context.query )
        }
     },
    actions: { 
    
        assignDataToContext: assign({
            response: (context, event) => event.data
        }),
        assignErrorToContext: assign({
            errorMessage: (context, event) => 'An unknown error occurred',
        }),
        notifyParent: sendParent((context, event) => {
            return {
                type: context.broadcastEvent,
                data: {
                    id: context.id,
                    responseTimestamp: context.responseTimestamp, 
                    endpoint: context.endpoint, 
                    data: context.response,
                }
            }
        })
    }
});