// This file is part of photo21
// Copyright (C) 2022  Amicale des élèves de l'ENS Paris-Saclay
// SPDX-License-Identifier: GPL-3.0-or-later

// When user drags files, register them in the file field
const dropZone = document.getElementById('drop_zone');
const uploadInput = document.getElementById('id_file_field');
const form = document.getElementById('upload_form');

dropZone.ondrop = function (e) {
    e.preventDefault();
    this.className = 'upload-drop-zone';
    uploadInput.files = e.dataTransfer.files;
};

dropZone.ondragover = function () {
    this.className = 'upload-drop-zone drop';
    return false;
};

dropZone.ondragleave = function () {
    this.className = 'upload-drop-zone';
    return false;
};

// When user selects an existing gallery, disable new gallery fields
const gallerySelect = document.getElementById('id_gallery');
gallerySelectUpdate = () => {
    const useGallery = (gallerySelect.value !== "");
    document.getElementById('id_new_gallery_title').disabled = useGallery;
    document.getElementById('id_new_gallery_date_start').disabled = useGallery;
    document.getElementById('id_new_gallery_date_end').disabled = useGallery;
    document.getElementById('id_new_gallery_tags').disabled = useGallery;
    document.getElementById('id_new_gallery_description').disabled = useGallery;
};
gallerySelect.addEventListener('change', gallerySelectUpdate);
gallerySelectUpdate();

// Hide basic submit button
const submitbtn = document.getElementById('submit-id-submit');
submitbtn.style.display = 'none';

// Create upload + pause buttons in a flex row
const btnWrap = document.createElement('div');
btnWrap.className = 'd-flex align-items-center gap-2 mt-2';

const ctnbtn = document.createElement('button');
ctnbtn.className = submitbtn.className.replace(/\bmt-\d\b/g, '').trim();
ctnbtn.type = 'button';
ctnbtn.textContent = gettext('Upload');

const pausebtn = document.createElement('button');
pausebtn.className = 'btn btn-warning';
pausebtn.type = 'button';
pausebtn.textContent = gettext('Pause');
pausebtn.style.display = 'none';

btnWrap.appendChild(ctnbtn);
btnWrap.appendChild(pausebtn);
form.appendChild(btnWrap);

// Create progress bar
const progressWrap = document.createElement('div');
progressWrap.className = 'progress mt-3';
progressWrap.style.display = 'none';
const progressBar = document.createElement('div');
progressBar.className = 'progress-bar progress-bar-striped progress-bar-animated';
progressBar.setAttribute('role', 'progressbar');
progressBar.style.width = '0%';
progressWrap.appendChild(progressBar);

// Concurrency label
const concurrencyLabel = document.createElement('small');
concurrencyLabel.className = 'text-muted mt-1';
concurrencyLabel.style.display = 'none';

form.appendChild(progressWrap);
form.appendChild(concurrencyLabel);

let pause = false;
let uploading = false;

function beforeUnloadHandler(e) {
    e.preventDefault();
}
window.addEventListener('beforeunload', (e) => { if (uploading) beforeUnloadHandler(e); });

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

pausebtn.addEventListener('click', () => {
    pause = !pause;
    pausebtn.textContent = pause ? gettext('Resume') : gettext('Pause');
    pausebtn.className = pause ? 'btn btn-success' : 'btn btn-warning';
});

async function uploadFile(file, galleryID, csrfvalue) {
    const sendform = new FormData();
    sendform.append('csrfmiddlewaretoken', csrfvalue);
    sendform.append('file_field', file);
    sendform.append('gallery', galleryID);
    const start = performance.now();
    const res = await fetch('/upload/', {
        method: 'POST',
        body: sendform,
        headers: { 'Accept': 'application/json' }
    });
    if (!res.ok) {
        let detail = '';
        try { const j = await res.json(); detail = j.error || ''; } catch (_) {}
        console.error('Error with ' + file.name + ' (HTTP ' + res.status + ')' + (detail ? ': ' + JSON.stringify(detail) : ''));
    }
    return performance.now() - start;
}

ctnbtn.addEventListener('click', async () => {
    const files = Array.from(uploadInput.files);
    if (!files.length) {
        window.alert(gettext('Please select files first.'));
        return;
    }

    uploading = true;
    ctnbtn.disabled = true;

    const csrfvalue = document.getElementsByName('csrfmiddlewaretoken')[0].value;
    const total = files.length;
    let completed = 0;

    // Create gallery / validate form
    const fdata = new FormData(uploadInput.form);
    fdata.delete('file_field');
    const response = await fetch('/upload/', {
        method: 'POST',
        body: fdata,
        headers: { 'Accept': 'application/json' }
    });
    const returned = await response.json();

    if (returned.code != 200) {
        const msgs = Object.entries(returned.error).map(([f, e]) => f + ': ' + e.join(', ')).join('\n');
        window.alert(msgs);
        ctnbtn.disabled = false;
        return;
    }

    const galleryID = returned.galleryID;

    uploadInput.disabled = true;
    gallerySelect.disabled = true;
    dropZone.style.pointerEvents = 'none';
    pausebtn.style.display = 'inline-block';
    progressWrap.style.display = 'flex';
    concurrencyLabel.style.display = 'block';

    // Auto-tuning state
    const MIN_CONCURRENCY = 1;
    const MAX_CONCURRENCY = 6;
    let concurrency = 1;
    let lastRate = null;
    let lastMeasureTime = performance.now();
    let lastCompleted = 0;

    function updateProgress() {
        const pct = Math.round(100 * completed / total);
        progressBar.style.width = pct + '%';
        progressBar.textContent = pct + '% (' + completed + '/' + total + ')';
        concurrencyLabel.textContent = gettext('Parallel uploads:') + ' ' + concurrency;
    }

    function tuneConcurrency() {
        const now = performance.now();
        const elapsed = now - lastMeasureTime;
        if (elapsed < 1000) return;
        const rate = (completed - lastCompleted) / elapsed;
        lastMeasureTime = now;
        lastCompleted = completed;
        if (lastRate === null || rate > lastRate * 1.05)
            concurrency = Math.min(concurrency + 1, MAX_CONCURRENCY);
        else if (rate < lastRate * 0.90)
            concurrency = Math.max(concurrency - 1, MIN_CONCURRENCY);
        lastRate = rate;
    }

    // Parallel worker pool
    const queue = [...files];
    let active = 0;

    await new Promise((resolve) => {
        function next() {
            if (completed === total) { resolve(); return; }

            while (!pause && active < concurrency && queue.length > 0) {
                const file = queue.shift();
                active++;
                uploadFile(file, galleryID, csrfvalue)
                    .catch(e => console.error(e))
                    .finally(() => { completed++; tuneConcurrency(); active--; updateProgress(); next(); });
            }

            if (pause && active === 0 && queue.length > 0)
                setTimeout(next, 200);
        }
        next();
    });

    // Finalize
    const fend = new FormData(uploadInput.form);
    fend.delete('file_field');
    fend.delete('new_gallery_title');
    fend.delete('new_gallery_date_start');
    fend.delete('new_gallery_date_end');
    fend.append('gallery', galleryID);
    fend.append('end', 'end');
    await fetch('/upload/', {
        method: 'POST',
        body: fend,
        headers: { 'Accept': 'application/json' }
    });

    uploading = false;
    uploadInput.disabled = false;
    gallerySelect.disabled = false;
    dropZone.style.pointerEvents = '';
    pausebtn.style.display = 'none';
    progressBar.classList.remove('progress-bar-animated');
    progressBar.textContent = gettext('Upload complete — please reload the page');
    concurrencyLabel.textContent = gettext('Best concurrency found:') + ' ' + concurrency;
});