const config = require('../config');
const { createBusRequest } = require('../utils/busAuth');
const { default: axios } = require('axios');


const INDICE_ATENCION_URL = config.bus.documentRegistryUrl;

const LOCAL_URL = "https://federador.qa-bus-interoperabilidad.svc.cluster.local:8080/fhir/DocumentReference";

function maskPrivateURL(patientId) {
    return patientId.replace(LOCAL_URL, INDICE_ATENCION_URL);
}



async function findDocumentReferenceById(token, id) {
    const request = createBusRequest(token);
    const response = await request.get(
        URL.parse(`${INDICE_ATENCION_URL}/${id}`)
    );
    return response.data;
}


async function findDocumentReferenceByUrl(token, id) {
    const request = createBusRequest(token);
    const response = await request.get(
        URL.parse(id, INDICE_ATENCION_URL)
    );
    return response.data;
}

/**
 * Posts a DocumentReference to the document registry
 * (POST /fhir/DocumentReference).
 * @param {string} documentRegistryUrl - Base URL of the document registry service.
 * @param {string} token - Bearer access token.
 * @param {object} documentReference - FHIR DocumentReference resource to register.
 * @returns {Promise<object>} The created DocumentReference resource returned by the registry.
 * @todo Agregar system http://federador.msal.gob.ar/uri para armar el identificador del custodian: http://federador.msal.gob.ar/uri|<custodianId>
 */
async function createDocumentReference(token, documentReference) {
    const request = createBusRequest(token);
    const response = await request.post(
        URL.parse(INDICE_ATENCION_URL),
        documentReference
    );
    const location = maskPrivateURL(response.headers['location']);
    return findDocumentReferenceByUrl(token, location);
}
/**
 * Searches DocumentReferences in the document registry by patient subject identifier
 * (GET /fhir/DocumentReference?subject=system|value).
 * @param {string} documentRegistryUrl - Base URL of the document registry service.
 * @param {string} token - Bearer access token.
 * @param {string} subjectSystem - Identifier system of the patient.
 * @param {string} subjectValue - Identifier value of the patient.
 * @returns {Promise<object>} FHIR Bundle (searchset) with matching DocumentReferences.
 */
async function findDocumentReferenceBySubject(token, subjectSystem, subjectValue) {
    const request = createBusRequest(token);
    const response = await request.get(
        URL.parse(INDICE_ATENCION_URL),
        {
            params: { subject: `${subjectSystem}|${subjectValue}` },
        }
    );
    return response.data;
}

/**
 * Parses a FHIR token search value (`system|code`, `|code` o `code`) into its parts.
 * `system === null` indica la forma `|code` (exige coding sin system).
 * `system === undefined` indica la forma `code` (sin restricción de system).
 * @param {string} token
 * @returns {{ system: string|null|undefined, code: string }}
 */
function parseTypeToken(token) {
    const pipeIndex = token.indexOf('|');
    if (pipeIndex === -1) {
        return { system: undefined, code: token };
    }
    const system = token.slice(0, pipeIndex);
    return { system: system === '' ? null : system, code: token.slice(pipeIndex + 1) };
}

/**
 * Indica si el CodeableConcept `type` de un DocumentReference matchea el token FHIR dado,
 * replicando la semántica estándar de búsqueda por token (`system|code`, `|code` o `code`)
 * que el índice de documentos aplicaría del lado del servidor.
 * @param {object} resource - DocumentReference resource.
 * @param {string} token - Token FHIR de DocumentReference.type.
 * @returns {boolean}
 */
function matchesTypeToken(resource, token) {
    const { system, code } = parseTypeToken(token);
    const codings = resource?.type?.coding ?? [];
    return codings.some(coding => {
        if (system === null) {
            return !coding.system && coding.code === code;
        }
        if (system !== undefined) {
            return coding.system === system && coding.code === code;
        }
        return coding.code === code;
    });
}

/**
 * Filtra las entries de un Bundle searchset de DocumentReference por type,
 * ajustando `total` a la cantidad de entries resultantes.
 * @param {object} bundle - FHIR Bundle (searchset).
 * @param {string} type - Token FHIR de DocumentReference.type.
 * @returns {object} Bundle filtrado.
 */
function filterBundleByType(bundle, type) {
    if (!bundle || !Array.isArray(bundle.entry)) {
        return bundle;
    }
    const entry = bundle.entry.filter(e => matchesTypeToken(e.resource, type));
    return { ...bundle, entry, total: entry.length };
}

/**
 * Searches DocumentReferences in the document registry by patient internal ID,
 * opcionalmente filtrando por tipo de documento
 * (GET /fhir/DocumentReference?patient=value[&type=system|code]).
 *
 * Si `config.bus.filterDocumentTypeLocally` está activo y se pidió `type`, el parámetro
 * `type` no se envía al índice de documentos: se piden todos los DocumentReference del
 * subject y el filtrado por tipo se hace localmente sobre el Bundle resultante.
 * @param {string} documentRegistryUrl - Base URL of the document registry service.
 * @param {string} token - Bearer access token.
 * @param {string} patientId - Internal patient ID in the document registry.
 * @param {string} [type] - Token FHIR (`system|code` o `code`) de DocumentReference.type, ej: `http://loinc.org|60591-5`.
 * @returns {Promise<object>} FHIR Bundle (searchset) with matching DocumentReferences.
 */
async function findDocumentReferenceByPatient(token, patientId, type) {
    const request = createBusRequest(token);
    const filterLocally = Boolean(type) && config.bus.filterDocumentTypeLocally;
    const params = { subject: patientId };
    if (type && !filterLocally) {
        params.type = type;
    }
    const response = await request.get(
        URL.parse(INDICE_ATENCION_URL),
        { params }
    );
    return filterLocally ? filterBundleByType(response.data, type) : response.data;
}

/**
 * Searches DocumentReferences in the document registry filtered by subject, custodian and type
 * (GET /fhir/DocumentReference?subject=...&custodian=...&type=...).
 * @param {string} documentRegistryUrl - Base URL of the document registry service.
 * @param {string} token - Bearer access token.
 * @param {{ system: string, value: string }} subject   - Patient identifier (TokenParam).
 * @param {{ system: string, value: string }} custodian - Custodian identifier (TokenParam).
 * @param {{ system: string, value: string }} type      - Document type (TokenParam, e.g. { system: 'http://loinc.org', value: '60591-5' }).
 * @returns {Promise<object>} FHIR Bundle (searchset) with matching DocumentReferences.
 */
async function searchDocumentReference(token, subject, custodian, type) {
    const request = createBusRequest(token);
    const response = await request.get(
        URL.parse(INDICE_ATENCION_URL),
        {
            params: {
                subject: `${subject.system}|${subject.value}`,
                custodian: `${custodian.system}|${custodian.value}`,
                type: `${type.system}|${type.value}`,
            },
        });
    return response.data;
}

module.exports = {
    findDocumentReferenceById,
    createDocumentReference,
    findDocumentReferenceBySubject,
    findDocumentReferenceByPatient,
    searchDocumentReference
};