// Copyright (c) 2009-2017 The OTS Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file.

#include "sill.h"

#include "feat.h"

#include <cmath>

#include <unordered_set>

namespace ots {

bool OpenTypeSILL::Parse(const uint8_t* data, size_t length) {

  Buffer table(data, length);

  if (!table.ReadU32(&this->version) || this->version >> 16 != 1) {

    return Drop("Failed to read valid version");

  }

  if (!table.ReadU16(&this->numLangs)) {

    return Drop("Failed to read numLangs");

  }

  // The following three fields are deprecated and ignored. We fix them up here

  // just for internal consistency, but the Graphite engine doesn't care.

  if (!table.ReadU16(&this->searchRange) ||

      !table.ReadU16(&this->entrySelector) ||

      !table.ReadU16(&this->rangeShift)) {

    return Drop("Failed to read searchRange..rangeShift");

  }

  if (this->numLangs == 0) {

    if (this->searchRange != 0 || this->entrySelector != 0 || this->rangeShift != 0) {

      this->searchRange = this->entrySelector = this->rangeShift = 0;

    }

  } else {

    unsigned floorLog2 = std::floor(std::log2(this->numLangs));

    if (this->searchRange != (unsigned)std::pow(2, floorLog2) ||

        this->entrySelector != floorLog2 ||

        this->rangeShift != this->numLangs - this->searchRange) {

      this->searchRange = (unsigned)std::pow(2, floorLog2);

      this->entrySelector = floorLog2;

      this->rangeShift = this->numLangs - this->searchRange;

    }

  }

  std::unordered_set<size_t> unverified;

  //this->entries.resize(static_cast<unsigned long>(this->numLangs) + 1, this);

  for (unsigned long i = 0; i <= this->numLangs; ++i) {

    this->entries.emplace_back(this);

    LanguageEntry& entry = this->entries[i];

    if (!entry.ParsePart(table)) {

      return Drop("Failed to read entries[%u]", i);

    }

    for (unsigned j = 0; j < entry.numSettings; ++j) {

      size_t offset = entry.offset + j * 8;

      if (offset < entry.offset || offset > length) {

        return DropGraphite("Invalid LangFeatureSetting offset %zu/%zu",

                            offset, length);

      }

      unverified.insert(offset);

        // need to verify that this LanguageEntry points to valid

        // LangFeatureSetting

    }

  }

  while (table.remaining()) {

    unverified.erase(table.offset());

    LangFeatureSetting setting(this);

    if (!setting.ParsePart(table)) {

      return Drop("Failed to read a LangFeatureSetting");

    }

    settings.push_back(setting);

  }

  if (!unverified.empty()) {

    return Drop("%zu incorrect offsets into settings", unverified.size());

  }

  if (table.remaining()) {

    return Warning("%zu bytes unparsed", table.remaining());

  }

  return true;

}

bool OpenTypeSILL::Serialize(OTSStream* out) {

  if (!out->WriteU32(this->version) ||

      !out->WriteU16(this->numLangs) ||

      !out->WriteU16(this->searchRange) ||

      !out->WriteU16(this->entrySelector) ||

      !out->WriteU16(this->rangeShift) ||

      !SerializeParts(this->entries, out) ||

      !SerializeParts(this->settings, out)) {

    return Error("Failed to write table");

  }

  return true;

}

bool OpenTypeSILL::LanguageEntry::ParsePart(Buffer& table) {

  if (!table.ReadU8(&this->langcode[0]) ||

      !table.ReadU8(&this->langcode[1]) ||

      !table.ReadU8(&this->langcode[2]) ||

      !table.ReadU8(&this->langcode[3])) {

    return parent->Error("LanguageEntry: Failed to read langcode");

  }

  if (!table.ReadU16(&this->numSettings)) {

    return parent->Error("LanguageEntry: Failed to read numSettings");

  }

  if (!table.ReadU16(&this->offset)) {

    return parent->Error("LanguageEntry: Failed to read offset");

  }

  return true;

}

bool OpenTypeSILL::LanguageEntry::SerializePart(OTSStream* out) const {

  if (!out->WriteU8(this->langcode[0]) ||

      !out->WriteU8(this->langcode[1]) ||

      !out->WriteU8(this->langcode[2]) ||

      !out->WriteU8(this->langcode[3]) ||

      !out->WriteU16(this->numSettings) ||

      !out->WriteU16(this->offset)) {

    return parent->Error("LanguageEntry: Failed to write");

  }

  return true;

}

bool OpenTypeSILL::LangFeatureSetting::ParsePart(Buffer& table) {

  OpenTypeFEAT* feat = static_cast<OpenTypeFEAT*>(

      parent->GetFont()->GetTypedTable(OTS_TAG_FEAT));

  if (!feat) {

    return parent->Error("FeatureDefn: Required Feat table is missing");

  }

  if (!table.ReadU32(&this->featureId) ||

      !feat->IsValidFeatureId(this->featureId)) {

    return parent->Error("LangFeatureSetting: Failed to read valid featureId");

  }

  if (!table.ReadS16(&this->value)) {

    return parent->Error("LangFeatureSetting: Failed to read value");

  }

  if (!table.ReadU16(&this->reserved)) {

    return parent->Error("LangFeatureSetting: Failed to read reserved");

  }

  if (this->reserved != 0) {

    parent->Warning("LangFeatureSetting: Nonzero reserved");

  }

  return true;

}

bool OpenTypeSILL::LangFeatureSetting::SerializePart(OTSStream* out) const {

  if (!out->WriteU32(this->featureId) ||

      !out->WriteS16(this->value) ||

      !out->WriteU16(this->reserved)) {

    return parent->Error("LangFeatureSetting: Failed to read reserved");

  }

  return true;

}

}  // namespace ots