const tokenInput = document.querySelector('#token');
const ffmpegPathInput = document.querySelector('#ffmpeg-path');
const rememberTokenCheckbox = document.querySelector('#remember-token');
const setTokenButton = document.querySelector('#set-token');
const rememberFFmpegPathCheckbox = document.querySelector('#remember-ffmpeg-path');
const setFFmpegPathButton = document.querySelector('#set-ffmpeg-path');
const lessonInput = document.querySelector('#lesson-query');
const getLessonButton = document.querySelector('#get-lesson');
let token = localStorage.getItem('token') || '';
let ffmpegPath = localStorage.getItem('ffmpegPath') || '';

if (token !== '') {
    tokenInput.value = token;
    rememberTokenCheckbox.checked = true;
    fetch("/api/v1/token", {
        method: 'POST',
        body: token,
    }).then(rsp => {
        if (rsp.status !== 200) {
            setTokenButton.innerHTML = `:( (${rsp.status})`;
        }
    });
}

if (ffmpegPath !== '') {
    ffmpegPathInput.value = token;
    rememberFFmpegPathCheckbox.checked = true;
    fetch("/api/v1/ffmpeg-path", {
        method: 'POST',
        body: token,
    }).then(rsp => {
        if (rsp.status !== 200) {
            setTokenButton.innerHTML = `:( (${rsp.status})`;
        }
    });
}

function randomString(length) {
    return `a${Math.random().toString(36).slice(2, length + 2)}`;
}

// React simulator
function getResult() {
    const element = document.createElement("div");
    element.className = "block";
    document.body.appendChild(document.createElement("br"));
    document.body.appendChild(element);
    return element;
}

setTokenButton.addEventListener('click', async () => {
    token = tokenInput.value;
    const rsp = await fetch("/api/v1/token", {
        method: 'POST',
        body: token,
    });
    if (rsp.status !== 200) {
        setTokenButton.innerHTML = `:( (${rsp.status})`;
        return;
    }
    if (rememberTokenCheckbox.checked) {
        localStorage.setItem('token', token);
    } else {
        localStorage.removeItem('token');
    }
});

setFFmpegPathButton.addEventListener('click', async () => {
    ffmpegPath = ffmpegPathInput.value;
    const rsp = await fetch("/api/v1/ffmpeg-path", {
        method: 'POST',
        body: ffmpegPath,
    });
    if (rsp.status !== 200) {
        setFFmpegPathButton.innerHTML = `:( (${rsp.status})`;
        return;
    }
    if (rememberFFmpegPathCheckbox.checked) {
        localStorage.setItem('ffmpegPath', ffmpegPath);
    } else {
        localStorage.removeItem('ffmpegPath');
    }
});

getLessonButton.addEventListener('click', async () => {
    const input = lessonInput.value;
    let id = Number.parseInt(input);
    if (Number.isNaN(id)) {
        const url = input.split('/');
        url.pop();
        id = Number.parseInt(url.pop());
    }
    const rsp = await fetch(`/api/v1/lessons/${id}`);
    const result = getResult();
    const data = await rsp.json();
    const ids = {};
    // React :nerd:
    result.innerHTML = "<h2>Lesson Information</h2>\n";
    result.innerHTML += `Name: ${decodeURIComponent(data.name)}`;
    result.innerHTML += "<h3>Videos available</h3>";
    for (const video of data.videos) {
        const uniqueId = randomString(15);
        ids[uniqueId] = video;
        result.innerHTML += `
        <input type="checkbox" id="${uniqueId}" name="${uniqueId}" value="${uniqueId}">
        <label for="${uniqueId}">${decodeURIComponent(video.name)}</label>
        <br>`;
    }
    let videoDlResult = null;
    const promises = [];
    const downloadSelectedButton = document.createElement("button");
    downloadSelectedButton.innerHTML = "Download Selected";
    downloadSelectedButton.addEventListener('click', async () => {
        for (const [id, video] of Object.entries(ids)) {
            promises.push(async () => {
                const checkbox = document.querySelector(`#${id}`);
                // Disable the checkbox since the user can't download the same video twice
                checkbox.disabled = true;
                if (!checkbox.checked) {
                    return;
                }
                const videoRsp = await fetch(`/api/v1/videos/${video.id}`);
                if (videoRsp.status !== 200) {
                    console.error(`Failed to get video ${video.name}`);
                    return;
                }
                const videoData = await videoRsp.json();
                if (videoDlResult === null) {
                    result.appendChild(document.createElement("br"));
                    result.appendChild(document.createElement("br"));
                    videoDlResult = document.createElement("div");
                    videoDlResult.className = "block";
                    result.appendChild(videoDlResult);
                }
                const progressId = randomString(15);
                const progressStrId = randomString(15);
                videoDlResult.innerHTML += `<span>${video.name}.mp4 <progress id="${progressId}" value="0" max="100"></progress> <span id="${progressStrId}">0%</span></span><br>`
                const rsp = await fetch(`/api/v1/download-video?${new URLSearchParams({
                    url: encodeURIComponent(videoData.m3u8),
                    output: encodeURIComponent(`videos/${video.name}.mp4`),
                })}`);
                const reader = rsp.body.getReader();
                while (true) {
                    // wait for next encoded chunk
                    const { done, value } = await reader.read();
                     // check if stream is done
                    if (done) break;
                    // Decodes data chunk and yields it
                    const progress = Math.floor(Number.parseFloat(new TextDecoder().decode(value)));
                    document.querySelector(`#${progressId}`).value = progress;
                    document.querySelector(`#${progressStrId}`).innerText = `${progress}%`;
                }
                if (rsp.status !== 200) {
                    console.error(`Failed to download ${video.name}`);
                }
            });
        }
        await Promise.all(promises.map(p => p()));
    });
    result.appendChild(downloadSelectedButton);
    // result.innerHTML += "<button>Download All</button>";

});