import { exec } from 'child_process';
import * as fs from 'fs';

// Config for scheduling the next time the main process (sending of horoscope) is run
interface Config {
  daysInterval: number;
  timeOfDay: string;
  emailReceiver: string;
  mailHost: string;
  mailPort: number;
}

// Node structure for the Parse Tree (it's a degenerated tree with one or zero children per node)
interface Node {
  type: "Root" | "Hexagram" | "Judgement" | "Images" | "ChangingLines" ;
  child?: Node;
  value?: string;
}

var config : Config;

const nodemailer = require('nodemailer');

function executeCommand(): void {

  exec('iching divine', (error, stdout, stderr) => {

    console.log(`Begin`);

    if (error) {
        console.error(`Error: ${error.message}`);
        return;
    }

    if (stderr) {
        console.error(`Stderr: ${stderr}`);
        return;
    }

    //Load config once
    if (config == undefined) {
      config = loadConfig();
    } 

    console.log(`Send E-Mail`);
    sendEmail(stdout);

    // Calculate next execution time
    const nextRunDate = calculateNextRunDate(config.daysInterval, config.timeOfDay);
    console.log(`Next execution: ${nextRunDate}`);    

    // Start Scheduling
    scheduleNextRun(nextRunDate);
  });
}

// Run function once initially, called from Dockerfile
executeCommand();

// Load the Configuration
function loadConfig(): Config {

  console.log(`Load Config`);
  
  const data = fs.readFileSync('config.json', 'utf-8');
  return JSON.parse(data);
}

// Send E-Mail
async function sendEmail(content: string) {

  // Create Transporter
  const transporter = nodemailer.createTransport({
    //host: "mailhog.mailhog.svc.cluster.local", // MailHog ClusterIP
    host: config.mailHost,
    //port: 1025,         // Standard-MailHog SMTP-Port
    port: config.mailPort,
    secure: false       // MailHog needs no encryption
  });


  try {
    const info = await transporter.sendMail({
      from: '"The Oracle" <the.oracle@holy.mountain>',
      to: config.emailReceiver,
      subject: "Your Horoscope Is Ready",
      text: content,
      html: html(content)
    });

    console.log("E-Mail sent: ", info.messageId);
  } catch (error) {
    console.error("Error Sending E-Mail:", error);
  }
}

//Calculate the time for the next execution of the main process, depending on configuration.
//Returns the time of the next process loop.
function calculateNextRunDate(daysInterval: number, timeOfDay: string): Date {
  const currentDate = new Date();
  
  // Splitte die Uhrzeit in Stunden und Minuten
  const [hours, minutes] = timeOfDay.split(':').map(Number);

  // Berechne das Datum für die nächste Ausführung
  currentDate.setHours(hours, minutes, 0, 0); // Setze die Uhrzeit auf Y (z.B. 14:30)

  // Wenn die Uhrzeit bereits vorbei ist, verschiebe das Datum auf den nächsten Tag
  if (currentDate < new Date()) {
    currentDate.setDate(currentDate.getDate() + 1); // Setze auf den nächsten Tag
  }

  // Berechne das Datum für den nächsten Ausführungszeitpunkt unter Berücksichtigung von X Tagen
  currentDate.setDate(currentDate.getDate() + daysInterval);

  return currentDate;

  //TODO: JUST FOR DEBUGGING!!!
  /*currentDate.setMinutes(currentDate.getMinutes() + 2); 
  return currentDate;*/
}

//Schedule the next process loop.
function scheduleNextRun(nextRunDate: Date) {
  const now = new Date();
  const timeUntilNextRun = nextRunDate.getTime() - now.getTime();

  if (timeUntilNextRun > 0) {
    setTimeout(() => {
      console.log('Prozess wird ausgeführt!');

      //run the main process
      executeCommand();

    }, timeUntilNextRun);
  }
}

// Generate 1) Parse Tree and 2) HTML
export function html(inputText: string): string {
  const parseTree = parse(inputText);
  const htmlOutput = render(parseTree);

  return htmlOutput;
}

// Generate the Parse Tree
function parse(input: string): Node {

  console.log("Parse input text");

  const root: Node = { type: "Root"};
  var currentNode: Node = root;

  const lines = input.split("\n");

  for (const line of lines) {
    if (line.startsWith("Hexagram")) {
      const hexagram: Node = { type: "Hexagram"};
      currentNode.child = hexagram;
      currentNode = hexagram;
      currentNode.value = "<h1>" + line + "</h1>";
    } else if (line.startsWith("Judgement")) {
      const judgement: Node = { type: "Judgement"};
      currentNode.child = judgement;
      currentNode = judgement;
      currentNode.value = "<h3>" + line + "</h3>";
    } else if (line.startsWith("Images")) {
      const images: Node = { type: "Images"};
      currentNode.child = images;
      currentNode = images;
      currentNode.value = "<h3>" + line + "</h3>";
    } else if (line.startsWith("~") && currentNode.type != "ChangingLines") {
      const changingLines: Node = { type: "ChangingLines"};
      currentNode.child = changingLines;
      currentNode = changingLines;
      currentNode.value = line; // + "<br>";  TODO: try without this <br>
    } else {
      currentNode.value = currentNode.value + line + "<br>";
    }
  }

  return root;
}

// Generate HTML from Parse Tree
function render(node: Node): string {

  if (node == undefined) {
    console.log("...finished...")

    return "";
  }

  console.log("Render node" + node.type);

  var outputHTML: string = "";

  switch (node.type) {
    case "Root":
      return render(node.child!);
    case "Hexagram":      
      node.value = node.value?.replace("<h1>", "<div style=\"border: 1px dotted gray; border-radius: 10px; padding-left: 10px; padding-right: 10px; padding-top: 10px; padding-bottom: 10px; width: auto; display: inline-block; box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.2);\"><h1>");
      node.value = node.value?.replace("</h1>", "</h1><div style=\"border: 1px solid gray; border-radius: 25px; padding-left: 30px; padding-right: 30px; padding-top: 20px; width: auto; display: inline-block; text-align: center; box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.2);\"><h2>"); 
      node.value = node.value?.replace("<br>", "  -  ");
      outputHTML = "<br><p>" + node.value + "</h2></div></p>";
      outputHTML = outputHTML + render(node.child!);

      return outputHTML;

    case "Images":
      outputHTML = "<p>" + node.value + "</p></div>"; //EXTRA closing div
      outputHTML = outputHTML + render(node.child!);

      return outputHTML;      

    case "ChangingLines" :
      const regex = new RegExp("~", "g");
      node.value = node.value?.replace(regex, "");
      //outputHTML = "<br><p><div style=\"border: 1px dashed gray; border-radius: 10px; padding-left: 10px; padding-right: 10px; padding-top: 10px; width: auto; display: inline-block; color: gray; text-align: center; box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.2);\">" + node.value + "</div></p><br>";
      outputHTML = "<br><br><p><div style=\"padding-left: 20px; padding-right: 20px; padding-top: 20px; display: inline-block; color: gray; text-align: center;\">" + node.value + "</div></p><br>";
      outputHTML = outputHTML + render(node.child!);

      return outputHTML;

    default:
      outputHTML = "<p>" + node.value + "</p>";
      outputHTML = outputHTML + render(node.child!);

      return outputHTML;
  }


}