// Copyright 2021 Espressif Systems (Shanghai) PTE LTD
//
// 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.

#pragma once

#include <memory>
#include <functional>
#include <exception>
#include <cstddef>
#include <cstdint>
#include <utility>
#include "esp_err.h"
#include "esp_modem_primitives.hpp"

namespace esp_modem {

/**
 * @defgroup ESP_MODEM_TERMINAL
 * @brief Definition of an abstract terminal to be attached to DTE class
 */

/** @addtogroup ESP_MODEM_TERMINAL
* @{
*/

/**
 * @brief Terminal errors
 */
enum class terminal_error {
    BUFFER_OVERFLOW,
    CHECKSUM_ERROR,
    UNEXPECTED_CONTROL_FLOW,
    DEVICE_GONE,
};

/**
 * @brief Terminal interface. All communication interfaces must comply to this interface in order to be used as a DTE
 */
class Terminal {
public:
    virtual ~Terminal() = default;

    void set_error_cb(std::function<void(terminal_error)> f)
    {
        on_error = std::move(f);
    }

    virtual void set_read_cb(std::function<bool(uint8_t *data, size_t len)> f)
    {
        on_read = std::move(f);
    }

    /**
     * @brief Writes data to the terminal
     * @param data Data pointer
     * @param len Data len
     * @return length of data written
     */
    virtual int write(uint8_t *data, size_t len) = 0;

    /**
     * @brief Read from the terminal. This function doesn't block, but return all available data.
     * @param data Data pointer to store the read payload
     * @param len Maximum data len to read
     * @return length of data actually read
     */
    virtual int read(uint8_t *data, size_t len) = 0;

    virtual void start() = 0;

    virtual void stop() = 0;

protected:
    std::function<bool(uint8_t *data, size_t len)> on_read;
    std::function<void(terminal_error)> on_error;
};

/**
 * @}
 */

} // namespace esp_modem