world_json.h

#pragma once
#include "gaia/config/config.h"
 
#include <cstring>
 
#include "gaia/ser/ser_json.h"
 
namespace gaia {
  namespace ecs {
    namespace detail {
      inline bool runtime_field_json_layout(
          const ComponentCacheItem& item, const RuntimeField& field, ser::serialization_type_id& type,
          uint32_t& fieldSize) noexcept {
        if (!runtime_primitive_serialization_type(field.type, type))
          return false;
 
        const auto elemCount = ComponentCacheItem::field_element_count(field);
        if (field.type != Char8 && elemCount != 1)
          return false;
 
        const auto elemSize = ComponentCacheItem::primitive_type_size(field.type);
        const auto fieldSize64 = (uint64_t)elemSize * (uint64_t)elemCount;
        const auto end = (uint64_t)field.offset + fieldSize64;
        if (elemSize == 0 || fieldSize64 > UINT32_MAX || end > item.comp.size())
          return false;
 
        fieldSize = (uint32_t)fieldSize64;
        return true;
      }
    } // namespace detail
 
    inline bool component_to_json(const ComponentCacheItem& item, const void* pComponentData, ser::ser_json& writer) {
      GAIA_ASSERT(pComponentData != nullptr);
      if (pComponentData == nullptr)
        return false;
 
      bool ok = true;
      const auto* pBase = reinterpret_cast<const uint8_t*>(pComponentData);
 
      writer.begin_object();
      for (const auto& field: item.fields) {
        writer.key(field.name);
        ser::serialization_type_id type = ser::serialization_type_id::ignore;
        uint32_t fieldSize = 0;
        if (!detail::runtime_field_json_layout(item, field, type, fieldSize)) {
          writer.value_null();
          ok = false;
          continue;
        }
        const auto* pFieldData = pBase + field.offset;
        ok = ser::detail::write_runtime_field_json(writer, pFieldData, type, fieldSize) && ok;
      }
      writer.end_object();
 
      return ok;
    }
 
    inline ser::json_str component_to_json(const ComponentCacheItem& item, const void* pComponentData, bool& ok) {
      ser::ser_json writer;
      ok = component_to_json(item, pComponentData, writer);
      return writer.str();
    }
 
    inline bool json_to_component(
        const ComponentCacheItem& item, void* pComponentData, ser::ser_json& reader, ser::JsonDiagnostics& diagnostics,
        ser::json_str_view componentPath = {}) {
      GAIA_ASSERT(pComponentData != nullptr);
      if (pComponentData == nullptr)
        return false;
 
      auto make_field_path = [&](ser::json_str_view fieldName) {
        if (componentPath.empty())
          return ser::json_str(fieldName);
        if (fieldName.empty())
          return ser::json_str(componentPath);
 
        ser::json_str path;
        path.reserve(componentPath.size() + 1 + fieldName.size());
        path.append(componentPath.data(), componentPath.size());
        path.append('.');
        path.append(fieldName.data(), fieldName.size());
        return path;
      };
      auto warn = [&](ser::JsonDiagReason reason, const ser::json_str& path, const char* message) {
        diagnostics.add(ser::JsonDiagSeverity::Warning, reason, path, message);
      };
 
      if (reader.parse_null()) {
        warn(ser::JsonDiagReason::NullComponentPayload, make_field_path(""), "Component payload is null.");
        return true;
      }
 
      if (!reader.expect('{'))
        return false;
 
      bool rawFound = false;
      bool fieldFound = false;
      ser::ser_buffer_binary rawPayload;
      auto* pBase = reinterpret_cast<uint8_t*>(pComponentData);
 
      reader.ws();
      if (reader.consume('}')) {
        warn(
            ser::JsonDiagReason::MissingRuntimeFieldsOrRawPayload, make_field_path(""),
            "Component object is empty and contains no runtime fields or $raw payload.");
        return true;
      }
 
      while (true) {
        ser::json_str_view key;
        bool keyFromScratch = false;
        if (!reader.parse_string_view(key, &keyFromScratch))
          return false;
        ser::json_str keyStorage;
        if (keyFromScratch) {
          keyStorage.assign(key.data(), key.size());
          key = keyStorage;
        }
        if (!reader.expect(':'))
          return false;
 
        if (key == "$raw") {
          rawFound = true;
          if (!ser::detail::parse_json_byte_array(reader, rawPayload))
            return false;
        } else if (item.field_count() != 0 && item.comp.soa() == 0) {
          const RuntimeField* pField = nullptr;
          for (const auto& field: item.fields) {
            const auto fieldNameLen = (size_t)GAIA_STRLEN(field.name, ComponentCacheItem::MaxNameLength);
            if (key.size() == fieldNameLen && memcmp(key.data(), field.name, key.size()) == 0) {
              pField = &field;
              break;
            }
          }
 
          if (pField == nullptr) {
            warn(ser::JsonDiagReason::UnknownField, make_field_path(key), "Unknown runtime field.");
            if (!reader.skip_value())
              return false;
          } else {
            ser::serialization_type_id type = ser::serialization_type_id::ignore;
            uint32_t fieldSize = 0;
            if (!detail::runtime_field_json_layout(item, *pField, type, fieldSize)) {
              warn(
                  ser::JsonDiagReason::FieldOutOfBounds, make_field_path(key),
                  "Runtime field points outside component size or uses an unsupported type.");
              if (!reader.skip_value())
                return false;
            } else {
              fieldFound = true;
              auto* pFieldData = pBase + pField->offset;
              bool fieldOk = true;
              if (!ser::detail::read_runtime_field_json(reader, pFieldData, type, fieldSize, fieldOk))
                return false;
              if (!fieldOk) {
                warn(
                    ser::JsonDiagReason::FieldValueAdjusted, make_field_path(key),
                    "Field value was lossy, truncated, or unsupported for the target runtime field type.");
              }
            }
          }
        } else {
          warn(
              ser::JsonDiagReason::MissingRuntimeFieldsOrRawPayload, make_field_path(key),
              "Runtime field metadata is unavailable for keyed field payloads.");
          if (!reader.skip_value())
            return false;
        }
 
        reader.ws();
        if (reader.consume(','))
          continue;
        if (reader.consume('}'))
          break;
        return false;
      }
 
      if (rawFound) {
        if (item.comp.soa() != 0) {
          warn(
              ser::JsonDiagReason::SoaRawUnsupported, make_field_path("$raw"),
              "$raw payload is not supported for SoA components.");
          return true;
        }
 
        auto s = ser::make_serializer(rawPayload);
        s.seek(0);
        item.load(s, pBase, 0, 1, 1);
      }
 
      if (!rawFound && !fieldFound)
        warn(
            ser::JsonDiagReason::MissingRuntimeFieldsOrRawPayload, make_field_path(""),
            "Component payload contains neither recognized runtime fields nor $raw data.");
 
      return true;
    }
 
    inline bool
    json_to_component(const ComponentCacheItem& item, void* pComponentData, ser::ser_json& reader, bool& ok) {
      ser::JsonDiagnostics diagnostics;
      const bool parsed = json_to_component(item, pComponentData, reader, diagnostics);
      ok = !diagnostics.has_issues();
      return parsed;
    }
 
    inline bool World::save_json(ser::ser_json& writer, ser::JsonSaveFlags flags) const {
      auto write_raw_component = [&](const ComponentCacheItem& item, const uint8_t* pData, uint32_t from, uint32_t to,
                                     uint32_t cap) {
        ser::ser_buffer_binary raw;
        auto s = ser::make_serializer(raw);
        item.save(s, pData, from, to, cap);
 
        writer.begin_object();
        writer.key("$raw");
        writer.begin_array();
        const auto* pRaw = raw.data();
        GAIA_FOR(raw.bytes()) writer.value_int(pRaw[i]);
        writer.end_array();
        writer.end_object();
      };
 
      bool ok = true;
      const bool includeBinarySnapshot = (flags & ser::JsonSaveFlags::BinarySnapshot) != 0;
      const bool allowRawFallback = (flags & ser::JsonSaveFlags::RawFallback) != 0;
      ser::bin_stream binarySnapshot;
      if (includeBinarySnapshot) {
        auto s = ser::make_serializer(binarySnapshot);
        s.reset();
        save_to(s);
      }
 
      writer.clear();
      writer.begin_object();
      writer.key("format");
      writer.value_int(WorldSerializerJSONVersion);
      writer.key("worldVersion");
      writer.value_int(m_worldVersion);
      if (includeBinarySnapshot) {
        writer.key("binary");
        writer.begin_array();
        {
          const auto* pData = (const uint8_t*)binarySnapshot.data();
          GAIA_FOR(binarySnapshot.bytes()) writer.value_int(pData[i]);
        }
        writer.end_array();
      }
      writer.key("archetypes");
      writer.begin_array();
 
      for (const auto* pArchetype: m_archetypes) {
        if (pArchetype == nullptr || pArchetype->chunks().empty())
          continue;
 
        writer.begin_object();
        writer.key("id");
        writer.value_int((uint32_t)pArchetype->id());
        writer.key("hash");
        writer.value_int((uint64_t)pArchetype->lookup_hash().hash);
 
        writer.key("components");
        writer.begin_array();
        {
          for (const auto entity: pArchetype->ids_view()) {
            const auto itemName = name(entity);
            if (!itemName.empty())
              writer.value_string(itemName.data(), itemName.size());
            else
              writer.value_string("<unnamed>");
          }
        }
        writer.end_array();
 
        writer.key("entities");
        writer.begin_array();
        {
          for (const auto* pChunk: pArchetype->chunks()) {
            if (pChunk == nullptr || pChunk->empty())
              continue;
 
            const auto ents = pChunk->entity_view();
            const auto recs = pChunk->comp_rec_view();
            GAIA_FOR((uint32_t)ents.size()) {
              const auto entity = ents[i];
 
              writer.begin_object();
              {
                writer.key("entity");
                {
                  writer.begin_object();
                  writer.key("id");
                  writer.value_int(entity.id());
                  writer.key("gen");
                  writer.value_int(entity.gen());
                  writer.key("pair");
                  writer.value_bool(entity.pair());
                  writer.key("kind");
                  writer.value_string(EntityKindString[entity.kind()]);
                  const auto entityName = name(entity);
                  if (!entityName.empty()) {
                    writer.key("name");
                    writer.value_string(entityName.data(), entityName.size());
                  }
                  writer.end_object();
                }
 
                writer.key("components");
                writer.begin_object();
                {
                  GAIA_FOR_((uint32_t)recs.size(), j) {
                    const auto& rec = recs[j];
                    const auto& item = *rec.pItem;
                    const auto name = symbol(item.entity);
                    writer.key(name.data(), name.size());
 
                    // Tags have no associated payload.
                    if (rec.comp.size() == 0) {
                      writer.value_bool(true);
                      continue;
                    }
 
                    const auto row = item.entity.kind() == EntityKind::EK_Uni ? 0U : i;
 
                    if (item.field_count() != 0 && rec.comp.soa() == 0) {
                      const auto* pCompData = pChunk->comp_ptr(j, row);
                      ok = ecs::component_to_json(item, pCompData, writer) && ok;
                    } else {
                      if (allowRawFallback)
                        write_raw_component(item, rec.pData, row, row + 1, pChunk->capacity());
                      else {
                        writer.value_null();
                        ok = false;
                      }
                    }
                  }
                  writer.end_object();
                }
              }
              writer.end_object();
            }
          }
        }
 
        writer.end_array();
        writer.end_object();
      }
 
      writer.end_array();
      writer.end_object();
      return ok;
    }
 
    inline ser::json_str World::save_json(bool& ok, ser::JsonSaveFlags flags) const {
      ser::ser_json writer;
      ok = save_json(writer, flags);
      return writer.str();
    }
 
    inline bool World::load_json(const char* json, uint32_t len, ser::JsonDiagnostics& diagnostics) {
      diagnostics.clear();
      if (json == nullptr)
        return false;
      if (len == 0) {
        diagnostics.add(
            ser::JsonDiagSeverity::Error, ser::JsonDiagReason::InvalidJson, "$",
            "Input JSON length must be provided and non-zero.");
        return false;
      }
 
      const auto dataLen = len;
      const auto* p = json;
      const auto* end = json + dataLen;
      auto warn = [&](ser::JsonDiagReason reason, ser::json_str_view path, const char* message) {
        diagnostics.add(ser::JsonDiagSeverity::Warning, reason, path, message);
      };
      auto error = [&](ser::JsonDiagReason reason, ser::json_str_view path, const char* message) {
        diagnostics.add(ser::JsonDiagSeverity::Error, reason, path, message);
      };
 
      // Validate top-level format version first.
      {
        ser::ser_json header(json, dataLen);
        if (!header.expect('{')) {
          error(ser::JsonDiagReason::InvalidJson, "$", "Root JSON value must be an object.");
          return false;
        }
 
        bool hasFormat = false;
        uint32_t formatValue = 0;
 
        header.ws();
        if (!header.consume('}')) {
          while (true) {
            ser::json_str_view key;
            if (!header.parse_string_view(key))
              return false;
            if (!header.expect(':'))
              return false;
 
            if (key == "format") {
              double d = 0.0;
              if (!header.parse_number(d))
                return false;
              if (d < 0.0 || d > 4294967295.0)
                return false;
              const auto v = (uint32_t)d;
              if ((double)v != d)
                return false;
              formatValue = v;
              hasFormat = true;
            } else {
              if (!header.skip_value())
                return false;
            }
 
            header.ws();
            if (header.consume(','))
              continue;
            if (header.consume('}'))
              break;
            return false;
          }
        }
 
        header.ws();
        if (!header.eof())
          return false;
 
        if (!hasFormat) {
          error(ser::JsonDiagReason::MissingFormatField, "$.format", "Missing required 'format' field.");
          return false;
        }
 
        if (formatValue != WorldSerializerJSONVersion) {
          error(
              ser::JsonDiagReason::UnsupportedFormatVersion, "$.format",
              "Unsupported format version. Expected numeric value 1.");
          return false;
        }
      }
 
      // Prefer fast-path: binary snapshot payload.
      {
        const char key[] = "\"binary\"";
        const uint32_t keyLen = (uint32_t)(sizeof(key) - 1);
        const char* keyPos = nullptr;
        for (const char* it = p; it + keyLen <= end; ++it) {
          if (memcmp(it, key, keyLen) == 0) {
            keyPos = it;
            break;
          }
        }
        if (keyPos != nullptr) {
          const char* arr = nullptr;
          for (const char* it = keyPos + keyLen; it < end; ++it) {
            if (*it == '[') {
              arr = it;
              break;
            }
          }
          if (arr != nullptr) {
            ser::bin_stream serializer;
            ser::ser_json binaryReader(arr, (uint32_t)(end - arr));
            if (!ser::detail::parse_json_byte_array(binaryReader, serializer))
              return false;
 
            return load(serializer);
          }
        }
      }
 
      // Fallback: semantic world JSON parser.
      ser::ser_json jp(json, dataLen);
 
      struct CompDataLoc {
        uint8_t* pBase = nullptr;
        uint32_t row = 0;
        uint32_t cap = 0;
        bool valid = false;
      };
 
      auto locate_component_data = [&](Entity entity, const ComponentCacheItem& item) -> CompDataLoc {
        CompDataLoc loc{};
        if (!has(entity))
          return loc;
 
        auto& ec = fetch(entity);
        const auto compIdx = core::get_index(ec.pChunk->ids_view(), item.entity);
        if (compIdx == BadIndex)
          return loc;
 
        loc.pBase = ec.pChunk->comp_ptr_mut(compIdx, 0);
        loc.row = item.entity.kind() == EntityKind::EK_Uni ? 0U : ec.row;
        loc.cap = ec.pChunk->capacity();
        loc.valid = true;
        return loc;
      };
 
      auto has_direct_component = [&](Entity entity, Entity componentEntity) -> bool {
        if (!has(entity))
          return false;
        const auto& ec = fetch(entity);
        return core::get_index(ec.pChunk->ids_view(), componentEntity) != BadIndex;
      };
 
      auto parse_and_apply_component_value = [&](Entity entity, const ComponentCacheItem& item,
                                                 ser::json_str_view compPath) -> bool {
        jp.ws();
        if (jp.eof())
          return false;
 
        // Tag values are currently ignored by semantic loader.
        const char next = jp.peek();
        if (next == 't' || next == 'f') {
          bool tagValue = false;
          if (!jp.parse_bool(tagValue))
            return false;
          warn(
              ser::JsonDiagReason::TagValueIgnored, compPath,
              "Tag-like boolean component payload is ignored in semantic mode.");
          return true;
        }
 
        if (jp.parse_null()) {
          warn(
              ser::JsonDiagReason::NullComponentPayload, compPath,
              "Null component payload is ignored in semantic mode.");
          return true;
        }
 
        if (!has_direct_component(entity, item.entity))
          add(entity, item.entity);
 
        auto loc = locate_component_data(entity, item);
        if (!loc.valid) {
          warn(
              ser::JsonDiagReason::MissingComponentStorage, compPath,
              "Component storage is unavailable on the target entity.");
          return jp.skip_value();
        }
 
        auto* pRowData = loc.pBase + (uintptr_t)item.comp.size() * loc.row;
        if (!ecs::json_to_component(item, pRowData, jp, diagnostics, compPath))
          return false;
        return true;
      };
 
      auto parse_entity_meta = [&](bool& isPair, ser::json_str& nameOut) -> bool {
        if (!jp.expect('{'))
          return false;
 
        jp.ws();
        if (jp.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view key;
          if (!jp.parse_string_view(key))
            return false;
          if (!jp.expect(':'))
            return false;
 
          if (key == "pair") {
            if (!jp.parse_bool(isPair))
              return false;
          } else if (key == "name") {
            if (!jp.parse_string(nameOut))
              return false;
          } else {
            if (!jp.skip_value())
              return false;
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
 
        return true;
      };
 
      auto parse_components_for_entity = [&](Entity& entity, bool& created, bool isPair,
                                             const ser::json_str& entityName) -> bool {
        if (!jp.expect('{'))
          return false;
 
        jp.ws();
        if (jp.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view compName;
          bool compNameFromScratch = false;
          if (!jp.parse_string_view(compName, &compNameFromScratch))
            return false;
          ser::json_str compNameStorage;
          if (compNameFromScratch) {
            compNameStorage.assign(compName.data(), compName.size());
            compName = compNameStorage;
          }
          if (!jp.expect(':'))
            return false;
 
          const bool isInternalComp = compName.size() >= 10 && memcmp(compName.data(), "gaia::ecs::", 10) == 0;
          if (isPair || isInternalComp) {
            if (!jp.skip_value())
              return false;
          } else {
            const auto componentEntity = get(compName.data(), (uint32_t)compName.size());
            const auto* pItem = componentEntity != EntityBad ? comp_cache().find(componentEntity) : nullptr;
            if (pItem == nullptr) {
              warn(
                  ser::JsonDiagReason::UnknownComponent, compName,
                  "Component is not registered in the component cache.");
              if (!jp.skip_value())
                return false;
            } else if (pItem->comp.size() == 0) {
              // Ignore tag-only components in semantic mode for now.
              warn(
                  ser::JsonDiagReason::TagComponentUnsupported, compName,
                  "Tag-only component semantic JSON loading is currently unsupported.");
              if (!jp.skip_value())
                return false;
            } else {
              if (!created) {
                entity = add();
                created = true;
                if (!entityName.empty()) {
                  const auto existing = get(entityName.data(), (uint32_t)entityName.size());
                  if (existing == EntityBad)
                    name(entity, entityName.data(), (uint32_t)entityName.size());
                  else
                    warn(
                        ser::JsonDiagReason::DuplicateEntityName, "entity.name",
                        "Entity name already exists; keeping existing mapping.");
                }
              }
 
              if (!parse_and_apply_component_value(entity, *pItem, compName))
                return false;
            }
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
 
        return true;
      };
 
      auto parse_entity_entry = [&]() -> bool {
        if (!jp.expect('{')) {
          error(ser::JsonDiagReason::InvalidJson, "$", "Root JSON value must be an object.");
          return false;
        }
 
        bool isPair = false;
        ser::json_str entityName;
        Entity entity = EntityBad;
        bool created = false;
 
        jp.ws();
        if (jp.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view key;
          if (!jp.parse_string_view(key))
            return false;
          if (!jp.expect(':'))
            return false;
 
          if (key == "entity") {
            if (!parse_entity_meta(isPair, entityName))
              return false;
          } else if (key == "components") {
            if (!parse_components_for_entity(entity, created, isPair, entityName))
              return false;
          } else {
            if (!jp.skip_value())
              return false;
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
 
        return true;
      };
 
      auto parse_archetypes = [&]() -> bool {
        if (!jp.expect('['))
          return false;
 
        jp.ws();
        if (jp.consume(']'))
          return true;
 
        while (true) {
          if (!jp.expect('{'))
            return false;
 
          jp.ws();
          if (!jp.consume('}')) {
            while (true) {
              ser::json_str_view key;
              if (!jp.parse_string_view(key))
                return false;
              if (!jp.expect(':'))
                return false;
 
              if (key == "entities") {
                if (!jp.expect('['))
                  return false;
 
                jp.ws();
                if (!jp.consume(']')) {
                  while (true) {
                    if (!parse_entity_entry())
                      return false;
 
                    jp.ws();
                    if (jp.consume(','))
                      continue;
                    if (jp.consume(']'))
                      break;
                    return false;
                  }
                }
              } else {
                if (!jp.skip_value())
                  return false;
              }
 
              jp.ws();
              if (jp.consume(','))
                continue;
              if (jp.consume('}'))
                break;
              return false;
            }
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume(']'))
            break;
          return false;
        }
 
        return true;
      };
 
      if (!jp.expect('{'))
        return false;
 
      bool hasArchetypes = false;
      jp.ws();
      if (!jp.consume('}')) {
        while (true) {
          ser::json_str_view key;
          if (!jp.parse_string_view(key))
            return false;
          if (!jp.expect(':'))
            return false;
 
          if (key == "archetypes") {
            hasArchetypes = true;
            if (!parse_archetypes())
              return false;
          } else {
            if (!jp.skip_value())
              return false;
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
      }
 
      jp.ws();
      if (!jp.eof())
        return false;
      if (!hasArchetypes) {
        error(ser::JsonDiagReason::MissingArchetypesSection, "$.archetypes", "Missing required 'archetypes' section.");
        return false;
      }
 
      return true;
    }
 
    inline bool World::load_json(const char* json, uint32_t len) {
      ser::JsonDiagnostics diagnostics;
      const bool parsed = load_json(json, len, diagnostics);
      return parsed && !diagnostics.has_issues();
    }
 
    inline bool World::load_json(ser::json_str_view json, ser::JsonDiagnostics& diagnostics) {
      return load_json(json.data(), json.size(), diagnostics);
    }
 
    inline bool World::load_json(ser::json_str_view json) {
      ser::JsonDiagnostics diagnostics;
      const bool parsed = load_json(json.data(), json.size(), diagnostics);
      return parsed && !diagnostics.has_issues();
    }
  } // namespace ecs
} // namespace gaia