/*************************************************************************/
/*  grid_container.cpp                                                   */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "grid_container.h"

void GridContainer::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_SORT_CHILDREN: {
			RBMap<int, int> col_minw; // Max of min_width of all controls in each col (indexed by col).
			RBMap<int, int> row_minh; // Max of min_height of all controls in each row (indexed by row).
			RBSet<int> col_expanded; // Columns which have the SIZE_EXPAND flag set.
			RBSet<int> row_expanded; // Rows which have the SIZE_EXPAND flag set.

			int hsep = get_theme_constant("hseparation");
			int vsep = get_theme_constant("vseparation");

			// Compute the per-column/per-row data.
			int valid_controls_index = 0;
			for (int i = 0; i < get_child_count(); i++) {
				Control *c = Object::cast_to<Control>(get_child(i));
				if (!c || !c->is_visible_in_tree()) {
					continue;
				}
				if (c->is_set_as_toplevel()) {
					continue;
				}

				int row = valid_controls_index / columns;
				int col = valid_controls_index % columns;
				valid_controls_index++;

				Size2i ms = c->get_combined_minimum_size();
				if (col_minw.has(col)) {
					col_minw[col] = MAX(col_minw[col], ms.width);
				} else {
					col_minw[col] = ms.width;
				}
				if (row_minh.has(row)) {
					row_minh[row] = MAX(row_minh[row], ms.height);
				} else {
					row_minh[row] = ms.height;
				}

				if (c->get_h_size_flags() & SIZE_EXPAND) {
					col_expanded.insert(col);
				}
				if (c->get_v_size_flags() & SIZE_EXPAND) {
					row_expanded.insert(row);
				}
			}

			int max_col = MIN(valid_controls_index, columns);
			int max_row = ceil((float)valid_controls_index / (float)columns);

			// Consider all empty columns expanded.
			for (int i = valid_controls_index; i < columns; i++) {
				col_expanded.insert(i);
			}

			// Evaluate the remaining space for expanded columns/rows.
			Size2 remaining_space = get_size();
			for (RBMap<int, int>::Element *E = col_minw.front(); E; E = E->next()) {
				if (!col_expanded.has(E->key())) {
					remaining_space.width -= E->get();
				}
			}

			for (RBMap<int, int>::Element *E = row_minh.front(); E; E = E->next()) {
				if (!row_expanded.has(E->key())) {
					remaining_space.height -= E->get();
				}
			}
			remaining_space.height -= vsep * MAX(max_row - 1, 0);
			remaining_space.width -= hsep * MAX(max_col - 1, 0);

			bool can_fit = false;
			while (!can_fit && col_expanded.size() > 0) {
				// Check if all minwidth constraints are OK if we use the remaining space.
				can_fit = true;
				int max_index = col_expanded.front()->get();
				for (RBSet<int>::Element *E = col_expanded.front(); E; E = E->next()) {
					if (col_minw[E->get()] > col_minw[max_index]) {
						max_index = E->get();
					}
					if (can_fit && (remaining_space.width / col_expanded.size()) < col_minw[E->get()]) {
						can_fit = false;
					}
				}

				// If not, the column with maximum minwidth is not expanded.
				if (!can_fit) {
					col_expanded.erase(max_index);
					remaining_space.width -= col_minw[max_index];
				}
			}

			can_fit = false;
			while (!can_fit && row_expanded.size() > 0) {
				// Check if all minheight constraints are OK if we use the remaining space.
				can_fit = true;
				int max_index = row_expanded.front()->get();
				for (RBSet<int>::Element *E = row_expanded.front(); E; E = E->next()) {
					if (row_minh[E->get()] > row_minh[max_index]) {
						max_index = E->get();
					}
					if (can_fit && (remaining_space.height / row_expanded.size()) < row_minh[E->get()]) {
						can_fit = false;
					}
				}

				// If not, the row with maximum minheight is not expanded.
				if (!can_fit) {
					row_expanded.erase(max_index);
					remaining_space.height -= row_minh[max_index];
				}
			}

			// Finally, fit the nodes.
			int col_remaining_pixel = 0;
			int col_expand = 0;
			if (col_expanded.size() > 0) {
				col_expand = remaining_space.width / col_expanded.size();
				col_remaining_pixel = remaining_space.width - col_expanded.size() * col_expand;
			}

			int row_remaining_pixel = 0;
			int row_expand = 0;
			if (row_expanded.size() > 0) {
				row_expand = remaining_space.height / row_expanded.size();
				row_remaining_pixel = remaining_space.height - row_expanded.size() * row_expand;
			}

			int col_ofs = 0;
			int row_ofs = 0;

			// Calculate the index of rows and columns that receive the remaining pixel.
			int col_remaining_pixel_index = 0;
			for (int i = 0; i < max_col; i++) {
				if (col_remaining_pixel == 0) {
					break;
				}
				if (col_expanded.has(i)) {
					col_remaining_pixel_index = i + 1;
					col_remaining_pixel--;
				}
			}
			int row_remaining_pixel_index = 0;
			for (int i = 0; i < max_row; i++) {
				if (row_remaining_pixel == 0) {
					break;
				}
				if (row_expanded.has(i)) {
					row_remaining_pixel_index = i + 1;
					row_remaining_pixel--;
				}
			}

			valid_controls_index = 0;
			for (int i = 0; i < get_child_count(); i++) {
				Control *c = Object::cast_to<Control>(get_child(i));
				if (!c || !c->is_visible_in_tree()) {
					continue;
				}
				int row = valid_controls_index / columns;
				int col = valid_controls_index % columns;
				valid_controls_index++;

				if (col == 0) {
					col_ofs = 0;
					if (row > 0) {
						row_ofs += (row_expanded.has(row - 1) ? row_expand : row_minh[row - 1]) + vsep;

						if (row_expanded.has(row - 1) && row - 1 < row_remaining_pixel_index) {
							// Apply the remaining pixel of the previous row.
							row_ofs++;
						}
					}
				}

				Size2 s(col_expanded.has(col) ? col_expand : col_minw[col], row_expanded.has(row) ? row_expand : row_minh[row]);

				// Add the remaining pixel to the expanding columns and rows, starting from left and top.
				if (col_expanded.has(col) && col < col_remaining_pixel_index) {
					s.x++;
				}
				if (row_expanded.has(row) && row < row_remaining_pixel_index) {
					s.y++;
				}

				Point2 p(col_ofs, row_ofs);
				fit_child_in_rect(c, Rect2(p, s));
				col_ofs += s.width + hsep;
			}

		} break;
		case NOTIFICATION_THEME_CHANGED: {
			minimum_size_changed();
		} break;
	}
}

void GridContainer::set_columns(int p_columns) {
	ERR_FAIL_COND(p_columns < 1);
	columns = p_columns;
	queue_sort();
	minimum_size_changed();
}

int GridContainer::get_columns() const {
	return columns;
}

void GridContainer::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_columns", "columns"), &GridContainer::set_columns);
	ClassDB::bind_method(D_METHOD("get_columns"), &GridContainer::get_columns);

	ADD_PROPERTY(PropertyInfo(Variant::INT, "columns", PROPERTY_HINT_RANGE, "1,1024,1"), "set_columns", "get_columns");
}

Size2 GridContainer::get_minimum_size() const {
	RBMap<int, int> col_minw;
	RBMap<int, int> row_minh;

	int hsep = get_theme_constant("hseparation");
	int vsep = get_theme_constant("vseparation");

	int max_row = 0;
	int max_col = 0;

	int valid_controls_index = 0;
	for (int i = 0; i < get_child_count(); i++) {
		Control *c = Object::cast_to<Control>(get_child(i));
		if (!c || !c->is_visible()) {
			continue;
		}
		int row = valid_controls_index / columns;
		int col = valid_controls_index % columns;
		valid_controls_index++;

		Size2i ms = c->get_combined_minimum_size();
		if (col_minw.has(col)) {
			col_minw[col] = MAX(col_minw[col], ms.width);
		} else {
			col_minw[col] = ms.width;
		}

		if (row_minh.has(row)) {
			row_minh[row] = MAX(row_minh[row], ms.height);
		} else {
			row_minh[row] = ms.height;
		}
		max_col = MAX(col, max_col);
		max_row = MAX(row, max_row);
	}

	Size2 ms;

	for (RBMap<int, int>::Element *E = col_minw.front(); E; E = E->next()) {
		ms.width += E->get();
	}

	for (RBMap<int, int>::Element *E = row_minh.front(); E; E = E->next()) {
		ms.height += E->get();
	}

	ms.height += vsep * max_row;
	ms.width += hsep * max_col;

	return ms;
}

GridContainer::GridContainer() {
	set_mouse_filter(MOUSE_FILTER_PASS);
	columns = 1;
}