const pretext = "root@baipyr.us:~# ";
let startPosition = 0;
let cursorPosition = 0;
let cursorYOffset = 0;

const tbDiv = document.getElementById("textbox");
tbDiv.innerHTML = pretext+tbDiv.innerHTML;
const length = tbDiv.innerText.length+1;
startPosition = length;
cursorPosition = length;
const textIn = document.getElementById("input");
const textCur = document.getElementById("current");
const cursor = document.getElementById("cursor");
cursor.style.transform = `translate(${length-1}ch)`;

textIn.oninput = () => {
    textCur.textContent += textIn.value;
    textIn.value = "";
    cursorPosition++;
    updateCursor();
};
textIn.focus();

document.addEventListener("selectionchange", e => {
    if (e.target !== textIn) {
        const selection = window.getSelection();
        if (selection.type === "Caret")
            textIn.focus();
    }
});

document.addEventListener("keydown", e => {
    const index = cursorPosition - startPosition;
    const text = textCur.textContent;
    switch (e.key) {
        case "Backspace":
            // Ein Zeichen nach links löschen
            if (index === 0)
                return;
            if (index <= textCur.textContent.length-1) {
                const a = text.substring(0, index-1);
                const b = text.substring(index, text.length);
                textCur.textContent=a+b;
            } else
                textCur.textContent = text.substring(0,text.length-1);
            cursorPosition--;
            updateCursor();
            break;
        case "ArrowLeft":
            // Ein Zeichen nach links
            if (cursorPosition > startPosition) {
                cursorPosition--;
                updateCursor();
            }
            break;
        case "ArrowRight":
            // Ein Zeichen nach reckts
            if (index < textCur.textContent.length) {
                cursorPosition++;
                updateCursor();
            }
            break;
        case "Delete":
            // Ein Zeichen nach rechts löschen
            if (index === 0 || index >= textCur.textContent.length)
                return;
            const a = text.substring(0, index);
            const b = text.substring(index+1, text.length);
            textCur.textContent=a+b;
            break;
        case "Enter":
            // Befehl absenden / Zeilenumbruch
            const textIn = document.getElementById("input");
            tbDiv.removeChild(textIn);
            tbDiv.removeChild(textCur);

            // Run command and return output???
            let commandOutput = "";

            const aTag = str => `<a style="color: lightgrey;">${str}</a>`;
            if (commandOutput !== "") {
                commandOutput = `${aTag(commandOutput)}<br>`;
                cursorYOffset++;
            }
            tbDiv.innerHTML += `${aTag(text)}<br>${commandOutput}${pretext}`;
            textCur.textContent = "";
            tbDiv.appendChild(textCur);
            tbDiv.appendChild(textIn);
            cursorPosition = startPosition;
            cursorYOffset++;
            updateCursor();
            break;
        case "ArrowUp":
            // Einen Befehl zurück in der History
            break;
        case "ArrowDown":
            // Einen Befehl nach vorne in der History
            break;
        case "Tab":
            // Autocomplete
            break;
    }
});

function updateCursor() {
    let cursor = document.getElementById("cursor");
    cursor.style.transform = `translate(${cursorPosition-1}ch, ${cursorYOffset}em)`;
}

setInterval(()=>{
    cursor.style.opacity = !parseInt(cursor.style.opacity)+0;
},1000);