// Copyright 2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

include "encoding.fbs";
include "collation.fbs";

namespace serial;

enum DistanceType : uint8 {
  Null       = 0,
  L2_Squared = 1,
}

table TableSchema {
  columns:[Column] (required);
  clustered_index:Index (required);
  secondary_indexes:[Index];
  checks:[CheckConstraint];
  collation:Collation;

  // this field is necessary because older dolt clients weren't using TryAccessor for Columns, but are in TableSchemas
  has_features_after_try_accessors:bool;

  // table comment
  comment:string;

  // target row size (used with adaptive encoded columns)
  target_row_size:uint16 = 2048;
}

table Column {
  // column name
  name:string (required);

  // sql column type
  sql_type:string;

  // sql default value. For generated columns, this is the generated expression rather than the default.
  default_value:string;

  // sql comment
  comment:string;

  // sql display order
  display_order:int16;

  // column tag
  tag: uint64;

  // storage encoding
  encoding:Encoding;

  // column meta
  primary_key:bool;
  nullable:bool;
  auto_increment:bool;
  hidden:bool;
  generated:bool;
  virtual:bool;

  // sql on update value
  on_update_value:string;

  // a marker value only written when the column uses adaptive encoding, which will force older clients to upgrade
  // before reading this data.
  uses_adaptive_encoding:bool;

  // hidden system columns are not directly accessible or visible by users, and are used to
  // store functional expression results for use in secondary indexes
  hidden_system:bool;
  
  // A range of 1.x releases from approximately 1.86.0 onwards had a nasty bug with adaptive encoded values where
  // data loss could occur during garbage collection or pull operations. This field forces clients from that release 
  // range to upgrade before reading schemas with adaptive encoded columns.
  adaptive_encoding_breaking_change:bool;
}

table Index {
  // index name
  name:string;

  // sql comment
  comment:string;

  // ordered list of columns defining the index.
  // stored as indices into columns vector.
  index_columns:[uint16] (required);

  // ordered list of columns corresponding to
  // key tuple fields within index storage.
  // stored as indices into columns vector.
  //
  // for secondary indexes, this is typically
  // index columns + primary key columns.
  key_columns:[uint16] (required);

  // ordered list of columns corresponding to
  // value tuple fields within index storage.
  // stored as indices into columns vector.
  //
  // typically, this is only populated for
  // clustered primary key indexes.
  value_columns:[uint16];

  // index meta
  primary_key:bool;
  unique_key:bool;
  system_defined:bool;

  prefix_lengths:[uint16];
  spatial_key:bool;

  // fulltext information
  fulltext_key:bool;
  fulltext_info:FulltextInfo;

  // vector information
  // these fields should be set for vector indexes and otherwise omitted, for backwards compatibility
  vector_key:bool;
  vector_info:VectorInfo;

  // WHERE clause expression string for partial indexes (empty for full indexes)
  predicate:string;
}

table FulltextInfo {
  config_table:string;
  position_table:string;
  doc_count_table:string;
  global_count_table:string;
  row_count_table:string;
  key_type:uint8;
  key_name:string;
  key_positions:[uint16];
}

table VectorInfo {
    distance_type:DistanceType;
}

table CheckConstraint {
    name:string;
    expression:string;
    enforced:bool;
    is_not_valid:bool;
}

// KEEP THIS IN SYNC WITH fileidentifiers.go
file_identifier "DSCH";

root_type TableSchema;