#include "WindowManager.h"
#include "Painter.h"
#include "Widget.h"
#include "Window.h"
#include "AbstractScreen.h"
#include "EventLoop.h"
#include "FrameBuffer.h"

static const int windowFrameWidth = 2;
static const int windowTitleBarHeight = 16;

static inline Rect titleBarRectForWindow(const Rect& window)
{
    return {
        window.x() - windowFrameWidth,
        window.y() - windowTitleBarHeight - windowFrameWidth,
        window.width() + windowFrameWidth * 2,
        windowTitleBarHeight + windowFrameWidth
    };
}

static inline Rect titleBarTitleRectForWindow(const Rect& window)
{
    auto titleBarRect = titleBarRectForWindow(window);
    return {
        titleBarRect.x() + windowFrameWidth,
        titleBarRect.y(),
        titleBarRect.width() - windowFrameWidth * 2,
        titleBarRect.height()
    };
}

static inline Rect borderRectForWindow(const Rect& window)
{
    auto titleBarRect = titleBarRectForWindow(window);
    return { titleBarRect.x() - 1,
        titleBarRect.y() - 1,
        titleBarRect.width() + 2,
        windowFrameWidth + windowTitleBarHeight + window.height() + 4
    };
}

static inline Rect outerRectForWindow(const Rect& window)
{
    auto rect = borderRectForWindow(window);
    rect.inflate(2, 2);
    return rect;
}

static WindowManager* s_the_window_manager;

WindowManager& WindowManager::the()
{
    if (!s_the_window_manager)
        s_the_window_manager = new WindowManager;
    return *s_the_window_manager;
}

void WindowManager::initialize()
{
    s_the_window_manager = nullptr;
}

WindowManager::WindowManager()
{
    m_activeWindowBorderColor = Color(0, 64, 192);
    m_activeWindowTitleColor = Color::White;

    m_inactiveWindowBorderColor = Color(64, 64, 64);
    m_inactiveWindowTitleColor = Color::White;

    invalidate();
}

WindowManager::~WindowManager()
{
}

void WindowManager::paintWindowFrame(Window& window)
{
    Painter p(*m_rootWidget);

    //printf("[WM] paintWindowFrame {%p}, rect: %d,%d %dx%d\n", &window, window.rect().x(), window.rect().y(), window.rect().width(), window.rect().height());

    auto titleBarRect = titleBarRectForWindow(window.rect());
    auto titleBarTitleRect = titleBarTitleRectForWindow(window.rect());
    auto outerRect = outerRectForWindow(window.rect());
    auto borderRect = borderRectForWindow(window.rect());

    Rect bottomRect {
        window.x() - windowFrameWidth,
        window.y() + window.height(),
        window.width() + windowFrameWidth * 2,
        windowFrameWidth };

    Rect leftRect {
        window.x() - windowFrameWidth,
        window.y(),
        windowFrameWidth,
        window.height()
    };

    Rect rightRect {
        window.x() + window.width(),
        window.y(),
        windowFrameWidth,
        window.height()
    };


    if (!m_lastDragRect.is_empty()) {
        p.xorRect(m_lastDragRect, Color::Red);
        m_lastDragRect = Rect();
    }

    if (m_dragWindow.ptr() == &window) {
        p.xorRect(outerRect, Color::Red);
        m_lastDragRect = outerRect;
        return;
    }

    auto titleColor = &window == activeWindow() ? m_activeWindowTitleColor : m_inactiveWindowTitleColor;
    auto borderColor = &window == activeWindow() ? m_activeWindowBorderColor : m_inactiveWindowBorderColor;

    p.drawRect(borderRect, Color::MidGray);
    p.drawRect(outerRect, borderColor);

    p.fillRect(titleBarRect, borderColor);
    p.fillRect(bottomRect, borderColor);
    p.fillRect(leftRect, borderColor);
    p.fillRect(rightRect, borderColor);

    p.drawText(titleBarTitleRect, window.title(), Painter::TextAlignment::CenterLeft, titleColor);
}

void WindowManager::addWindow(Window& window)
{
    m_windows.set(&window);
    m_windows_in_order.append(&window);
    if (!activeWindow())
        setActiveWindow(&window);
}

void WindowManager::move_to_front(Window& window)
{
    m_windows_in_order.remove(&window);
    m_windows_in_order.append(&window);
}

void WindowManager::did_paint(Window& window)
{
    invalidate(window);
    compose();
}

void WindowManager::removeWindow(Window& window)
{
    if (!m_windows.contains(&window))
        return;

    invalidate(window);
    m_windows.remove(&window);
    m_windows_in_order.remove(&window);
    if (!activeWindow() && !m_windows.is_empty())
        setActiveWindow(*m_windows.begin());
    compose();
}

void WindowManager::notifyTitleChanged(Window& window)
{
    printf("[WM] Window{%p} title set to '%s'\n", &window, window.title().characters());
}

void WindowManager::notifyRectChanged(Window& window, const Rect& old_rect, const Rect& new_rect)
{
    printf("[WM] Window %p rect changed (%d,%d %dx%d) -> (%d,%d %dx%d)\n", &window, old_rect.x(), old_rect.y(), old_rect.width(), old_rect.height(), new_rect.x(), new_rect.y(), new_rect.width(), new_rect.height());
    invalidate(outerRectForWindow(old_rect));
    invalidate(outerRectForWindow(new_rect));
    compose();
}

void WindowManager::handleTitleBarMouseEvent(Window& window, MouseEvent& event)
{
    if (event.type() == Event::MouseDown) {
        printf("[WM] Begin dragging Window{%p}\n", &window);
        m_dragWindow = window.makeWeakPtr();;
        m_dragOrigin = event.position();
        m_dragWindowOrigin = window.position();
        m_dragStartRect = outerRectForWindow(window.rect());
        window.setIsBeingDragged(true);
        return;
    }
}

void WindowManager::processMouseEvent(MouseEvent& event)
{
    if (event.type() == Event::MouseUp) {
        if (m_dragWindow) {
            printf("[WM] Finish dragging Window{%p}\n", m_dragWindow.ptr());
            invalidate(m_dragStartRect);
            invalidate(*m_dragWindow);
            m_dragWindow->setIsBeingDragged(false);
            m_dragEndRect = outerRectForWindow(m_dragWindow->rect());
            m_dragWindow = nullptr;
            compose();
            return;
        }
    }

    if (event.type() == Event::MouseMove) {
        if (m_dragWindow) {
            Point pos = m_dragWindowOrigin;
            printf("[WM] Dragging [origin: %d,%d] now: %d,%d\n", m_dragOrigin.x(), m_dragOrigin.y(), event.x(), event.y());
            pos.moveBy(event.x() - m_dragOrigin.x(), event.y() - m_dragOrigin.y());
            m_dragWindow->setPositionWithoutRepaint(pos);
            paintWindowFrame(*m_dragWindow);
            FrameBuffer::the().flush();
            return;
        }
    }

    for (auto* window = m_windows_in_order.tail(); window; window = window->prev()) {
        if (titleBarRectForWindow(window->rect()).contains(event.position())) {
            if (event.type() == Event::MouseDown) {
                move_to_front(*window);
                setActiveWindow(window);
            }
            handleTitleBarMouseEvent(*window, event);
            return;
        }

        if (window->rect().contains(event.position())) {
            if (event.type() == Event::MouseDown) {
                move_to_front(*window);
                setActiveWindow(window);
            }
            // FIXME: Re-use the existing event instead of crafting a new one?
            auto localEvent = make<MouseEvent>(event.type(), event.x() - window->rect().x(), event.y() - window->rect().y(), event.button());
            window->event(*localEvent);
            return;
        }
    }
}

void WindowManager::compose()
{
    printf("[WM] recompose_count: %u\n", ++m_recompose_count);
    auto& framebuffer = FrameBuffer::the();
    {
        for (auto& r : m_invalidated_rects) {
            dbgprintf("Repaint root %d,%d %dx%d\n", r.x(), r.y(), r.width(), r.height());
            PaintEvent event(r);
            m_rootWidget->paintEvent(event);
        }
    }
    for (auto* window = m_windows_in_order.head(); window; window = window->next()) {
        if (!window->backing())
            continue;
        paintWindowFrame(*window);
        if (m_dragWindow.ptr() == window)
            continue;
        framebuffer.blit(window->position(), *window->backing());
    }
    framebuffer.flush();
    m_last_drawn_cursor_location = { -1, -1 };
    redraw_cursor();
    m_invalidated_rects.clear();
}

void WindowManager::redraw_cursor()
{
    auto cursor_location = AbstractScreen::the().cursor_location();
    Painter painter(*m_rootWidget);
    painter.set_draw_op(Painter::DrawOp::Xor);
    auto draw_cross = [&painter] (const Point& p) {
        painter.drawLine({ p.x() - 10, p.y() }, { p.x() + 10, p.y() }, Color::Red);
        painter.drawLine({ p.x(), p.y() - 10 }, { p.x(), p.y() + 10 }, Color::Red);
    };
    if (cursor_location != m_last_drawn_cursor_location && m_last_drawn_cursor_location.x() != -1)
        draw_cross(m_last_drawn_cursor_location);
    draw_cross(cursor_location);
    m_last_drawn_cursor_location = cursor_location;
    FrameBuffer::the().flush();
}

void WindowManager::event(Event& event)
{
    if (event.isMouseEvent())
        return processMouseEvent(static_cast<MouseEvent&>(event));

    if (event.isKeyEvent()) {
        // FIXME: This is a good place to hook key events globally. :)
        if (m_activeWindow)
            return m_activeWindow->event(event);
        return Object::event(event);
    }

    return Object::event(event);
}

void WindowManager::setRootWidget(Widget* widget)
{
    // FIXME: Should we support switching root widgets?
    ASSERT(!m_rootWidget);
    ASSERT(widget);

    m_rootWidget = widget;
    EventLoop::main().postEvent(m_rootWidget, make<ShowEvent>());
}

void WindowManager::setActiveWindow(Window* window)
{
    if (window == m_activeWindow.ptr())
        return;

    if (auto* previously_active_window = m_activeWindow.ptr()) {
        invalidate(*previously_active_window);
        EventLoop::main().postEvent(previously_active_window, make<Event>(Event::WindowBecameInactive));
    }
    m_activeWindow = window->makeWeakPtr();
    if (m_activeWindow) {
        invalidate(*m_activeWindow);
        EventLoop::main().postEvent(m_activeWindow.ptr(), make<Event>(Event::WindowBecameActive));
    }

    compose();
}

bool WindowManager::isVisible(Window& window) const
{
    return m_windows.contains(&window);
}

void WindowManager::invalidate()
{
    m_invalidated_rects.clear();
    m_invalidated_rects.append(AbstractScreen::the().rect());
}

void WindowManager::invalidate(const Rect& rect)
{
    if (!rect.is_empty())
        m_invalidated_rects.append(rect);
}

void WindowManager::invalidate(const Window& window)
{
    invalidate(outerRectForWindow(window.rect()));
}