const downloadsMap = new Map(); // downloadId -> { tabId, filename }

chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
    if (!msg || !msg.action) {
        sendResponse({ status: "unknown" });
        return;
    }

    if (msg.action === "videoProgressCompleted") {
        console.log('Video completed:', msg.videoId, 'name:', msg.name);
        sendResponse({ status: "success" });
        return;
    }

    if (msg.action === "startBackgroundDownload") {
        const url = msg.url;
        let filename = msg.filename || ('download_' + Date.now());

        if (!url) {
            sendResponse({ status: "error", message: "No URL provided" });
            return;
        }

        try {
            chrome.downloads.download(
                {
                    url: url,
                    filename: filename,
                    conflictAction: "uniquify",
                    saveAs: false
                },
                downloadId => {
                    if (chrome.runtime.lastError) {
                        console.error('chrome.downloads.download error:', chrome.runtime.lastError.message);
                        sendResponse({ status: "error", message: chrome.runtime.lastError.message });
                    } else {
                        const tabId = (sender && sender.tab && sender.tab.id) ? sender.tab.id : null;
                        downloadsMap.set(downloadId, { tabId, filename });
                        sendResponse({ status: "started", downloadId });
                    }
                }
            );
            return true;
        } catch (e) {
            console.error('Exception starting download', e);
            sendResponse({ status: "error", message: String(e) });
            return;
        }
    }

    sendResponse({ status: "ok" });
});

// Listen for download changes and forward progress/state to the tab
chrome.downloads.onChanged.addListener(delta => {
    const info = downloadsMap.get(delta.id);
    if (!info || !info.tabId) return;

    if (delta.bytesReceived) {
        chrome.downloads.search({ id: delta.id }, items => {
            const item = items && items[0];
            if (!item) return;

            const received = item.bytesReceived || 0;
            const total = item.totalBytes || 0;
            const percent = total > 0 ? Math.round(100 * received / total) : null;

            chrome.tabs.sendMessage(info.tabId, {
                action: 'downloadProgress',
                downloadId: delta.id,
                bytesReceived: received,
                totalBytes: total,
                percent
            }, () => { /* ignore response */ });
        });
    }

    if (delta.state && delta.state.current === 'complete') {
        chrome.tabs.sendMessage(info.tabId, {
            action: 'downloadComplete',
            downloadId: delta.id,
            filename: info.filename
        }, () => { /* ignore response */ });
        downloadsMap.delete(delta.id);
    }

    if (delta.state && delta.state.current === 'interrupted') {
        chrome.tabs.sendMessage(info.tabId, {
            action: 'downloadFailed',
            downloadId: delta.id,
            filename: info.filename,
            reason: delta.state && delta.state.current
        }, () => { /* ignore response */ });
        downloadsMap.delete(delta.id);
    }
});