/*
 * This file is part of LibNSLayout
 * Licensed under the ISC License, http://opensource.org/licenses/ISC
 * Copyright 2015 Michael Drake <tlsa@netsurf-browser.org>
 * Copyright 2015 John-Mark Bell <jmb@netsurf-browser.org>
 */

#ifndef nslayout_nslayout_h_
#define nslayout_nslayout_h_

#ifdef __cplusplus
extern "C"
{
#endif

#include <libcss/libcss.h>
#include <dom/dom.h>

/** An opaque client-owned replaced element */
typedef void nslayout_replaced;

/** A rectangle */
typedef struct nslayout_rect {
	int x;
	int y;
	int w;
	int h;
} nslayout_rect;

/** Render list */
typedef struct nslayout_render_list {
} nslayout_render_list;

/** Render list */
typedef struct nslayout_layout nslayout_layout;

/**
 * A LibNSLayout request
 *
 * Passed to the client via nslayout_callback
 */
typedef struct nslayout_request {
	/** Request type */
	enum type {
		NSLAYOUT_GET_RESOURCE,
		NSLAYOUT_CREATE_REPLACED,
		NSLAYOUT_RENDER,
		NSLAYOUT_SET_EXTENTS,
		NSLAYOUT_GET_INTRINSIC_SIZE
	} type;
	/** Request's type-specific parameters */
	union {
		struct {
			const char *url; /**< Absolute URL */
		} get_resource;
		struct {
			dom_element *element; /**< DOM element */
		} create_replaced;
		struct {
			nslayout_render_list *list; /**< Render list */
		} render;
		struct {
			unsigned int width;  /**< Document width  in px */
			unsigned int height; /**< Document height in px */
		} set_extents;
		struct {
			nslayout_replaced *replaced; /** A replacement object */
		} get_intrinsic_size;
	} request;
	/** Request's type-specific return values */
	union {
		struct {
			nslayout_replaced **replaced; /** Replacement object */
		} get_resource;
		struct {
			nslayout_replaced **replaced; /** Replacement object */
		} create_replaced;
		struct {
			unsigned int *width;  /** Replacement object's width  */
			unsigned int *height; /** Replacement object's height */
		} get_intrinsic_size;
	} response;
} nslayout_request;

/** Libnslayout return codes */
typedef enum nslayout_error {
	NSLAYOUT_OK,
	NSLAYOUT_NO_MEM
} nslayout_error;

/**
 * Initialise LibNSLayout
 *
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_init(void);

/**
 * Finalise LibNSLayout
 *
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_fini(void);

/**
 * LibNSLayout client callback function
 *
 * \param req		The request details.
 * \param layout	The layout we're making a request for.
 * \param pw		The client's private data for this layout.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
typedef nslayout_error (*nslayout_callback)(
		nslayout_request *req,
		nslayout_layout *layout,
		void *pw);

/**
 * Create a Layout object for a given DOM
 *
 * \param doc		The LibDOM document to build a layout for.
 * \param css_ctx	The LibCSS selection context for the document.
 * \param media		The LibCSS media to use when selecting for this layout.
 * \param cb		The client's private data for this layout.
 * \param pw		The client's private data for this layout.
 * \param layout	Returns a pointer to the created layout object.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_layout_create(
		dom_document *doc,
		css_select_ctx *css_ctx,
		css_media_type *media,
		nslayout_callback cb,
		void *pw,
		nslayout_layout **layout);

/**
 * Destroy a Layout object
 *
 * \param layout	Returns a pointer to the created layout object.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_layout_destroy(
		nslayout_layout *layout);

/**
 * Update the viewport for a layout
 *
 * Note: Before this is called, the layout engine will create internal
 *       data structures for the document, but will not start to position
 *       things and will not emit render lists.
 *
 * \param layout	Layout to set viewport for.
 * \param viewport	Viewport dimensions and offset.
 * \param scale		Rendering scale.
 * \param dpi		DPI of render target with viewport.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_update_viewport(
		nslayout_layout *layout,
		nslayout_rect *viewport,
		css_fixed scale,
		unsigned int dpi);

/**
 * Find the top-most element at a given point, in terms of z-order.
 *
 * \param layout	Layout to locate an element in.
 * \param element	Updated to area with position relative to viewport.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_element_get_location(
		nslayout_layout *layout,
		nslayout_rect *area);

/**
 * Find the top-most element at a given point, in terms of z-order.
 *
 * \param layout	Layout to find an element in.
 * \param x		Mouse x-coordinate (viewport relative).
 * \param y		Mouse y-coordinate (viewport relative).
 * \param element	Updated to point at the element we found.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_element_at_point(
		nslayout_layout *layout,
		unsigned int x,
		unsigned int y,
		dom_event_target **element);

/**
 * Mark an element (or part of it) as needing redraw.
 *
 * \param layout	Layout to indicate redraw is required for.
 * \param element	Element to mark as needing redraw.
 * \param rel_area	Area of element to redraw relative to object's top-left.
 *                      May be NULL, to redraw whole element.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_layout_dirty_element(
		nslayout_layout *layout,
		dom_element *element,
		nslayout_rect *rel_area);

/**
 * Mark an area as needing redraw.
 *
 * \param layout	Layout to indicate redraw is required for.
 * \param area		Area to redraw relative to viewport's top-left.
 * \return NSLAYOUT_OK on success, appropriate error otherwise.
 */
nslayout_error nslayout_layout_dirty_area(
		nslayout_layout *layout,
		nslayout_rect *area);

#ifdef __cplusplus
}
#endif

#endif