// Luanti
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2023 v-rob, Vincent Robinson <robinsonvincent89@gmail.com>

#include "ui/box.h"

#include "debug.h"
#include "log.h"
#include "porting.h"
#include "ui/elem.h"
#include "ui/manager.h"
#include "ui/window.h"
#include "util/serialize.h"

#include <SDL2/SDL.h>

namespace ui
{
	Window &Box::getWindow()
	{
		return m_elem.getWindow();
	}

	const Window &Box::getWindow() const
	{
		return m_elem.getWindow();
	}

	void Box::reset()
	{
		m_content.clear();
		m_style.reset();

		for (State i = 0; i < m_style_refs.size(); i++) {
			m_style_refs[i] = NO_STYLE;
		}
	}

	void Box::read(std::istream &full_is)
	{
		auto is = newIs(readStr16(full_is));
		u32 style_mask = readU32(is);

		for (State i = 0; i < m_style_refs.size(); i++) {
			// If we have a style for this state in the mask, add it to the
			// list of styles.
			if (!testShift(style_mask)) {
				continue;
			}

			u32 index = readU32(is);
			if (getWindow().getStyleStr(index) != nullptr) {
				m_style_refs[i] = index;
			} else {
				errorstream << "Style " << index << " does not exist" << std::endl;
			}
		}
	}

	void Box::restyle()
	{
		// First, clear our current style and compute what state we're in.
		m_style.reset();
		State state = STATE_NONE;

		if (m_elem.isBoxFocused(*this))
			state |= STATE_FOCUSED;
		if (m_elem.isBoxSelected(*this))
			state |= STATE_SELECTED;
		if (m_elem.isBoxHovered(*this))
			state |= STATE_HOVERED;
		if (m_elem.isBoxPressed(*this))
			state |= STATE_PRESSED;
		if (m_elem.isBoxDisabled(*this))
			state |= STATE_DISABLED;

		// Loop over each style state from lowest precedence to highest since
		// they should be applied in that order.
		for (State i = 0; i < m_style_refs.size(); i++) {
			// If this state we're looking at is a subset of the current state,
			// then it's a match for styling.
			if ((state & i) != i) {
				continue;
			}

			u32 index = m_style_refs[i];

			// If the index for this state has an associated style string,
			// apply it to our current style.
			if (index != NO_STYLE) {
				auto is = newIs(*getWindow().getStyleStr(index));
				m_style.read(is);
			}
		}

		// Since our box has been restyled, the previously computed layout
		// information is no longer valid.
		m_min_layout = SizeF();
		m_min_content = SizeF();

		m_display_rect = RectF();
		m_icon_rect = RectF();
		m_content_rect = RectF();

		m_clip_rect = RectF();

		// Finally, make sure to restyle our content.
		for (Box *box : m_content) {
			box->restyle();
		}
	}

	void Box::resize()
	{
		for (Box *box : m_content) {
			box->resize();
		}

		switch (m_style.layout.type) {
		case LayoutType::PLACE:
			resizePlace();
			break;
		}

		resizeBox();
	}

	void Box::relayout(RectF layout_rect, RectF layout_clip)
	{
		relayoutBox(layout_rect, layout_clip);

		switch (m_style.layout.type) {
		case LayoutType::PLACE:
			relayoutPlace();
			break;
		}
	}

	void Box::draw()
	{
		if (m_style.display != DisplayMode::HIDDEN) {
			drawBox();
			drawIcon();
		}

		for (Box *box : m_content) {
			box->draw();
		}
	}

	bool Box::isPointed() const
	{
		return m_clip_rect.contains(getWindow().getPointerPos());
	}

	bool Box::isContentPointed() const {
		// If we're pointed, then we clearly have a pointed box.
		if (isPointed()) {
			return true;
		}

		// Search through our content. If any of them are contained within the
		// same element as this box, they are candidates for being pointed.
		for (Box *box : m_content) {
			if (&box->getElem() == &m_elem && box->isContentPointed()) {
				return true;
			}
		}

		return false;
	}

	bool Box::processInput(const SDL_Event &event)
	{
		switch (event.type) {
		case UI_USER(FOCUS_REQUEST):
			// The box is dynamic, so it can be focused.
			return true;

		case UI_USER(FOCUS_CHANGED):
			// If the box is no longer focused, it can't be pressed.
			if (event.user.data1 == &m_elem) {
				setPressed(false);
			}
			return false;

		case UI_USER(FOCUS_SUBVERTED):
			// If some non-focused element used an event instead of this one,
			// unpress the box because user interaction has been diverted.
			setPressed(false);
			return false;

		case UI_USER(HOVER_REQUEST):
			// The box can be hovered if the pointer is inside it.
			return isPointed();

		case UI_USER(HOVER_CHANGED):
			// Make this box hovered if the element became hovered and the
			// pointer is inside this box.
			setHovered(event.user.data2 == &m_elem && isPointed());
			return true;

		default:
			return false;
		}
	}

	bool Box::processFullPress(const SDL_Event &event, void (*on_press)(Elem &))
	{
		switch (event.type) {
		case SDL_KEYDOWN:
			// If the space key is pressed not due to a key repeat, then the
			// box becomes pressed. If the escape key is pressed while the box
			// is pressed, that unpresses the box without triggering it.
			if (event.key.keysym.sym == SDLK_SPACE && !event.key.repeat) {
				setPressed(true);
				return true;
			} else if (event.key.keysym.sym == SDLK_ESCAPE && isPressed()) {
				setPressed(false);
				return true;
			}
			return false;

		case SDL_KEYUP:
			// Releasing the space key while the box is pressed causes it to be
			// unpressed and triggered.
			if (event.key.keysym.sym == SDLK_SPACE && isPressed()) {
				setPressed(false);
				on_press(m_elem);
				return true;
			}
			return false;

		case SDL_MOUSEBUTTONDOWN:
			// If the box is hovered, then pressing the left mouse button
			// causes it to be pressed. Otherwise, the mouse is directed at
			// some other box.
			if (isHovered() && event.button.button == SDL_BUTTON_LEFT) {
				setPressed(true);
				return true;
			}
			return false;

		case SDL_MOUSEBUTTONUP:
			// If the mouse button was released, the box becomes unpressed. If
			// it was released while inside the bounds of the box, that counts
			// as the box being triggered.
			if (event.button.button == SDL_BUTTON_LEFT) {
				bool was_pressed = isPressed();
				setPressed(false);

				if (isHovered() && was_pressed) {
					on_press(m_elem);
					return true;
				}
			}
			return false;

		default:
			return processInput(event);
		}
	}

	RectF Box::getLayerSource(const Layer &layer)
	{
		RectF src = layer.source;

		// If we have animations, we need to adjust the source rect by the
		// frame offset in accordance with the current frame.
		if (layer.num_frames > 1) {
			float frame_height = src.H() / layer.num_frames;
			src.B = src.T + frame_height;

			float frame_offset = frame_height *
				((porting::getTimeMs() / layer.frame_time) % layer.num_frames);
			src.T += frame_offset;
			src.B += frame_offset;
		}

		return src;
	}

	SizeF Box::getLayerSize(const Layer &layer)
	{
		return getLayerSource(layer).size() * getTextureSize(layer.image);
	}

	DispF Box::getMiddleEdges()
	{
		// Scale the middle rect by the scaling factor and de-normalize it into
		// actual pixels based on the image source rect.
		return m_style.box_middle * DispF(getLayerSize(m_style.box)) * m_style.box.scale;
	}

	void Box::resizeBox()
	{
		// If the box is set to clip its contents in either dimension, we can
		// set the minimum content size to zero for that coordinate.
		if (m_style.layout.clip == DirFlags::X || m_style.layout.clip == DirFlags::BOTH) {
			m_min_content.W = 0.0f;
		}
		if (m_style.layout.clip == DirFlags::Y || m_style.layout.clip == DirFlags::BOTH) {
			m_min_content.H = 0.0f;
		}

		// We need to factor the icon into the minimum size of the box. The
		// minimum size of the padding rect is either the size of the contents
		// or the scaled icon, depending on which is larger. If the scale is
		// zero, then the icon doesn't add anything to the minimum size.
		SizeF icon_size = getLayerSize(m_style.icon) * m_style.icon.scale;
		SizeF padding_size = m_min_content.max(icon_size);

		// If the icon should not overlap the content, then we must take into
		// account the extra space required for this, including the gutter.
		if (!m_style.icon_overlap && m_style.icon.image != nullptr) {
			switch (m_style.icon_place) {
			case IconPlace::CENTER:
				break;
			case IconPlace::LEFT:
			case IconPlace::RIGHT:
				padding_size.W = m_min_content.W + icon_size.W + m_style.icon_gutter;
				break;
			case IconPlace::TOP:
			case IconPlace::BOTTOM:
				padding_size.H = m_min_content.H + icon_size.H + m_style.icon_gutter;
				break;
			}

			padding_size = padding_size.clip();
		}

		// Now that we have a minimum size for the padding rect, we can
		// calculate the display rect size by adjusting for the padding and
		// middle rect edges. We also clamp the size of the display rect to be
		// at least as large as the user-specified minimum size.
		SizeF display_size = (padding_size + getMiddleEdges().extents() +
			m_style.sizing.padding.extents()).max(m_style.sizing.size);

		// The final minimum size is the display size adjusted for the margin.
		m_min_layout = (display_size + m_style.sizing.margin.extents()).clip();
	}

	void Box::relayoutBox(RectF layout_rect, RectF layout_clip)
	{
		// The display rect is created by insetting the layout rect by the
		// margin. The padding rect is inset from that by the middle rect edges
		// and the padding. We must make sure these do not have negative sizes.
		m_display_rect = layout_rect.insetBy(m_style.sizing.margin).clip();
		RectF padding_rect = m_display_rect.insetBy(
			getMiddleEdges() + m_style.sizing.padding).clip();

		// The icon is aligned and scaled in a particular area of the box.
		// First, get the basic size of the icon rect.
		SizeF icon_size = getLayerSize(m_style.icon);

		// Then, modify it based on the scale that we should use. A scale of
		// zero means the image should take up as much room as possible while
		// still preserving the aspect ratio of the image.
		if (m_style.icon.scale == 0.0f) {
			SizeF max_icon = padding_rect.size();

			// If the icon should not overlap the content, then we need to
			// adjust the area in which we compute the maximum scale by
			// subtracting the content and gutter from the padding rect size.
			if (!m_style.icon_overlap && m_style.icon.image != nullptr) {
				switch (m_style.icon_place) {
				case IconPlace::CENTER:
					break;
				case IconPlace::LEFT:
				case IconPlace::RIGHT:
					max_icon.W -= m_min_content.W + m_style.icon_gutter;
					break;
				case IconPlace::TOP:
				case IconPlace::BOTTOM:
					max_icon.H -= m_min_content.H + m_style.icon_gutter;
					break;
				}

				max_icon = max_icon.clip();
			}

			// Choose the scale factor based on the space we have for the icon,
			// choosing the smaller of the two possible image size ratios.
			icon_size *= std::min(max_icon.W / icon_size.W, max_icon.H / icon_size.H);
		} else {
			icon_size *= m_style.icon.scale;
		}

		// Now that we have the size of the icon, we can compute the icon rect
		// based on the desired placement of the icon.
		PosF icon_start  = padding_rect.TopLeft;
		PosF icon_center = icon_start + (padding_rect.size() - icon_size) / 2.0f;
		PosF icon_end    = icon_start + (padding_rect.size() - icon_size);

		switch (m_style.icon_place) {
		case IconPlace::CENTER:
			m_icon_rect = RectF(icon_center, icon_size);
			break;
		case IconPlace::LEFT:
			m_icon_rect = RectF(PosF(icon_start.X, icon_center.Y), icon_size);
			break;
		case IconPlace::TOP:
			m_icon_rect = RectF(PosF(icon_center.X, icon_start.Y), icon_size);
			break;
		case IconPlace::RIGHT:
			m_icon_rect = RectF(PosF(icon_end.X, icon_center.Y), icon_size);
			break;
		case IconPlace::BOTTOM:
			m_icon_rect = RectF(PosF(icon_center.X, icon_end.Y), icon_size);
			break;
		}

		// If the overlap property is set or the icon is centered, the content
		// rect is identical to the padding rect. Otherwise, the content rect
		// needs to be adjusted to account for the icon and gutter.
		m_content_rect = padding_rect;

		if (!m_style.icon_overlap && m_style.icon.image != nullptr) {
			switch (m_style.icon_place) {
			case IconPlace::CENTER:
				break;
			case IconPlace::LEFT:
				m_content_rect.L += icon_size.W + m_style.icon_gutter;
				break;
			case IconPlace::TOP:
				m_content_rect.T += icon_size.H + m_style.icon_gutter;
				break;
			case IconPlace::RIGHT:
				m_content_rect.R -= icon_size.W + m_style.icon_gutter;
				break;
			case IconPlace::BOTTOM:
				m_content_rect.B -= icon_size.H + m_style.icon_gutter;
				break;
			}

			m_content_rect = m_content_rect.clip();
		}

		// We set our clipping rect based on the display mode.
		switch (m_style.display) {
		case DisplayMode::VISIBLE:
		case DisplayMode::HIDDEN:
			// If the box is visible or hidden, then we clip the box and its
			// content as normal against the drawing and layout clip rects.
			m_clip_rect = m_display_rect.intersectWith(layout_clip);
			break;
		case DisplayMode::OVERFLOW:
			// If the box allows overflow, then clip to the drawing rect, since
			// we never want to expand outside our own visible boundaries, but
			// we don't clip to the layout clip rect.
			m_clip_rect = m_display_rect;
			break;
		case DisplayMode::CLIPPED:
			// If the box and its content should be entirely removed, then we
			// clip everything entirely.
			m_clip_rect = RectF();
			break;
		}
	}

	void Box::resizePlace()
	{
		for (Box *box : m_content) {
			// Calculate the size of the box according to the span and scale
			// factor. If the scale is zero, we don't know how big the span
			// will end up being, so the span size goes to zero.
			SizeF span_size = box->m_style.sizing.span * m_style.layout.scale;

			// Ensure that the computed minimum size for our content is at
			// least as large as the minimum size of the box and its span size.
			m_min_content = m_min_content.max(box->m_min_layout).max(span_size);
		}
	}

	void Box::relayoutPlace()
	{
		for (Box *box : m_content) {
			const Sizing &sizing = box->m_style.sizing;

			// Compute the scale factor. If the scale is zero, then we use the
			// size of the parent box to achieve normalized coordinates.
			SizeF scale = m_style.layout.scale == 0.0f ?
				m_content_rect.size() : SizeF(m_style.layout.scale);

			// Calculate the position and size of the box relative to the
			// origin, taking into account the scale factor and anchor. Also
			// make sure the size doesn't go below the minimum size.
			SizeF size = (sizing.span * scale).max(box->m_min_layout);
			SizeF pos = (sizing.pos * scale) - (sizing.anchor * size);

			// The layout rect of the box is made by shifting the above rect by
			// the top left of the content rect.
			RectF layout_rect = RectF(m_content_rect.TopLeft + pos, size);
			box->relayout(layout_rect, m_clip_rect);
		}
	}

	void Box::drawBox()
	{
		// First, fill the display rectangle with the fill color.
		getWindow().drawRect(m_display_rect, m_clip_rect, m_style.box.fill);

		// If there's no image, then we don't need to do a bunch of
		// calculations in order to draw nothing.
		if (m_style.box.image == nullptr) {
			return;
		}

		// For the image, first get the source rect adjusted for animations.
		RectF src = getLayerSource(m_style.box);

		// We need to make sure the the middle rect is relative to the source
		// rect rather than the entire image, so scale the edges appropriately.
		DispF middle_src = m_style.box_middle * DispF(src.size());
		DispF middle_dst = getMiddleEdges();

		// If the source rect for this image is flipped, we need to flip the
		// sign of our middle rect as well to get the right adjustments.
		if (src.W() < 0.0f) {
			middle_src.L = -middle_src.L;
			middle_src.R = -middle_src.R;
		}
		if (src.H() < 0.0f) {
			middle_src.T = -middle_src.T;
			middle_src.B = -middle_src.B;
		}

		for (int slice_y = 0; slice_y < 3; slice_y++) {
			for (int slice_x = 0; slice_x < 3; slice_x++) {
				// Compute each slice of the nine-slice image. If the middle
				// rect equals the whole source rect, the middle slice will
				// occupy the entire display rectangle.
				RectF slice_src = src;
				RectF slice_dst = m_display_rect;

				switch (slice_x) {
				case 0:
					slice_dst.R = slice_dst.L + middle_dst.L;
					slice_src.R = slice_src.L + middle_src.L;
					break;

				case 1:
					slice_dst.L += middle_dst.L;
					slice_dst.R -= middle_dst.R;
					slice_src.L += middle_src.L;
					slice_src.R -= middle_src.R;
					break;

				case 2:
					slice_dst.L = slice_dst.R - middle_dst.R;
					slice_src.L = slice_src.R - middle_src.R;
					break;
				}

				switch (slice_y) {
				case 0:
					slice_dst.B = slice_dst.T + middle_dst.T;
					slice_src.B = slice_src.T + middle_src.T;
					break;

				case 1:
					slice_dst.T += middle_dst.T;
					slice_dst.B -= middle_dst.B;
					slice_src.T += middle_src.T;
					slice_src.B -= middle_src.B;
					break;

				case 2:
					slice_dst.T = slice_dst.B - middle_dst.B;
					slice_src.T = slice_src.B - middle_src.B;
					break;
				}

				// If we have a tiled image, then some of the tiles may bleed
				// out of the slice rect, so we need to clip to both the
				// clipping rect and the destination rect.
				RectF slice_clip = m_clip_rect.intersectWith(slice_dst);

				// If this slice is empty or has been entirely clipped, then
				// don't bother drawing anything.
				if (slice_clip.empty()) {
					continue;
				}

				// This may be a tiled image, so we need to calculate the size
				// of each tile. If the image is not tiled, this should equal
				// the size of the destination rect.
				SizeF tile_size = slice_dst.size();

				if (m_style.box_tile != DirFlags::NONE) {
					// We need to calculate the tile size based on the texture
					// size and the scale of each tile. If the scale is too
					// small, then the number of tiles will explode, so we
					// clamp it to a reasonable minimum of 1/8 of a pixel.
					SizeF tex_size = getTextureSize(m_style.box.image);
					float tile_scale = std::max(m_style.box.scale, 0.125f);

					if (m_style.box_tile != DirFlags::Y) {
						tile_size.W = slice_src.W() * tex_size.W * tile_scale;
					}
					if (m_style.box_tile != DirFlags::X) {
						tile_size.H = slice_src.H() * tex_size.H * tile_scale;
					}
				}

				// Now we can draw each tile for this slice. If the image is
				// not tiled, then each of these loops will run only once.
				float tile_y = slice_dst.T;

				while (tile_y < slice_dst.B) {
					float tile_x = slice_dst.L;

					while (tile_x < slice_dst.R) {
						// Draw the texture in the appropriate destination rect
						// for this tile, and clip it to the clipping rect for
						// this slice.
						RectF tile_dst = RectF(PosF(tile_x, tile_y), tile_size);

						getWindow().drawTexture(tile_dst, slice_clip,
								m_style.box.image, slice_src, m_style.box.tint);

						tile_x += tile_size.W;
					}
					tile_y += tile_size.H;
				}
			}
		}
	}

	void Box::drawIcon()
	{
		// The icon rect is computed while the box is being laid out, so we
		// just need to draw it with the fill color behind it.
		getWindow().drawRect(m_icon_rect, m_clip_rect, m_style.icon.fill);
		getWindow().drawTexture(m_icon_rect, m_clip_rect, m_style.icon.image,
			getLayerSource(m_style.icon), m_style.icon.tint);
	}

	bool Box::isHovered() const
	{
		return m_elem.getHoveredBox() == getId();
	}

	bool Box::isPressed() const
	{
		return m_elem.getPressedBox() == getId();
	}

	void Box::setHovered(bool hovered)
	{
		if (hovered) {
			m_elem.setHoveredBox(getId());
		} else if (isHovered()) {
			m_elem.setHoveredBox(NO_ID);
		}
	}

	void Box::setPressed(bool pressed)
	{
		if (pressed) {
			m_elem.setPressedBox(getId());
		} else if (isPressed()) {
			m_elem.setPressedBox(NO_ID);
		}
	}
}