// ── Chat Widget JavaScript ──
// NOTE: Uses BASE_PATH from main.js (loaded before this file on index.html)

let chatSessionId = sessionStorage.getItem('chat_session');
if (!chatSessionId) {
    chatSessionId = 'sess-' + Date.now().toString(36) + '-' + Math.random().toString(36).slice(2, 10);
    sessionStorage.setItem('chat_session', chatSessionId);
}

let chatOpen = false;
let isSending = false;
let historyLoaded = false;
let usedQuestions = 0;
let maxQuestions = 10;
let limitReached = false;
let isAnonymous = false;

document.addEventListener('DOMContentLoaded', () => {
    const fab = document.getElementById('chat-fab');
    const panel = document.getElementById('chat-panel');
    const closeBtn = document.getElementById('chat-close');
    const sendBtn = document.getElementById('chat-send');
    const input = document.getElementById('chat-input');
    const fileInput = document.getElementById('chat-file');
    const uploadBtn = document.getElementById('chat-upload');
    const removeFileBtn = document.getElementById('remove-file');

    loadChatConfig();

    fab.addEventListener('click', () => {
        chatOpen = !chatOpen;
        panel.classList.toggle('open', chatOpen);
        if (chatOpen && !historyLoaded) {
            loadChatHistory();
            historyLoaded = true;
        }
        if (chatOpen) input.focus();
    });

    closeBtn.addEventListener('click', () => {
        chatOpen = false;
        panel.classList.remove('open');
    });

    sendBtn.addEventListener('click', sendMessage);
    input.addEventListener('keydown', e => {
        if (e.key === 'Enter' && !e.shiftKey) {
            e.preventDefault();
            sendMessage();
        }
    });

    uploadBtn.addEventListener('click', () => fileInput.click());
    fileInput.addEventListener('change', () => {
        const preview = document.getElementById('file-preview');
        const nameEl = document.getElementById('file-name');
        if (fileInput.files.length > 0) {
            nameEl.textContent = fileInput.files[0].name;
            preview.classList.add('show');
        }
    });
    removeFileBtn.addEventListener('click', () => {
        fileInput.value = '';
        document.getElementById('file-preview').classList.remove('show');
    });
});

async function loadChatConfig() {
    try {
        const resp = await fetch(BASE_PATH + '/api/chat/config');
        if (resp.ok) {
            const data = await resp.json();
            maxQuestions = data.max_questions || 10;
            usedQuestions = data.used_questions || 0;
            isAnonymous = !!data.anonymous;
            limitReached = usedQuestions >= maxQuestions;

            // For anonymous users, also check from session storage
            if (isAnonymous) {
                const storedUsed = parseInt(sessionStorage.getItem('anon_used_q') || '0');
                usedQuestions = storedUsed;
                limitReached = usedQuestions >= maxQuestions;
            }
        }
    } catch (e) { /* use defaults */ }
    const greetingEl = document.getElementById('greeting-msg');
    if (greetingEl) {
        if (isAnonymous) {
            greetingEl.textContent = `您好！我是AI职业助手。您当前为匿名访问，可提问${maxQuestions}次。如需更多次数，请联系管理员获取访问令牌。`;
        } else {
            greetingEl.textContent = `您好！我是AI职业助手，可以介绍候选人的背景、技能和经历，也支持上传JD进行匹配分析。您可提问${maxQuestions}次。`;
        }
    }
    updateCounter();
    updateInputState();
}

async function loadChatHistory() {
    try {
        const resp = await fetch(BASE_PATH + `/api/chat/history/${chatSessionId}`);
        if (!resp.ok) return;
        const history = await resp.json();
        for (const msg of history) {
            appendBubble(msg.role, msg.content);
        }
        scrollToBottom();
    } catch (e) {
        console.error('Failed to load history:', e);
    }
}

async function sendMessage() {
    if (isSending || limitReached) return;

    const input = document.getElementById('chat-input');
    const fileInput = document.getElementById('chat-file');
    const message = input.value.trim();
    const file = fileInput.files[0] || null;

    if (!message && !file) return;

    // Show user message
    let displayMsg = message;
    if (file) {
        displayMsg = message ? `${message}\n[附件: ${file.name}]` : `[附件: ${file.name}]`;
    }
    appendBubble('user', displayMsg);
    usedQuestions++;
    if (isAnonymous) {
        sessionStorage.setItem('anon_used_q', String(usedQuestions));
    }
    updateCounter();

    // Clear inputs
    input.value = '';
    fileInput.value = '';
    document.getElementById('file-preview').classList.remove('show');

    // Show typing indicator
    const typing = document.getElementById('typing-indicator');
    typing.classList.add('show');
    scrollToBottom();
    isSending = true;

    try {
        const formData = new FormData();
        formData.append('session_id', chatSessionId);
        formData.append('message', message);
        if (file) formData.append('file', file);

        const response = await fetch(BASE_PATH + '/api/chat', {
            method: 'POST',
            body: formData,
        });

        typing.classList.remove('show');

        if (!response.ok) {
            appendBubble('assistant', '抱歉，出现了错误，请稍后再试。');
            isSending = false;
            return;
        }

        const bubble = appendBubble('assistant', '');
        const reader = response.body.getReader();
        const decoder = new TextDecoder();
        let buffer = '';
        let fullText = '';

        while (true) {
            const { value, done } = await reader.read();
            if (done) break;
            buffer += decoder.decode(value, { stream: true });

            const lines = buffer.split('\n');
            buffer = lines.pop();

            for (const line of lines) {
                const trimmed = line.trim();
                if (!trimmed.startsWith('data:')) continue;
                const dataStr = trimmed.slice(5).trim();
                if (!dataStr) continue;
                try {
                    const data = JSON.parse(dataStr);
                    if (data.limit_reached) limitReached = true;
                    if (data.done) continue;
                    if (data.content) {
                        fullText += data.content;
                        bubble.textContent = fullText;
                        scrollToBottom();
                    }
                } catch (e) { /* skip */ }
            }
        }

        // Check if limit reached after this question
        if (usedQuestions >= maxQuestions) {
            limitReached = true;
        }
        updateInputState();
    } catch (e) {
        document.getElementById('typing-indicator').classList.remove('show');
        appendBubble('assistant', '网络异常，请稍后再试。');
    }

    isSending = false;
}

function updateCounter() {
    let counter = document.getElementById('question-counter');
    if (!counter) {
        counter = document.createElement('div');
        counter.id = 'question-counter';
        counter.style.cssText = 'text-align:center;font-size:12px;color:#94a3b8;padding:4px 0;border-bottom:1px solid #e2e8f0;';
        const header = document.querySelector('.chat-header');
        if (header) header.parentNode.insertBefore(counter, header.nextSibling);
    }
    const remaining = maxQuestions - usedQuestions;
    const label = isAnonymous ? '匿名提问剩余' : '剩余提问次数';
    counter.innerHTML = `${label}: ${remaining < 0 ? 0 : remaining} / ${maxQuestions}`;
    if (isAnonymous) {
        counter.innerHTML += `  <a href="#" onclick="enterToken();return false;" style="color:#3b82f6;text-decoration:underline;font-size:12px;">输入令牌</a>`;
    }
    counter.style.color = remaining <= 2 ? '#ef4444' : '#94a3b8';
}

function updateInputState() {
    const input = document.getElementById('chat-input');
    const sendBtn = document.getElementById('chat-send');
    const uploadBtn = document.getElementById('chat-upload');
    if (limitReached) {
        input.disabled = true;
        input.placeholder = isAnonymous
            ? '匿名次数已用完，请获取令牌继续'
            : '次数已用完，请联系管理员';
        sendBtn.disabled = true;
        sendBtn.style.opacity = '0.5';
        uploadBtn.disabled = true;
        uploadBtn.style.opacity = '0.5';
    }
}

async function enterToken() {
    const token = prompt('请输入访问令牌 (Access Token):');
    if (!token || !token.trim()) return;
    try {
        const resp = await fetch(BASE_PATH + '/api/verify-token', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ token: token.trim() }),
        });
        if (resp.ok) {
            window.location.reload();
        } else {
            alert('无效或已过期的访问令牌');
        }
    } catch (e) {
        alert('网络错误，请稍后重试');
    }
}

function appendBubble(role, text) {
    const container = document.getElementById('chat-messages');
    const bubble = document.createElement('div');
    bubble.className = `message-bubble message-${role}`;
    bubble.textContent = text;
    container.appendChild(bubble);
    scrollToBottom();
    return bubble;
}

function scrollToBottom() {
    const container = document.getElementById('chat-messages');
    container.scrollTop = container.scrollHeight;
}