function clearData(){
    localStorage.removeItem('db_name');
    location.href = "/"
}

document.addEventListener('DOMContentLoaded', async () => {
    const fileInput = document.getElementById('fileInput');
    const queryForm = document.getElementById('queryForm');
    const chatContainer = document.getElementById('chatContainer');
    const exportButton = document.getElementById('exportButton');
    const previewFrame = document.getElementById('filePreview');

    let dbName = localStorage.getItem('db_name') || "";
    let history = [];

    async function navToPage(pageNumber) {
        pageNumber = pageNumber.replace('p.', '');
    
        if (!dbName) return;
    
        try {
            const response = await fetch(`/preview/${dbName}`);
            
            if (!response.ok) throw new Error('Failed to fetch PDF');
    
            const blob = await response.blob();
            const blobUrl = URL.createObjectURL(blob);
    
            previewFrame.src = `${blobUrl}#page=${pageNumber}`;
        } catch (e) {
            console.error('Error loading PDF:', e);
            previewFrame.src = `/preview/${dbName}#page=1`;
        }
    }
    

    window.navToPage = navToPage; 

    async function loadChatHistory() {
        try {
            const response = await fetch(`/get_history/${dbName}`);
            
            if (response.ok) {
                const result = await response.json();
                history = result.history;

                history.forEach(([ query, response]) => {
                    appendMessage(query, 'user');
                    appendFormattedMessage(response, sources=[], 'bot');
                });

                navToPage('p.1');
            } else {
                console.log("No history found or error fetching history.");
            }
        } catch (error) {
            console.error("Failed to load chat history:", error);
        }
    }

    async function verifyDb() {
        if (!dbName) return;

        try {
            const response = await fetch(`/check_db/${dbName}`); 
            if (response.ok) {
                loadChatHistory(); 
            } else {
                console.log("DB not found, clearing cache.");
                localStorage.removeItem('db_name');
                dbName = "";
            }
        } catch (error) {
            console.error("Failed to verify DB:", error);
            localStorage.removeItem('db_name');
            dbName = "";
        }
    }

    if (dbName) {
        verifyDb();
    }

    // FIle Upload
    fileInput.addEventListener('change', async () => {
        const formData = new FormData();
        formData.append('file', fileInput.files[0]);

        const response = await fetch('/ingest', {
            method: 'POST',
            body: formData
        });

        const result = await response.json();

        if (response.ok) {
            dbName = result.db_name;
            localStorage.setItem('db_name', dbName);

            navToPage('p.1');
            appendMessage(`📄 File uploaded successfully`, 'bot');
        } else {
            appendMessage(`❌ Error: ${result.error}`, 'bot');
        }
    });

    exportButton.addEventListener('click', async () => {
        if (!dbName) return;

        const url = `/export_chat/${dbName}`;
        const link = document.createElement('a');
        link.href = url;
        link.download = `chat_history_${dbName}.pdf`;
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
    });

    // RAG Queries
    queryForm.addEventListener('submit', async (e) => {
        e.preventDefault();
        const queryInput = document.getElementById('queryInput').value;

        appendMessage(queryInput, 'user');

        const response = await fetch('/query', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ query: queryInput, db_name: dbName })
        });

        const result = await response.json();

        if (response.ok) {
            appendFormattedMessage(result.response, result.sources, 'bot');
            
            if (result.sources.length > 0) {
                navToPage(result.sources[0]);
            }
            
            history.push({ query: queryInput, response: result.response, sources: result.sources });
        } else {
            appendMessage(`❌ Error: ${result.error}`, 'bot');
        }
    });

    // Response 
    function appendFormattedMessage(message, sources, type) {
        const messageDiv = document.createElement('div');
        messageDiv.classList.add('chat-message', type === 'user' ? 'user-message' : 'bot-message');

        const contentDiv = document.createElement('div');
        contentDiv.classList.add('message-content');

        contentDiv.innerHTML = message.replace('\n', '<br>');

        if (sources.length > 0) {
            const sourceDiv = document.createElement('div');
            sourceDiv.classList.add('source-info');
            sourceDiv.innerHTML = `<small>Sources: </small>`;

            sources.forEach(source => {
                sourceDiv.innerHTML += `<small class="source" onclick="navToPage('${source}')"> ${source}</small>`;
            });

            contentDiv.appendChild(sourceDiv);
        }

        messageDiv.appendChild(contentDiv);
        chatContainer.appendChild(messageDiv);
        chatContainer.scrollTop = chatContainer.scrollHeight;
    }

    // Message
    function appendMessage(message, type) {
        const messageDiv = document.createElement('div');
        messageDiv.classList.add('chat-message', type === 'user' ? 'user-message' : 'bot-message');
        messageDiv.innerHTML = `<p>${message}</p>`;
        chatContainer.appendChild(messageDiv);
        chatContainer.scrollTop = chatContainer.scrollHeight;
    }
});