/*
 * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibGfx/Bitmap.h>
#include <LibGfx/ClassicWindowTheme.h>
#include <LibGfx/FontDatabase.h>
#include <LibGfx/Painter.h>
#include <LibGfx/Palette.h>
#include <LibGfx/StylePainter.h>

namespace Gfx {

static constexpr int menubar_height = 20;

ClassicWindowTheme::ClassicWindowTheme()
{
}

ClassicWindowTheme::~ClassicWindowTheme()
{
}

Gfx::IntRect ClassicWindowTheme::titlebar_icon_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette) const
{
    if (window_type == WindowType::ToolWindow)
        return {};

    auto titlebar_rect = this->titlebar_rect(window_type, window_rect, palette);
    Gfx::IntRect icon_rect {
        titlebar_rect.x() + 2,
        titlebar_rect.y(),
        16,
        16,
    };
    icon_rect.center_vertically_within(titlebar_rect);
    icon_rect.translate_by(0, 1);
    return icon_rect;
}

Gfx::IntRect ClassicWindowTheme::titlebar_text_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette) const
{
    auto titlebar_rect = this->titlebar_rect(window_type, window_rect, palette);
    auto titlebar_icon_rect = this->titlebar_icon_rect(window_type, window_rect, palette);
    return {
        titlebar_rect.x() + 3 + (titlebar_icon_rect.is_empty() ? 0 : (titlebar_icon_rect.width() + 2)),
        titlebar_rect.y(),
        titlebar_rect.width() - 5 - (titlebar_icon_rect.is_empty() ? 0 : (titlebar_icon_rect.width() + 2)),
        titlebar_rect.height()
    };
}

void ClassicWindowTheme::paint_normal_frame(Painter& painter, WindowState window_state, const IntRect& window_rect, const StringView& window_title, const Bitmap& icon, const Palette& palette, const IntRect& leftmost_button_rect, int menu_row_count, [[maybe_unused]] bool window_modified) const
{
    auto frame_rect = frame_rect_for_window(WindowType::Normal, window_rect, palette, menu_row_count);
    frame_rect.set_location({ 0, 0 });
    Gfx::StylePainter::paint_window_frame(painter, frame_rect, palette);

    auto& title_font = FontDatabase::default_font().bold_variant();

    auto titlebar_rect = this->titlebar_rect(WindowType::Normal, window_rect, palette);
    auto titlebar_icon_rect = this->titlebar_icon_rect(WindowType::Normal, window_rect, palette);
    auto titlebar_inner_rect = titlebar_text_rect(WindowType::Normal, window_rect, palette);
    auto titlebar_title_rect = titlebar_inner_rect;
    titlebar_title_rect.set_width(title_font.width(window_title));

    auto [title_color, border_color, border_color2, stripes_color, shadow_color] = compute_frame_colors(window_state, palette);

    painter.draw_line(titlebar_rect.bottom_left().translated(0, 1), titlebar_rect.bottom_right().translated(0, 1), palette.button());
    painter.draw_line(titlebar_rect.bottom_left().translated(0, 2), titlebar_rect.bottom_right().translated(0, 2), palette.button());

    painter.fill_rect_with_gradient(titlebar_rect, border_color, border_color2);

    int stripe_right = leftmost_button_rect.left() - 3;
    if (stripes_color.alpha() > 0) {
        int stripe_left = titlebar_title_rect.right() + 5;
        if (stripe_left && stripe_right && stripe_left < stripe_right) {
            for (int i = 2; i <= titlebar_inner_rect.height() - 2; i += 2) {
                painter.draw_line({ stripe_left, titlebar_inner_rect.y() + i }, { stripe_right, titlebar_inner_rect.y() + i }, stripes_color);
            }
        }
    }

    auto clipped_title_rect = titlebar_title_rect;
    clipped_title_rect.set_width(stripe_right - clipped_title_rect.x());
    if (!clipped_title_rect.is_empty()) {
        painter.draw_text(clipped_title_rect.translated(1, 2), window_title, title_font, Gfx::TextAlignment::CenterLeft, shadow_color, Gfx::TextElision::Right);
        // FIXME: The translated(0, 1) wouldn't be necessary if we could center text based on its baseline.
        painter.draw_text(clipped_title_rect.translated(0, 1), window_title, title_font, Gfx::TextAlignment::CenterLeft, title_color, Gfx::TextElision::Right);
    }

    painter.draw_scaled_bitmap(titlebar_icon_rect, icon, icon.rect());
}

void ClassicWindowTheme::paint_tool_window_frame(Painter& painter, WindowState window_state, const IntRect& window_rect, const StringView& title_text, const Palette& palette, const IntRect& leftmost_button_rect) const
{
    auto frame_rect = frame_rect_for_window(WindowType::ToolWindow, window_rect, palette, 0);
    frame_rect.set_location({ 0, 0 });
    Gfx::StylePainter::paint_window_frame(painter, frame_rect, palette);

    auto& title_font = FontDatabase::default_font().bold_variant();

    auto titlebar_rect = this->titlebar_rect(WindowType::ToolWindow, window_rect, palette);
    auto titlebar_inner_rect = titlebar_text_rect(WindowType::ToolWindow, window_rect, palette);
    auto titlebar_title_rect = titlebar_inner_rect;
    titlebar_title_rect.set_width(title_font.width(title_text));

    auto [title_color, border_color, border_color2, stripes_color, shadow_color] = compute_frame_colors(window_state, palette);

    painter.draw_line(titlebar_rect.bottom_left().translated(0, 1), titlebar_rect.bottom_right().translated(0, 1), palette.button());
    painter.draw_line(titlebar_rect.bottom_left().translated(0, 2), titlebar_rect.bottom_right().translated(0, 2), palette.button());

    painter.fill_rect_with_gradient(titlebar_rect, border_color, border_color2);

    int stripe_right = leftmost_button_rect.left() - 3;

    auto clipped_title_rect = titlebar_title_rect;
    clipped_title_rect.set_width(stripe_right - clipped_title_rect.x());
    if (!clipped_title_rect.is_empty()) {
        painter.draw_text(clipped_title_rect.translated(1, 2), title_text, title_font, Gfx::TextAlignment::CenterLeft, shadow_color, Gfx::TextElision::Right);
        // FIXME: The translated(0, 1) wouldn't be necessary if we could center text based on its baseline.
        painter.draw_text(clipped_title_rect.translated(0, 1), title_text, title_font, Gfx::TextAlignment::CenterLeft, title_color, Gfx::TextElision::Right);
    }
}

IntRect ClassicWindowTheme::menubar_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette, int menu_row_count) const
{
    if (window_type != WindowType::Normal)
        return {};
    return { 4, 3 + titlebar_height(window_type, palette) + 2, window_rect.width(), menubar_height * menu_row_count };
}

IntRect ClassicWindowTheme::titlebar_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette) const
{
    auto& title_font = FontDatabase::default_font().bold_variant();
    auto window_titlebar_height = titlebar_height(window_type, palette);
    // FIXME: The top of the titlebar doesn't get redrawn properly if this padding is different
    int total_vertical_padding = title_font.glyph_height() - 1;

    if (window_type == WindowType::Notification)
        return { window_rect.width() + 3, total_vertical_padding / 2 - 1, window_titlebar_height, window_rect.height() };
    return { 4, 4, window_rect.width(), window_titlebar_height };
}

ClassicWindowTheme::FrameColors ClassicWindowTheme::compute_frame_colors(WindowState state, const Palette& palette) const
{
    switch (state) {
    case WindowState::Highlighted:
        return { palette.highlight_window_title(), palette.highlight_window_border1(), palette.highlight_window_border2(), palette.highlight_window_title_stripes(), palette.highlight_window_title_shadow() };
    case WindowState::Moving:
        return { palette.moving_window_title(), palette.moving_window_border1(), palette.moving_window_border2(), palette.moving_window_title_stripes(), palette.moving_window_title_shadow() };
    case WindowState::Active:
        return { palette.active_window_title(), palette.active_window_border1(), palette.active_window_border2(), palette.active_window_title_stripes(), palette.active_window_title_shadow() };
    case WindowState::Inactive:
        return { palette.inactive_window_title(), palette.inactive_window_border1(), palette.inactive_window_border2(), palette.inactive_window_title_stripes(), palette.inactive_window_title_shadow() };
    default:
        VERIFY_NOT_REACHED();
    }
}

void ClassicWindowTheme::paint_notification_frame(Painter& painter, const IntRect& window_rect, const Palette& palette, const IntRect& close_button_rect) const
{
    auto frame_rect = frame_rect_for_window(WindowType::Notification, window_rect, palette, 0);
    frame_rect.set_location({ 0, 0 });
    Gfx::StylePainter::paint_window_frame(painter, frame_rect, palette);

    auto titlebar_rect = this->titlebar_rect(WindowType::Notification, window_rect, palette);
    painter.fill_rect_with_gradient(Gfx::Orientation::Vertical, titlebar_rect, palette.active_window_border1(), palette.active_window_border2());

    if (palette.active_window_title_stripes().alpha() > 0) {
        int stripe_top = close_button_rect.bottom() + 4;
        int stripe_bottom = window_rect.height() - 3;
        if (stripe_top && stripe_bottom && stripe_top < stripe_bottom) {
            for (int i = 2; i <= palette.window_title_height() - 2; i += 2) {
                painter.draw_line({ titlebar_rect.x() + i, stripe_top }, { titlebar_rect.x() + i, stripe_bottom }, palette.active_window_title_stripes());
            }
        }
    }
}

IntRect ClassicWindowTheme::frame_rect_for_window(WindowType window_type, const IntRect& window_rect, const Gfx::Palette& palette, int menu_row_count) const
{
    auto window_titlebar_height = titlebar_height(window_type, palette);

    switch (window_type) {
    case WindowType::Normal:
    case WindowType::ToolWindow:
        return {
            window_rect.x() - 4,
            window_rect.y() - window_titlebar_height - 5 - menu_row_count * menubar_height,
            window_rect.width() + 8,
            window_rect.height() + 9 + window_titlebar_height + menu_row_count * menubar_height
        };
    case WindowType::Notification:
        return {
            window_rect.x() - 3,
            window_rect.y() - 3,
            window_rect.width() + 6 + window_titlebar_height,
            window_rect.height() + 6
        };
    default:
        return window_rect;
    }
}

Vector<IntRect> ClassicWindowTheme::layout_buttons(WindowType window_type, const IntRect& window_rect, const Palette& palette, size_t buttons) const
{
    int window_button_width = palette.window_title_button_width();
    int window_button_height = palette.window_title_button_height();
    int pos;
    Vector<IntRect> button_rects;
    if (window_type == WindowType::Notification)
        pos = titlebar_rect(window_type, window_rect, palette).top() + 2;
    else
        pos = titlebar_text_rect(window_type, window_rect, palette).right() + 1;

    for (size_t i = 0; i < buttons; i++) {
        if (window_type == WindowType::Notification) {
            // The button height & width have to be equal or it leaks out of its area
            Gfx::IntRect rect { 0, pos, window_button_height, window_button_height };
            rect.center_horizontally_within(titlebar_rect(window_type, window_rect, palette));
            button_rects.append(rect);
            pos += window_button_height;
        } else {
            pos -= window_button_width;
            Gfx::IntRect rect { pos, 0, window_button_width, window_button_height };
            rect.center_vertically_within(titlebar_text_rect(window_type, window_rect, palette));
            button_rects.append(rect);
        }
    }
    return button_rects;
}

int ClassicWindowTheme::titlebar_height(WindowType window_type, const Palette& palette) const
{
    auto& title_font = FontDatabase::default_font().bold_variant();
    switch (window_type) {
    case WindowType::Normal:
    case WindowType::Notification:
        return max(palette.window_title_height(), title_font.glyph_height() + 8);
    case WindowType::ToolWindow:
        return max(palette.window_title_height() - 4, title_font.glyph_height() + 4);
    default:
        return 0;
    }
}

}