#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "symbol_table.h"

struct symbol_t *new_table(void) {
	return (struct symbol_t *)NULL;
}

struct symbol_t *clone_table(struct symbol_t *table) {
	struct symbol_t *element;
	struct symbol_t *new_tablex;

	element=table;
	new_tablex=new_table();
	while((struct symbol_t *)NULL!=element) {
		/* check return value */
		new_tablex=table_add_symbol(new_tablex,element->identifier,element->type,0);
		element=element->next;
	}

	return new_tablex;
}

struct symbol_t *table_add_symbol(struct symbol_t *table, char *identifier, short type, short check) {
	struct symbol_t *element;
	struct symbol_t *new_element;

	if(table_lookup(table,identifier)!=(struct symbol_t *)NULL) {
		if(check) {
			fprintf(stderr,"Duplicate field %s.\n",identifier);
			exit(3);
		}

		table=table_remove_symbol(table,identifier);
	}
	
	new_element=(struct symbol_t *)malloc(sizeof(struct symbol_t));
	new_element->next=(struct symbol_t *)NULL;
	new_element->identifier=strdup(identifier);
	new_element->type=type;

	if((struct symbol_t *)NULL==table) {
		return new_element;
	}
	element=table;

	while((struct symbol_t *)NULL!=element->next) {
		element=element->next;
	}

	element->next=new_element;
	
	return table;
}

struct symbol_t *table_lookup(struct symbol_t *table, char *identifier) {
	struct symbol_t *element;

	element=table;

	if((struct symbol_t *)NULL==table) {
		return (struct symbol_t *)NULL;
	}
	
	if(strcmp(element->identifier,identifier)==0) {
		return element;
	}
	
	while((struct symbol_t *)NULL!=element->next) {
		element=element->next;
		if(strcmp(element->identifier,identifier)==0) {
			return element;
		}
	}

	return (struct symbol_t *)NULL;
}

struct symbol_t *table_merge(struct symbol_t *table, struct symbol_t *to_add, short check) {
	struct symbol_t *element;
	struct symbol_t *new_table=clone_table(table);
	
	element=to_add;
	while(element!=(struct symbol_t *)NULL) {
		new_table=table_add_symbol(new_table,element->identifier,element->type,check);
		element=element->next;
	}

	return new_table;
}

struct symbol_t *table_remove_symbol(struct symbol_t *table, char *identifier) {
	struct symbol_t *element;
	struct symbol_t *previous_element;
	struct symbol_t *new_element;

	if((struct symbol_t *)NULL==table) {
		return table;
	}

	previous_element=(struct symbol_t *)NULL;
	element=table;

	while((struct symbol_t *)NULL!=element) {
		if(strcmp(element->identifier,identifier)==0) {
			if((struct symbol_t *)NULL==previous_element) {
				new_element=element->next;
			}
			else {
				previous_element->next=element->next;
				new_element=table;
			}
			(void)free(element->identifier);
			(void)free(element);
			return new_element;
		}
		previous_element=element;
		element=element->next;
	}

	return table;
}

void check_variable(struct symbol_t *table, char *identifier) {
	struct symbol_t *element=table_lookup(table,identifier);
	if(element!=(struct symbol_t *)NULL) {
		if(element->type!=SYMBOL_TYPE_VAR) {
			fprintf(stderr,"Identifier %s not a variable.\n",identifier);
			exit(3);
		}
	}
	else {
		fprintf(stderr,"Unknown identifier %s.\n",identifier);
		exit(3);
	}
}

void check_field(struct symbol_t *table, char *identifier) {
	struct symbol_t *element=table_lookup(table,identifier);
	if(element!=(struct symbol_t *)NULL) {
		if(element->type!=SYMBOL_TYPE_FIELD) {
			fprintf(stderr,"Identifier %s not a variable.\n",identifier);
			exit(3);
		}
	}
	else {
		fprintf(stderr,"Unknown identifier %s.\n",identifier);
		exit(3);
	}
}