#include "U8glib.h"

U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_DEV_0 | U8G_I2C_OPT_NO_ACK | U8G_I2C_OPT_FAST); // Fast I2C / TWI


byte row; // just for menu purposes
bool menuLock;// just for menu purposes
float xMax;
const byte maxArrayLength = 10; // this example supports up to 10 readings max for 128 and 20 for 256
// --------------------------------------- USER VARIABLES -------------------------------------------------------
char titles[4][12] = {"Temperature", "Humidity", "PH", "EC"};
float temperature[maxArrayLength] = {21.6, 21.4, 20.8, 20.2, 20.5, 24.1, 25.5, 27.2, 18.7, 16.5};
byte humidity[maxArrayLength] = {44, 47, 43, 43, 44, 42, 36, 32, 49, 52};
float ph[maxArrayLength] = {6.42, 5.29, 6.51, 5.54, 4.59, 3.66, 4.73, 4.84, 4.87, 4.92};
float ec[maxArrayLength] = {0, 2.2, 3.7, 5.9, 6.0, 4.3, 4.8, 3.2, 4.1, 5.4};
float tempArray[maxArrayLength];

const byte downButton_Pin = A2;
const byte selectButton_Pin = A1;
const byte upButton_Pin = A0;
void setup() {
  pinMode(downButton_Pin, INPUT);
  pinMode(upButton_Pin, INPUT);
  pinMode(selectButton_Pin, INPUT);
  u8g.setColorIndex(1);
  u8g.setFont(u8g_font_fur11);
  u8g.setFontPosTop();
}

void loop() {
  buttons();
  loadPage();
}

void buttons() {
  if (digitalRead(upButton_Pin) == HIGH) {
    if (row < 3 && !menuLock) {
      row++;
      delay(200);
    }
  }
  else if (digitalRead(downButton_Pin) == HIGH) {
    if (row > 0 && !menuLock) {
      row--;
      delay(200);
    }
  }
  else if (digitalRead(selectButton_Pin) == HIGH) {
    menuLock = !menuLock;
    delay(200);
  }
}

void loadPage() {
  u8g.firstPage();
  do {
    drawPage();
  }
  while (u8g.nextPage());
}

void drawPage() {
  if (!menuLock) {
    printTitle(row, 24); //(byte titleNumber, byte y)
  }
  else if (row == 0) {
    drawGraph(temperature, maxArrayLength, false);
  }
  else if (row == 1) {
    adjustArrayToFloat(humidity, 6, false); // should be maxArrayLength instead of 6, but just to show you the graph does adjust accordingly
  }
  else if (row == 2) {
    drawGraph(ph, maxArrayLength, false);
  }
  else if (row == 3) {
    drawGraph(ec, maxArrayLength, false);
  }
}

void adjustArrayToFloat(byte *dataB, byte arrayLenght, bool displayQuadrant) {
  for (byte i = 0; i < arrayLenght; i++) {
    tempArray[i] = dataB[i];
  }
  drawGraph(tempArray, arrayLenght, displayQuadrant);
}

void drawGraph (float *data, byte arrayLenght, bool displayQuadrant) {
  //printTitle(row, 0);
  for (byte i = 0 ; i < arrayLenght; i++) {
    if (data[i] > xMax) {
      xMax = data[i];
    }
  }
  // work out the x position to start the graph at, based on the width on the x axis numbers.
  byte graphXstartPosition;
  if (xMax > 10) {
    graphXstartPosition = 17;
  }
  else {
    graphXstartPosition = 10;
  }
  // draw x line and numbers
  float xIncrement = xMax / 4;
  byte xLablePosition = 0;
  float tempXmax = xMax;
  for (byte i = 0 ; i < 5; i++) {
    if (tempXmax > 10 || graphXstartPosition == 10) {
      u8g.setPrintPos(0, xLablePosition);
    }
    else {
      u8g.setPrintPos(8, xLablePosition);
    }
    u8g.print(tempXmax, 0);
    xLablePosition += 13;
    tempXmax -= xIncrement;
  }
  u8g.drawLine(graphXstartPosition, 0, graphXstartPosition, 51);
  // draw y line and numbers
  byte yLablePosition = graphXstartPosition + 1;
  for (byte i = 1 ; i < arrayLenght + 1; i++) {
    u8g.setPrintPos(yLablePosition, 52);
    u8g.print(i);
    yLablePosition += 10;
  }
  byte endOfcursorX = u8g.getPrintCol();
  u8g.drawLine(graphXstartPosition, 51, endOfcursorX, 51);
  // draw line graph
  float xGap = 51 / xMax;
  byte yGap = graphXstartPosition + 5;
  float plotXstartPosition;
  float plotXendPosition;
  for (byte i = 0 ; i < arrayLenght - 1; i++) { // note its one less than the array size as we are adding 1 to i.
    plotXstartPosition = 51 - xGap * data[i];
    plotXendPosition = 51 - xGap * data[i + 1];
    u8g.drawLine(yGap, plotXstartPosition, yGap + 10, plotXendPosition);
    if (displayQuadrant) {
      u8g.drawDisc(yGap, plotXstartPosition, 2);
    }
    yGap += 11;
  }
  if (displayQuadrant) {
    u8g.drawDisc(yGap, plotXendPosition, 2);
  }
  xMax = 0;
}

void printTitle (byte titleNumber, byte y) {
  byte center = ((u8g.getWidth() - u8g.getStrWidth(titles[titleNumber])) / 2);
  u8g.setPrintPos(center, y);
  u8g.print(titles[titleNumber]);
}