#include <string.h>

#include "util.h"
#include "id.h"


#define	NODE2ID(n)	((struct id *) n)


static struct id *free_id = NULL;


int comp_id(const struct id *a, const struct id *b)
{
	int len = a->len < b->len ? a->len : b->len;
	int cmp;

	cmp = memcmp(a->s, b->s, len);
	if (cmp)
		return cmp;
	return a->len < b->len ? -1 : a->len > b->len;
}


struct tree *make_tree(int (*comp)(const struct id *a, const struct id *b))
{
	struct tree *tree;

	tree = alloc_type(struct tree);
	tree->comp = comp;
	tree->root = NULL;
	return tree;
}


static struct node *add_node(struct tree *tree, struct node *node)
{
	struct node **p, *last;
	int cmp;

	p = &tree->root;
	last = NULL;
	while (*p) {
		last = *p;
		cmp = tree->comp(NODE2ID(node), NODE2ID(*p));
		if (cmp < 0)
			p = &(*p)->left;
		else if (cmp > 0)
			p = &(*p)->right;
		else
			return *p;
	}
	*p = node;
	node->up = last;
	node->left = node->right = NULL;
	return NULL;
}


struct id *make_id(struct tree *tree, const char *s, size_t len)
{
	struct id *id;
	struct node *node;

	if (!free_id)
		free_id = alloc_type(struct id);
	id = free_id;
	id->s = s;
	id->len = len;
	id->value = NULL;
	node = add_node(tree, &id->node);
	if (node)
		return NODE2ID(node);
	free_id = NULL;
	return id;
}


const struct id *find_id(const struct tree *tree, const char *s, size_t len)
{
	struct id id = {
		.s = s,
		.len = len
	};
	const struct node *n = tree->root;
	int cmp;

	while (n) {
		cmp = tree->comp(&id, NODE2ID(n));
		if (cmp < 0)
			n = n->left;
		else if (cmp > 0)
			n = n->right;
		else
			return NODE2ID(n);
	}
	return NULL;
}


const struct id *first_id(const struct tree *tree)
{
	const struct node *n = tree->root;

	if (!n)
		return NULL;
	while (n->left)
		n = n->left;
	return NODE2ID(n);
}


const struct id *next_id(const struct id *id)
{
	const struct node *n = &id->node;

	if (n->right) {
		n = n->right;
		while (n->left)
			n = n->left;
		return NODE2ID(n);
	}
	while (n->up) {
		if (n == n->up->left)
			return NODE2ID(n->up);
		n = n->up;
	}
	return NULL;
}