//---
//	node: Mathematical constructs in the formula tree
//---

#ifndef TEX_NODE
#define TEX_NODE

#include <TeX/config.h>
#include <TeX/defs.h>
#include <stddef.h>
#include <stdint.h>

/* A special class number for nodes that contain plain text. */
#define TEX_NODECLASS_TEXT 0
/* Special class for environment nodes, also a special case */
#define TEX_NODECLASS_ENV 1

struct TeX_Flow;
struct TeX_Env;

/* TeX_Node
   This object represents a mathematical construct. It can be plain text, a
   fraction, a square root or a matrix. It has specific layout and rendering
   that are supplied by its class. */
struct TeX_Node
{
	/* Pointer to next element in the flow */
	struct TeX_Node *next;

	union {
		/* Plain text content encoded as UTF-8 */
		uint8_t *text;
		/* Environment pointer */
		struct TeX_Env *env;
		/* Functional arguments */
		struct TeX_Flow *args[TEX_NODE_MAX_CHILDREN];
	};

	/* Node is invalid or hidden */
	uint hidden :1;
	/* Node class identifier */
	uint type :7;
	/* Class variant or fixed argument */
	uint subtype :8;

	/* Size and placement */
	uint16_t width;
	uint16_t height;
	uint16_t line;

	/* Location within the flow, as x and baseline displacement */
	uint16_t x;
	int16_t l;

} __attribute__((packed, aligned(sizeof (void *))));

//---
//	Node creation and destruction functions
//---

/* TeX_node_text(): Make a text node */
struct TeX_Node *TeX_node_text(char const *utf8);

/* TeX_node_command(): Make a command node without arguments
   Returns NULL if no such command is defined. */
struct TeX_Node *TeX_node_command(char const *command);

/* TeX_node_add_arg(): Add an argument to a command node
   If [node] is a command node and has at least on free argument slot, then
   adds [arg] to it. Otherwise, destroys [arg].
   Always returns [flow] (useful for nested calls). */
struct TeX_Node *TeX_node_add_arg(struct TeX_Node *node, struct TeX_Flow *arg);

/* TeX_node_absorb(): Absorb text into a command node
   This special function is for command nodes that use the absorption syntax,
   eg. "\left(" where the argument consists of a single character and is not
   surrounded by braces. The first character of [text] (which should be only
   one character if it comes from the parser) is saved as argument. [text] is
   not freed. Always returns [node]. */
struct TeX_Node *TeX_node_absorb(struct TeX_Node *node, char const *text);

/* TeX_node_env(): Make a environment node
   This function creates an node that wraps an environment and inserts it into
   a formula. */
struct TeX_Node *TeX_node_env(struct TeX_Env *env);

/* TeX_node_free(): Free a TeX_Node and all its children */
void TeX_node_free(struct TeX_Node *node);

//---
//	Layout and rendering
//---

/* TeX_node_layout(): Compute the layout of a node
   This functions computes the layout of a node and its children, and stores
   the results in the node's metadata. */
void TeX_node_layout(struct TeX_Node *node);

/* TeX_node_render(): Render a node and its children
   The node's layout must have been computed first. */
void TeX_node_render(struct TeX_Node const * node, int x, int y, int color);

#endif /* TEX_NODE */