email.js

const { cleanHTML, isValidEmail, isValidString } = require("../helpers/parseInput")
const { sgSendEmail } = require("../services/sendGrid")
const { pmSendEmail } = require("../services/postMark")
const { logEmail, logStatus } = require("./datastore")

/**
 * Ensures that the required parameters are valid and cleans the HTML body
 * @param { {} } params The parameters received
 * @param { Boolean } enableHtmlEmail Whether HTML emails are enabled
 * @param { [] } allowedHtmlTags If HTML emails is enabled, then the HTML tags that are allowed
 * @returns { {} } A dictionary of the cleaned parameters. On error, returns an error object with the reason
 */
exports.precheckParams = (params, enableHtmlEmail=false, allowedHtmlTags=[]) => {
    let requiredParams = { 
        to: params.to, 
        to_name: params.to_name, 
        from: params.from, 
        from_name: params.from_name, 
        subject: params.subject, 
        body: params.body 
    }

    // Ensure we have the required parameters and they are all strings
    let missingParams = Object.keys(requiredParams).filter((key) => {
        if (!requiredParams[key] || !isValidString(requiredParams[key])) return key
    })

    if (missingParams.length > 0) {
        throw Error(`Missing required parameters: ${missingParams.join(", ")}. They must be strings.`)
    }

    // Ensure the email addresses are valid
    if (requiredParams.to && !isValidEmail(requiredParams.to) || requiredParams.from && !isValidEmail(requiredParams.from)) {
		throw Error(`An email address is invalid. Emails addresses given: ${requiredParams.to}, ${requiredParams.from}`)
	}

    let cleanBody = cleanHTML(requiredParams.body, allowedHtmlTags)
	return { ...requiredParams, body: cleanBody, isHTML: enableHtmlEmail }
}

/**
 * Sends email via Sendgrid and if that fails, retries to send via Postmark
 * @param { {} } params The parsed and clean parameters
 */
exports.sendEmail = async (params) => {
    let service = "SendGrid"
    try {
        await sgSendEmail({ ...params })
        logStatus({ message: "Successfully sent email via Sendgrid" })
    } catch (e) {
        let message = `Error sending with Sendgrid: ${e.message}`
        await pmSendEmail({ ...params }).catch(e => {
            throw Error(`${message}, unable to send via Postmark: ${e.message}`) 
        })
        logStatus({ message: `${message}. Sent via PostMark instead!`})
        service = "PostMark"
    }
    logEmail({ params, meta: { service, sent: Date.now() } })
}