/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2012-2015 Los Alamos National Security, LLC.  All rights
 *                         reserved.
 * Copyright (c) 2014-2016 Intel, Inc. All rights reserved.
 * Copyright (c) 2014-2016 Research Organization for Information Science
 *                         and Technology (RIST). All rights reserved.
 * Copyright (c) 2016      Mellanox Technologies, Inc.
 *                         All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 *
 */

/* This code was taken from Open MPI project, file
   opal/mca/pmix/base/pmix_base_fns.c
*/

#include <assert.h>
#include <string.h>
#include "pmi2_utils.h"

/* base64 encoding with illegal (to Cray PMI) characters removed ('=' is replaced by ' ') */
static inline unsigned char pmi_base64_encsym (unsigned char value) {
    assert (value < 64);

    if (value < 26) {
    return 'A' + value;
    } else if (value < 52) {
    return 'a' + (value - 26);
    } else if (value < 62) {
    return '0' + (value - 52);
    }

    return (62 == value) ? '+' : '/';
}

static inline unsigned char pmi_base64_decsym (unsigned char value) {
    if ('+' == value) {
    return 62;
    } else if ('/' == value) {
    return 63;
    } else if (' ' == value) {
    return 64;
    } else if (value <= '9') {
    return (value - '0') + 52;
    } else if (value <= 'Z') {
    return (value - 'A');
    } else if (value <= 'z') {
    return (value - 'a') + 26;
    }

    return 64;
}

static inline void pmi_base64_encode_block (const unsigned char in[3], char out[4], int len) {
    out[0] = pmi_base64_encsym (in[0] >> 2);

    /* len is the length of in[] - we need to make sure we don't reference uninitialized data, hence the conditionals */
    out[1] = 1 < len ? pmi_base64_encsym(((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4)) :
                       pmi_base64_encsym((in[0] & 0x03) << 4);
    /* Cray PMI doesn't allow = in PMI attributes so pad with spaces */
    out[2] = 1 < len ? pmi_base64_encsym((in[1] & 0x0f) << 2) : ' ';
    out[2] = 2 < len ? pmi_base64_encsym(((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6)) : out[2];

    out[3] = 2 < len ? pmi_base64_encsym(in[2] & 0x3f) : ' ';
}

static inline int pmi_base64_decode_block (const char in[4], unsigned char out[3]) {
    char in_dec[4];

    in_dec[0] = pmi_base64_decsym (in[0]);
    in_dec[1] = pmi_base64_decsym (in[1]);
    in_dec[2] = pmi_base64_decsym (in[2]);
    in_dec[3] = pmi_base64_decsym (in[3]);

    out[0] = in_dec[0] << 2 | in_dec[1] >> 4;
    if (64 == in_dec[2]) {
    return 1;
    }

    out[1] = in_dec[1] << 4 | in_dec[2] >> 2;
    if (64 == in_dec[3]) {
    return 2;
    }

    out[2] = ((in_dec[2] << 6) & 0xc0) | in_dec[3];
    return 3;
}


/* PMI only supports strings. For now, do a simple base64. */
char *pmi_encode(const void *val, size_t vallen)
{
    char *outdata, *tmp;
    size_t i;

    outdata = calloc (((2 + vallen) * 4) / 3 + 2, 1);
    if (NULL == outdata) {
    return NULL;
    }

    for (i = 0, tmp = outdata ; i < vallen ; i += 3, tmp += 4) {
        pmi_base64_encode_block((unsigned char *) val + i, tmp, vallen - i);
    }

    tmp[0] = (unsigned char)'\0';

    return outdata;
}

uint8_t *pmi_decode (const char *data, size_t *retlen)
{
    size_t input_len = strlen(data) / 4;
    unsigned char *ret;
    int out_len;
    size_t i;

    /* default */
    *retlen = 0;

    ret = calloc (1, 3 * input_len + 1);
    if (NULL == ret) {
        return ret;
    }

    for (i = 0, out_len = 0 ; i < input_len ; i++, data += 4) {
    out_len += pmi_base64_decode_block(data, ret + 3 * i);
    }

    ret[out_len] = '\0';
    *retlen = out_len;
    return ret;
}
