patch.js

function base64ToUrl(base64, mimeType = '') {
    // Split the base64 string if it contains a data URL prefix
    const [prefix, data] = base64.includes(',') ? base64.split(',') : ['', base64];
  
    // Try to extract the MIME type from the prefix if not provided
    const mime = mimeType || (prefix.match(/data:(.*?);base64/) || [])[1] || 'application/octet-stream';
  
    // Decode base64 to raw binary data
    const binary = atob(data);
    const len = binary.length;
    const bytes = new Uint8Array(len);
    for (let i = 0; i < len; i++) {
      bytes[i] = binary.charCodeAt(i);
    }
  
    // Create a blob and generate a URL
    const blob = new Blob([bytes], { type: mime });
    return URL.createObjectURL(blob);
  }
  
function getElementByXpath(path, timeout = 5000) {
    return new Promise((resolve, reject) => {
        const intervalTime = 500;
        let elapsedTime = 0;
        const interval = setInterval(() => {
            let node = document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
            if (node) {
                clearInterval(interval);
                resolve(node);
            }
            elapsedTime += intervalTime;
            if (elapsedTime >= timeout) {
                clearInterval(interval);
                reject(new Error(`XPath "${path}" not found within ${timeout}ms`));
            }
        }, intervalTime);
    });
}

async function uploadFileFromURL(url, filename, file_element) {
    try {
        if (!file_element) throw new Error("File input element not found.");
        const response = await fetch(url);
        if (!response.ok) throw new Error(`Failed to fetch file: ${response.statusText}`);
        const blob = await response.blob();
        const newFile = new File([blob], filename, { type: blob.type });
        const dataTransfer = new DataTransfer();
        if (file_element.multiple) {
            for (const file of file_element.files) {
                dataTransfer.items.add(file);
            }
        }
        dataTransfer.items.add(newFile);
        file_element.files = dataTransfer.files;
        file_element.dispatchEvent(new Event("change", { bubbles: true }));
    } catch (error) {
        console.error("Error:", error);
    }
}

function waitForElement(selector, timeout = 5000) {
    return new Promise((resolve, reject) => {
        const intervalTime = 500;
        let elapsedTime = 0;

        const interval = setInterval(() => {
            const element = document.querySelector(selector);
            if (element) {
                clearInterval(interval);
                resolve(element);
            }

            elapsedTime += intervalTime;
            if (elapsedTime >= timeout) {
                clearInterval(interval);
                reject(new Error(`Element "${selector}" not found within ${timeout}ms`));
            }
        }, intervalTime);
    });
}

document.addEventListener("DOMContentLoaded", function () {
    getElementByXpath("//*[text()='Hide top bar']", 5000)
        .then((node) => {
            node.scrollIntoView();
            node.click();
            return waitForElement("#midi_file_input");
        })
        .then((file_upload) => {
            if (!file_upload) throw new Error("File input element not found.");

            // Wait for stability before proceeding
            return new Promise(resolve => setTimeout(() => resolve(file_upload), 500));
        })
        .then((file_upload) => {
            return waitForElement(".show_top_button").then((node) => {
                node.remove();
                selector = document.getElementById("renderer_mode_selector");
                selector.selectedIndex = 2;
                selector.dispatchEvent(new Event('change'));
                // return uploadFileFromURL("/output.mid", "output.mid", file_upload);
            });
        })
        .catch((error) => {
            console.error("Error:", error);
        });
});
window.addEventListener("message", async (event) => {
    if (event.data?.type === "load-midi" && event.data.name) {
        const url = event.data.url;
        const file_name = event.data.name
        const input = document.getElementById("midi_file_input");
        if (url && input) {
            await uploadFileFromURL(url, file_name, input);
        }
    }
});