// ==UserScript==
// @name         Soyjak.st File Hash Randomizer
// @namespace    http://tampermonkey.net/
// @version      1.2
// @description  Adds a "Hash Rand" checkbox to file uploads on soyjak.st that randomizes the file hash by appending randomized bytes.
// @author       You
// @match        https://soyjak.st/*
// @grant        none
// ==/UserScript==

(function () {
    'use strict';

    // -------------------------------------------------------------------------
    // Inject Hash Rand checkbox into a .tmb-container
    // -------------------------------------------------------------------------
    function injectCheckbox(container) {
        if (container.querySelector('.sf-hashrand-label')) return;
        const flags = container.querySelectorAll('.tmb-flag');
        if (!flags.length) return;

        const wrapper = document.createElement('div');
        wrapper.className = 'tmb-flag';
        wrapper.innerHTML = `<label class="sf-hashrand-label" style="cursor:pointer;">Hash Rand<input class="file-hashrand" type="checkbox"></label>`;
        flags[flags.length - 1].insertAdjacentElement('afterend', wrapper);
    }

    // -------------------------------------------------------------------------
    // Observe DOM for new .tmb-container elements
    // -------------------------------------------------------------------------
    function processContainer(container) {
        injectCheckbox(container);
    }

    // Initial sweep
    document.querySelectorAll('.tmb-container').forEach(processContainer);

    // Observer for dynamically added nodes (Normal reply box)
    new MutationObserver((mutations) => {
        for (const m of mutations) {
            for (const node of m.addedNodes) {
                if (!(node instanceof Element)) continue;
                if (node.classList.contains('tmb-container')) processContainer(node);
                else node.querySelectorAll('.tmb-container').forEach(processContainer);
            }
        }
    }).observe(document.body, { childList: true, subtree: true });

    // Interval sweep to catch dynamically spawned/cloned forms like the Quick Reply box
    setInterval(() => {
        document.querySelectorAll('.tmb-container:not(:has(.sf-hashrand-label))').forEach(processContainer);
    }, 500);

    // -------------------------------------------------------------------------
    // Generate a randomized byte array
    // -------------------------------------------------------------------------
    function getRandomBytes(length) {
        const bytes = new Uint8Array(length);
        crypto.getRandomValues(bytes);
        return bytes;
    }

    // -------------------------------------------------------------------------
    // Append randomized bytes to a File to alter its hash
    // -------------------------------------------------------------------------
    async function randomizeFileHash(file) {
        const randomBytes = getRandomBytes(64);
        const originalBuffer = await file.arrayBuffer();
        const newBuffer = new Uint8Array(originalBuffer.byteLength + randomBytes.byteLength);

        newBuffer.set(new Uint8Array(originalBuffer), 0);
        newBuffer.set(randomBytes, originalBuffer.byteLength);

        return new File([newBuffer], file.name, { type: file.type });
    }

    // -------------------------------------------------------------------------
    // Network interception — apply hash randomization on submit
    // -------------------------------------------------------------------------
    const origOpen = XMLHttpRequest.prototype.open;
    const origSend = XMLHttpRequest.prototype.send;

    XMLHttpRequest.prototype.open = function (method, url, ...rest) {
        this._interceptUrl = url;
        return origOpen.call(this, method, url, ...rest);
    };

    XMLHttpRequest.prototype.send = async function (body) {
        if (this._interceptUrl?.includes('/post.php') && body instanceof FormData) {
            // Tiny delay ensures the Quick Reply box has fully finalized its DOM
            // elements before we scan for the checkboxes
            await new Promise(r => setTimeout(r, 100));
            body = await patchFormData(body);
        }
        return origSend.call(this, body);
    };

    const origFetch = window.fetch;
    window.fetch = async function (input, init) {
        const url = typeof input === 'string' ? input : input?.url;
        if (url?.includes('/post.php') && init?.body instanceof FormData) {
            await new Promise(r => setTimeout(r, 100));
            init = { ...init, body: await patchFormData(init.body) };
        }
        return origFetch.call(this, input, init);
    };

    async function patchFormData(fd) {
        const containers = [...document.querySelectorAll('.tmb-container')];
        const newFd = new FormData();
        let fileIndex = 0;

        for (const [key, value] of fd.entries()) {
            if (value instanceof File) {
                const container = containers[fileIndex];

                // VICHAN CLONE FIX:
                // Because the Quick Reply box is a clone of the main form, vichan
                // ties the file data to the main form's index. We must check if ANY
                // container has the box ticked to bypass the clone disconnect.
                let shouldRandomize = container?.querySelector('.file-hashrand')?.checked ?? false;
                if (!shouldRandomize) {
                    shouldRandomize = document.querySelector('.file-hashrand:checked') !== null;
                }

                fileIndex++;

                let outFile = value;

                if (shouldRandomize) {
                    outFile = await randomizeFileHash(value);
                }

                newFd.append(key, outFile);
            } else {
                newFd.append(key, value);
            }
        }
        return newFd;
    }

})();