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 * Copyright (c) 2009-2022, Google LLC
 * All rights reserved.
 *
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 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Google LLC nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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 */

#include "upb/internal/mini_descriptor.h"

#include "upb/mini_table.h"

// Must be last.
#include "upb/port_def.inc"

/* DescState ******************************************************************/

// Manages the storage for mini descriptor strings as they are being encoded.
// TODO(b/234740652): Move some of this state directly into the encoder, maybe.

typedef struct {
  upb_MtDataEncoder e;
  size_t bufsize;
  char* buf;
  char* ptr;
} DescState;

static void upb_DescState_Init(DescState* d) {
  d->bufsize = kUpb_MtDataEncoder_MinSize * 2;
  d->buf = NULL;
  d->ptr = NULL;
}

static bool upb_DescState_Grow(DescState* d, upb_Arena* a) {
  const size_t oldbufsize = d->bufsize;
  const int used = d->ptr - d->buf;

  if (!d->buf) {
    d->buf = upb_Arena_Malloc(a, d->bufsize);
    if (!d->buf) return false;
    d->ptr = d->buf;
    d->e.end = d->buf + d->bufsize;
  }

  if (oldbufsize - used < kUpb_MtDataEncoder_MinSize) {
    d->bufsize *= 2;
    d->buf = upb_Arena_Realloc(a, d->buf, oldbufsize, d->bufsize);
    if (!d->buf) return false;
    d->ptr = d->buf + used;
    d->e.end = d->buf + d->bufsize;
  }

  return true;
}

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

// Copied from upbc/protoc-gen-upb.cc TODO(salo): can we consolidate?
static uint64_t upb_Field_Modifiers(const upb_FieldDef* f) {
  uint64_t out = 0;
  if (upb_FieldDef_IsRepeated(f)) {
    out |= kUpb_FieldModifier_IsRepeated;
  }
  if (upb_FieldDef_IsPacked(f)) {
    out |= kUpb_FieldModifier_IsPacked;
  }
  if (upb_FieldDef_Type(f) == kUpb_FieldType_Enum) {
    const upb_FileDef* file_def = upb_EnumDef_File(upb_FieldDef_EnumSubDef(f));
    if (upb_FileDef_Syntax(file_def) == kUpb_Syntax_Proto2) {
      out |= kUpb_FieldModifier_IsClosedEnum;
    }
  }
  if (upb_FieldDef_IsOptional(f) && !upb_FieldDef_HasPresence(f)) {
    out |= kUpb_FieldModifier_IsProto3Singular;
  }
  if (upb_FieldDef_IsRequired(f)) {
    out |= kUpb_FieldModifier_IsRequired;
  }
  return out;
}

static uint64_t upb_Message_Modifiers(const upb_MessageDef* m) {
  uint64_t out = 0;
  const upb_FileDef* file_def = upb_MessageDef_File(m);
  if (upb_FileDef_Syntax(file_def) == kUpb_Syntax_Proto3) {
    out |= kUpb_MessageModifier_ValidateUtf8;
    out |= kUpb_MessageModifier_DefaultIsPacked;
  }
  if (upb_MessageDef_ExtensionRangeCount(m)) {
    out |= kUpb_MessageModifier_IsExtendable;
  }
  return out;
}

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

// Sort by field number.
static int upb_MiniDescriptor_CompareFields(const void* a, const void* b) {
  const upb_FieldDef* A = *(void**)a;
  const upb_FieldDef* B = *(void**)b;
  if (upb_FieldDef_Number(A) < upb_FieldDef_Number(B)) return -1;
  if (upb_FieldDef_Number(A) > upb_FieldDef_Number(B)) return 1;
  return 0;
}

const char* _upb_MiniDescriptor_EncodeEnum(const upb_EnumDef* e,
                                           const upb_EnumValueDef** sorted,
                                           upb_Arena* a) {
  DescState s;
  upb_DescState_Init(&s);

  upb_MtDataEncoder_StartEnum(&s.e);

  const size_t value_count = upb_EnumDef_ValueCount(e);

  // Duplicate values are allowed but we only encode each value once.
  uint32_t previous = 0;

  for (size_t i = 0; i < value_count; i++) {
    const uint32_t current =
        upb_EnumValueDef_Number(sorted ? sorted[i] : upb_EnumDef_Value(e, i));
    if (i != 0 && previous == current) continue;

    if (!upb_DescState_Grow(&s, a)) return NULL;
    s.ptr = upb_MtDataEncoder_PutEnumValue(&s.e, s.ptr, current);
    previous = current;
  }

  if (!upb_DescState_Grow(&s, a)) return NULL;
  s.ptr = upb_MtDataEncoder_EndEnum(&s.e, s.ptr);

  // There will always be room for this '\0' in the encoder buffer because
  // kUpb_MtDataEncoder_MinSize is overkill for upb_MtDataEncoder_EndEnum().
  UPB_ASSERT(s.ptr < s.buf + s.bufsize);
  *s.ptr++ = '\0';

  return s.buf;
}

const char* _upb_MiniDescriptor_EncodeField(const upb_FieldDef* f,
                                            upb_Arena* a) {
  UPB_ASSERT(upb_FieldDef_IsExtension(f));

  DescState s;
  upb_DescState_Init(&s);

  if (!upb_DescState_Grow(&s, a)) return NULL;
  upb_MtDataEncoder_StartMessage(&s.e, s.ptr, 0);

  const upb_FieldType type = upb_FieldDef_Type(f);
  const int number = upb_FieldDef_Number(f);
  const uint64_t modifiers = upb_Field_Modifiers(f);

  if (!upb_DescState_Grow(&s, a)) return NULL;
  upb_MtDataEncoder_PutField(&s.e, s.ptr, type, number, modifiers);

  if (!upb_DescState_Grow(&s, a)) return NULL;
  *s.ptr++ = '\0';

  return s.buf;
}

const char* _upb_MiniDescriptor_EncodeMessage(const upb_MessageDef* m,
                                              upb_Arena* a) {
  DescState s;
  upb_DescState_Init(&s);

  // Make a copy.
  const size_t field_count = upb_MessageDef_FieldCount(m);
  const upb_FieldDef** sorted =
      (const upb_FieldDef**)upb_Arena_Malloc(a, field_count * sizeof(void*));
  if (!sorted) return NULL;

  // Sort the copy.
  for (size_t i = 0; i < field_count; i++) {
    sorted[i] = upb_MessageDef_Field(m, i);
  }
  qsort(sorted, field_count, sizeof(void*), upb_MiniDescriptor_CompareFields);

  // Start encoding.
  if (!upb_DescState_Grow(&s, a)) return NULL;
  upb_MtDataEncoder_StartMessage(&s.e, s.ptr, upb_Message_Modifiers(m));

  // Encode the fields.
  for (size_t i = 0; i < field_count; i++) {
    const upb_FieldDef* field_def = sorted[i];
    const upb_FieldType type = upb_FieldDef_Type(field_def);
    const int number = upb_FieldDef_Number(field_def);
    const uint64_t modifiers = upb_Field_Modifiers(field_def);

    if (!upb_DescState_Grow(&s, a)) return NULL;
    s.ptr = upb_MtDataEncoder_PutField(&s.e, s.ptr, type, number, modifiers);
  }

  // Encode the oneofs.
  const int oneof_count = upb_MessageDef_OneofCount(m);
  for (int i = 0; i < oneof_count; i++) {
    if (!upb_DescState_Grow(&s, a)) return NULL;
    s.ptr = upb_MtDataEncoder_StartOneof(&s.e, s.ptr);

    const upb_OneofDef* oneof_def = upb_MessageDef_Oneof(m, i);
    const int field_count = upb_OneofDef_FieldCount(oneof_def);
    for (int j = 0; j < field_count; j++) {
      const upb_FieldDef* field_def = upb_OneofDef_Field(oneof_def, j);
      const int number = upb_FieldDef_Number(field_def);

      if (!upb_DescState_Grow(&s, a)) return NULL;
      s.ptr = upb_MtDataEncoder_PutOneofField(&s.e, s.ptr, number);
    }
  }

  if (!upb_DescState_Grow(&s, a)) return NULL;
  *s.ptr++ = '\0';

  return s.buf;
}