#include "BorderlessWindowChrome.h"

#include <algorithm>
#include <cmath>
#include <dwmapi.h>

namespace XCEngine::UI::Editor::Host {

namespace {

using ::XCEngine::UI::UIColor;
using ::XCEngine::UI::UIDrawList;
using ::XCEngine::UI::UIPoint;
using ::XCEngine::UI::UIRect;

constexpr UIColor kTransparentColor(0.0f, 0.0f, 0.0f, 0.0f);

float ResolveGlyphBoxSize(const UIRect& rect, float ratio, float minSize) {
    return (std::max)(minSize, static_cast<float>(std::round(rect.height * ratio)));
}

bool IsPointInsideRect(const UIRect& rect, const UIPoint& point) {
    return rect.width > 0.0f &&
        rect.height > 0.0f &&
        point.x >= rect.x &&
        point.x <= rect.x + rect.width &&
        point.y >= rect.y &&
        point.y <= rect.y + rect.height;
}

void AppendMinimizeGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float halfWidth = ResolveGlyphBoxSize(rect, 0.38f, 10.0f) * 0.5f;
    const float y = centerY;
    drawList.AddLine(
        UIPoint(centerX - halfWidth, y),
        UIPoint(centerX + halfWidth, y),
        color,
        thickness);
}

void AppendMaximizeGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float boxSize = ResolveGlyphBoxSize(rect, 0.32f, 9.0f);
    const float halfExtent = boxSize * 0.5f;
    const float left = centerX - halfExtent;
    const float top = centerY - halfExtent;
    const float right = left + boxSize;
    const float bottom = top + boxSize;
    drawList.AddLine(UIPoint(left, top), UIPoint(right, top), color, thickness);
    drawList.AddLine(UIPoint(left, top), UIPoint(left, bottom), color, thickness);
    drawList.AddLine(UIPoint(right, top), UIPoint(right, bottom), color, thickness);
    drawList.AddLine(UIPoint(left, bottom), UIPoint(right, bottom), color, thickness);
}

void AppendRestoreGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float boxSize = ResolveGlyphBoxSize(rect, 0.29f, 8.0f);
    const float halfExtent = boxSize * 0.5f;
    const float offset = 1.0f;

    const float backLeft = centerX - halfExtent + offset;
    const float backTop = centerY - halfExtent - offset;
    const float backRight = backLeft + boxSize;
    const float backBottom = backTop + boxSize;

    const float frontLeft = centerX - halfExtent - offset;
    const float frontTop = centerY - halfExtent + offset;
    const float frontRight = frontLeft + boxSize;
    const float frontBottom = frontTop + boxSize;

    // Only draw the exposed segments of the back window.
    drawList.AddLine(UIPoint(backLeft, backTop), UIPoint(backRight, backTop), color, thickness);
    drawList.AddLine(UIPoint(backLeft, backTop), UIPoint(backLeft, frontTop), color, thickness);
    drawList.AddLine(UIPoint(backRight, backTop), UIPoint(backRight, backBottom), color, thickness);
    drawList.AddLine(UIPoint(frontRight, backBottom), UIPoint(backRight, backBottom), color, thickness);

    drawList.AddLine(UIPoint(frontLeft, frontTop), UIPoint(frontRight, frontTop), color, thickness);
    drawList.AddLine(UIPoint(frontLeft, frontTop), UIPoint(frontLeft, frontBottom), color, thickness);
    drawList.AddLine(UIPoint(frontRight, frontTop), UIPoint(frontRight, frontBottom), color, thickness);
    drawList.AddLine(UIPoint(frontLeft, frontBottom), UIPoint(frontRight, frontBottom), color, thickness);
}

void AppendCloseGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float halfWidth = ResolveGlyphBoxSize(rect, 0.29f, 8.0f) * 0.5f;
    const float halfHeight = halfWidth;
    drawList.AddLine(
        UIPoint(centerX - halfWidth, centerY - halfHeight),
        UIPoint(centerX + halfWidth, centerY + halfHeight),
        color,
        thickness);
    drawList.AddLine(
        UIPoint(centerX + halfWidth, centerY - halfHeight),
        UIPoint(centerX - halfWidth, centerY + halfHeight),
        color,
        thickness);
}

::XCEngine::UI::UIColor ResolveButtonFillColor(
    BorderlessWindowChromeHitTarget target,
    const BorderlessWindowChromeState& state,
    const BorderlessWindowChromePalette& palette) {
    const bool hovered = state.hoveredTarget == target;
    const bool pressed = state.pressedTarget == target;
    if (target == BorderlessWindowChromeHitTarget::CloseButton) {
        if (pressed) {
            return palette.closeButtonPressedColor;
        }
        if (hovered) {
            return palette.closeButtonHoverColor;
        }
        return kTransparentColor;
    }

    if (pressed) {
        return palette.buttonPressedColor;
    }
    if (hovered) {
        return palette.buttonHoverColor;
    }
    return kTransparentColor;
}

::XCEngine::UI::UIColor ResolveIconColor(
    BorderlessWindowChromeHitTarget target,
    const BorderlessWindowChromeState& state,
    const BorderlessWindowChromePalette& palette) {
    if (target == BorderlessWindowChromeHitTarget::CloseButton &&
        (state.hoveredTarget == target || state.pressedTarget == target)) {
        return palette.closeIconHoverColor;
    }

    return palette.iconColor;
}

int QuerySystemMetricForDpi(int index, UINT dpi) {
    const HMODULE user32 = GetModuleHandleW(L"user32.dll");
    if (user32 != nullptr) {
        using GetSystemMetricsForDpiFn = int(WINAPI*)(int, UINT);
        const auto getSystemMetricsForDpi =
            reinterpret_cast<GetSystemMetricsForDpiFn>(
                GetProcAddress(user32, "GetSystemMetricsForDpi"));
        if (getSystemMetricsForDpi != nullptr) {
            return getSystemMetricsForDpi(index, dpi);
        }
    }

    return GetSystemMetrics(index);
}

bool IsWindowAlignedToMonitorWorkArea(HWND hwnd) {
    if (hwnd == nullptr) {
        return false;
    }

    RECT windowRect = {};
    if (!GetWindowRect(hwnd, &windowRect)) {
        return false;
    }

    const HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
    if (monitor == nullptr) {
        return false;
    }

    MONITORINFO monitorInfo = {};
    monitorInfo.cbSize = sizeof(monitorInfo);
    if (!GetMonitorInfoW(monitor, &monitorInfo)) {
        return false;
    }

    const RECT& workArea = monitorInfo.rcWork;
    return windowRect.left == workArea.left &&
        windowRect.top == workArea.top &&
        windowRect.right == workArea.right &&
        windowRect.bottom == workArea.bottom;
}

void ApplyDwmBoolWindowAttribute(HWND hwnd, DWORD attribute, BOOL value) {
    if (hwnd == nullptr) {
        return;
    }

    using DwmSetWindowAttributeFn = HRESULT(WINAPI*)(HWND, DWORD, LPCVOID, DWORD);
    static const auto setWindowAttribute = []() -> DwmSetWindowAttributeFn {
        HMODULE dwmapi = GetModuleHandleW(L"dwmapi.dll");
        if (dwmapi == nullptr) {
            dwmapi = LoadLibraryW(L"dwmapi.dll");
        }
        if (dwmapi == nullptr) {
            return nullptr;
        }

        return reinterpret_cast<DwmSetWindowAttributeFn>(
            GetProcAddress(dwmapi, "DwmSetWindowAttribute"));
    }();

    if (setWindowAttribute != nullptr) {
        setWindowAttribute(hwnd, attribute, &value, sizeof(value));
    }
}

void ApplyDwmColorWindowAttribute(HWND hwnd, DWORD attribute, COLORREF value) {
    if (hwnd == nullptr) {
        return;
    }

    using DwmSetWindowAttributeFn = HRESULT(WINAPI*)(HWND, DWORD, LPCVOID, DWORD);
    static const auto setWindowAttribute = []() -> DwmSetWindowAttributeFn {
        HMODULE dwmapi = GetModuleHandleW(L"dwmapi.dll");
        if (dwmapi == nullptr) {
            dwmapi = LoadLibraryW(L"dwmapi.dll");
        }
        if (dwmapi == nullptr) {
            return nullptr;
        }

        return reinterpret_cast<DwmSetWindowAttributeFn>(
            GetProcAddress(dwmapi, "DwmSetWindowAttribute"));
    }();

    if (setWindowAttribute != nullptr) {
        setWindowAttribute(hwnd, attribute, &value, sizeof(value));
    }
}

void ApplyDwmIntWindowAttribute(HWND hwnd, DWORD attribute, int value) {
    if (hwnd == nullptr) {
        return;
    }

    using DwmSetWindowAttributeFn = HRESULT(WINAPI*)(HWND, DWORD, LPCVOID, DWORD);
    static const auto setWindowAttribute = []() -> DwmSetWindowAttributeFn {
        HMODULE dwmapi = GetModuleHandleW(L"dwmapi.dll");
        if (dwmapi == nullptr) {
            dwmapi = LoadLibraryW(L"dwmapi.dll");
        }
        if (dwmapi == nullptr) {
            return nullptr;
        }

        return reinterpret_cast<DwmSetWindowAttributeFn>(
            GetProcAddress(dwmapi, "DwmSetWindowAttribute"));
    }();

    if (setWindowAttribute != nullptr) {
        setWindowAttribute(hwnd, attribute, &value, sizeof(value));
    }
}

} // namespace

BorderlessWindowChromeLayout BuildBorderlessWindowChromeLayout(
    const UIRect& titleBarRect,
    float leadingOccupiedRight,
    const BorderlessWindowChromeMetrics& metrics) {
    BorderlessWindowChromeLayout layout = {};
    layout.titleBarRect = titleBarRect;
    if (titleBarRect.width <= 0.0f || titleBarRect.height <= 0.0f) {
        return layout;
    }

    const float buttonWidth = (std::max)(metrics.buttonWidth, 0.0f);
    const float buttonX3 = titleBarRect.x + titleBarRect.width - metrics.buttonInsetX - buttonWidth;
    const float buttonX2 = buttonX3 - buttonWidth;
    const float buttonX1 = buttonX2 - buttonWidth;

    layout.minimizeButtonRect = UIRect(buttonX1, titleBarRect.y, buttonWidth, titleBarRect.height);
    layout.maximizeRestoreButtonRect = UIRect(buttonX2, titleBarRect.y, buttonWidth, titleBarRect.height);
    layout.closeButtonRect = UIRect(buttonX3, titleBarRect.y, buttonWidth, titleBarRect.height);

    const float dragLeft =
        (std::max)(titleBarRect.x, leadingOccupiedRight + metrics.dragPaddingLeft);
    const float dragRight =
        (std::max)(dragLeft, layout.minimizeButtonRect.x - metrics.dragPaddingRight);
    layout.dragRect = UIRect(
        dragLeft,
        titleBarRect.y,
        (std::max)(0.0f, dragRight - dragLeft),
        titleBarRect.height);
    return layout;
}

BorderlessWindowChromeHitTarget HitTestBorderlessWindowChrome(
    const BorderlessWindowChromeLayout& layout,
    const UIPoint& point) {
    if (IsPointInsideRect(layout.closeButtonRect, point)) {
        return BorderlessWindowChromeHitTarget::CloseButton;
    }
    if (IsPointInsideRect(layout.maximizeRestoreButtonRect, point)) {
        return BorderlessWindowChromeHitTarget::MaximizeRestoreButton;
    }
    if (IsPointInsideRect(layout.minimizeButtonRect, point)) {
        return BorderlessWindowChromeHitTarget::MinimizeButton;
    }
    if (IsPointInsideRect(layout.dragRect, point)) {
        return BorderlessWindowChromeHitTarget::DragRegion;
    }
    return BorderlessWindowChromeHitTarget::None;
}

void AppendBorderlessWindowChrome(
    UIDrawList& drawList,
    const BorderlessWindowChromeLayout& layout,
    const BorderlessWindowChromeState& state,
    bool maximized,
    const BorderlessWindowChromePalette& palette,
    const BorderlessWindowChromeMetrics& metrics) {
    const struct ButtonEntry {
        BorderlessWindowChromeHitTarget target;
        UIRect rect;
    } buttons[] = {
        { BorderlessWindowChromeHitTarget::MinimizeButton, layout.minimizeButtonRect },
        { BorderlessWindowChromeHitTarget::MaximizeRestoreButton, layout.maximizeRestoreButtonRect },
        { BorderlessWindowChromeHitTarget::CloseButton, layout.closeButtonRect }
    };

    for (const ButtonEntry& button : buttons) {
        const UIColor fill = ResolveButtonFillColor(button.target, state, palette);
        if (fill.a > 0.0f) {
            drawList.AddFilledRect(button.rect, fill);
        }

        const UIColor iconColor = ResolveIconColor(button.target, state, palette);
        switch (button.target) {
        case BorderlessWindowChromeHitTarget::MinimizeButton:
            AppendMinimizeGlyph(
                drawList,
                button.rect,
                iconColor,
                metrics.iconThickness);
            break;
        case BorderlessWindowChromeHitTarget::MaximizeRestoreButton:
            if (maximized) {
                AppendRestoreGlyph(
                    drawList,
                    button.rect,
                    iconColor,
                    metrics.iconThickness);
            } else {
                AppendMaximizeGlyph(
                    drawList,
                    button.rect,
                    iconColor,
                    metrics.iconThickness);
            }
            break;
        case BorderlessWindowChromeHitTarget::CloseButton:
            AppendCloseGlyph(
                drawList,
                button.rect,
                iconColor,
                metrics.iconThickness);
            break;
        case BorderlessWindowChromeHitTarget::DragRegion:
        case BorderlessWindowChromeHitTarget::None:
        default:
            break;
        }
    }
}

void EnableBorderlessWindowShadow(HWND hwnd) {
    if (hwnd == nullptr) {
        return;
    }

    using DwmExtendFrameIntoClientAreaFn = HRESULT(WINAPI*)(HWND, const MARGINS*);
    static const auto extendFrameIntoClientArea = []() -> DwmExtendFrameIntoClientAreaFn {
        HMODULE dwmapi = GetModuleHandleW(L"dwmapi.dll");
        if (dwmapi == nullptr) {
            dwmapi = LoadLibraryW(L"dwmapi.dll");
        }
        if (dwmapi == nullptr) {
            return nullptr;
        }
        return reinterpret_cast<DwmExtendFrameIntoClientAreaFn>(
            GetProcAddress(dwmapi, "DwmExtendFrameIntoClientArea"));
    }();
    if (extendFrameIntoClientArea != nullptr) {
        const bool maximized = IsZoomed(hwnd) || IsWindowAlignedToMonitorWorkArea(hwnd);
        const MARGINS margins = maximized
            ? MARGINS{ 0, 0, 0, 0 }
            : MARGINS{ 1, 1, 1, 1 };
        extendFrameIntoClientArea(hwnd, &margins);
    }
}

void RefreshBorderlessWindowDwmDecorations(HWND hwnd) {
    if (hwnd == nullptr) {
        return;
    }

    // Borderless host cannot participate in compositor-driven minimize/maximize
    // transitions without Windows stretching the last presented client frame.
    // Disable those transitions for this window, then refresh the shadow state.
    ApplyDwmIntWindowAttribute(hwnd, DWMWA_NCRENDERING_POLICY, DWMNCRP_DISABLED);
    ApplyDwmBoolWindowAttribute(hwnd, DWMWA_ALLOW_NCPAINT, FALSE);
    ApplyDwmBoolWindowAttribute(hwnd, DWMWA_TRANSITIONS_FORCEDISABLED, TRUE);
    ApplyDwmBoolWindowAttribute(hwnd, DWMWA_USE_IMMERSIVE_DARK_MODE, TRUE);
    ApplyDwmColorWindowAttribute(hwnd, DWMWA_CAPTION_COLOR, RGB(26, 26, 26));
    ApplyDwmColorWindowAttribute(hwnd, DWMWA_TEXT_COLOR, RGB(235, 235, 235));
    ApplyDwmColorWindowAttribute(hwnd, DWMWA_BORDER_COLOR, RGB(26, 26, 26));
    EnableBorderlessWindowShadow(hwnd);
}

bool HandleBorderlessWindowGetMinMaxInfo(HWND hwnd, LPARAM lParam) {
    if (hwnd == nullptr || lParam == 0) {
        return false;
    }

    auto* minMaxInfo = reinterpret_cast<MINMAXINFO*>(lParam);
    if (minMaxInfo == nullptr) {
        return false;
    }

    const HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
    if (monitor == nullptr) {
        return false;
    }

    MONITORINFO monitorInfo = {};
    monitorInfo.cbSize = sizeof(monitorInfo);
    if (!GetMonitorInfoW(monitor, &monitorInfo)) {
        return false;
    }

    const RECT& workArea = monitorInfo.rcWork;
    const RECT& monitorArea = monitorInfo.rcMonitor;
    minMaxInfo->ptMaxPosition.x = workArea.left - monitorArea.left;
    minMaxInfo->ptMaxPosition.y = workArea.top - monitorArea.top;
    minMaxInfo->ptMaxSize.x = workArea.right - workArea.left;
    minMaxInfo->ptMaxSize.y = workArea.bottom - workArea.top;
    minMaxInfo->ptMaxTrackSize = minMaxInfo->ptMaxSize;
    return true;
}

LRESULT HandleBorderlessWindowNcCalcSize(
    HWND hwnd,
    WPARAM wParam,
    LPARAM lParam,
    UINT dpi) {
    (void)hwnd;
    (void)wParam;
    (void)lParam;
    (void)dpi;
    return 0;
}

} // namespace XCEngine::UI::Editor::Host