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#include <stdio.h>

#define ST7789_CLK 21
#define ST7789_DATA 22
#define ST7789_RST 27  // active low
#define ST7789_CS 26   // active low
#define ST7789_DC 25   // 1=data, 0=cmd

#define DATA_MODE gpio_set_level(ST7789_DC, 1);
#define CMD_MODE gpio_set_level(ST7789_DC, 0);

// TFT LCD 76x284
// 4-wire SPI with DCX

#include <driver/gpio.h>
#include <spi_bus.h>

inline void wait(const uint16_t ms) { vTaskDelay(pdMS_TO_TICKS(ms)); }

void st7789_init(spi_bus_device_handle_t dev);
void st7789_setAddrWindow(spi_bus_device_handle_t dev, uint16_t x, uint16_t y,
                          uint16_t w, uint16_t h);

void app_main(void) {
  gpio_reset_pin(ST7789_DC);
  gpio_reset_pin(ST7789_RST);

  gpio_set_direction(ST7789_RST, GPIO_MODE_OUTPUT);
  gpio_set_direction(ST7789_DC, GPIO_MODE_OUTPUT);

  // hw reset
  gpio_set_level(ST7789_RST, 1);
  wait(1);
  gpio_set_level(ST7789_RST, 0);
  wait(1);
  gpio_set_level(ST7789_RST, 1);

  spi_bus_handle_t bus_hdl = {0};
  spi_bus_device_handle_t dev = {0};

  spi_config_t bus_cfg = {.mosi_io_num = ST7789_DATA,
                          .miso_io_num = -1,
                          .sclk_io_num = ST7789_CLK,
                          .max_transfer_sz = 1};

  spi_device_config_t st7789_cfg = {
      .cs_io_num = ST7789_CS, .mode = 0, .clock_speed_hz = SPI_MASTER_FREQ_10M};

  bus_hdl = spi_bus_create(SPI3_HOST, &bus_cfg);
  if (!bus_hdl) {
    printf("SPI bus error: Cannot create SPI bus\n");
    exit(-1);
  }
  dev = spi_bus_device_create(bus_hdl, &st7789_cfg);
  if (!dev) {
    printf("SPI bus error: Cannot create SPI device\n");
    exit(-1);
  }

  // <---perform SPI here--->
  st7789_init(dev);

  CMD_MODE
  spi_bus_transfer_byte(dev, 0x2C, NULL);  // memory write
  DATA_MODE
  for (uint8_t i = 0; i < 25; i++) {
    for (uint8_t j = 0; j < 25; j++) {
      // fill 25x25 area with 0xAAAA
      spi_bus_transfer_byte(dev, 0xAA, NULL);
      spi_bus_transfer_byte(dev, 0xAA, NULL);
    }
  }
  CMD_MODE
  // <---endregion--->

  spi_bus_device_delete(&dev);
  spi_bus_delete(&bus_hdl);
}

void st7789_init(spi_bus_device_handle_t dev) {
  spi_bus_transfer_byte(dev, 0x01, NULL);  // sw reset
  wait(10);

  spi_bus_transfer_byte(dev, 0x26, NULL);  // set gamma
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x01, NULL);  // gamma 2.2
  CMD_MODE

  spi_bus_transfer_byte(dev, 0x36, NULL);  // memory data access control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x00, NULL);  // 000000_xxb - normal mode
  CMD_MODE

  spi_bus_transfer_byte(dev, 0x3A, NULL);  // pixel format
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x26, NULL);  // 0_101_0_101 - 65K@16bit
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xB0, NULL);  // RAM control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x00, NULL);  // RAM access from MCU
  spi_bus_transfer_byte(dev, 0xCA, NULL);  // RAM LE+MSB
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xB2, NULL);  // porch settings
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x0C, NULL);
  spi_bus_transfer_byte(dev, 0x0C, NULL);
  spi_bus_transfer_byte(dev, 0x00, NULL);
  spi_bus_transfer_byte(dev, 0x33, NULL);
  spi_bus_transfer_byte(dev, 0x33, NULL);
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xB7, NULL);  // gate control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x45, NULL);  // 13.65-10.43V
  CMD_MODE

  spi_bus_transfer_byte(dev, 0x2B, NULL);  // VCOM
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x2B, NULL);  // 1.175V
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xC0, NULL);  // LCM
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x2C, NULL);  // XBGR, XMX, XMH
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xC2, NULL);  // VDV and VRH
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x01, NULL);  // VDV and VRH from CMD wire
  spi_bus_transfer_byte(dev, 0xFF, NULL);  // always FFh
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xC3, NULL);  // VRH
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x11, NULL);  // 4.4+V
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xC4, NULL);  // VDV
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x20, NULL);  // 0V
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xC6, NULL);  // framerate control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x0F, NULL);  // 60Hz
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xD0, NULL);  // power control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0xA4, NULL);  // always A4h
  spi_bus_transfer_byte(dev, 0xA1, NULL);  // 6.8V, -4.8V, 2.3V
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xE0, NULL);  // positive voltage gamma control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0xD0, NULL);
  spi_bus_transfer_byte(dev, 0x00, NULL);
  spi_bus_transfer_byte(dev, 0x05, NULL);
  spi_bus_transfer_byte(dev, 0x0E, NULL);
  spi_bus_transfer_byte(dev, 0x15, NULL);
  spi_bus_transfer_byte(dev, 0x0D, NULL);
  spi_bus_transfer_byte(dev, 0x37, NULL);
  spi_bus_transfer_byte(dev, 0x43, NULL);
  spi_bus_transfer_byte(dev, 0x47, NULL);
  spi_bus_transfer_byte(dev, 0x09, NULL);
  spi_bus_transfer_byte(dev, 0x15, NULL);
  spi_bus_transfer_byte(dev, 0x12, NULL);
  spi_bus_transfer_byte(dev, 0x16, NULL);
  spi_bus_transfer_byte(dev, 0x19, NULL);
  CMD_MODE

  spi_bus_transfer_byte(dev, 0xE0, NULL);  // negative voltage gamma control
  DATA_MODE
  spi_bus_transfer_byte(dev, 0xD0, NULL);
  spi_bus_transfer_byte(dev, 0x00, NULL);
  spi_bus_transfer_byte(dev, 0x05, NULL);
  spi_bus_transfer_byte(dev, 0x0D, NULL);
  spi_bus_transfer_byte(dev, 0x0C, NULL);
  spi_bus_transfer_byte(dev, 0x06, NULL);
  spi_bus_transfer_byte(dev, 0x2D, NULL);
  spi_bus_transfer_byte(dev, 0x44, NULL);
  spi_bus_transfer_byte(dev, 0x40, NULL);
  spi_bus_transfer_byte(dev, 0x0E, NULL);
  spi_bus_transfer_byte(dev, 0x1C, NULL);
  spi_bus_transfer_byte(dev, 0x18, NULL);
  spi_bus_transfer_byte(dev, 0x16, NULL);
  spi_bus_transfer_byte(dev, 0x19, NULL);
  CMD_MODE

  spi_bus_transfer_byte(dev, 0x11, NULL);  // sleep out
  wait(5);
  spi_bus_transfer_byte(dev, 0x29, NULL);  // display on
  spi_bus_transfer_byte(dev, 0x13, NULL);  // normal display on
  spi_bus_transfer_byte(dev, 0x21, NULL);  // inv on

  /*spi_bus_transfer_byte(dev, 0x2A, NULL);  // column addr set
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x00, NULL);  // XS[15:8]
  spi_bus_transfer_byte(dev, 0x00, NULL);  // XS[7:0]
  spi_bus_transfer_byte(dev, 0x00, NULL);  // XE[15:8]
  spi_bus_transfer_byte(dev, 0x00, NULL);  // XE[7:0]
  CMD_MODE

  spi_bus_transfer_byte(dev, 0x2B, NULL);  // row addr set
  DATA_MODE
  spi_bus_transfer_byte(dev, 0x00, NULL);  // YS[15:8]
  spi_bus_transfer_byte(dev, 0x00, NULL);  // YS[7:0]
  spi_bus_transfer_byte(dev, 0x00, NULL);  // YE[15:8]
  spi_bus_transfer_byte(dev, 0x00, NULL);  // YE[7:0]
  CMD_MODE*/
  st7789_setAddrWindow(dev, 0, 0, 76, 284);
}

void st7789_setAddrWindow(spi_bus_device_handle_t dev, uint16_t x, uint16_t y,
                          uint16_t w, uint16_t h) {
  const uint16_t xs = x;
  const uint16_t xe = x + w;
  const uint16_t ys = y;
  const uint16_t ye = y + h;

  CMD_MODE
  spi_bus_transfer_byte(dev, 0x2A, NULL);  // column addr set
  DATA_MODE
  spi_bus_transfer_byte(dev, xs >> 8, NULL);    // XS[15:8]
  spi_bus_transfer_byte(dev, xs & 0xff, NULL);  // XS[7:0]
  spi_bus_transfer_byte(dev, xe >> 8, NULL);    // XE[15:8]
  spi_bus_transfer_byte(dev, xe & 0xff, NULL);  // XE[7:0]
  CMD_MODE

  spi_bus_transfer_byte(dev, 0x2B, NULL);  // row addr set
  DATA_MODE
  spi_bus_transfer_byte(dev, ys >> 8, NULL);    // YS[15:8]
  spi_bus_transfer_byte(dev, ys & 0xff, NULL);  // YS[7:0]
  spi_bus_transfer_byte(dev, ye >> 8, NULL);    // Ye[15:8]
  spi_bus_transfer_byte(dev, ye & 0xff, NULL);  // Ye[7:0]
  CMD_MODE
}