Entity.js

/**
 * Expose the Entity class.
 */
module.exports = Entity;

/**
 * Dependencies.
 */
const rfc2047 = require('rfc2047');
const debug = require('debug')('mimemessage:Entity');
const debugerror = require('debug')('mimemessage:ERROR:Entity');
const grammar = require('./grammar');
const parseHeaderValue = require('./parse').parseHeaderValue;
const encoding = require('./encoding');

debugerror.log = console.warn.bind(console);

function Entity() {
    debug('new()');

    this.headers = {};
    this.internalBody = null;
}

Entity.prototype.contentType = function(value) {
    // Get.
    if (!value && value !== null) {
        return this.headers['Content-Type'];
        // Set.
    }
    if (value) {
        this.headers['Content-Type'] = parseHeaderValue(grammar.headerRules['Content-Type'], value);
        // Delete.
    } else {
        delete this.headers['Content-Type'];
    }
};

Entity.prototype.contentDisposition = function(value) {
    // Get.
    if (!value && value !== null) {
        return this.headers['Content-Disposition'];
        // Set.
    }
    if (value) {
        this.headers['Content-Disposition'] = parseHeaderValue(grammar.headerRules['Content-Disposition'], value);
        // Delete.
    } else {
        delete this.headers['Content-Disposition'];
    }
};

Entity.prototype.contentTransferEncoding = function(value) {
    const contentTransferEncoding = this.headers['Content-Transfer-Encoding'];

    // Get.
    if (!value && value !== null) {
        return contentTransferEncoding ? contentTransferEncoding.value : undefined;
        // Set.
    }
    if (value) {
        this.headers['Content-Transfer-Encoding'] = parseHeaderValue(
            grammar.headerRules['Content-Transfer-Encoding'],
            value
        );
        // Delete.
    } else {
        delete this.headers['Content-Transfer-Encoding'];
    }
};

Entity.prototype.header = function(name, value) {
    const headername = grammar.headerize(name);

    // Get.
    if (!value && value !== null) {
        if (this.headers[headername]) {
            return this.headers[headername].value;
        }
        // Set.
    } else if (value) {
        this.headers[headername] = {
            value
        };
        // Delete.
    } else {
        delete this.headers[headername];
    }
};

Object.defineProperty(Entity.prototype, 'body', {
    get() {
        return this.internalBody;
    },
    set(body) {
        if (body) {
            setBody.call(this, body);
        } else {
            delete this.internalBody;
        }
    }
});

Entity.prototype.isMultiPart = function() {
    const contentType = this.headers['Content-Type'];

    return contentType && contentType.type === 'multipart';
};

Entity.prototype.toString = function(options = { noHeaders: false, unicode: false }) {
    let raw = '';
    const contentType = this.headers['Content-Type'];

    const encode = options.unicode ? (x) => x : rfc2047.encode;

    if (!options.noHeaders) {
        // MIME headers.

        const headers = Object.keys(this.headers).map(
            (name) => {
                const val = this.headers[name].value;
                const list = val.split(';').map((val) => val.split('=').map(encode).join('='));
                return name + ': ' + list.join(';') + '\r\n';
            }
        );
        raw = headers.join('') + '\r\n';
    }

    // Body.
    if (Array.isArray(this.internalBody)) {
        const boundary = contentType.params.boundary;

        let i;
        const len = this.internalBody.length;
        for (i = 0; i < len; i++) {
            if (i > 0) {
                raw += '\r\n';
            }
            raw += '--' + boundary + '\r\n' + this.internalBody[i].toString(options);
        }
        raw += '\r\n--' + boundary + '--';
    } else if (typeof this.internalBody === 'string') {
        const { value } = this.headers['Content-Transfer-Encoding'] || {};
        const { params: { charset = '' } = {} } = this.contentType() || {};
        const transform = [];

        if (charset.replace(/-/g, '').toLowerCase() === 'utf8') {
            transform.push(encoding.encodeUTF8);
        }

        if (value === 'base64') {
            transform.push(encoding.encodeBase64);
        } else if (value === 'quoted-printable') {
            transform.push(encoding.encodeQP);
        }

        raw += transform.reduce((body, cb) => cb(body), this.internalBody);
    } else if (typeof this.internalBody === 'object') {
        raw += JSON.stringify(this.internalBody);
    }

    return raw;
};

const random16bitHex = () =>
    Math.floor(Math.random() * (2 << 15))
        .toString(16)
        .padStart(4, 0);
const random128bitHex = () =>
    new Array(8)
        .fill(null)
        .map(random16bitHex)
        .join('');

const generateBoundary = () => `---------------------${random128bitHex()}`;

/**
 * Private API.
 */

function setBody(body) {
    const contentType = this.headers['Content-Type'];

    this.internalBody = body;

    // Multipart internalBody.
    if (Array.isArray(body)) {
        if (!contentType || contentType.type !== 'multipart') {
            this.contentType('multipart/mixed;boundary=' + generateBoundary());
        } else if (!contentType.params.boundary) {
            this.contentType(contentType.fulltype + ';boundary=' + generateBoundary());
        }
        // Single internalBody.
    } else if (!contentType || contentType.type === 'multipart') {
        this.contentType('text/plain;charset=utf-8');
    }
}