#include "fitz-internal.h"
#include "mupdf-internal.h"

struct info
{
	pdf_obj *resources;
	pdf_obj *mediabox;
	pdf_obj *cropbox;
	pdf_obj *rotate;
};

static void
put_marker_bool(fz_context *ctx, pdf_obj *rdb, char *marker, int val)
{
	pdf_obj *tmp;

	tmp = pdf_new_bool(ctx, val);
	fz_try(ctx)
	{
		pdf_dict_puts(rdb, marker, tmp);
	}
	fz_always(ctx)
	{
		pdf_drop_obj(tmp);
	}
	fz_catch(ctx)
	{
		fz_rethrow(ctx);
	}
}

typedef struct pdf_page_load_s pdf_page_load;

struct pdf_page_load_s
{
	int max;
	int pos;
	pdf_obj *node;
	pdf_obj *kids;
	struct info info;
};

static void
pdf_load_page_tree_node(pdf_document *xref, pdf_obj *node, struct info info)
{
	pdf_obj *dict, *kids, *count;
	pdf_obj *obj;
	fz_context *ctx = xref->ctx;
	pdf_page_load *stack = NULL;
	int stacklen = -1;
	int stackmax = 0;

	fz_try(ctx)
	{
		do
		{
			if (!node || pdf_dict_mark(node))
			{
				/* NULL node, or we've been here before.
				 * Nothing to do. */
			}
			else
			{
				kids = pdf_dict_gets(node, "Kids");
				count = pdf_dict_gets(node, "Count");
				if (pdf_is_array(kids) && pdf_is_int(count))
				{
					/* Push this onto the stack */
					obj = pdf_dict_gets(node, "Resources");
					if (obj)
						info.resources = obj;
					obj = pdf_dict_gets(node, "MediaBox");
					if (obj)
						info.mediabox = obj;
					obj = pdf_dict_gets(node, "CropBox");
					if (obj)
						info.cropbox = obj;
					obj = pdf_dict_gets(node, "Rotate");
					if (obj)
						info.rotate = obj;
					stacklen++;
					if (stacklen == stackmax)
					{
						stack = fz_resize_array(ctx, stack, stackmax ? stackmax*2 : 10, sizeof(*stack));
						stackmax = stackmax ? stackmax*2 : 10;
					}
					stack[stacklen].kids = kids;
					stack[stacklen].node = node;
					stack[stacklen].pos = -1;
					stack[stacklen].max = pdf_array_len(kids);
					stack[stacklen].info = info;
				}
				else if ((dict = pdf_to_dict(node)) != NULL)
				{
					if (info.resources && !pdf_dict_gets(dict, "Resources"))
						pdf_dict_puts(dict, "Resources", info.resources);
					if (info.mediabox && !pdf_dict_gets(dict, "MediaBox"))
						pdf_dict_puts(dict, "MediaBox", info.mediabox);
					if (info.cropbox && !pdf_dict_gets(dict, "CropBox"))
						pdf_dict_puts(dict, "CropBox", info.cropbox);
					if (info.rotate && !pdf_dict_gets(dict, "Rotate"))
						pdf_dict_puts(dict, "Rotate", info.rotate);

					if (xref->page_len == xref->page_cap)
					{
						fz_warn(ctx, "found more pages than expected");
						xref->page_refs = fz_resize_array(ctx, xref->page_refs, xref->page_cap+1, sizeof(pdf_obj*));
						xref->page_objs = fz_resize_array(ctx, xref->page_objs, xref->page_cap+1, sizeof(pdf_obj*));
						xref->page_cap ++;
					}

					xref->page_refs[xref->page_len] = pdf_keep_obj(node);
					xref->page_objs[xref->page_len] = pdf_keep_obj(dict);
					xref->page_len ++;
					pdf_dict_unmark(node);
				}
			}
			/* Get the next node */
			if (stacklen < 0)
				break;
			while (++stack[stacklen].pos == stack[stacklen].max)
			{
				pdf_dict_unmark(stack[stacklen].node);
				stacklen--;
				if (stacklen < 0) /* No more to pop! */
					break;
				node = stack[stacklen].node;
				info = stack[stacklen].info;
				pdf_dict_unmark(node); /* Unmark it, cos we're about to mark it again */
			}
			if (stacklen >= 0)
				node = pdf_array_get(stack[stacklen].kids, stack[stacklen].pos);
		}
		while (stacklen >= 0);
	}
	fz_always(ctx)
	{
		while (stacklen >= 0)
			pdf_dict_unmark(stack[stacklen--].node);
		fz_free(ctx, stack);
	}
	fz_catch(ctx)
	{
		fz_rethrow(ctx);
	}
}

static void
pdf_load_page_tree(pdf_document *xref)
{
	fz_context *ctx = xref->ctx;
	pdf_obj *catalog;
	pdf_obj *pages;
	pdf_obj *count;
	struct info info;

	if (xref->page_refs)
		return;

	catalog = pdf_dict_gets(xref->trailer, "Root");
	pages = pdf_dict_gets(catalog, "Pages");
	count = pdf_dict_gets(pages, "Count");

	if (!pdf_is_dict(pages))
		fz_throw(ctx, "missing page tree");
	if (!pdf_is_int(count) || pdf_to_int(count) < 0)
		fz_throw(ctx, "missing page count");

	xref->page_cap = pdf_to_int(count);
	xref->page_len = 0;
	xref->page_refs = fz_malloc_array(ctx, xref->page_cap, sizeof(pdf_obj*));
	xref->page_objs = fz_malloc_array(ctx, xref->page_cap, sizeof(pdf_obj*));

	info.resources = NULL;
	info.mediabox = NULL;
	info.cropbox = NULL;
	info.rotate = NULL;

	pdf_load_page_tree_node(xref, pages, info);
}

int
pdf_count_pages(pdf_document *xref)
{
	pdf_load_page_tree(xref);
	return xref->page_len;
}

int
pdf_lookup_page_number(pdf_document *xref, pdf_obj *page)
{
	int i, num = pdf_to_num(page);

	pdf_load_page_tree(xref);
	for (i = 0; i < xref->page_len; i++)
		if (num == pdf_to_num(xref->page_refs[i]))
			return i;
	return -1;
}

/* We need to know whether to install a page-level transparency group */

static int pdf_resources_use_blending(fz_context *ctx, pdf_obj *rdb);

static int
pdf_extgstate_uses_blending(fz_context *ctx, pdf_obj *dict)
{
	pdf_obj *obj = pdf_dict_gets(dict, "BM");
	if (pdf_is_name(obj) && strcmp(pdf_to_name(obj), "Normal"))
		return 1;
	return 0;
}

static int
pdf_pattern_uses_blending(fz_context *ctx, pdf_obj *dict)
{
	pdf_obj *obj;
	obj = pdf_dict_gets(dict, "Resources");
	if (pdf_resources_use_blending(ctx, obj))
		return 1;
	obj = pdf_dict_gets(dict, "ExtGState");
	return pdf_extgstate_uses_blending(ctx, obj);
}

static int
pdf_xobject_uses_blending(fz_context *ctx, pdf_obj *dict)
{
	pdf_obj *obj = pdf_dict_gets(dict, "Resources");
	return pdf_resources_use_blending(ctx, obj);
}

static int
pdf_resources_use_blending(fz_context *ctx, pdf_obj *rdb)
{
	pdf_obj *obj;
	int i, n, useBM = 0;

	if (!rdb)
		return 0;

	/* Have we been here before and stashed an answer? */
	obj = pdf_dict_gets(rdb, ".useBM");
	if (obj)
		return pdf_to_bool(obj);

	/* stop on cyclic resource dependencies */
	if (pdf_dict_mark(rdb))
		return 0;

	fz_try(ctx)
	{
		obj = pdf_dict_gets(rdb, "ExtGState");
		n = pdf_dict_len(obj);
		for (i = 0; i < n; i++)
			if (pdf_extgstate_uses_blending(ctx, pdf_dict_get_val(obj, i)))
				goto found;

		obj = pdf_dict_gets(rdb, "Pattern");
		n = pdf_dict_len(obj);
		for (i = 0; i < n; i++)
			if (pdf_pattern_uses_blending(ctx, pdf_dict_get_val(obj, i)))
				goto found;

		obj = pdf_dict_gets(rdb, "XObject");
		n = pdf_dict_len(obj);
		for (i = 0; i < n; i++)
			if (pdf_xobject_uses_blending(ctx, pdf_dict_get_val(obj, i)))
				goto found;
		if (0)
		{
found:
			useBM = 1;
		}
	}
	fz_always(ctx)
	{
		pdf_dict_unmark(rdb);
	}
	fz_catch(ctx)
	{
		fz_rethrow(ctx);
	}

	put_marker_bool(ctx, rdb, ".useBM", useBM);
	return useBM;
}

pdf_page *
pdf_load_page(pdf_document *xref, int number)
{
	fz_context *ctx = xref->ctx;
	pdf_page *page;
	pdf_annot *annot;
	pdf_obj *pageobj, *pageref, *obj;
	fz_rect mediabox, cropbox, realbox;
	fz_matrix ctm;
	float userunit;

	pdf_load_page_tree(xref);
	if (number < 0 || number >= xref->page_len)
		fz_throw(ctx, "cannot find page %d", number + 1);

	pageobj = xref->page_objs[number];
	pageref = xref->page_refs[number];

	page = fz_malloc_struct(ctx, pdf_page);
	page->resources = NULL;
	page->contents = NULL;
	page->transparency = 0;
	page->links = NULL;
	page->annots = NULL;

	obj = pdf_dict_gets(pageobj, "UserUnit");
	if (pdf_is_real(obj))
		userunit = pdf_to_real(obj);
	else
		userunit = 1;

	mediabox = pdf_to_rect(ctx, pdf_dict_gets(pageobj, "MediaBox"));
	if (fz_is_empty_rect(mediabox))
	{
		fz_warn(ctx, "cannot find page size for page %d", number + 1);
		mediabox.x0 = 0;
		mediabox.y0 = 0;
		mediabox.x1 = 612;
		mediabox.y1 = 792;
	}

	cropbox = pdf_to_rect(ctx, pdf_dict_gets(pageobj, "CropBox"));
	if (!fz_is_empty_rect(cropbox))
		mediabox = fz_intersect_rect(mediabox, cropbox);

	page->mediabox.x0 = fz_min(mediabox.x0, mediabox.x1) * userunit;
	page->mediabox.y0 = fz_min(mediabox.y0, mediabox.y1) * userunit;
	page->mediabox.x1 = fz_max(mediabox.x0, mediabox.x1) * userunit;
	page->mediabox.y1 = fz_max(mediabox.y0, mediabox.y1) * userunit;

	if (page->mediabox.x1 - page->mediabox.x0 < 1 || page->mediabox.y1 - page->mediabox.y0 < 1)
	{
		fz_warn(ctx, "invalid page size in page %d", number + 1);
		page->mediabox = fz_unit_rect;
	}

	page->rotate = pdf_to_int(pdf_dict_gets(pageobj, "Rotate"));
	/* Snap page->rotate to 0, 90, 180 or 270 */
	if (page->rotate < 0)
		page->rotate = 360 - ((-page->rotate) % 360);
	if (page->rotate >= 360)
		page->rotate = page->rotate % 360;
	page->rotate = 90*((page->rotate + 45)/90);
	if (page->rotate > 360)
		page->rotate = 0;

	ctm = fz_concat(fz_rotate(-page->rotate), fz_scale(1, -1));
	realbox = fz_transform_rect(ctm, page->mediabox);
	ctm = fz_concat(ctm, fz_scale(userunit, userunit));
	ctm = fz_concat(ctm, fz_translate(-realbox.x0, -realbox.y0));
	page->ctm = ctm;

	obj = pdf_dict_gets(pageobj, "Annots");
	if (obj)
	{
		page->links = pdf_load_link_annots(xref, obj, page->ctm);
		page->annots = pdf_load_annots(xref, obj, page->ctm);
	}

	page->resources = pdf_dict_gets(pageobj, "Resources");
	if (page->resources)
		pdf_keep_obj(page->resources);

	obj = pdf_dict_gets(pageobj, "Contents");
	fz_try(ctx)
	{
		page->contents = pdf_keep_obj(obj);

		if (pdf_resources_use_blending(ctx, page->resources))
			page->transparency = 1;

		for (annot = page->annots; annot && !page->transparency; annot = annot->next)
			if (annot->ap && pdf_resources_use_blending(ctx, annot->ap->resources))
				page->transparency = 1;
	}
	fz_catch(ctx)
	{
		pdf_free_page(xref, page);
		fz_throw(ctx, "cannot load page %d contents (%d 0 R)", number + 1, pdf_to_num(pageref));
	}

	return page;
}

fz_rect
pdf_bound_page(pdf_document *xref, pdf_page *page)
{
	fz_rect bounds, mediabox = fz_transform_rect(fz_rotate(page->rotate), page->mediabox);
	bounds.x0 = bounds.y0 = 0;
	bounds.x1 = mediabox.x1 - mediabox.x0;
	bounds.y1 = mediabox.y1 - mediabox.y0;
	return bounds;
}

fz_link *
pdf_load_links(pdf_document *xref, pdf_page *page)
{
	return fz_keep_link(xref->ctx, page->links);
}

void
pdf_free_page(pdf_document *xref, pdf_page *page)
{
	pdf_drop_obj(page->resources);
	pdf_drop_obj(page->contents);
	if (page->links)
		fz_drop_link(xref->ctx, page->links);
	if (page->annots)
		pdf_free_annot(xref->ctx, page->annots);
	/* xref->focus, when not NULL, refers to one of
	 * the annotations and must be NULLed when the
	 * annotations are destroyed. xref->focus_obj
	 * keeps track of the actual annotation object. */
	xref->focus = NULL;
	fz_free(xref->ctx, page);
}