/*
 * Copyright (c) 2014-2018 Cesanta Software Limited
 * All rights reserved
 *
 * 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 "mgos.h"
#include "mgos_pwm.h"
#include "mgos_spi.h"

#define LED_PIN 2
#define CS_PIN 15
#define SPI_MODE 3
#define LCD_RESET_PIN 16

#define LCD_DATA                1       // Data bit
#define LCD_COMMAND             0       // Command bit
#define LCD_CLEAR_SCREEN        0x01    // Clear screen
#define LCD_ADDRESS_RESET       0x02    // The address counter is reset
#define LCD_BASIC_FUNCTION      0x30    // Basic instruction set
#define LCD_EXTEND_FUNCTION     0x34    // Extended instruction set



static void st7920_spi_write(const uint8_t *data, uint32_t size) {
    struct mgos_spi *spi = mgos_spi_get_global();

    if (!spi) {
        LOG(LL_ERROR, ("SPI is disabled, set spi.enable=true"));
        return;
    }

    struct mgos_spi_txn txn = {
        .cs   = 0,
        .mode = SPI_MODE,
        .freq = 200000,
    };
    txn.hd.tx_data   = data,
    txn.hd.tx_len    = size,
    txn.hd.dummy_len = 0,
    txn.hd.rx_len    = 0,
    txn.hd.rx_data   = NULL,
    mgos_spi_run_txn(spi, false, &txn);
}

static void st7920_spi_write8_cmd(bool command, uint8_t byte) {

    st7920_spi_write(command ? 0xFA : 0xF8, 1);
    st7920_spi_write(byte & 0xF0, 1);
    st7920_spi_write((byte << 4) & 0xF0, 1);
}

void ST7920_Init() {
    mgos_gpio_setup_output(LCD_RESET_PIN, 0);
    mgos_gpio_write(LCD_RESET_PIN, 0);
    mgos_msleep(100);
    mgos_gpio_write(LCD_RESET_PIN, 1);

    st7920_spi_write8_cmd(LCD_COMMAND, LCD_BASIC_FUNCTION); // Function set
    st7920_spi_write8_cmd(LCD_COMMAND, LCD_CLEAR_SCREEN);   // Display clear
    st7920_spi_write8_cmd(LCD_COMMAND, 0x06); // Entry mode set
    st7920_spi_write8_cmd(LCD_COMMAND, 0x0C); // Display control

}

enum mgos_app_init_result mgos_app_init(void) {

    mgos_gpio_setup_output(LED_PIN, 0);

    ST7920_Init();

    return MGOS_APP_INIT_SUCCESS;
}