/* copied from abac_graph.c 
   implementation of the low level using
   yap prolog
*/

#include <err.h>
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <Yap/YapInterface.h>

#include "abac_internal.h"

#include "abac_pl_yap.h"
#include "abac_util.h"

#include "uthash.h"

extern abac_list_t *abac_credential_clauses(abac_credential_t *);
extern char *abac_id_clause(abac_id_credential_t *);
extern abac_aspect_t *abac_yy_get_rule_tail_aspect();
extern abac_aspect_t *abac_yy_get_rule_head_aspect();

static int debug=0;

/* track constraint's external clause's -unique name id */

static int constraint_label_count=0;
static char *constraint_label="isABAC_constraint";

// pl -- place holder for now 
struct _abac_pl_t {
    FILE *fptr;
    char *fname;
    char *yap_certs;
};

/***********************************************************/
static int _get_next_constraint_label_idx()
{
    constraint_label_count++;
    return constraint_label_count;
}

static int _get_constraint_label_idx()
{
    return constraint_label_count;
}

/***********************************************************/

static int _insert_clause(char *str)
{
    YAP_Term *eterm;
    YAP_Term goalArgs=YAP_ReadBuffer(str, eterm);
    char *tmp=YAP_CompileClause(goalArgs);
    if (tmp!=NULL) { /* something is wrong */
        printf("error: result of compile clause (%s)\n", tmp);
        printf("error: str used (%s)\n", str);
        return 1;
    }
    return 0;
}

static int _insert_cred_clause(char *cstr)
{
    int ret=ABAC_CERT_SUCCESS;
    int rc=_insert_clause(cstr);
    if (rc)
        return ABAC_CERT_BAD_YAP;
    return ABAC_CERT_SUCCESS;
}

void show_yap_db(const char *msg)
{
    char lstr[]="listing";
    YAP_Term *eterm; /* error term */

    printf("\n\n========= yap db (%s)\n",msg);
    YAP_Term goal=YAP_ReadBuffer(lstr, eterm);
    int rc =YAP_RunGoal( goal );
    if (rc) {
        printf("listing ok.. \n");
    } else {
        printf("listing's rc is bad.. \n");
        YAP_Exit(1);
    }
    printf("========= \n\n");
}

/**
 * Include some utility routines
 */
abac_pl_t *abac_pl_utility(void) {
/*
append([],L,L).
append([X|L1],L2,[X|L3]):-append(L1,L2,L3).

appendL([],[]).
appendL([H|T], L) :-
   appendL(T,L2), append(H,L2,L).
*/
    if(_insert_clause("append([],L,L)"))
        YAP_Exit(1);
    if(_insert_clause("append([X|L1],L2,[X|L3]):-append(L1,L2,L3)"))
        YAP_Exit(1);
    if(_insert_clause("appendL([],[])"))
        YAP_Exit(1);
    if(_insert_clause("appendL([H|T], L) :- appendL(T,L2), append(H,L2,L)"))
        YAP_Exit(1);
}

/**
 * Create a new yap structure.
 */
abac_pl_t *abac_pl_new(void) {

    if (YAP_FastInit(NULL) == YAP_BOOT_ERROR)
        YAP_Exit(1);

    if (YAP_RunGoal(YAP_MkAtomTerm(YAP_LookupAtom("source")))) {
        if(debug) printf("calling source..\n");
        } else {
            if(debug) printf("calling source failed..\n");
            YAP_Exit(1);
    }

    abac_pl_utility();
  
    abac_pl_t *pl = abac_xmalloc(sizeof(abac_pl_t));
    pl->fptr=NULL;
    pl->fname=NULL;
    pl->yap_certs=NULL;
    return pl;
}

/**
 * Add a credential to the db
 */
int abac_pl_add_credential(abac_pl_t *pl, abac_credential_t *cred)
{
    int rc=0;
    abac_list_t *clauses=abac_credential_clauses(cred);
    if (clauses != NULL) {
        char *cur;
        abac_list_foreach(clauses, cur,
            if(cur) {
                if(debug) printf("inserting =>%s\n",cur);
                rc=_insert_cred_clause(cur);
            }
        );
    }
    return rc;
}

int abac_pl_add_type_credential(abac_pl_t *pl, abac_id_credential_t *id_cert)
{
    char *clause=abac_id_clause(id_cert);
    if (clause != NULL) {
        int rc=_insert_cred_clause(clause);
        return rc;
    }
    return 0;
}

/*  string1(S):- S="abc";S="efg";S="ijk" */
char *abac_pl_add_range_constraint_clause(char *var, char *tmplist)
{
    int i=_get_next_constraint_label_idx();
    char *tmp=NULL;
    asprintf(&tmp,"%s_%d(%s) :- %s", constraint_label, i, var, tmplist); 
    int rc=_insert_cred_clause(tmp);
    free(tmp);
    if(rc) 
        panic("abac_pl_add_range_constraint_clause, failed to insert");
    asprintf(&tmp,"%s_%d(%s)", constraint_label, i, var);
    return tmp;
}

/* cases, 
     ['str']
     ['str1','str2']
     ([] is not possible, and don't care)
*/
static void _credentials_from_string(abac_stack_t *credentials,char *slist) {
    char *cptr=slist; /* current ptr */
    char *sptr; /* string ptr */
    char *ptr;
    int len=0;
    char *string;
    abac_credential_t *cred=NULL;
    int cnt=0;

    /* find first [' */  
    ptr=strstr(cptr,"['");
    if(ptr == NULL) 
         return;
    cptr=ptr+2;
    sptr=cptr;
    while (1) {
        /* find next ',' or '] */
        ptr=strstr(cptr,"','");
        if(ptr!=NULL) {
             cptr=ptr+3;
             len=(ptr-sptr);
             string=strndup(sptr,len);
             cred=abac_credential_lookup(string);
             free(string); 
             if(cred) {
                 int i=abac_stack_unique_push(credentials, cred);
                 if(i) cnt++;
                 } else {
                 printf("BAD BAD BAD\n");
             }
             sptr=cptr;
             } else {
             ptr=strstr(cptr,"']");
             if(ptr!=NULL) {
                 len=(ptr-sptr);
                 string=strndup(sptr,len);
                 cred=abac_credential_lookup(string);
                 free(string);
                 if(cred) {
                     int i=abac_stack_unique_push(credentials, cred);
                     if(i) cnt++;
                     } else {
                     printf("BAD BAD BAD\n");
                 }
                 break;
             }
        }
    }
    if(debug)
        printf("DEBUG:total %d credentials\n", cnt);
}

/* make a query and extract just 1 set of result */
static abac_stack_t *_make_yap_query(char *prin, char *rule, char* estring)
{
    YAP_Term *eterm0;
    YAP_Term *eterm1;
    YAP_Term arg[3];
    char tmp[5000];
    abac_stack_t *cred_list = abac_stack_new();

    if(debug) printf(" the principal part(%s)\n", prin);
    if(prin[0]=='\'' || prin[0]=='"') {
        arg[0]=YAP_ReadBuffer(prin,eterm0);
        } else {
            arg[0]=YAP_MkAtomTerm(YAP_LookupAtom(prin)); 
    }
    if(debug) printf(" the role/oset part(%s)\n", estring);
    arg[1]=YAP_ReadBuffer(estring,eterm1);

    /* var for credential list */
    arg[2]=YAP_MkVarTerm();

    YAP_Atom f = YAP_LookupAtom("isMember");
    YAP_Functor func = YAP_MkFunctor(f, 3);
    YAP_Term goal=YAP_MkApplTerm(func, 3, arg);

    int rc =YAP_RunGoal( goal );
    if (rc) {
        printf("YAP query succeed\n");
        YAP_WriteBuffer(arg[2], tmp, 5000,YAP_WRITE_HANDLE_VARS);
        /* this is returned as ['string1','string2'] */
        if(debug) printf("    query answer : %s\n", tmp);
        _credentials_from_string(cred_list,tmp); 
/**** XXX
        while (YAP_RestartGoal()) {
            if(debug) printf("another success\n");
            YAP_WriteBuffer(arg[2], tmp, 5000,YAP_WRITE_HANDLE_VARS);
        if(debug) printf("    restart query answer : %s\n", tmp);
            _credentials_from_string(cred_list,tmp); 
        }
***/
    } else {
        printf("YAP query failed\n");
        /* YAP_Exit(1); */
    }
    return cred_list;
}

/* 2 types 
      acme.buys_rocket <- coyote (coyote=prin, acme.buys_rocket=role)
        ==> isMember(coyote,role(acme,buys_rocket), L)
      acme.buys_rocket <- acme.preferred_customer  -- NOT valid 
*/
static abac_stack_t *_query_with_aspect(abac_pl_t *pl, abac_aspect_t* head, abac_aspect_t* tail)
{
    char tmp[5000];
    abac_stack_t *ret=NULL;

    if(debug)
        show_yap_db("DEBUG:calling within _query_with_aspect");

    char *nm;
    PROLOG(nm=abac_aspect_principal_name(head););

    /* could be obj or principal */
    char *prin_nm=NULL;
    if(abac_aspect_is_object(tail)) {
        prin_nm=abac_aspect_object_name(tail);
        } else {
            PROLOG(prin_nm=abac_aspect_principal_name(tail););
    }

    if(abac_aspect_aspect_name(tail)!=NULL) {
        printf("fail, a.o <- b.o and a.r <- a.r query is not implemented yet !!!\n");
        YAP_Exit(1);
    }

    if (prin_nm == NULL || nm == NULL) {
        printf("fail, query's call got bad aspect names .. \n");
        YAP_Exit(1);
    }

    if(debug) printf("printing up the yap query ..\n");

    char *pstring;
    PROLOG(pstring=abac_aspect_aspect_param_string(head););

    char *stub=abac_aspect_type_string(head);
    if(pstring) {
        sprintf(tmp,"%s(%s,%s,%s)", stub, nm, abac_aspect_aspect_name(head),pstring);
        free(pstring);
        } else {
            sprintf(tmp,"%s(%s,%s)", stub, nm, abac_aspect_aspect_name(head));
    }

    ret=_make_yap_query(prin_nm,nm,tmp);
    return ret;
}

/**
 * Get all the credentials (attribute/issuer cert pairs) from prolog
 * (which returns in string form)
 */
abac_stack_t *abac_pl_credentials(abac_pl_t *pl)
{
    abac_stack_t *ret=abac_verifier_dump_creds();
    return ret;
}

abac_stack_t *abac_pl_principals(abac_pl_t *pl)
{
    abac_stack_t *ret=abac_verifier_dump_principals();
    return ret;
}

/**
 * Make a query into prolog db
--role acme.preferred_customer --principal coyote
--role acme.prefer_customer.buy_rockets --principlal coyote
--oset acme.rockets -- object mrx-21 
--oset acme.villans -- principal coyote
 */
abac_stack_t *abac_pl_query(abac_pl_t *pl, char *roleoset, char *prinobj)
{
    abac_stack_t *ret=NULL;
    int len=strlen(roleoset)+strlen(prinobj)+5;
    char* attr_string=(char *) abac_xmalloc(sizeof(char)*len);
    sprintf(attr_string,"%s<-%s", roleoset, prinobj);

    if(debug)
        printf("abac_pl_query, query string is (%s)\n",attr_string);

    /* call into yacc parser */
    abac_reset_yyfptr(attr_string);
    abac_yy_init();
    int rc=yyparse();
    if (rc) {
        free(attr_string);
        return NULL;
    }

    abac_aspect_t *head_aspect = abac_yy_get_rule_head_aspect();
    abac_aspect_t *tail_aspect = abac_yy_get_rule_tail_aspect();
    ret=_query_with_aspect(pl,head_aspect,tail_aspect);

    return ret;
}

abac_stack_t *abac_pl_query_with_structure(abac_pl_t *pl, abac_aspect_t *head_aspect, abac_aspect_t *tail_aspect)
{
    abac_stack_t *ret=NULL;
    ret=_query_with_aspect(pl,head_aspect,tail_aspect);

    return ret;
}

void abac_pl_free(abac_pl_t *pl) {
    if(pl->fptr) {
        fflush(pl->fptr);
        free(pl->fptr);
    }
    if(pl->fname) {
        unlink(pl->fname);
        free(pl->fname);
    }
    free(pl);
}