/*
   3-Google_calendar_example for e-radionica.com Inkplate 6
   For this example you will need only USB cable and Inkplate 6.
   Select "Inkplate 6(ESP32)" from Tools -> Board menu.
   Don't have "Inkplate 6(ESP32)" option? Follow our tutorial and add it:
   https://e-radionica.com/en/blog/add-inkplate-6-to-arduino-ide/

   This project shows you how Inkplate 6 can be used to display 
   events in your Google Calendar using their provided API

   For this to work you need to change your timezone, wifi credentials and your private calendar url
   which you can find following these steps:

    1. Open your google calender
    2. Click the 3 menu dots of the calender you want to access
    3. Click 'Settings and sharing'
    4. Navigate to 'Integrate Calender'
    5. Take the 'Secret address in iCal format'
   
   (https://support.google.com/calendar/thread/2408874?hl=en)

   Want to learn more about Inkplate? Visit www.inkplate.io
   Looking to get support? Write on our forums: http://forum.e-radionica.com/en/
   3 August 2020 by e-radionica.com
*/

// Include Inkplate library to the sketch
#include "Inkplate.h"

// Including fonts
#include "Fonts/FreeSans12pt7b.h"
#include "Fonts/FreeSans9pt7b.h"

// Includes
#include <ctime>
#include <algorithm>
#include "Network.h"

// CHANGE HERE ---------------

char *ssid = "";
char *pass = "";
char *calendarURL = "";
int timeZone = 2;

// ---------------------------

// Delay between API calls
#define DELAY_MS 5000

// Variables to keep count of when to get new data, and when to just update time
int refreshes = 0;
const int refreshesToGet = 10;

// Initiate out Inkplate object
Inkplate display(INKPLATE_3BIT);

// Our networking functions, see Network.cpp for info
Network network;

// Variables for time and raw event info
char date[64];
char data[32000];

// For storing next 3 days info
char dates[32 * 3];

// Struct for storing calender event info
struct entry
{
    char name[128];
    char time[128];
    char location[128];
    int day;
    int timeStamp;
};

// Here we store calendar entries
int entriesNum = 0;
entry entries[128];

// Function for drawing calendar info
void drawInfo()
{
    // Setting font and color
    display.setTextColor(0, 7);
    display.setFont(&FreeSans12pt7b);
    display.setTextSize(1);

    display.setCursor(20, 20);

    // Find email in raw data
    char temp[64];
    char *start = strstr(data, "X-WR-CALNAME:");

    // If not found return
    if (!start)
        return;

    // Find where it ends
    start += 13;
    char *end = strchr(start, '\n');

    strncpy(temp, start, end - start - 1);
    temp[end - start - 1] = 0;

    // Print it
    display.println(temp);
}

// Drawing what time it is
void drawTime()
{
    // Initial text settings
    display.setTextColor(0, 7);
    display.setFont(&FreeSans12pt7b);
    display.setTextSize(1);

    display.setCursor(423, 20);

    // Our function to get time
    network.getTime(date);

    int t = date[16];
    date[16] = 0;
    display.println(date);
    date[16] = t;
}

// Draw lines in which to put events
void drawGrid()
{
    // upper left and low right coordinates
    int x1 = 3, y1 = 30;
    int x2 = 600 - 3, y2 = 798;

    // header size, for day info
    int header = 30;

    // Columns and rows
    int n = 1, m = 3;

    // Line drawing
    display.drawFastHLine(x1, y1 + header, x2 - x1, 0);
    for (int i = 0; i < n + 1; ++i)
    {
        display.drawFastHLine(x1, (int)((float)y1 + (float)i * (float)(y2 - y1) / (float)n), x2 - x1, 0);
    }
    for (int i = 0; i < m + 1; ++i)
    {
        display.drawFastVLine((int)((float)x1 + (float)i * (float)(x2 - x1) / (float)m), y1, y2 - y1, 0);
        display.setFont(&FreeSans9pt7b);

        // Display day info using time offset
        char temp[64];
        network.getTime(temp, i * 3600L * 24);
        temp[10] = 0;

        display.setCursor((int)((float)x1 + (float)i * (float)(x2 - x1) / (float)m) + 15, y1 + header - 6);
        display.println(temp);
    }
}

// Format event times, example 13:00 to 14:00
void getToFrom(char *dst, char *from, char *to, int *day, int *timeStamp)
{
    // ANSI C time struct
    struct tm ltm = {0}, ltm2 = {0};
    char temp[128], temp2[128];
    strncpy(temp, from, 16);
    temp[16] = 0;

    // https://github.com/esp8266/Arduino/issues/5141, quickfix
    memmove(temp + 5, temp + 4, 16);
    memmove(temp + 8, temp + 7, 16);
    memmove(temp + 14, temp + 13, 16);
    memmove(temp + 16, temp + 15, 16);
    temp[4] = temp[7] = temp[13] = temp[16] = '-';

    // time.h function
    strptime(temp, "%Y-%m-%dT%H-%M-%SZ", &ltm);

    // create start and end event structs
    struct tm event, event2;
    time_t epoch = mktime(&ltm) + (time_t)timeZone * 3600L;
    gmtime_r(&epoch, &event);
    strncpy(dst, asctime(&event) + 11, 5);

    dst[5] = '-';

    strncpy(temp2, to, 16);
    temp2[16] = 0;

    // Same as above

    // https://github.com/esp8266/Arduino/issues/5141, quickfix
    memmove(temp2 + 5, temp2 + 4, 16);
    memmove(temp2 + 8, temp2 + 7, 16);
    memmove(temp2 + 14, temp2 + 13, 16);
    memmove(temp2 + 16, temp2 + 15, 16);
    temp2[4] = temp2[7] = temp2[13] = temp2[16] = '-';

    strptime(temp2, "%Y-%m-%dT%H-%M-%SZ", &ltm2);

    time_t epoch2 = mktime(&ltm2) + (time_t)timeZone * 3600L;
    gmtime_r(&epoch2, &event2);
    strncpy(dst + 6, asctime(&event2) + 11, 5);

    dst[11] = 0;

    char day0[64], day1[64], day2[64];

    // Find UNIX timestamps for next days to see where to put event
    network.getTime(day0, 0);
    network.getTime(day1, 24 * 3600);
    network.getTime(day2, 48 * 3600);

    *timeStamp = epoch;

    network.getTime(temp);
    if (strncmp(day0, asctime(&event), 10) == 0)
        *day = 0;
    else if (strncmp(day1, asctime(&event), 10) == 0)
        *day = 1;
    else if (strncmp(day2, asctime(&event), 10) == 0)
        *day = 2;
    else // event not in next 3 days, don't display
        *day = -1;
}

// Function to drw event
bool drawEvent(entry *event, int day, int beginY, int maxHeigth, int *heigthNeeded)
{
    // Upper left coordintes
    int x1 = 3 + 4 + (594 / 3) * day;
    int y1 = beginY + 3;

    // Setting text font
    display.setFont(&FreeSans12pt7b);

    int n = 0;
    char line[128];

    // Insert line brakes into setTextColor
    int lastSpace = -100;
    display.setCursor(x1, beginY + 22);
    for (int i = 0; i < min((size_t)64, strlen(event->name)); ++i)
    {

        line[n] = event->name[i];
        if (line[n] == ' ')
            lastSpace = n;
        line[++n] = 0;

        int16_t xt1, yt1;
        uint16_t w, h;

        display.getTextBounds(line, 0, 0, &xt1, &yt1, &w, &h);

        // Char out of bounds, put in next line
        if (w > 590 / 3 - 20)
        {
            // if there was a space 5 chars before, break line there
            if (n - lastSpace < 5)
            {
                i -= n - lastSpace - 1;
                line[lastSpace] = 0;
            }

            display.setCursor(x1, display.getCursorY());
            display.println(line);

            line[0] = 0;
            n = 0;
        }
    }

    // display last line
    display.setCursor(x1, display.getCursorY());
    display.println(line);

    display.setCursor(x1, display.getCursorY());
    display.setFont(&FreeSans9pt7b);

    // Print time
    // also, if theres a location print it
    if (strlen(event->location) != 1)
    {
        display.println(event->time);

        display.setCursor(x1, display.getCursorY());
        display.print(event->location);
    }
    else
    {
        display.print(event->time);
    }

    // Draw event rect bounds
    display.drawRoundRect(x1 - 2, y1, 590 / 3 - 2, display.getCursorY() + 5 - y1, 10, 0);

    // Set how high is the event
    *heigthNeeded = display.getCursorY() + 10 - y1;

    // Return is it overflowing
    return display.getCursorY() < maxHeigth - 5;
}

// Struct event comparison function, by timestamp
int cmp(const void *a, const void *b)
{

    entry *entryA = (entry *)a;
    entry *entryB = (entry *)b;

    return (entryA->timeStamp - entryB->timeStamp);
}

// Main data drawing data
void drawData()
{
    long i = 0;
    long n = strlen(data);

    // reset count
    entriesNum = 0;

    // Search raw data for events
    while (i < n && strstr(data + i, "BEGIN:VEVENT"))
    {
        // Find next event start and end
        i = strstr(data + i, "BEGIN:VEVENT") - data + 12;
        char *end = strstr(data + i, "END:VEVENT");

        // Find all relevant event data
        char *summary = strstr(data + i, "SUMMARY:") + 8;
        char *location = strstr(data + i, "LOCATION:") + 9;
        char *timeStart = strstr(data + i, "DTSTART:") + 8;
        char *timeEnd = strstr(data + i, "DTEND:") + 6;

        if (summary && summary < end)
        {
            strncpy(entries[entriesNum].name, summary, strchr(summary, '\n') - summary);
            entries[entriesNum].name[strchr(summary, '\n') - summary] = 0;
        }
        if (location && location < end)
        {
            strncpy(entries[entriesNum].location, location, strchr(location, '\n') - location);
            entries[entriesNum].location[strchr(location, '\n') - location] = 0;
        }
        if (timeStart && timeStart < end && timeEnd < end)
        {
            getToFrom(entries[entriesNum].time, timeStart, timeEnd, &entries[entriesNum].day, &entries[entriesNum].timeStamp);
        }
        ++entriesNum;
    }

    // Sort entries by time
    qsort(entries,
          entriesNum,
          sizeof(entry),
          cmp);

    // Events displayed and overflown counters
    int columns[3] = {0};
    bool clogged[3] = {0};
    int cloggedCount[3] = {0};

    // Displaying events one by one
    for (int i = 0; i < entriesNum; ++i)
    {
        // If column overflowed just add event to not shown
        if (entries[i].day != -1 && clogged[entries[i].day])
            ++cloggedCount[entries[i].day];
        if (entries[i].day == -1 || clogged[entries[i].day])
            continue;

        // We store hot much height did one event take up
        int shift = 0;
        bool s = drawEvent(&entries[i], entries[i].day, columns[entries[i].day] + 64, 800 - 4, &shift);

        columns[entries[i].day] += shift;

        // If it overflowed, set column to clogged and add one event as not shown
        if (!s)
        {
            ++cloggedCount[entries[i].day];
            clogged[entries[i].day] = 1;
        }
    }

    // Display not shown events info
    for (int i = 0; i < 3; ++i)
    {
        if (clogged[i])
        {
            display.fillRoundRect(6 + i * (594 / 3), 800 - 24, (594 / 3) - 5, 20, 10, 0);
            display.setCursor(10, 800 - 6);
            display.setTextColor(7, 0);
            display.setFont(&FreeSans9pt7b);
            display.print(cloggedCount[i]);
            display.print(" more events");
        }
    }
}

void setup()
{
    Serial.begin(115200);

    // Initial display settings
    display.begin();

    display.clearDisplay();
    display.clean();
    display.setRotation(1);
    display.setTextWrap(false);
    display.setTextColor(0, 7);

    // Welcome screen
    display.setCursor(5, 230);
    display.setTextSize(2);
    display.println(F("Welcome to Inkplate 6 Google Calendar example!"));
    display.setCursor(5, 250);
    display.println(F("Connecting to WiFi..."));
    display.display();

    delay(5000);
    network.begin();
    // Our begin function
    network.begin();
}

void loop()
{
    // Keep trying to get data if it fails the first time
    if (refreshes % refreshesToGet == 0)
        while (!network.getData(data))
        {
            Serial.println("Failed getting data, retrying");
            delay(1000);
        }

    // Initial screen clearing
    display.clearDisplay();

    // Drawing all data, functions for that are above
    if (refreshes % refreshesToGet == 0)
    {
        drawInfo();
        drawGrid();
        drawData();
    }
    drawTime();

    // Actually display all data
    if (refreshes % refreshesToGet == 0)
        display.display();
    else
        display.partialUpdate();

    // Increment refreshes
    ++refreshes;

    // Go to sleep before checking again
    esp_sleep_enable_timer_wakeup(1000L * DELAY_MS);
    (void)esp_light_sleep_start();
}