/*
 * Copyright 2017 The Android Open Source Project
 *
 * 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 <cstdint>
#include <list>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#include "bta/include/bta_gatt_api.h"

/* BTA GATTC implementation does not allow for multiple commands queuing. So one
 * client making calls to BTA_GATTC_ReadCharacteristic, BTA_GATTC_ReadCharDescr,
 * BTA_GATTC_WriteCharValue, BTA_GATTC_WriteCharDescr must wait for the callacks
 * before scheduling next operation.
 *
 * Methods below can be used as replacement to BTA_GATTC_* in BTA app. They do
 * queue the commands if another command is currently being executed.
 *
 * If you decide to use those methods in your app, make sure to not mix it with
 * existing BTA_GATTC_* API.
 */
class BtaGattQueue {
public:
  static void Clean(tCONN_ID conn_id);
  static void ReadCharacteristic(tCONN_ID conn_id, uint16_t handle, GATT_READ_OP_CB cb,
                                 void* cb_data);
  static void ReadDescriptor(tCONN_ID conn_id, uint16_t handle, GATT_READ_OP_CB cb, void* cb_data);
  static void WriteCharacteristic(tCONN_ID conn_id, uint16_t handle, std::vector<uint8_t> value,
                                  tGATT_WRITE_TYPE write_type, GATT_WRITE_OP_CB cb, void* cb_data);
  static void WriteDescriptor(tCONN_ID conn_id, uint16_t handle, std::vector<uint8_t> value,
                              tGATT_WRITE_TYPE write_type, GATT_WRITE_OP_CB cb, void* cb_data);
  static void ConfigureMtu(tCONN_ID conn_id, uint16_t mtu);
  /* This method uses "Read Multiple Variable Length Characteristic Values".
   * If EATT is not enabled on remote, it would send multiple regular Characteristic Reads, and
   * concatenate their values into Length Value Tuple List
   */
  static void ReadMultiCharacteristic(tCONN_ID conn_id, tBTA_GATTC_MULTI& p_read_multi,
                                      GATT_READ_MULTI_OP_CB cb, void* cb_data);

  /* Holds pending GATT operations */
  struct gatt_operation {
    uint8_t type;
    uint16_t handle;
    tBTA_GATTC_MULTI handles;
    GATT_READ_OP_CB read_cb;
    GATT_READ_MULTI_OP_CB read_multi_cb;
    void* read_cb_data;
    GATT_WRITE_OP_CB write_cb;
    void* write_cb_data;
    GATT_CONFIGURE_MTU_OP_CB mtu_cb;
    void* mtu_cb_data;

    /* write-specific fields */
    tGATT_WRITE_TYPE write_type;
    std::vector<uint8_t> value;
  };

private:
  static void mark_as_not_executing(tCONN_ID conn_id);
  static void gatt_execute_next_op(tCONN_ID conn_id);
  static void gatt_read_op_finished(tCONN_ID conn_id, tGATT_STATUS status, uint16_t handle,
                                    uint16_t len, uint8_t* value, void* data);
  static void gatt_write_op_finished(tCONN_ID conn_id, tGATT_STATUS status, uint16_t handle,
                                     uint16_t len, const uint8_t* value, void* data);
  static void gatt_configure_mtu_op_finished(tCONN_ID conn_id, tGATT_STATUS status, void* data);
  static void gatt_read_multi_op_finished(tCONN_ID conn_id, tGATT_STATUS status,
                                          tBTA_GATTC_MULTI& handle, uint16_t len, uint8_t* value,
                                          void* data);
  static void gatt_read_multi_op_simulate(tCONN_ID conn_id, tGATT_STATUS status, uint16_t handle,
                                          uint16_t len, uint8_t* value, void* data_read);
  // maps connection id to operations waiting for execution
  static std::unordered_map<tCONN_ID, std::list<gatt_operation>> gatt_op_queue;
  // contain connection ids that currently execute operations
  static std::unordered_set<tCONN_ID> gatt_op_queue_executing;
};