#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,type)!=(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,short sType) {
    struct symbol_t *element;

    element=table;

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

    if(strcmp(element->identifier,identifier)==0 && element->type == sType) {
        return element;
    }

    while((struct symbol_t *)NULL!=element->next) {
        element=element->next;
        if(strcmp(element->identifier,identifier)==0 && element->type == sType ) {
            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,SYMBOL_TYPE_VAR);
    if(element!=(struct symbol_t *)NULL) {
        if(element->type!=SYMBOL_TYPE_VAR) {
            fprintf(stderr,"Identifier %s not a variable.\n",identifier);
            exit(3);
        }
    }
    else {
        if( table_lookup( table,identifier, SYMBOL_TYPE_FIELD ) == ( struct symbol_t *)0 ){
        fprintf(stderr,"Unknown identifier (variable) %s.\n",identifier);
        exit(3);
        }
    }
}

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