import AjaxService from 'ember-ajax/services/ajax';
import config from 'ghost-admin/config/environment';
import {AjaxError, isAjaxError} from 'ember-ajax/errors';
import {computed} from '@ember/object';
import {get} from '@ember/object';
import {isArray as isEmberArray} from '@ember/array';
import {isNone} from '@ember/utils';
import {inject as service} from '@ember/service';

const JSON_CONTENT_TYPE = 'application/json';
const GHOST_REQUEST = /\/ghost\/api\//;

function isJSONContentType(header) {
    if (!header || isNone(header)) {
        return false;
    }
    return header.indexOf(JSON_CONTENT_TYPE) === 0;
}

/* Version mismatch error */

export class VersionMismatchError extends AjaxError {
    constructor(payload) {
        super(payload, 'API server is running a newer version of Ghost, please upgrade.');
    }
}

export function isVersionMismatchError(errorOrStatus, payload) {
    if (isAjaxError(errorOrStatus)) {
        return errorOrStatus instanceof VersionMismatchError;
    } else {
        return get(payload || {}, 'errors.firstObject.type') === 'VersionMismatchError';
    }
}

/* Server unreachable error */

export class ServerUnreachableError extends AjaxError {
    constructor(payload) {
        super(payload, 'Server was unreachable');
    }
}

export function isServerUnreachableError(error) {
    if (isAjaxError(error)) {
        return error instanceof ServerUnreachableError;
    } else {
        return error === 0 || error === '0';
    }
}

/* Request entity too large error */

export class RequestEntityTooLargeError extends AjaxError {
    constructor(payload) {
        super(payload, 'Request is larger than the maximum file size the server allows');
    }
}

export function isRequestEntityTooLargeError(errorOrStatus) {
    if (isAjaxError(errorOrStatus)) {
        return errorOrStatus instanceof RequestEntityTooLargeError;
    } else {
        return errorOrStatus === 413;
    }
}

/* Unsupported media type error */

export class UnsupportedMediaTypeError extends AjaxError {
    constructor(payload) {
        super(payload, 'Request contains an unknown or unsupported file type.');
    }
}

export function isUnsupportedMediaTypeError(errorOrStatus) {
    if (isAjaxError(errorOrStatus)) {
        return errorOrStatus instanceof UnsupportedMediaTypeError;
    } else {
        return errorOrStatus === 415;
    }
}

/* Maintenance error */

export class MaintenanceError extends AjaxError {
    constructor(payload) {
        super(payload, 'Ghost is currently undergoing maintenance, please wait a moment then retry.');
    }
}

export function isMaintenanceError(errorOrStatus) {
    if (isAjaxError(errorOrStatus)) {
        return errorOrStatus instanceof MaintenanceError;
    } else {
        return errorOrStatus === 503;
    }
}

/* Theme validation error */

export class ThemeValidationError extends AjaxError {
    constructor(payload) {
        super(payload, 'Theme is not compatible or contains errors.');
    }
}

export function isThemeValidationError(errorOrStatus, payload) {
    if (isAjaxError(errorOrStatus)) {
        return errorOrStatus instanceof ThemeValidationError;
    } else {
        return get(payload || {}, 'errors.firstObject.type') === 'ThemeValidationError';
    }
}

/* end: custom error types */

let ajaxService = AjaxService.extend({
    session: service(),

    isTesting: undefined,

    // flag to tell our ESA authenticator not to try an invalidate DELETE request
    // because it's been triggered by this service's 401 handling which means the
    // DELETE would fail and get stuck in an infinite loop
    // TODO: find a more elegant way to handle this
    skipSessionDeletion: false,

    headers: computed('session.isAuthenticated', function () {
        let headers = {};

        headers['X-Ghost-Version'] = config.APP.version;
        headers['App-Pragma'] = 'no-cache';

        if (this.session.isAuthenticated && this.isTesting) {
            headers.Authorization = 'Test';
        }

        return headers;
    }).volatile(),

    init() {
        this._super(...arguments);
        if (this.isTesting === undefined) {
            this.isTesting = config.environment === 'test';
        }
    },

    // ember-ajax recognises `application/vnd.api+json` as a JSON-API request
    // and formats appropriately, we want to handle `application/json` the same
    _makeRequest(hash) {
        if (isJSONContentType(hash.contentType) && hash.type !== 'GET') {
            if (typeof hash.data === 'object') {
                hash.data = JSON.stringify(hash.data);
            }
        }

        hash.withCredentials = true;

        return this._super(hash);
    },

    handleResponse(status, headers, payload, request) {
        if (this.isVersionMismatchError(status, headers, payload)) {
            return new VersionMismatchError(payload);
        } else if (this.isServerUnreachableError(status, headers, payload)) {
            return new ServerUnreachableError(payload);
        } else if (this.isRequestEntityTooLargeError(status, headers, payload)) {
            return new RequestEntityTooLargeError(payload);
        } else if (this.isUnsupportedMediaTypeError(status, headers, payload)) {
            return new UnsupportedMediaTypeError(payload);
        } else if (this.isMaintenanceError(status, headers, payload)) {
            return new MaintenanceError(payload);
        } else if (this.isThemeValidationError(status, headers, payload)) {
            return new ThemeValidationError(payload);
        }

        let isGhostRequest = GHOST_REQUEST.test(request.url);
        let isAuthenticated = this.get('session.isAuthenticated');
        let isUnauthorized = this.isUnauthorizedError(status, headers, payload);

        if (isAuthenticated && isGhostRequest && isUnauthorized) {
            this.skipSessionDeletion = true;
            this.session.invalidate();
        }

        return this._super(...arguments);
    },

    normalizeErrorResponse(status, headers, payload) {
        if (payload && typeof payload === 'object') {
            let errors = payload.error || payload.errors || payload.message || undefined;

            if (errors) {
                if (!isEmberArray(errors)) {
                    errors = [errors];
                }

                payload.errors = errors.map(function (error) {
                    if (typeof error === 'string') {
                        return {message: error};
                    } else {
                        return error;
                    }
                });
            }
        }

        return this._super(status, headers, payload);
    },

    isVersionMismatchError(status, headers, payload) {
        return isVersionMismatchError(status, payload);
    },

    isServerUnreachableError(status) {
        return isServerUnreachableError(status);
    },

    isRequestEntityTooLargeError(status) {
        return isRequestEntityTooLargeError(status);
    },

    isUnsupportedMediaTypeError(status) {
        return isUnsupportedMediaTypeError(status);
    },

    isMaintenanceError(status, headers, payload) {
        return isMaintenanceError(status, payload);
    },

    isThemeValidationError(status, headers, payload) {
        return isThemeValidationError(status, payload);
    }
});

// we need to reopen so that internal methods use the correct contentType
ajaxService.reopen({
    contentType: 'application/json; charset=UTF-8'
});

export default ajaxService;