/**
 * Generic api method that can be adapted to any fetch request
 */
const makeFetch = (method, url, body, options) => {
    let opts = {
        method: method,
        headers: {
            'Content-Type': 'application/json;charset=utf-8'
        },
        body: (body !== null) ? JSON.stringify(body) : null
    };

    if (typeof options !== 'undefined') {
        opts = Object.assign(opts, options);
    }

    return fetch(url, opts)
    .then(response => {
        if (response.ok) {
            return response.json();
        }

        if (response.status === 422) {
            console.log('422 error')
            return response.json().then(response => {
                throw ValidationException(response)
            });
        }

        if (response.status === 403) {
            console.log('403 error')
            throw AccessException(response);
        }

        throw {
            name: 'Exception',
            sta: response.status,
            txt: response.statusText,
            err: new Error(),
            violations: response.body
        };
    });
}

/**
 * Fetch results with certain parameters
 */
const _fetchAction = (page, uri, params) => {
    const item_per_page = 50;
    if (params === undefined) {
        params = {};
    }
    let url = uri + '?' + new URLSearchParams({ item_per_page, page, ...params });

    return fetch(url, {
        method: 'GET',
        headers: {
            'Content-Type': 'application/json;charset=utf-8'
        },
    }).then(response => {
        if (response.ok) { return response.json(); }
        throw Error({ m: response.statusText });
    });
};

const fetchResults = async (uri, params) => {
    let promises = [],
        page = 1;
    let firstData = await _fetchAction(page, uri, params);

    promises.push(Promise.resolve(firstData.results));

    if (firstData.pagination.more) {
        do {
            page = ++page;
            promises.push(_fetchAction(page, uri, params).then(r => Promise.resolve(r.results)));
        } while (page * firstData.pagination.items_per_page < firstData.count)
    }

    return Promise.all(promises).then(values => values.flat());
};

const fetchScopes = () => {
    return fetchResults('/api/1.0/main/scope.json');
};


/**
 * Error objects to be thrown
 */
const ValidationException = (response) => {
    const error = {};
    error.name = 'ValidationException';
    error.violations = response.violations.map((violation) => `${violation.title}: ${violation.propertyPath}`);
    error.titles = response.violations.map((violation) => violation.title);
    error.propertyPaths = response.violations.map((violation) => violation.propertyPath);
    return error;
}

const AccessException = (response) => {
    const error = {};
    error.name = 'AccessException';
    error.violations = ['You are not allowed to perform this action'];

    return error;
}

export {
    makeFetch,
    fetchResults,
    fetchScopes
}