/**
**  abac_key.c
**  holding a private_key 
**/

// include the GNU extension of asprintf
#define _GNU_SOURCE

#include <stdio.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <assert.h>

#include "abac_internal.h"
#include "abac_util.h"

extern chunk_t abac_get_potato_cb(int try, char *name);

static int debug=0;
//
// abac_key object
//
// keyblob and potato are 'cleaned' explicitly
struct _abac_key_t {
    chunk_t keyblob;
    char* filename;
    chunk_t potato; // you know what, just as a hint
};

/****************************************************************/
//
// Helper functions below
//
void print_abac_key(char *msg, abac_key_t *ptr)
{
    printf("===============\n");
    if(ptr->keyblob.len !=0) {
        printf("[%s]ptr:loc(%d)\n",msg,(int) ptr->keyblob.ptr);
        printf("[%s]len:(%d)\n",msg,ptr->keyblob.len);
        printf("[%s]strlen:(%d)\n",msg,strlen(ptr->keyblob.ptr));
        if(strlen(ptr->keyblob.ptr) != ptr->keyblob.len) 
            printf("BAD, did not match\b\n");
    }
    if(ptr->filename)
        printf("[%s]filename:(%s)\n",msg,ptr->filename);
    if(ptr->potato.len !=0) {
        printf("[%s]pptr:loc(%d)\n",msg,(int)ptr->potato.ptr);
        printf("[%s]plen:(%d)\n",msg,ptr->potato.len);
        printf("[%s]pstrlen:(%d)\n",msg,strlen(ptr->potato.ptr));
    }
    printf("===============\n");
}

static private_key_t *_load_privkey_chunk(chunk_t chunk)
{
    if(debug) { 
        printf("_load_privkey_chunk, ptr loc(%d):(%d)\n",
                             (int) chunk.ptr, chunk.len);
    }
    private_key_t *key = lib->creds->create(lib->creds,
        CRED_PRIVATE_KEY, KEY_RSA,
        BUILD_BLOB_PEM, chunk,
        BUILD_END
    );
    return key;
}

static private_key_t *_load_enc_privkey_chunk(chunk_t chunk, chunk_t potato)
{
    if(debug) { 
        printf("_load_enc_privkey_chunk, ptr loc(%d):(%d)\n",
                                      (int) chunk.ptr, chunk.len);
    }
    mem_cred_t *mem;
    shared_key_t *shared;

    mem = mem_cred_create();
    lib->credmgr->add_set(lib->credmgr, &mem->set);
    shared = shared_key_create(SHARED_PRIVATE_KEY_PASS, chunk_clone(potato));
    mem->add_shared(mem, shared, NULL);

    // load signer key
    private_key_t *key =_load_privkey_chunk(chunk);

    lib->credmgr->remove_set(lib->credmgr, &mem->set);
    mem->destroy(mem);

    return key;
}

private_key_t *abac_key_private_key(abac_key_t *ptr)
{
    private_key_t *prv=NULL;
    if(ptr->potato.len !=0) {
        prv=_load_enc_privkey_chunk(ptr->keyblob, ptr->potato);
        } else  {
            if(debug)
                print_abac_key("abac_key_private_key",ptr);
            prv=_load_privkey_chunk(ptr->keyblob);
/* try to use callback to retrieve the potato token */
            if(prv == NULL && ptr->filename) {
               chunk_t pp=abac_get_potato_cb(2, ptr->filename);
               if(pp.len != 0) {
                   prv=_load_enc_privkey_chunk(ptr->keyblob, pp);
                   ptr->potato=pp;
               }
            }
    }

    return prv;
}

chunk_t abac_key_load_privkey_file(char *filename)
{
    chunk_t blob=chunk_empty;
    struct stat sb;
    void *addr;
    int fd;

    if(!file_exist(filename)) 
        return chunk_empty;

    fd = open(filename, O_RDONLY);
    if (fd == -1) {
        printf("warning, can not open the %s\n",filename);
        return blob;
    }   

    if (fstat(fd, &sb) == -1) {
        printf("warning, key file(%s) is empty\n",filename);
        close(fd);
        return blob;
    }

    addr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (addr == MAP_FAILED) {
        printf("warning, mapping '%s' failed\n", filename);
        close(fd);
        return blob;
    }

    blob.ptr=strndup(addr, sb.st_size);
    blob.len=sb.st_size;

    munmap(addr, sb.st_size);
    close(fd);
    return blob;
}

/**
 * Generate a private key.
 */
static chunk_t _generate_keyblob(void) {
    private_key_t *key=NULL;
    chunk_t encoding=chunk_empty;
    libabac_init();

    // generate the key
    key = lib->creds->create(
        lib->creds,
        CRED_PRIVATE_KEY, KEY_RSA,
        BUILD_KEY_SIZE, 2048,
        BUILD_END
    );
    if (key == NULL)
        errx(1, "Key generation failed");

    int ret = key->get_encoding(key, PRIVKEY_PEM, &encoding);
    if (!ret) {
        DESTROY_IF(key);
        errx(1, "Couldn't encode private key");
    }
    /* HACK.. it seems encoding ptr's string is often longer than
       encoding len */
    char *new_ptr=strndup(encoding.ptr,encoding.len);
    free(encoding.ptr);
    encoding.ptr=new_ptr;
    DESTROY_IF(key);
    return encoding;
}

/**
 * Write the private key to a file.
 * Returns false if there's no private key loaded
 */
int abac_key_write_privkey(abac_key_t *key, FILE *out) {

    fwrite(key->keyblob.ptr, key->keyblob.len, 1, out);
    return 1;
}

/**
 * Get a PEM-encoded chunk representing the private key 
 */
chunk_t abac_key_chunk(abac_key_t *ptr) {
    return ptr->keyblob;
}

/*****************************************************************/
/*  load with a filename                                         */
/*  load with a filename and potato                               */
/*  load with a chunk blob                                       */
/*  load with a chunk blob and a potato                           */
/*****************************************************************/
abac_key_t *abac_key_file_new(char *filename, chunk_t potato)
{
    abac_key_t *ptr = abac_xmalloc(sizeof(abac_key_t));
    if(potato.len != 0)
        ptr->potato=potato;
        else ptr->potato=chunk_empty;
    ptr->keyblob=abac_key_load_privkey_file(filename);
    ptr->filename=abac_xstrdup(filename);
    return ptr;
}

/* just use the keyblob, did not reallocate */
abac_key_t *abac_key_chunk_new(chunk_t keyblob, chunk_t potato)
{
    abac_key_t *ptr = abac_xmalloc(sizeof(abac_key_t));
    if(potato.len != 0)
        ptr->potato=potato;
        else ptr->potato=chunk_empty;
    ptr->keyblob=keyblob;
    ptr->filename=NULL;
    return ptr;
}

abac_key_t *abac_key_generate()
{
    abac_key_t *ptr = abac_xmalloc(sizeof(abac_key_t));
    ptr->potato=chunk_empty;
    ptr->filename=NULL;
    ptr->keyblob=_generate_keyblob();
    return ptr;
}

void abac_key_free(abac_key_t *ptr)
{
    if(ptr->potato.len != 0)
        chunk_clear(&ptr->potato);
    if(debug) {
         printf("FREEEEE abac_key loc(%d)\n",(int)ptr->keyblob.ptr);
    }
    chunk_clear(&ptr->keyblob);
    free(ptr);
}