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

struct symbol *new_tab(void)
{
	return SYMNULL;
}

struct symbol *clone_tab(struct symbol *tab)
{
	struct symbol *elm;
	struct symbol *new_tabx;

	elm = tab;
	new_tabx = new_tab();
	while(elm != SYMNULL) {
		new_tabx = tab_add_symbol(new_tabx, elm->ident, elm->type, 0);
		elm = elm->next;
	}

	return new_tabx;
}

struct symbol *tab_add_symbol(struct symbol *tab, char *ident, short type, short check)
{
	struct symbol *elm;
	struct symbol *new_elm;

	if(tab_lookup(tab,ident) != SYMNULL) {
		if(check) {
			fprintf(stderr, "Feld doppelt vorhanden: \"%s\"\n", ident);
			exit(3);
		}
		tab = tab_remove_symbol(tab, ident);
	}
	
	new_elm = (struct symbol *) malloc(sizeof(struct symbol));
	new_elm->next = SYMNULL;
	new_elm->ident = strdup(ident);
	new_elm->type = type;

	if(tab == SYMNULL) {
		return new_elm;
	}

	elm = tab;
	while(elm->next != SYMNULL) {
		elm = elm->next;
	}
	elm->next = new_elm;
	
	return tab;
}

struct symbol *tab_lookup(struct symbol *tab, char *ident)
{
	struct symbol *elm = tab;

	if(tab == SYMNULL) {
		return SYMNULL;
	}
	
	if(strcmp(elm->ident, ident) == 0) {
		return elm;
	}
	
	while(elm->next != SYMNULL) {
		elm = elm->next;
		if(strcmp(elm->ident, ident) == 0) {
			return elm;
		}
	}

	return SYMNULL;
}

struct symbol *tab_merge(struct symbol *tab, struct symbol *to_add, short check)
{
	struct symbol *elm = to_add;
	struct symbol *new_tab = clone_tab(tab);
	
	while(elm != SYMNULL) {
		new_tab = tab_add_symbol(new_tab, elm->ident, elm->type, check);
		elm = elm->next;
	}

	return new_tab;
}

struct symbol *tab_remove_symbol(struct symbol *tab, char *ident)
{
	struct symbol *elm = tab;
	struct symbol *previous_elm = SYMNULL;
	struct symbol *new_elm;

	if(tab == SYMNULL) {
		return SYMNULL;
	}

	while(elm != SYMNULL) {
		if(strcmp(elm->ident, ident) == 0) {
			if(previous_elm == SYMNULL) {
				new_elm = elm->next;
			} else {
				previous_elm->next = elm->next;
				new_elm = tab;
			}
			(void)free(elm->ident);
			(void)free(elm);
			return new_elm;
		}
		previous_elm = elm;
		elm = elm->next;
	}

	return tab;
}

void check_variable(struct symbol *tab, char *ident)
{
	struct symbol *elm = tab_lookup(tab, ident);
	if(elm != SYMNULL) {
		if(elm->type != S_VAR) {
			fprintf(stderr, "Identifier ist keine Variable: \"%s\"\n", ident);
			exit(3);
		}
	} else {
		fprintf(stderr, "Unbekannter Identifier: \"%s\"\n", ident);
		exit(3);
	}
}

void check_field(struct symbol *tab, char *ident)
{
	struct symbol *elm = tab_lookup(tab, ident);
	if(elm != SYMNULL) {
		if(elm->type != S_FIELD) {
			fprintf(stderr, "Identifier ist kein Feld: \"%s\"\n", ident);
			exit(3);
		}
	} else {
		fprintf(stderr, "Unbekannter Identifier: \"%s\"\n", ident);
		exit(3);
	}
}