// gmail_scanner.js

console.log("PhishGuard AI: Gmail Scanner loaded.");

// Gmail's DOM can change, but commonly the email text is stored in elements with class '.a3s' or '.ii.gt'
const EMAIL_BODY_SELECTOR = '.a3s, .ii.gt';

// Function to inject a visible warning banner into the Gmail UI
function injectWarningBanner(emailContainer, message) {
    // Prevent duplicate banners if one is already injected
    if (emailContainer.parentNode.querySelector('.phishguard-banner')) {
        return;
    }

    const banner = document.createElement('div');
    banner.className = 'phishguard-banner';
    
    // Styling the banner to look native but urgent, fitting Google's Material Design
    banner.style.backgroundColor = '#fce8e6';
    banner.style.color = '#c5221f';
    banner.style.border = '1px solid #faa59f';
    banner.style.borderRadius = '8px';
    banner.style.padding = '12px 16px';
    // Added margin to ensure it doesn't overlap text awkwardly
    banner.style.margin = '16px auto';
    banner.style.fontFamily = '"Google Sans", Roboto, Arial, sans-serif';
    banner.style.fontSize = '14px';
    banner.style.fontWeight = '500';
    banner.style.lineHeight = '20px';
    banner.style.display = 'flex';
    banner.style.alignItems = 'center';
    banner.style.boxShadow = '0 1px 2px 0 rgba(60,64,67,0.3), 0 1px 3px 1px rgba(60,64,67,0.15)';
    
    // Add SVG Icon for warning
    const iconSvg = `
        <svg focusable="false" width="24" height="24" viewBox="0 0 24 24" style="fill: #c5221f; margin-right: 16px; flex-shrink: 0;">
            <path d="M1 21h22L12 2 1 21zm12-3h-2v-2h2v2zm0-4h-2v-4h2v4z"></path>
        </svg>
    `;

    const textContent = document.createElement('span');
    textContent.innerText = message || '🚨 PhishGuard Warning: This email contains suspicious links.';

    // Construct the banner
    banner.innerHTML = iconSvg;
    banner.appendChild(textContent);

    // Insert banner at the top of the email container.
    // By inserting before the email container, we keep it visible at the top of the body.
    if (emailContainer.parentNode) {
        emailContainer.parentNode.insertBefore(banner, emailContainer);
    }
}


// Helper function to extract all unique URLs from the email body
function extractUrlsFromBody(emailContainer) {
    const links = emailContainer.querySelectorAll('a[href]');
    const urls = new Set(); // Use a Set to store unique URLs
    
    links.forEach(link => {
        const href = link.href;
        // Basic filter to ignore mailto: or javascript: links, and only keep http/https
        if (href && (href.startsWith('http://') || href.startsWith('https://'))) {
            urls.add(href);
        }
    });
    
    return Array.from(urls);
}

// Function to safely extract the sender's actual email address
function extractSenderEmail(emailContainer) {
    // Gmail usually groups each email message into a container block.
    // We traverse up to find a common parent containing both header and body.
    // '.kv' or 'table' or '.adn' is often the parent wrapper for an individual message.
    let messageWrapper = emailContainer.closest('.adn') || emailContainer.closest('.kv') || document;
    
    // The sender element usually has the class '.gD' and contains the 'email' attribute.
    const senderElement = messageWrapper.querySelector('.gD');
    
    if (senderElement && senderElement.getAttribute('email')) {
        return senderElement.getAttribute('email'); 
    }
    
    // Fallback: Sometimes the email address is enclosed in brackets inside a '.go' element.
    const fallbackSenderElement = messageWrapper.querySelector('.go');
    if (fallbackSenderElement && fallbackSenderElement.innerText) {
        // e.g. "<sender@example.com>" -> matched and extracted
        const match = fallbackSenderElement.innerText.match(/<([^>]+)>/);
        if (match && match[1]) {
            return match[1];
        }
    }
    
    return "Unknown Sender";
}

// Function to handle newly opened emails
function handleEmailOpened(emailContainer) {
    // Prevent re-scanning the same email element
    if (emailContainer.dataset.pgScanned === "true") {
        return;
    }
    
    console.log("PhishGuard AI: New email thread opened. Extracting data...");
    
    // Mark as scanned
    emailContainer.dataset.pgScanned = "true";
    
    // 1. Extract plain text content
    const emailBodyText = emailContainer.innerText;
    
    // 2. Extract embedded URLs
    const urls = extractUrlsFromBody(emailContainer);
    
    // 3. Extract sender email address
    const sender = extractSenderEmail(emailContainer);
    
    // 4. Extract subject line (.hP is a standard class for Gmail's main subject line)
    // Sometimes the subject might be in a '.bog' element. We'll default to 'h2.hP'.
    const subjectElement = document.querySelector('h2.hP') || document.querySelector('.bog');
    const subject = subjectElement ? subjectElement.innerText.trim() : "No Subject Found";
    
    // Package the extracted data into a JSON payload
    const emailPayload = {
        sender: sender,
        subject: subject,
        body: emailBodyText,
        urls: urls,
        timestamp: new Date().toISOString()
    };
    
    console.log("PhishGuard AI extracted payload:", emailPayload);
    
    // Send background message to service worker
    chrome.runtime.sendMessage(
        { 
            action: "analyzeEmail", 
            data: emailPayload 
        }, 
        (response) => {
            if (chrome.runtime.lastError) {
                console.error("PhishGuard AI: Error communicating with background script:", chrome.runtime.lastError);
                return;
            }
            
            console.log("PhishGuard AI Background Analysis Response:", response);
            
            // Assume the background script returns `response.analysis` containing `probability` or `isPhishing` flag
            const analysis = response && response.analysis ? response.analysis : {};
            
            if (analysis.isPhishing === true || analysis.probability > 0.70) {
                console.warn("PhishGuard AI: High risk email detected! Injecting banner...");
                injectWarningBanner(
                    emailContainer, 
                    '🚨 PhishGuard Warning: This email contains suspicious links and exhibits high-risk phishing behavior.'
                );
            }
        }
    );
}

// Set up a MutationObserver to watch for DOM changes
// This effectively detects when Gmail dynamically loads an individual email view into the DOM
const observer = new MutationObserver((mutationsList) => {
    for (const mutation of mutationsList) {
        if (mutation.type === 'childList') {
            mutation.addedNodes.forEach(node => {
                if (node.nodeType === Node.ELEMENT_NODE) {
                    // Check if the added node itself is the email body container
                    if (node.matches && node.matches(EMAIL_BODY_SELECTOR)) {
                        handleEmailOpened(node);
                    }
                    
                    // Also search securely within the added node structure for the email body
                    if (node.querySelectorAll) {
                        const emailBodies = node.querySelectorAll(EMAIL_BODY_SELECTOR);
                        emailBodies.forEach(body => handleEmailOpened(body));
                    }
                }
            });
        }
    }
});

// Start observing the document body for deeper added nodes (like when navigating between emails)
observer.observe(document.body, {
    childList: true,
    subtree: true
});

console.log("PhishGuard AI: MutationObserver is listening for email thread opens.");