/**
 * $Id: layout.c,v 1.1 2002/05/04 19:57:18 bursa Exp $
 */

#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libxml/HTMLparser.h"
#include "css.h"
#include "font.h"
#include "box.h"
#include "utils.h"

/**
 * internal functions
 */

signed long len(struct css_length * length, unsigned long em);

unsigned long layout_block_children(struct box * box, unsigned long width);
void layout_inline_container(struct box * box, unsigned long width);
void layout_table(struct box * box, unsigned long width);


/**
 * convert a struct css_length to pixels
 */

signed long len(struct css_length * length, unsigned long em)
{
	switch (length->unit) {
		case CSS_UNIT_EM: return length->value * em;
		case CSS_UNIT_EX: return length->value * em * 0.6;
		case CSS_UNIT_PX: return length->value;
		case CSS_UNIT_IN: return length->value * 90.0;
		case CSS_UNIT_CM: return length->value * 35.0;
		case CSS_UNIT_MM: return length->value * 3.5;
		case CSS_UNIT_PT: return length->value * 90.0 / 72.0;
		case CSS_UNIT_PC: return length->value * 90.0 / 6.0;
		default: return 0;
	}
	return 0;
}

/**
 * layout algorithm
 */

void layout_block(struct box * box, unsigned long width)
{
	struct css_style * style = box->style;
	switch (style->width.width) {
		case CSS_WIDTH_AUTO:
			box->width = width;
			break;
		case CSS_WIDTH_LENGTH:
			box->width = len(&style->width.value.length, 10);
			break;
		case CSS_WIDTH_PERCENT:
			box->width = width * style->width.value.percent / 100;
			break;
	}
	box->height = layout_block_children(box, box->width);
	switch (style->height.height) {
		case CSS_HEIGHT_AUTO:
			break;
		case CSS_HEIGHT_LENGTH:
			box->height = len(&style->height.length, 10);
			break;
	}
}

unsigned long layout_block_children(struct box * box, unsigned long width)
{
	struct box * c;
	unsigned long y = 1;
	
	for (c = box->children; c != 0; c = c->next) {
		switch (c->type) {
			case BOX_BLOCK:
				layout_block(c, width-4);
				c->x = 2;
				c->y = y;
				y += c->height + 1;
				break;
			case BOX_INLINE_CONTAINER:
				layout_inline_container(c, width-4);
				c->x = 2;
				c->y = y;
				y += c->height + 1;
				break;
			case BOX_TABLE:
				layout_table(c, width-4);
				c->x = 2;
				c->y = y;
				y += c->height + 1;
				break;
			default:
				die("block child not block, table, or inline container");
		}
	}
	return y;
}

void layout_inline_container(struct box * box, unsigned long width)
{
	/* TODO: write this */
	struct box * c;
	unsigned long y = 1;
	unsigned long x = 2;
	const char * end;
	struct box * new;

	for (c = box->children; c != 0; ) {
		c->width = font_split(0, c->font, c->text, width-2-x, &end)+1;
		if (*end == 0) {
			/* fits into this line */
			c->x = x;
			c->y = y;
			c->height = 2;
			x += c->width;
			c = c->next;
			continue;
		}
		if (end == c->text) {
			/* doesn't fit at all: move down a line */
			x = 2;
			y += 3;
			c->width = font_split(0, c->font, c->text, width-2-x, &end)+1;
			if (end == c->text) end = strchr(c->text, ' ');
			if (end == 0) end = c->text + 1;
		}
		/* split into two lines */ 
		c->x = x;
		c->y = y;
		c->height = 2;
		x = 2;
		y += 3;
		new = memcpy(xcalloc(1, sizeof(struct box)), c, sizeof(struct box));
		new->text = end + 1;
		new->next = c->next;
		c->next = new;
		c = new;
	}

	box->width = width;
	box->height = y + 3;
}

/**
 * layout a table
 *
 * this is the fixed table layout algorithm,
 * <http://www.w3.org/TR/REC-CSS2/tables.html#fixed-table-layout>
 */

void layout_table(struct box * table, unsigned long width)
{
	unsigned int columns;  /* total columns */
	unsigned int auto_columns;  /* number of columns with auto width */
	unsigned long table_width;
	unsigned long used_width = 0;  /* width used by fixed or percent columns */
	unsigned long auto_width;  /* width of each auto column (all equal) */
	unsigned long extra_width = 0;  /* extra width for each column if table is wider than columns */
	unsigned long x;
	unsigned long y = 1;
	unsigned long * xs;
	unsigned int i;
	struct box * c;
	struct box * r;

	assert(table->type == BOX_TABLE);

	/* find table width */
	switch (table->style->width.width) {
		case CSS_WIDTH_LENGTH:
			table_width = len(&table->style->width.value.length, 10);
			break;
		case CSS_WIDTH_PERCENT:
			table_width = width * table->style->width.value.percent / 100;
			break;
		case CSS_WIDTH_AUTO:
		default:
			table_width = width;
			break;
	}

	/* calculate column statistics */
	for (columns = 0, auto_columns = 0, c = table->children->children;
			c != 0; c = c->next) {
		assert(c->type == BOX_TABLE_CELL);
		switch (c->style->width.width) {
			case CSS_WIDTH_LENGTH:
				used_width += len(&c->style->width.value.length, 10);
				break;
			case CSS_WIDTH_PERCENT:
				used_width += table_width * c->style->width.value.percent / 100;
				break;
			case CSS_WIDTH_AUTO:
				auto_columns++;
				break;
		}
		columns++;
	}

	if (auto_columns == 0 && table->style->width.width != CSS_WIDTH_AUTO)
		extra_width = (table_width - used_width) / columns;
	else if (auto_columns != 0)
		auto_width = (table_width - used_width) / auto_columns;

	/*printf("%i %i %i %i %i\n", table_width, columns, auto_columns, used_width, auto_width);*/
	
	/* find column widths */
	xs = xcalloc(columns + 1, sizeof(*xs));
	xs[0] = x = 0;
	for (i = 1, c = table->children->children; c != 0; i++, c = c->next) {
		switch (c->style->width.width) {
			case CSS_WIDTH_LENGTH:
				x += len(&c->style->width.value.length, 10) + extra_width;
				break;
			case CSS_WIDTH_PERCENT:
				x += table_width * c->style->width.value.percent / 100 + extra_width;
				break;
			case CSS_WIDTH_AUTO:
				x += auto_width;
				break;
		}
		xs[i] = x;
		printf("%i ", x);
	}
	printf("\n");

	if (auto_columns == 0 && table->style->width.width == CSS_WIDTH_AUTO)
		table_width = used_width;
	
	/* position cells */
	for (r = table->children; r != 0; r = r->next) {
		unsigned long height = 0;
		for (i = 0, c = r->children; c != 0; i++, c = c->next) {
			c->width = xs[i+1] - xs[i];
			c->height = layout_block_children(c, c->width);
			switch (c->style->height.height) {
				case CSS_HEIGHT_AUTO:
					break;
				case CSS_HEIGHT_LENGTH:
					c->height = len(&c->style->height.length, 10);
					break;
			}
			c->x = xs[i];
			c->y = 1;
			if (c->height > height) height = c->height;
		}
		r->x = 0;
		r->y = y;
		r->width = table_width;
		r->height = height + 2;
		y += height + 3;
	}

	free(xs);
	
	table->width = table_width;
	table->height = y;
}