#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include "gd.h"
#include "gdfontl.h"

enum {
  CAL_BORDER = 2,
  CELL_BORDER = 5
};

char*    month_names[] = { "January", "February", "March", "April", "May", "June", "July", "August",
                           "September", "October", "November", "December" };
char*    week_days[] = { "Su", "Mo", "Tu", "We", "Th", "Fr", "Sa" };
char*    color_names[] = { "red", "green", "blue", "yellow" };
char*    user;
char*    map_url;

void generate_calendar (char* file_name, int month, int year, int personal_colors[], int group_colors[]);
void parse_appointments (int month, int year, FILE* fd, int personal_colors[], int group_colors[]);

int main (int argc, char* argv[])
{
  int    month;
  int    year;
  int    personal_colors[31];
  int    group_colors[31];
  int    i;
  char   file_name[50];

  sprintf (file_name, "/tmp/gif-cal%d", getpid ());
  for (i = 0; i < 31; i++) {
    personal_colors[i] = -1;
    group_colors[i] = -1;
  }
  user = argv[1];
  map_url = argv[2];
  month = atoi (argv[3]);
  year = atoi (argv[4]);
  parse_appointments (month, year, stdin, personal_colors, group_colors);
  generate_calendar (file_name, month, year, personal_colors, group_colors);
  printf ("%s\n", file_name);
  return 0;
}

int find_color (char* color)
{
  int    i;
  int    ncolors = sizeof (color_names) / sizeof (char*);

  for (i = 0; i < ncolors; i++)
    if (strcasecmp (color, color_names[i]) == 0) return i;
  return 0;
}

void parse_appointments (int month, int year, FILE* fd, int personal_colors[], int group_colors[])
{
  char    line[100];
  int     len;
  int     app_day;
  int     app_month;
  int     app_year;
  char    app_type[50];
  char    app_color[50];

  while (fgets (line, sizeof (line), fd) != NULL) {
    if ((len = strlen (line)) > 0)
      line[len - 1] = '\0';
    if (sscanf (line, "%d/%d/%d %50s %50s", &app_month, &app_day, &app_year, app_type, app_color) == 5 &&
        app_month == month && app_year == year)
      if (strcasecmp (app_type, "group") == 0)
        group_colors[app_day - 1] = find_color (app_color);
      else
        personal_colors[app_day - 1] = find_color (app_color);
  }
}

void generate_calendar (char* file_name, int month, int year, int personal_colors[], int group_colors[])
{
  gdImagePtr image;
  gdFontPtr  font = gdFontLarge;
  int        width;
  int        height;
  struct tm  date;
  int        ndays;
  int        wday;
  int        day;
  int        xpos;
  int        ypos;
  int        background;
  int        foreground;
  int        dark_gray;
  int        first_color;
  FILE*      fd;
  char       buffer[20];
  char       gif_name[50];
  char       map_name[50];

  sprintf (gif_name, "%s.gif", file_name);
  sprintf (map_name, "%s.map", file_name);
  width = 7 * 2 * font->w + 2 * CAL_BORDER + 6 * CELL_BORDER;
  height = 8 * font->h + 2 * CAL_BORDER + 7 * CELL_BORDER;
  image = gdImageCreate (width, height);
  background = gdImageColorAllocate (image, 0xCC, 0xCC, 0xCC);   /* gray */
  gdImageColorTransparent (image, background);
  foreground = gdImageColorAllocate (image, 0x00, 0x00, 0x00);   /* black */
  dark_gray = gdImageColorAllocate (image, 0x66, 0x66, 0x66);    /* dark gray */
  first_color = gdImageColorAllocate (image, 0xFF, 0x66, 0x66);  /* red */
  gdImageColorAllocate (image, 0x66, 0xFF, 0x66);                /* green */
  gdImageColorAllocate (image, 0x66, 0x66, 0xFF);                /* blue */
  gdImageColorAllocate (image, 0xFF, 0xFF, 0x66);                /* yellow */
  sprintf (buffer, "%s %d", month_names[month - 1], year);
  gdImageString (image, font, (width - strlen (buffer) * font->w) / 2, CAL_BORDER, buffer, foreground);
  for (wday = 0; wday < 7; wday++)
    gdImageString (image, font, CAL_BORDER + wday * (2 * font->w + CELL_BORDER),
                   CAL_BORDER + font->h + CELL_BORDER, week_days[wday],
                   wday == 0 || wday == 6 ? dark_gray : foreground);
  memset (&date, 0, sizeof (date));
  date.tm_year = year - 1900;
  date.tm_mon = month - 1;
  date.tm_mday = 1;
  mktime (&date);
  wday = date.tm_wday;
  if ((month % 2 == 0) == (month >= 8)) ndays = 31;
  else if (month != 2) ndays = 30;
  else if (year % 4 == 0) ndays = 29;
  else ndays = 28;
  if ((fd = fopen (map_name, "w")) != NULL)
    fprintf (fd, "<MAP NAME=\"CAL%04d%02d_MAP\">\n", year, month);
  ypos = CAL_BORDER + 2 * (font->h + CELL_BORDER);
  for (day = 1; day <= ndays; day++, wday++) {
    if (wday == 7) {
      wday = 0;
      ypos += font->h + CELL_BORDER;
    }
    xpos = CAL_BORDER + wday * (2 * font->w + CELL_BORDER);
    if (fd != NULL)
      fprintf (fd, "<AREA COORDS=\"%d,%d,%d,%d\" HREF=\"%s?date=%04d%02d%02d&user=%s\">\n",
               xpos, ypos, xpos + 2 * font->w, ypos + font->h, map_url, year, month, day, user);
    if (personal_colors[day - 1] >= 0)
      gdImageFilledRectangle (image, xpos, ypos, xpos + font->w, ypos + font->h, 
                              personal_colors[day - 1] + first_color);
    if (group_colors[day - 1] >= 0)
      gdImageFilledRectangle (image, xpos + font->w, ypos, xpos + 2 * font->w, ypos + font->h,
                              group_colors[day - 1] + first_color);
    sprintf (buffer, "%2d", day);
    gdImageString (image, font, xpos, ypos, buffer, wday == 0 || wday == 6 ? dark_gray : foreground);
  }
  if (fd != NULL) {
    fprintf (fd, "</MAP>\n");
    fclose (fd);
  }
  if ((fd = fopen (gif_name, "wb")) != NULL) {
    gdImageGif (image, fd);
    fclose (fd);
  }
  gdImageDestroy (image);
}