import _ from "lodash";
import deepExtend from "deep-extend";
import { readFileSync, promises as fs } from "graceful-fs";
import moment from "moment";
import { htmlToText } from "nodemailer-html-to-text";

import { config } from "../config";
import Logger from "../logger";
import { editNodeUrl } from "../utils/urlBuilder";
import { Transporter } from "nodemailer";
import { MailData, Mail } from "../types";

const templateBasePath = __dirname + "/../mailTemplates";
const snippetsBasePath = templateBasePath + "/snippets";

const templateFunctions: {
    [key: string]:
        | ((name: string, data: MailData) => string)
        | ((data: MailData) => string)
        | ((href: string, text: string) => string)
        | ((unix: number) => string);
} = {};

function renderSnippet(this: any, name: string, data: MailData): string {
    const snippetFile = snippetsBasePath + "/" + name + ".html";

    return _.template(readFileSync(snippetFile).toString())(
        deepExtend(
            {},
            this, // parent data
            data,
            templateFunctions
        )
    );
}

function snippet(name: string): (this: any, data: MailData) => string {
    return function (this: any, data: MailData): string {
        return renderSnippet.bind(this)(name, data);
    };
}

function renderLink(href: string, text: string): string {
    // noinspection HtmlUnknownTarget
    return _.template(
        '<a href="<%- href %>#" style="color: #E5287A;"><%- text %></a>'
    )({
        href: href,
        text: text || href,
    });
}

function renderHR(): string {
    return '<hr style="border-top: 1px solid #333333; border-left: 0; border-right: 0; border-bottom: 0;" />';
}

function formatDateTime(unix: number): string {
    return moment.unix(unix).locale("de").local().format("DD.MM.YYYY HH:mm");
}

function formatFromNow(unix: number): string {
    return moment.unix(unix).locale("de").fromNow();
}

templateFunctions.header = snippet("header");
templateFunctions.footer = snippet("footer");

templateFunctions.monitoringFooter = snippet("monitoring-footer");

templateFunctions.snippet = renderSnippet;

templateFunctions.link = renderLink;
templateFunctions.hr = renderHR;

templateFunctions.formatDateTime = formatDateTime;
templateFunctions.formatFromNow = formatFromNow;

export function configureTransporter(transporter: Transporter): void {
    transporter.use(
        "compile",
        htmlToText({
            tables: [".table"],
        })
    );
}

export async function render(
    mailOptions: Mail
): Promise<{ subject: string; body: string }> {
    const templatePathPrefix = templateBasePath + "/" + mailOptions.email;

    const subject = await fs.readFile(templatePathPrefix + ".subject.txt");
    const body = await fs.readFile(templatePathPrefix + ".body.html");

    const data = deepExtend(
        {},
        mailOptions.data,
        {
            community: config.client.community,
            editNodeUrl: editNodeUrl(),
        },
        templateFunctions
    );

    try {
        return {
            subject: _.template(subject.toString())(data).trim(),
            body: _.template(body.toString())(data),
        };
    } catch (error) {
        Logger.tag("mail", "template").error(
            "Error rendering template for mail[" + mailOptions.id + "]:",
            error
        );
        throw error;
    }
}