#include "picoled/ST7789.h"

#include <pico/stdlib.h>

namespace picoled
{

st7789::st7789(size_t width, size_t height, spi_inst_t* spi, uint8_t cs_pin, uint8_t dc_pin) :
  oled(width, height),
  spi(spi),
  cs_pin(cs_pin),
  dc_pin(dc_pin)
{
  command(0x01); sleep_ms(150); // reset device
  command(0x11); sleep_ms(10); // stop sleeping
  command(0x3A, 0x66); sleep_ms(10); // set display format
  {
    constexpr size_t PARAM_COUNT = 4;
    // no clue where these numbers come from
    // see https://github.com/adafruit/Adafruit-ST7735-Library/blob/62112b90eddcb2ecc51f474e9fe98b68eb26cb2a/Adafruit_ST7789.cpp#L111-L117
    const uint8_t params[PARAM_COUNT] =
      {
        0x00,
        0x35,
        0x00,
        0xBB
      };

    command(0x2A, params, PARAM_COUNT); // set column address range
  }
  {
    constexpr size_t PARAM_COUNT = 4;
    // no clue where these numbers come from
    // see https://github.com/adafruit/Adafruit-ST7735-Library/blob/62112b90eddcb2ecc51f474e9fe98b68eb26cb2a/Adafruit_ST7789.cpp#L111-L117
    const uint8_t params[PARAM_COUNT] =
      {
        0x00,
        0x28,
        0x01,
        0x17
      };

    command(0x2B, params, PARAM_COUNT); // set row address range
  }
  command(0x36, 0b11000000); // set memory addressing mode
  command(0x21); // turn on display inversion
  command(0x13); sleep_ms(10); // set display to normal mode
  command(0x29); sleep_ms(10); // turn on display
}

void st7789::update_impl() const
{
  command(0x2C, inactive_buffer().data_pointer(), get_width() * get_height() * 3);
}

void st7789::command(uint8_t cmd) const
{
  command(cmd, nullptr, 0);
}

void st7789::command(uint8_t cmd, uint8_t param) const
{
  command(cmd, &param, 1);
}

void st7789::command(uint8_t cmd, const uint8_t* params, size_t param_count) const
{
  gpio_put(cs_pin, false);  // select chip

  gpio_put(dc_pin, false); // command mode
  spi_write_blocking(spi, &cmd, 1);

  gpio_put(dc_pin, true);  // parameters are sent via data mode
  spi_write_blocking(spi, params, param_count);

  gpio_put(cs_pin, true); // deselect chip
}

pixel st7789::format(const pixel& p)
{
  const uint16_t red_scaled = p.red() * 0x3F / 0xFF; // scale to 6-bit color
  const uint16_t green_scaled = p.green() * 0x3F / 0xFF; // scale to 6-bit color
  const uint16_t blue_scaled = p.blue() * 0x3F / 0xFF; // scale to 6-bit color

  const uint8_t red = (red_scaled & 0xFF) << 2;
  const uint8_t green = (green_scaled & 0xFF) << 2;
  const uint8_t blue = (blue_scaled & 0xFF) << 2;

  return { red, green, blue };
}

}