import { useCallback, useEffect, useRef, useState } from "react";
import { useNavigate, Link } from "react-router-dom";
import { useAuth } from "../../context/AuthContext";
import { useTheme } from "../../context/ThemeContext";
import { useWorkspaceContext } from "../../context/WorkspaceContext";
import { listActivity } from "../../api/activity";
import "./Topbar.css";

const NOTIF_ICONS = {
    workflow_completed: "✅",
    review_requested: "👁️",
    workflow_started: "▶️",
    proposal_approved: "✓",
    proposal_rejected: "✗",
    document_uploaded: "📄",
    commit_created: "💾",
    proposal_created: "📝",
    workflow_failed: "❌",
};

export function Topbar() {
    const { user, logout } = useAuth();
    const { darkMode, toggleTheme } = useTheme();
    const { workspace, workspaces, loading, selectWorkspace, addWorkspace } =
        useWorkspaceContext();
    const navigate = useNavigate();
    const [workspaceMenuOpen, setWorkspaceMenuOpen] = useState(false);
    const [creating, setCreating] = useState(false);
    const [newName, setNewName] = useState("");
    const [searchQuery, setSearchQuery] = useState("");

    // Notifications state
    const [notifOpen, setNotifOpen] = useState(false);
    const [notifications, setNotifications] = useState([]);
    const [notifLoading, setNotifLoading] = useState(false);
    const [unreadCount, setUnreadCount] = useState(0);
    const lastReadRef = useRef(localStorage.getItem("dw_notif_read_at") || "");
    const notifRef = useRef(null);
    const pollRef = useRef(null);

    const displayName = user?.username || user?.email || "Workspace user";

    // Fetch notifications
    const fetchNotifications = useCallback(async () => {
        if (!workspace) return;
        try {
            const response = await listActivity(workspace.id, 8);
            const events = response?.events ?? (Array.isArray(response) ? response : []);
            if (Array.isArray(events)) {
                setNotifications(events);
                // Count events newer than last time user opened the bell
                const readAt = lastReadRef.current;
                if (readAt) {
                    const readTime = new Date(readAt).getTime();
                    const unread = events.filter(
                        (e) => e.timestamp && new Date(e.timestamp).getTime() > readTime
                    );
                    setUnreadCount(unread.length);
                } else {
                    // Never opened before — show all as unread
                    setUnreadCount(events.length);
                }
            }
        } catch {
            // silently handle
        }
    }, [workspace]);

    // Poll every 15 seconds for new notifications
    useEffect(() => {
        fetchNotifications();
        pollRef.current = setInterval(fetchNotifications, 15000);
        return () => clearInterval(pollRef.current);
    }, [fetchNotifications]);

    // Close notif dropdown on outside click
    useEffect(() => {
        const handleClick = (e) => {
            if (notifRef.current && !notifRef.current.contains(e.target)) {
                setNotifOpen(false);
            }
        };
        document.addEventListener("mousedown", handleClick);
        return () => document.removeEventListener("mousedown", handleClick);
    }, []);

    const handleOpenNotifs = () => {
        setNotifOpen((v) => !v);
        // Mark all current notifications as read
        const now = new Date().toISOString();
        lastReadRef.current = now;
        localStorage.setItem("dw_notif_read_at", now);
        setUnreadCount(0);
    };

    const handleLogout = () => {
        logout();
        navigate("/login");
    };

    const handleSelect = (id) => {
        selectWorkspace(id);
        setWorkspaceMenuOpen(false);
    };

    const handleCreate = async (e) => {
        e.preventDefault();
        const name = newName.trim();
        if (!name) return;
        await addWorkspace(name);
        setNewName("");
        setCreating(false);
        setWorkspaceMenuOpen(false);
    };

    const timeAgo = (timestamp) => {
        if (!timestamp) return "";
        const diff = Date.now() - new Date(timestamp).getTime();
        const mins = Math.floor(diff / 60000);
        if (mins < 1) return "just now";
        if (mins < 60) return `${mins}m ago`;
        const hrs = Math.floor(mins / 60);
        if (hrs < 24) return `${hrs}h ago`;
        return `${Math.floor(hrs / 24)}d ago`;
    };

    return (
        <header className="dw-topbar">
            <div className="dw-topbar__workspace-wrapper">
                <button
                    className="dw-topbar__workspace"
                    onClick={() => setWorkspaceMenuOpen((v) => !v)}
                    disabled={loading}
                >
                    <span className="dw-topbar__workspace-dot" aria-hidden="true" />
                    <span>{loading ? "Loading…" : workspace?.name || "No workspace"}</span>
                    <span className="dw-topbar__chevron">⌄</span>
                </button>

                {workspaceMenuOpen && (
                    <div
                        className="dw-topbar__menu dw-topbar__menu--workspace"
                        onMouseLeave={() => {
                            setWorkspaceMenuOpen(false);
                            setCreating(false);
                        }}
                    >
                        {workspaces.map((w) => (
                            <button
                                key={w.id}
                                className="dw-topbar__menu-item"
                                onClick={() => handleSelect(w.id)}
                            >
                                {w.id === workspace?.id ? "✓ " : ""}
                                {w.name}
                            </button>
                        ))}

                        <div className="dw-topbar__menu-divider" />
                        {creating && (
                            <form className="dw-topbar__create-form" onSubmit={handleCreate}>
                                <input
                                    autoFocus
                                    type="text"
                                    placeholder="Workspace name"
                                    value={newName}
                                    onChange={(e) => setNewName(e.target.value)}
                                />
                                <button type="submit" className="dw-topbar__menu-item">
                                    Create
                                </button>
                            </form>
                        )}
                    </div>
                )}
            </div>

            {/* New workspace button */}
            <button
                className="dw-topbar__upload-btn"
                onClick={() => { setWorkspaceMenuOpen(true); setCreating(true); }}
                title="New workspace"
            >
                +
            </button>

            <div className="dw-topbar__search">
                <span className="dw-topbar__search-icon" aria-hidden="true">
                    ⌕
                </span>
                <input
                    type="text"
                    placeholder="Search documents and knowledge…"
                    value={searchQuery}
                    onChange={(e) => setSearchQuery(e.target.value)}
                    onKeyDown={(e) => {
                        if (e.key === "Enter" && searchQuery.trim()) {
                            navigate(`/search?q=${encodeURIComponent(searchQuery.trim())}`);
                            setSearchQuery("");
                        }
                    }}
                />
                <button
                    className="dw-topbar__search-btn"
                    onClick={() => {
                        if (searchQuery.trim()) {
                            navigate(`/search?q=${encodeURIComponent(searchQuery.trim())}`);
                            setSearchQuery("");
                        }
                    }}
                    aria-label="Search"
                >
                    →
                </button>
            </div>

            <div className="dw-topbar__actions">
                {/* Notification Bell */}
                <div className="dw-topbar__notif-wrapper" ref={notifRef}>
                    <button
                        className="dw-topbar__icon-btn"
                        aria-label="Notifications"
                        onClick={handleOpenNotifs}
                    >
                        🔔
                        {unreadCount > 0 && (
                            <span className="dw-topbar__notif-badge">{unreadCount}</span>
                        )}
                    </button>

                    {notifOpen && (
                        <div className="dw-topbar__notif-dropdown">
                            <div className="dw-topbar__notif-header">
                                <span>Notifications</span>
                                <Link
                                    to="/activity"
                                    className="dw-topbar__notif-viewall"
                                    onClick={() => setNotifOpen(false)}
                                >
                                    View all
                                </Link>
                            </div>
                            {notifications.length === 0 ? (
                                <div className="dw-topbar__notif-empty">
                                    No recent activity.
                                </div>
                            ) : (
                                <div className="dw-topbar__notif-list">
                                    {notifications.map((n) => {
                                        const targetUrl = n.metadata?.workflow_id
                                            ? `/workflows/${n.metadata.workflow_id}`
                                            : "/activity";
                                        return (
                                            <Link
                                                key={n.id}
                                                to={targetUrl}
                                                className="dw-topbar__notif-item"
                                                onClick={() => setNotifOpen(false)}
                                            >
                                                <span className="dw-topbar__notif-icon">
                                                    {NOTIF_ICONS[n.type] || "•"}
                                                </span>
                                                <span className="dw-topbar__notif-message">
                                                    {n.message}
                                                </span>
                                                <span className="dw-topbar__notif-time">
                                                    {timeAgo(n.timestamp)}
                                                </span>
                                            </Link>
                                        );
                                    })}
                                </div>
                            )}
                        </div>
                    )}
                </div>

                <div className="dw-topbar__profile">
                    <button
                        className="dw-topbar__icon-btn dw-topbar__theme-btn"
                        onClick={toggleTheme}
                        title={darkMode ? "Switch to light mode" : "Switch to dark mode"}
                        aria-label={darkMode ? "Switch to light mode" : "Switch to dark mode"}
                    >
                        {darkMode ? "☀️" : "🌙"}
                    </button>
                </div>
            </div>
        </header>
    );
}