%define api.pure full
%define api.prefix {kalmia}
%locations
%define parse.error verbose
%param { yyscan_t scanner }

%code top {
	#include <stdio.h>
	#include <stdlib.h>
	#include <stdarg.h>
	#include <string.h>
}
%code requires {
	typedef void* yyscan_t;

	struct kai_attr_t {
		char *key;
		char *value;
		struct kai_attr_t *next;
	};

	struct kai_tag_t {
		char *type;
		struct kai_attr_t *attrs;

		struct kai_tag_t *children;
		char *content;

		struct kai_tag_t *next;
	};

	struct kai_tag_t * kai_parse_file(const char *filename);
	void kai_tag_destroy(struct kai_tag_t *tag);
}
%parse-param { struct kai_tag_t **document }
%code {
	/* flex definitions */
	int yylex(YYSTYPE *yylvalp, YYLTYPE *yyllocp, yyscan_t scanner);
	int kalmialex_init(yyscan_t *);
	void kalmiaset_in(FILE *, yyscan_t);
	int kalmialex_destroy(yyscan_t);

	int yyerror(YYLTYPE *yyllocp, yyscan_t unused, 
		struct kai_tag_t **unused2, const char *msg);

	#define TAG_MISMATCH(a, b) \
	do { \
		char buf[1024]; \
		snprintf(buf, 1024, "Tag name mismatch: \"%s\" != \"%s\"", a, b); \
		yyerror(&yylloc, NULL, NULL, (const char*) buf); \
		YYABORT; \
	} while (0)

	/* create/destroy kai_attr_t */
	struct kai_attr_t * kai_attr_new(char *key, char *value);
	struct kai_attr_t * kai_attr_last(struct kai_attr_t *head);
	void kai_attr_destroy(struct kai_attr_t *attr);

	/* create/destroy kai_tag_t */
	struct kai_tag_t * kai_tag_new(char *type, struct kai_attr_t *attrs);
	struct kai_tag_t * kai_tag_last(struct kai_tag_t *head);
	void kai_tag_destroy(struct kai_tag_t *tag);
}

%union {
	char *string;
	struct kai_attr_t *attr;
	struct kai_tag_t *tag;
}

/* tokens */
%token PROLOG
%token S_TAG_OPEN E_TAG_OPEN TAG_CLOSE EMPTY_TAG_CLOSE
%token <string> NAME
%token <string> ATTR
%token <string> TEXT
%token <string> CONTENT

/* tag targets */
%type <tag> start_tag
%type <string> end_tag
%type <tag> empty_tag
%type <tag> tag
%type <tag> tags

/* attribute targets */
%type <attr> attribute	
%type <attr> attributes


%%


document: 
	tag { *document = $1; }
	| PROLOG tag { *document = $2; }


tags:
	tag { $$ = $1; }
	| tags tag { $$ = $1; kai_tag_last($$)->next = $2; }
	;


tag:
	start_tag end_tag 
	{ 
		$$ = $1; 
		if (strcmp($$->type, $2) != 0) TAG_MISMATCH($$->type, $2); 
		free($2); 
	}
	| start_tag CONTENT end_tag
	{ 
		$$ = $1; 
		$$->content = $2;
		if (strcmp($$->type, $3) != 0) TAG_MISMATCH($$->type, $3);
		free($3); 
	}
	| start_tag tags end_tag 
	{ 
		$$ = $1; 
		$$->children = $2;
		if (strcmp($$->type, $3) != 0) TAG_MISMATCH($$->type, $3);
		free($3); 
	}
	| empty_tag { $$ = $1; }
	;

start_tag:
	S_TAG_OPEN NAME TAG_CLOSE
	{
		$$ = kai_tag_new($2, NULL);
		if ($$ == NULL) YYNOMEM;
	}
	| S_TAG_OPEN NAME attributes TAG_CLOSE
	{
		$$ = kai_tag_new($2, $3);
		if ($$ == NULL) YYNOMEM;
	}
	;


empty_tag:
	S_TAG_OPEN NAME EMPTY_TAG_CLOSE
	{
		$$ = kai_tag_new($2, NULL);
		if ($$ == NULL) YYNOMEM;
	}
	| S_TAG_OPEN NAME attributes EMPTY_TAG_CLOSE
	{
		$$ = kai_tag_new($2, $3);
		if ($$ == NULL) YYNOMEM;
	}
	;


end_tag:
	E_TAG_OPEN NAME TAG_CLOSE { $$ = $2; }
	;


attributes:
	attribute { $$ = $1; }
	| attributes attribute { $$ = $1; kai_attr_last($$)->next = $2; }
	;

attribute:
	ATTR '=' '"' TEXT '"' 
	{ 
		$$ = kai_attr_new($1, $4);
		if ($$ == NULL) YYNOMEM;
	}
	;


%%


/* print an error message */
int yyerror(
	YYLTYPE *yyllocp, 
	yyscan_t unused, 
	struct kai_tag_t **unused2, 
	const char *msg)
{
	fprintf(
		stderr, "[%d:%d]: %s\n",
		yyllocp->first_line, yyllocp->first_column, msg
	);
	return 1;
}



/* create a new kai_attr_t object */
struct kai_attr_t * kai_attr_new(char *key, char *value)
{
	struct kai_attr_t *attr = malloc(sizeof(struct kai_attr_t));
	if (attr == NULL) {
		return NULL;
	}
	attr->key = key;
	attr->value = value;
	attr->next = NULL;
	return attr;
}

/* get the end of a kai_attr_t list */
struct kai_attr_t * kai_attr_last(struct kai_attr_t *head)
{
	struct kai_attr_t *ptr = head;
	while (ptr->next != NULL) {
		ptr = ptr->next;
	}
	return ptr;
}

/* destroy a kai_attr_t list */
void kai_attr_destroy(struct kai_attr_t *attr)
{
	if (attr == NULL) {
		return;
	}

	kai_attr_destroy(attr->next);
	free(attr->key);
	free(attr->value);
	free(attr);
}



/* create a kai_tag_t object */
struct kai_tag_t * kai_tag_new(char *type, struct kai_attr_t *attrs)
{
	struct kai_tag_t *tag = malloc(sizeof(struct kai_tag_t));
	if (tag == NULL) {
		return NULL;
	}

	tag->type = type;
	tag->attrs = attrs;
	tag->children = NULL;
	tag->content = NULL;
	tag->next = NULL;
	return tag;
}

/* get the end of a kai_tag_t list */
struct kai_tag_t * kai_tag_last(struct kai_tag_t *head)
{
	struct kai_tag_t *ptr = head;
	while (ptr->next != NULL) {
		ptr = ptr->next;
	}
	return ptr;
}

/* destroy a kai_tag_t list */
void kai_tag_destroy(struct kai_tag_t *tag)
{
	if (tag == NULL) {
		return;
	}

	free(tag->type);
	kai_attr_destroy(tag->attrs);
	kai_tag_destroy(tag->children);
	free(tag->content);
	kai_tag_destroy(tag->next);
	free(tag);
}



/* parse a file into a document */
struct kai_tag_t * kai_parse_file(const char *filename)
{
	FILE *file = fopen(filename, "r");
	if (file == NULL) {
		fprintf(stderr, "Could not open file \"%s\"\n", filename);
		return NULL;
	}

	yyscan_t scanner;
	struct kai_tag_t *document;

	kalmialex_init(&scanner);
	kalmiaset_in(file, scanner);
	int result = kalmiaparse(scanner, &document);
	kalmialex_destroy(scanner);
	fclose(file);

	if (result != 0) {
		/* parse function will print error message */
		return NULL;
	}

	return document;
}