using System.Runtime.InteropServices;

namespace RemSound.App;

/// <summary>
/// Owns the system-tray icon RemSound shows while it's minimised. The icon's right-click
/// menu provides quick access to the most common actions without restoring the window —
/// useful for users who park RemSound in the tray and never look at the main window again.
///
/// Menu (2026-05-28 rewrite — the original four-item menu was just Show / Sending /
/// Receiving / Exit, with no recent-profiles entry and no live state on the checkable items):
///
///   * Show RemSound (Alt+W)         — restore the main window
///   * Enable sending (Alt+S)        — checkable, reflects sendMyAudioCheckbox state
///   * Enable receiving (Alt+R)      — checkable, reflects receiveAudioCheckbox state
///   * Profiles (Alt+P)              — submenu of AppConfig.RecentProfiles, picking one
///                                     switches the active profile
///   * Exit (Alt+X)                  — close the app
///
/// Tooltip (NotifyIcon.Text): set dynamically from MainForm's snapshot tick via
/// <see cref="SetTooltip"/>. Default is "RemSound" until the first refresh. Capped at
/// 127 characters because Windows truncates anything beyond that.
/// </summary>
internal sealed class MainFormTrayController : IDisposable
{
    /// <summary>Maximum NotifyIcon.Text length on Windows 10+. Windows truncates anything
    /// longer; truncating ourselves means the tooltip ends with our own "..." rather than
    /// being chopped mid-word.</summary>
    private const int MaxTooltipLength = 127;

    private readonly Form owner;
    private readonly NotifyIcon trayIcon = new();

    private readonly Func<bool> getSending;
    private readonly Action toggleSending;
    private readonly Func<bool> getReceiving;
    private readonly Action toggleReceiving;
    private readonly Func<IReadOnlyList<string>> getRecentProfilePaths;
    private readonly Action<string> switchToProfile;
    private readonly Func<string> buildTooltip;
    private readonly Action exit;

    /// <summary>The tooltip text the icon was last (re-)registered with. We compare against
    /// this so we only re-register on a real state change — a peer connecting or dropping, a
    /// lane switching, a recording starting or stopping. The tray tooltip has no per-second
    /// element (recording shows a plain "recording" flag, not a ticking timer), so the text
    /// only changes on those real events and the icon never flickers. Null until first shown.</summary>
    private string? lastRegistrationText;

    private readonly ToolStripMenuItem sendingItem;
    private readonly ToolStripMenuItem receivingItem;
    private readonly ToolStripMenuItem profilesItem;

    public MainFormTrayController(
        Form owner,
        Func<bool> getSending,
        Action toggleSending,
        Func<bool> getReceiving,
        Action toggleReceiving,
        Func<IReadOnlyList<string>> getRecentProfilePaths,
        Action<string> switchToProfile,
        Func<string> buildTooltip,
        Action exit)
    {
        this.owner = owner;
        this.getSending = getSending;
        this.toggleSending = toggleSending;
        this.getReceiving = getReceiving;
        this.toggleReceiving = toggleReceiving;
        this.getRecentProfilePaths = getRecentProfilePaths;
        this.switchToProfile = switchToProfile;
        this.buildTooltip = buildTooltip;
        this.exit = exit;

        // We deliberately don't bake any "starting up" / "running" string into the icon
        // here. The tooltip is computed fresh from buildTooltip() at the moment the icon
        // first becomes visible (in Minimize) and refreshed every second from MainForm's
        // snapshot tick after that. The reason: Windows' shell caches the tooltip text
        // it sees at NIM_ADD time and is reluctant to refresh hover text for the same
        // icon ID. Setting an "initial" string here meant that on a slow / minimised-at-
        // launch flow (e.g. the resume-after-update path with StartMinimised on), the
        // shell registered the icon with the stale string and kept showing it until the
        // user hid + re-showed the icon. By computing the right text once, just before
        // we set Visible = true for the first time, the shell sees the live state from
        // NIM_ADD onward.
        trayIcon.Icon = SystemIcons.Application;
        trayIcon.Visible = false;
        trayIcon.DoubleClick += (_, _) => Restore();

        var menu = new ContextMenuStrip();

        var showItem = new ToolStripMenuItem("Sho&w RemSound")
        {
            AccessibleName = "Show RemSound",
        };
        showItem.Click += (_, _) => Restore();

        sendingItem = new ToolStripMenuItem("Enable &sending")
        {
            CheckOnClick = false, // we set Checked manually in RefreshMenuState; toggle drives the actual app state via the callback
            AccessibleName = "Enable sending",
        };
        sendingItem.Click += (_, _) => toggleSending();

        receivingItem = new ToolStripMenuItem("Enable &receiving")
        {
            CheckOnClick = false,
            AccessibleName = "Enable receiving",
        };
        receivingItem.Click += (_, _) => toggleReceiving();

        profilesItem = new ToolStripMenuItem("&Profiles")
        {
            AccessibleName = "Profiles",
        };
        // Populate ONCE at construction so WinForms recognises this as a real submenu
        // (an empty DropDownItems collection means the framework treats the item as a
        // plain command, never opens the submenu, and DropDownOpening never fires —
        // which produced "Profiles does nothing" in the first cut of this controller).
        // After that, every DropDownOpening rebuilds the items so a profile loaded since
        // the last menu open shows up immediately.
        RebuildProfilesSubmenu();
        profilesItem.DropDownOpening += (_, _) => RebuildProfilesSubmenu();

        var exitItem = new ToolStripMenuItem("E&xit")
        {
            AccessibleName = "Exit RemSound",
        };
        exitItem.Click += (_, _) => exit();

        menu.Items.Add(showItem);
        menu.Items.Add(sendingItem);
        menu.Items.Add(receivingItem);
        menu.Items.Add(profilesItem);
        menu.Items.Add(new ToolStripSeparator());
        menu.Items.Add(exitItem);

        // Refresh the checkable items' state every time the menu opens so the visible
        // ticks match the current main-window state (which can have changed while the
        // user was clicking around elsewhere).
        menu.Opening += (_, _) => RefreshMenuState();

        trayIcon.ContextMenuStrip = menu;
    }

    /// <summary>Replace the tooltip the OS shows over the tray icon. Called from MainForm's
    /// 1 Hz snapshot tick to keep the text current with peer count + send/receive state.
    /// Truncated to the Windows 10+ limit (127 chars) — anything longer is silently chopped
    /// by the shell, so chopping ourselves keeps the truncation point visible.</summary>
    public void SetTooltip(string text)
    {
        // Same anti-duplicate rule as the ctor: avoid a single-word "RemSound" tooltip on
        // the "RemSound" process, since some screen readers render that as "RemSound RemSound".
        if (string.IsNullOrEmpty(text)) text = "RemSound — running";
        if (text.Length > MaxTooltipLength)
        {
            text = text[..(MaxTooltipLength - 1)] + "…";
        }
        // NotifyIcon.Text throws on the same string-assigning path under some shell
        // conditions (rare race during a session-end). Best-effort: swallow.
        try { trayIcon.Text = text; } catch { /* harmless */ }

        // Keep the icon's *registered* name — the text a screen reader announces — in step
        // with the live state. Windows stamps a tray icon's accessible name at the moment the
        // icon is added (NIM_ADD) and afterwards only refreshes the little hover bubble, not
        // that stamped name. So if the icon appears at launch before the first peer has
        // connected, the name is frozen as "no peers"; when the peer links up a second later
        // the bubble updates to "1 peer" but the frozen name stays — and NVDA reads BOTH (the
        // stale name, then the live bubble), which is the confusing double announcement.
        //
        // The cure is to re-add the icon (hide then re-show = NIM_DELETE + NIM_ADD) whenever
        // the text changes, which re-stamps the name with the current text. This is exactly
        // what the old "show the window then minimise again" workaround did by hand. The tray
        // tooltip has no per-second element (recording shows a plain "recording" flag, not a
        // ticking timer), so the text only changes on real events and this never flickers.
        if (!trayIcon.Visible)
        {
            // The first call arrives from Minimize() a moment before the icon is shown — just
            // record the baseline so the NIM_ADD that immediately follows is our reference.
            lastRegistrationText = text;
            return;
        }
        if (text == lastRegistrationText) return;
        // Don't yank the icon out from under an open right-click menu (that would dismiss it
        // mid-navigation). Leave the record stale so the next tick re-stamps once it closes.
        if (trayIcon.ContextMenuStrip?.Visible == true) return;
        lastRegistrationText = text;
        try
        {
            trayIcon.Visible = false;
            trayIcon.Visible = true;
        }
        catch { /* harmless — the 1 Hz snapshot tick will try again next second */ }
    }

    public void Toggle()
    {
        if (owner.Visible && owner.WindowState != FormWindowState.Minimized) Minimize();
        else Restore();
    }

    public void Restore()
    {
        // Only sound the "show" cue on a genuine hidden -> shown transition, not a no-op restore.
        var wasHidden = !owner.Visible || owner.WindowState == FormWindowState.Minimized;
        owner.Show();
        if (owner.WindowState == FormWindowState.Minimized)
        {
            owner.WindowState = FormWindowState.Normal;
        }
        owner.BringToFront();
        owner.Activate();
        // WinForms' Activate() is best-effort: Windows' foreground-lock feature blocks
        // arbitrary processes from stealing focus, and Activate() doesn't always win even
        // for a process that's clearly user-initiated. Calling SetForegroundWindow directly
        // bypasses the lock because the caller (a tray-menu click handler) is on a UI
        // thread that received recent user input — which Windows recognises as the
        // legitimate "user asked for this" case. Without this fix, "Show RemSound" puts
        // the window on screen but doesn't focus it, leaving NVDA users having to Alt+Tab
        // to actually hear the new content.
        try { SetForegroundWindow(owner.Handle); } catch { /* harmless — Restore still mostly worked */ }
        trayIcon.Visible = false;
        if (wasHidden) (owner as MainForm)?.PlayWindowVisibilityCue(show: true);
    }

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetForegroundWindow(IntPtr hWnd);

    /// <summary>Hide the window to the tray. <paramref name="playCue"/> defaults true for a genuine
    /// user-initiated minimise; the startup-minimise path passes false because that's not the user
    /// choosing to hide the window — and the usual "was it visible?" guard can't tell the two apart,
    /// since by the time the deferred startup minimise runs the window HAS been shown (Visible=true).</summary>
    public void Minimize(bool playCue = true)
    {
        // Only sound the "hide" cue on a genuine shown -> hidden transition the user asked for: not a
        // startup-minimise (playCue:false), and not a repeat call once already hidden (wasVisible).
        var wasVisible = owner.Visible;
        owner.Hide();
        if (wasVisible && playCue) (owner as MainForm)?.PlayWindowVisibilityCue(show: false);
        // Refresh the tooltip BEFORE showing the icon so the shell's NIM_ADD call carries
        // the current live state (peer count, send / receive routing, recording timer),
        // not a stale "starting up" string set earlier. The shell tends to cache hover
        // text from NIM_ADD time and is slow to update on subsequent NIM_MODIFY calls —
        // computing the right text now means the first hover already reads correctly.
        try { SetTooltip(buildTooltip()); }
        catch { /* harmless — fall through to the snapshot-tick refresh */ }
        trayIcon.Visible = true;
    }

    public void Dispose() => trayIcon.Dispose();

    private void RefreshMenuState()
    {
        // Live state of the two togglable items — read on demand from MainForm so a checkbox
        // change made via the main window or a global hotkey is reflected in the tray menu
        // the next time the user opens it.
        try { sendingItem.Checked = getSending(); } catch { sendingItem.Checked = false; }
        try { receivingItem.Checked = getReceiving(); } catch { receivingItem.Checked = false; }
    }

    private void RebuildProfilesSubmenu()
    {
        profilesItem.DropDownItems.Clear();
        IReadOnlyList<string> paths;
        try { paths = getRecentProfilePaths(); }
        catch { paths = Array.Empty<string>(); }

        var slot = 1;
        foreach (var path in paths)
        {
            if (string.IsNullOrWhiteSpace(path)) continue;
            if (!File.Exists(path)) continue; // skip missing files; the AppConfig list keeps the entry in case it reappears
            var title = Path.GetFileNameWithoutExtension(path);
            // Mnemonic prefix matches the File menu's Recent profiles submenu (&1..&5) so
            // muscle-memory between the in-app menu and the tray menu carries over. The
            // visible Text carries the number; AccessibleName is just the profile name so
            // NVDA reads "MyProfile, menu item, one of five" rather than the noisier
            // "Recent profile 1: MyProfile" that the original code was reading out.
            var item = new ToolStripMenuItem($"&{slot} {title}")
            {
                AccessibleName = title,
                Tag = path,
            };
            item.Click += (s, _) =>
            {
                var sender = (ToolStripMenuItem)s!;
                var profilePath = (string)sender.Tag!;
                try { switchToProfile(profilePath); }
                catch { /* the switch path surfaces its own errors via MainForm */ }
            };
            profilesItem.DropDownItems.Add(item);
            slot++;
        }

        if (profilesItem.DropDownItems.Count == 0)
        {
            profilesItem.DropDownItems.Add(new ToolStripMenuItem("(No recent profiles)")
            {
                Enabled = false,
                AccessibleName = "No recent profiles",
            });
        }
    }
}