/*
  Use a canvas to stop display flicker when updating.
  Partly successful. Display updates without flicker but update is very slow.
  Update appears to be in situ eather than page swapping.
  Even slower with a black and white bitmap???
  Had to set canvas size to half the display size to avoid crashes. Memory?
*/
#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h> // Hardware-specific library for ST7789
// #include <Fonts/FreeSansBold24pt7b.h>

// Display pin definitions
#define TFT_BL 21 // Backlight
#define TFT_SCLK 18 // 14
#define TFT_MOSI 23 // 13
#define TFT_MISO 15 // 12 
#define TFT_DC    2
#define TFT_CS    5 // 15
#define TFT_RST   4 // -1 // No reset defined
#define ST77XX_DARKGRAY 0x7bef // Not defined in Adafruit graphics
#define ST77XX_LIGHTGRAY 0xb5d6

Adafruit_ST7789 display = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_MOSI, TFT_SCLK, TFT_RST);
// Set canvas size to half screen size
GFXcanvas16 canvas(160, 170); // Half width (320) full height(170)
// GFXcanvas1 canvas(160, 170); // Half width (320) full height(170)

unsigned int charWidth = 6, charHeight = 8, charSize = 4;
// unsigned int hdg = 30; //int(random(360));

unsigned int RotX(int a, int b, float S, float C)  // Rotate and offset x coordinate
{
  // return (unsigned int)(a * C - b * S + display.width() * 3 / 4 - 1); // Centred on right half
  return (unsigned int)(a * C - b * S + display.width() / 4 - 1); // Centred on right half
}

unsigned int RotY(int a, int b, float S, float C)  // Rotate and offset y coordinate
{
  return (unsigned int)(a * S + b * C + display.height() / 2 - 1); // Half way down display
}

char* getSector(float H)
{
  // Select a sector on the compass rose that contains the heading
  static char Sector[4] = {'\0'};
  // Sixteen overlapping segments
  if (H > 348.5 || H < 11.5) // Top of compass
    strcpy(Sector, "N");
  else if (H > 11 && H < 34)
    strcpy(Sector, "NNE");
  else if (H > 33.5 && H < 56.5)
    strcpy(Sector, "NE");
  else if (H > 56 && H < 79)
    strcpy(Sector, "ENE");
  else if (H > 78.5 && H < 101.5)
    strcpy(Sector, "E");
  else if (H > 101 && H < 124)
    strcpy(Sector, "ESE");
  else if (H > 123.5 && H < 146.5)
    strcpy(Sector, "SE");
  else if (H > 146 && H < 169)
    strcpy(Sector, "SSE");
  else if (H > 168.5 && H < 191.5)
    strcpy(Sector, "S");
  else if (H > 191 && H < 214)
    strcpy(Sector, "SSW");
  else if (H > 213.5 && H < 236.5)
    strcpy(Sector, "SW");
  else if (H > 236 && H < 259)
    strcpy(Sector, "WSW");
  else if (H > 258.5 && H < 281.5)
    strcpy(Sector, "W");
  else if (H > 281 && H < 304)
    strcpy(Sector, "WNW");
  else if (H > 303.5 && H < 326.5)
    strcpy(Sector, "NW");
  else if (H > 326 && H < 349)
    strcpy(Sector, "NNW");
  else
    strcpy(Sector, "WTF");
  return Sector;
}

void updateDisplay(int Heading)
{
  const int NeedleHeight = canvas.height() / 2 - 6;
  const int NeedleWidth = NeedleHeight / 5;
  const unsigned int Radius = canvas.width() / 2 - 1;
  const unsigned int Xoffset = Radius;
  const unsigned int Yoffset = Radius;

  const int a1 = 0, b1 = NeedleHeight;
  const int a2 = -NeedleWidth, b2 = 0;
  const int a3 = 0, b3 = -NeedleHeight;
  const int a4 = NeedleWidth, b4 = 0;
  unsigned int x1, y1, x2, y2, x3, y3, x4, y4;  // Vertices of needle to be drawn
  unsigned int Offset;

  //Draw heading
  float H = Heading * PI / 180;  // Convert to radians for rotation
  char* SectorStr;
  // charSize = 2;
  charSize = 5;
  canvas.setTextWrap(false);
  canvas.fillScreen(ST77XX_WHITE); // Clear canvas
  canvas.setTextSize(charSize);
  canvas.setTextColor(ST77XX_BLACK);
  SectorStr = getSector(Heading);
  // Centred one and a half characters in. Assumes 32 high x 24 wide characters
  Offset = 3 * charWidth * charSize / 2 - ((strlen(SectorStr) * charSize * charWidth) / 2);
  canvas.setCursor(Offset + 4, charHeight * charSize / 2);        // Top line
  // canvas.setCursor(Offset + 4, 40 );        // Kludge for font
  canvas.println(SectorStr);
  // canvas.setCursor(4 + charWidth * charSize,
  //   display.height() / 2 - charSize * charHeight / 2 );  // Middle line
  canvas.setCursor(canvas.getCursorX() + charWidth * charSize, canvas.getCursorY()); // Middle line
  canvas.println('\\');  // backslash
  // canvas.setCursor(4, canvas.height() - 3 * charHeight * charSize / 2); // Bottom line
  // canvas.setCursor(4, 160); // Bottom line
  canvas.setCursor(canvas.getCursorX() + 4, canvas.getCursorY()); // Bottom line
  if (Heading < 100) canvas.print(0); // Add leading zeroes as required
  if (Heading < 10) canvas.print(0);
  canvas.print(Heading);
  display.drawRGBBitmap(0, 0, canvas.getBuffer(), canvas.width(), canvas.height());
  // display.drawBitmap(0, 0, canvas.getBuffer(), canvas.width(), canvas.height(), ST77XX_WHITE, ST77XX_BLACK);
  // Draw the compass
  if (H > 0.0) H = 2 * PI - H; // Flip to always point north
  float S = sin(H);
  float C = cos(H);
  // Rotate needle away from north by Heading degrees
  x1 = RotX(a1, b1, S, C);
  y1 = RotY(a1, b1, S, C);
  x2 = RotX(a2, b2, S, C);
  y2 = RotY(a2, b2, S, C);
  x3 = RotX(a3, b3, S, C);
  y3 = RotY(a3, b3, S, C);
  x4 = RotX(a4, b4, S, C);
  y4 = RotY(a4, b4, S, C);
  canvas.fillScreen(ST77XX_WHITE); // Clear canvas
  canvas.drawTriangle(x1, y1, x2, y2, x4, y4, ST77XX_BLACK); // South half outlined
  canvas.fillTriangle(x1, y1, x2, y2, Xoffset, Yoffset, ST77XX_LIGHTGRAY); // South half shaded
  canvas.fillTriangle(x2, y2, x3, y3, x4, y4, ST77XX_BLACK); // North half filled
  canvas.fillTriangle(x2, y2, x3, y3, Xoffset, Yoffset, ST77XX_DARKGRAY); // North half shaded
  canvas.drawCircle(Xoffset, Yoffset + 2, Radius, ST77XX_BLACK); // x,y,r
  canvas.drawCircle(Xoffset, Yoffset + 2, Radius - 1, ST77XX_BLACK); // Double thickness circle
  display.drawRGBBitmap(canvas.width(), 0, canvas.getBuffer(), canvas.width(), canvas.height());
  // display.drawBitmap(canvas.width(), 0, canvas.getBuffer(), canvas.width(), canvas.height(), ST77XX_WHITE, ST77XX_BLACK);
}


void setup()
{
  display.init(170, 320);
  display.setRotation(3); // Landscape with USB on right
  // canvas.setFont(&FreeSerifBold24pt7b); // Use custom font
  // canvas.setFont(&FreeSansBold24pt7b); // Use custom font
  canvas.setTextWrap(false);            // Clip text within canvas
  Serial.begin(115200);
  Serial.println("ESP32TFTcompassDisplayTestCanvas.ino");
  Serial.println("Initialising...");
  pinMode(TFT_BL, OUTPUT); // Turn on backlight
  digitalWrite(TFT_BL, HIGH);
  Serial.println("Displaying last fix");
  display.fillScreen(ST77XX_WHITE); // Clear screen
  display.setTextColor(ST77XX_BLACK);
  display.setTextSize(charSize);
  display.setCursor(0, 0);
  display.println("Last fix:");
  display.println(-33.70244, 5);  // 9 characters
  display.println(151.09931, 5);  // 10 characters
  display.println(12.43, 2);  // 5 characters
  delay(2000);
  display.fillScreen(ST77XX_WHITE);
}

void loop()
{
  static bool Inverted = false;

  // updateDisplay(random(10)-random(5) + hdg);
  // updateDisplay(hdg + random(10 - random(5)));
  // frabble();
  // delay(200);
  display.invertDisplay(Inverted);
  Inverted = !Inverted;
  delay(5000);
}