/*
 * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#ifndef ASN_DISABLE_OER_SUPPORT

#include <asn_internal.h>
#include <constr_SEQUENCE.h>
#include <OPEN_TYPE.h>
#include <errno.h>

/*
 * This macro "eats" the part of the buffer which is definitely "consumed",
 * i.e. was correctly converted into local representation or rightfully skipped.
 */
#undef ADVANCE
#define ADVANCE(num_bytes)                                                     \
  do {                                                                         \
    size_t num = num_bytes;                                                    \
    ptr        = ((const char*) ptr) + num;                                    \
    size -= num;                                                               \
    consumed_myself += num;                                                    \
  } while (0)

/*
 * Switch to the next phase of parsing.
 */
#undef NEXT_PHASE
#undef PHASE_OUT
#define NEXT_PHASE(ctx)                                                        \
  do {                                                                         \
    ctx->phase++;                                                              \
    ctx->step = 0;                                                             \
  } while (0)

/*
 * Check whether we are inside the extensions group.
 */
#define IN_EXTENSION_GROUP(specs, memb_idx)                                    \
  ((specs)->first_extension >= 0 &&                                            \
   (unsigned) (specs)->first_extension <= (memb_idx))

#define IN_ROOT_GROUP_PRED(edx)                                                \
  edx < (specs->first_extension < 0 ? td->elements_count :                     \
                                      (size_t) specs->first_extension)

#define FOR_IN_ROOT_GROUP(edx) for (edx = 0; IN_ROOT_GROUP_PRED(edx); edx++)

/*
 * Return a standardized complex structure.
 */
#undef RETURN
#define RETURN(_code)                                                          \
  do {                                                                         \
    rval.code     = _code;                                                     \
    rval.consumed = consumed_myself;                                           \
    return rval;                                                               \
  } while (0)

/*
 * Return pointer to a member.
 */
static void** element_ptrptr(
    void* struct_ptr, asn_TYPE_member_t* elm, void** tmp_save_ptr) {
  if (elm->flags & ATF_POINTER) {
    /* Member is a pointer to another structure */
    return (void**) ((char*) struct_ptr + elm->memb_offset);
  } else {
    assert(tmp_save_ptr);
    *tmp_save_ptr = (void*) ((char*) struct_ptr + elm->memb_offset);
    return tmp_save_ptr;
  }
}

static const void* element_ptr(
    const void* struct_ptr, const asn_TYPE_member_t* elm) {
  if (elm->flags & ATF_POINTER) {
    /* Member is a pointer to another structure */
    return *(const void* const*) ((const char*) struct_ptr + elm->memb_offset);
  } else {
    return (const void*) ((const char*) struct_ptr + elm->memb_offset);
  }
}

asn_dec_rval_t SEQUENCE_decode_oer(
    const asn_codec_ctx_t* opt_codec_ctx, const asn_TYPE_descriptor_t* td,
    const asn_oer_constraints_t* constraints, void** struct_ptr,
    const void* ptr, size_t size) {
  const asn_SEQUENCE_specifics_t* specs =
      (const asn_SEQUENCE_specifics_t*) td->specifics;
  asn_dec_rval_t rval = {RC_OK, 0};
  void* st            = *struct_ptr; /* Target structure */
  asn_struct_ctx_t* ctx;             /* Decoder context */
  size_t consumed_myself = 0;        /* Consumed bytes from ptr. */

  (void) constraints;

  if (ASN__STACK_OVERFLOW_CHECK(opt_codec_ctx)) ASN__DECODE_FAILED;

  /*
   * Create the target structure if it is not present already.
   */
  if (st == 0) {
    st = *struct_ptr = CALLOC(1, specs->struct_size);
    if (st == 0) {
      RETURN(RC_FAIL);
    }
  }

  /*
   * Restore parsing context.
   */
  ctx = (asn_struct_ctx_t*) ((char*) st + specs->ctx_offset);

  /*
   * Start to parse where left previously.
   */
  switch (ctx->phase) {
    case 0: {
      /*
       * Fetch preamble.
       */
      asn_bit_data_t* preamble;
      int has_extensions_bit = (specs->first_extension >= 0);
      size_t preamble_bits   = (has_extensions_bit + specs->roms_count);
      size_t preamble_bytes  = ((7 + preamble_bits) >> 3);

      ASN_DEBUG("OER SEQUENCE %s Decoding PHASE 0", td->name);

      ASN_DEBUG(
          "Expecting preamble bits %" ASN_PRI_SIZE
          " for %s (including %d extension bits)",
          preamble_bits, td->name, has_extensions_bit);

      if (preamble_bytes > size) {
        ASN__DECODE_STARVED;
      }

      preamble = asn_bit_data_new_contiguous(ptr, preamble_bits);
      if (!preamble) {
        RETURN(RC_FAIL);
      }
      preamble->nboff = has_extensions_bit;
      ctx->ptr        = preamble;
      ADVANCE(preamble_bytes);
    }
      NEXT_PHASE(ctx);
      /* FALL THROUGH */
    case 1: {
      /* Decode components of the extension root */
      asn_bit_data_t* preamble = ctx->ptr;
      size_t edx;

      ASN_DEBUG("OER SEQUENCE %s Decoding PHASE 1 (Root)", td->name);

      assert(preamble);

      for (edx = (ctx->step >> 1); IN_ROOT_GROUP_PRED(edx);
           edx++, ctx->step = (ctx->step & ~1) + 2) {
        asn_TYPE_member_t* elm = &td->elements[edx];

        ASN_DEBUG("Decoding %s->%s", td->name, elm->name);

        assert(!IN_EXTENSION_GROUP(specs, edx));

        if (ctx->step & 1) {
          goto microphase2_decode_continues;
        }

        if (elm->optional) {
          int32_t present = asn_get_few_bits(preamble, 1);
          if (present < 0) {
            ASN_DEBUG("Presence map ended prematurely: %d", present);
            RETURN(RC_FAIL);
          } else if (present == 0) {
            if (elm->default_value_set) {
              /* Fill-in DEFAULT */
              void* tmp;
              if (elm->default_value_set(element_ptrptr(st, elm, &tmp))) {
                RETURN(RC_FAIL);
              }
            }
            /* The member is not present. */
            continue;
          }
          /* Present OPTIONAL or DEFAULT component. */
        }

        /*
         * MICROPHASE 2: Invoke the member-specific decoder.
         */
        ctx->step |= 1; /* Confirm entering next microphase */
      microphase2_decode_continues:
        if (elm->flags & ATF_OPEN_TYPE) {
          rval = OPEN_TYPE_oer_get(opt_codec_ctx, td, st, elm, ptr, size);
        } else {
          void* save_memb_ptr; /* Temporary reference. */
          void** memb_ptr2;    /* Pointer to a pointer to a memmber */

          memb_ptr2 = element_ptrptr(st, elm, &save_memb_ptr);

          rval = elm->type->op->oer_decoder(
              opt_codec_ctx, elm->type,
              elm->encoding_constraints.oer_constraints, memb_ptr2, ptr, size);
        }
        switch (rval.code) {
          case RC_OK:
            ADVANCE(rval.consumed);
            break;
          case RC_WMORE:
            ASN_DEBUG(
                "More bytes needed at element %s \"%s\"", td->name, elm->name);
            ADVANCE(rval.consumed);
            RETURN(RC_WMORE);
          case RC_FAIL:
            ASN_DEBUG(
                "Decoding failed at element %s \"%s\"", td->name, elm->name);
            RETURN(RC_FAIL);
        }
      } /* for(all root members) */
    }
      NEXT_PHASE(ctx);
      /* FALL THROUGH */
    case 2:
      assert(ctx->ptr);
      {
        /* Cleanup preamble. */
        asn_bit_data_t* preamble = ctx->ptr;
        asn_bit_data_t* extadds;
        int has_extensions_bit = (specs->first_extension >= 0);
        int extensions_present =
            has_extensions_bit &&
            (preamble->buffer == NULL ||
             (((const uint8_t*) preamble->buffer)[0] & 0x80));
        uint8_t unused_bits;
        size_t len = 0;
        ssize_t len_len;

        ASN_DEBUG("OER SEQUENCE %s Decoding PHASE 2", td->name);

        preamble->buffer = 0; /* Will do extensions_present==1 next time. */

        if (!extensions_present) {
          ctx->phase = 10;
          RETURN(RC_OK);
        }

        /*
         * X.696 (08/2015) #16.1 (c), #16.4
         * Read in the extension addition presence bitmap.
         */

        len_len = oer_fetch_length(ptr, size, &len);
        if (len_len > 0) {
          ADVANCE(len_len);
        } else if (len_len < 0) {
          RETURN(RC_FAIL);
        } else {
          RETURN(RC_WMORE);
        }

        if (len == 0) {
          /* 16.4.1-2 */
          RETURN(RC_FAIL);
        } else if (len > size) {
          RETURN(RC_WMORE);
        }

        /* Account for unused bits */
        unused_bits = 0x7 & *(const uint8_t*) ptr;
        ADVANCE(1);
        len--;
        if (unused_bits && len == 0) {
          RETURN(RC_FAIL);
        }

        /* Get the extensions map */
        extadds = asn_bit_data_new_contiguous(ptr, len * 8 - unused_bits);
        if (!extadds) {
          RETURN(RC_FAIL);
        }
        FREEMEM(preamble);
        ctx->ptr = extadds;
        ADVANCE(len);
      }
      NEXT_PHASE(ctx);
      ctx->step =
          (specs->first_extension < 0 ? td->elements_count :
                                        (size_t) specs->first_extension);
      /* Fall through */
    case 3:
      ASN_DEBUG("OER SEQUENCE %s Decoding PHASE 3 (Extensions)", td->name);
      for (; ctx->step < (signed) td->elements_count; ctx->step++) {
        asn_bit_data_t* extadds = ctx->ptr;
        size_t edx              = ctx->step;
        asn_TYPE_member_t* elm  = &td->elements[edx];
        void* tmp_memb_ptr;
        void** memb_ptr2 = element_ptrptr(st, elm, &tmp_memb_ptr);

        switch (asn_get_few_bits(extadds, 1)) {
          case -1:
            /*
             * Not every one of our extensions is known to the remote side.
             * Continue filling in their defaults though.
             */
            /* Fall through */
          case 0:
            /* Fill-in DEFAULT */
            if (elm->default_value_set && elm->default_value_set(memb_ptr2)) {
              RETURN(RC_FAIL);
            }
            continue;
          case 1: {
            /* Read OER open type */
            ssize_t ot_size = oer_open_type_get(
                opt_codec_ctx, elm->type,
                elm->encoding_constraints.oer_constraints, memb_ptr2, ptr,
                size);
            assert(ot_size <= (ssize_t) size);
            if (ot_size > 0) {
              ADVANCE(ot_size);
            } else if (ot_size < 0) {
              RETURN(RC_FAIL);
            } else {
              /* Roll back open type parsing */
              asn_get_undo(extadds, 1);
              RETURN(RC_WMORE);
            }
            break;
          }
          default:
            RETURN(RC_FAIL);
        }
      }

      NEXT_PHASE(ctx);
      /* Fall through */
    case 4:
      ASN_DEBUG("OER SEQUENCE %s Decoding PHASE 4", td->name);
      /* Read in the rest of Open Types while ignoring them */
      for (;;) {
        asn_bit_data_t* extadds = ctx->ptr;
        switch (asn_get_few_bits(extadds, 1)) {
          case 0:
            continue;
          case 1: {
            ssize_t skipped = oer_open_type_skip(ptr, size);
            if (skipped > 0) {
              ADVANCE(skipped);
            } else if (skipped < 0) {
              RETURN(RC_FAIL);
            } else {
              asn_get_undo(extadds, 1);
              RETURN(RC_WMORE);
            }
            continue;
          }
          case -1:
            /* No more Open Type encoded components */
            break;
          default:
            RETURN(RC_FAIL);
        }
        break;
      }
  }

  RETURN(RC_OK);
}

/*
 * Encode as Canonical OER.
 */
asn_enc_rval_t SEQUENCE_encode_oer(
    const asn_TYPE_descriptor_t* td, const asn_oer_constraints_t* constraints,
    const void* sptr, asn_app_consume_bytes_f* cb, void* app_key) {
  const asn_SEQUENCE_specifics_t* specs =
      (const asn_SEQUENCE_specifics_t*) td->specifics;
  size_t computed_size    = 0;
  int has_extensions_bit  = (specs->first_extension >= 0);
  size_t preamble_bits    = (has_extensions_bit + specs->roms_count);
  uint32_t has_extensions = 0;
  size_t edx;
  int ret;

  (void) constraints;

  if (preamble_bits) {
    asn_bit_outp_t preamble;

    memset(&preamble, 0, sizeof(preamble));
    preamble.output = cb;
    preamble.op_key = app_key;

    if (has_extensions_bit) {
      for (edx = specs->first_extension; edx < td->elements_count; edx++) {
        asn_TYPE_member_t* elm = &td->elements[edx];
        const void* memb_ptr   = element_ptr(sptr, elm);
        if (memb_ptr) {
          if (elm->default_value_cmp && elm->default_value_cmp(memb_ptr) == 0) {
            /* Do not encode default values in extensions */
          } else {
            has_extensions = 1;
            break;
          }
        }
      }
      ret = asn_put_few_bits(&preamble, has_extensions, 1);
      assert(ret == 0);
      if (ret < 0) {
        ASN__ENCODE_FAILED;
      }
    }

    /*
     * Encode optional components bitmap.
     */
    if (specs->roms_count) {
      FOR_IN_ROOT_GROUP(edx) {
        asn_TYPE_member_t* elm = &td->elements[edx];

        if (IN_EXTENSION_GROUP(specs, edx)) break;

        if (elm->optional) {
          const void* memb_ptr   = element_ptr(sptr, elm);
          uint32_t has_component = memb_ptr != NULL;
          if (has_component && elm->default_value_cmp &&
              elm->default_value_cmp(memb_ptr) == 0) {
            has_component = 0;
          }
          ret = asn_put_few_bits(&preamble, has_component, 1);
          if (ret < 0) {
            ASN__ENCODE_FAILED;
          }
        }
      }
    }

    asn_put_aligned_flush(&preamble);
    computed_size += preamble.flushed_bytes;
  } /* if(preamble_bits) */

  /*
   * Put root components and extensions root.
   */
  for (edx = 0; edx < td->elements_count; edx++) {
    asn_TYPE_member_t* elm = &td->elements[edx];
    asn_enc_rval_t er;
    const void* memb_ptr;

    if (IN_EXTENSION_GROUP(specs, edx)) break;

    memb_ptr = element_ptr(sptr, elm);
    if (memb_ptr) {
      if (elm->default_value_cmp && elm->default_value_cmp(memb_ptr) == 0) {
        /* Skip default values in encoding */
        continue;
      }
    } else {
      if (elm->optional) continue;
      /* Mandatory element is missing */
      ASN__ENCODE_FAILED;
    }
    if (!elm->type->op->oer_encoder) {
      ASN_DEBUG("OER encoder is not defined for type %s", elm->type->name);
      ASN__ENCODE_FAILED;
    }
    er = elm->type->op->oer_encoder(
        elm->type, elm->encoding_constraints.oer_constraints, memb_ptr, cb,
        app_key);
    if (er.encoded == -1) {
      ASN_DEBUG("... while encoding %s member \"%s\"\n", td->name, elm->name);
      return er;
    }
    computed_size += er.encoded;
  }

  /*
   * Before encode extensions, encode extensions additions presense bitmap
   # X.696 (08/2015) #16.4.
   */
  if (has_extensions) {
    asn_bit_outp_t extadds;

    /* Special case allowing us to use exactly one byte for #8.6 */
    size_t aoms_length_bits  = specs->aoms_count;
    size_t aoms_length_bytes = (7 + aoms_length_bits) >> 3;
    uint8_t unused_bits      = 0x07 & (8 - (aoms_length_bits & 0x07));

    assert(1 + aoms_length_bytes <= 127);

    memset(&extadds, 0, sizeof(extadds));
    extadds.output = cb;
    extadds.op_key = app_key;

    /* #8.6 length determinant */
    ret = asn_put_few_bits(&extadds, (1 + aoms_length_bytes), 8);
    if (ret < 0) ASN__ENCODE_FAILED;

    /* Number of unused bytes, #16.4.2 */
    ret = asn_put_few_bits(&extadds, unused_bits, 8);
    if (ret < 0) ASN__ENCODE_FAILED;

    /* Encode presence bitmap #16.4.3 */
    for (edx = specs->first_extension; edx < td->elements_count; edx++) {
      asn_TYPE_member_t* elm = &td->elements[edx];
      const void* memb_ptr   = element_ptr(sptr, elm);
      if (memb_ptr && elm->default_value_cmp &&
          elm->default_value_cmp(memb_ptr) == 0) {
        memb_ptr = 0; /* Do not encode default value. */
      }
      ret |= asn_put_few_bits(&extadds, memb_ptr ? 1 : 0, 1);
    }
    if (ret < 0) ASN__ENCODE_FAILED;

    asn_put_aligned_flush(&extadds);
    computed_size += extadds.flushed_bytes;

    /* Now, encode extensions */
    for (edx = specs->first_extension; edx < td->elements_count; edx++) {
      asn_TYPE_member_t* elm = &td->elements[edx];
      const void* memb_ptr   = element_ptr(sptr, elm);

      if (memb_ptr) {
        if (elm->default_value_cmp && elm->default_value_cmp(memb_ptr) == 0) {
          /* Do not encode default value. */
        } else {
          ssize_t wrote = oer_open_type_put(
              elm->type, elm->encoding_constraints.oer_constraints, memb_ptr,
              cb, app_key);
          if (wrote == -1) {
            ASN__ENCODE_FAILED;
          }
          computed_size += wrote;
        }
      } else if (!elm->optional) {
        ASN__ENCODE_FAILED;
      }
    }
  } /* if(has_extensions) */

  {
    asn_enc_rval_t er = {0, 0, 0};
    er.encoded        = computed_size;
    ASN__ENCODED_OK(er);
  }
}

#endif /* ASN_DISABLE_OER_SUPPORT */
