about summary refs log tree commit diff
path: root/wcal.c
blob: 86298de498e62fe18d5692b2f886692834484f87 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
/*
 * wcal - ISO weekly calendar
 *
 * To the extent possible under law, Leah Neukirchen <leah@vuxu.org>
 * has waived all copyright and related or neighboring rights to this work.
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

/*
 * -1 show current month (default)
 * -3 show three months
 * -y show whole year
 * -c show current week only
 * -i print infinite calendar
 * -d YYYY-MM-DD different value for today
 */

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

int flag1, flag3, flagc, flagC, flagi, flagy;

const char monthname[13][4] = {
	"   ",
	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

const char wdayname[8][3] = {
	"  ",
	"Mo", "Tu", "We", "Th", "Fr", "Sa", "Su"
};

/* all args are 1-indexed */
long
ymd2jd(int year, int month, int day)
{
	month--;
	if (month >= 12 || month < 0) {
		int adj = month / 12;
		month %= 12;
		if (month < 0) {
			adj--;
			month += 12;
		}
		year += adj;
	}
	month++;

	if (month < 3) {
		year--;
		month += 12;
	}
	year += 4800;
	return day + (153*(month-3)+2)/5 +
	    365*year + year/4 - year/100 + year/400 - 32045;
}

/* Mon = 1, Sun = 7 */
void
jd2ymdwi(long jd, int *year, int *month, int *day, int *wday, int *isoweek)
{
	int _;
	long e = 4*(jd+1401+(4*jd+274277)/146097*3/4-38) + 3;
	long h = e%1461/4*5 + 2;

	*day = h%153/5 + 1;
	int m = *month = (h/153+2)%12 + 1;
	int y = *year = e/1461 - 4716 + (14-m)/12;
	int w = *wday = jd%7 + 1;

	int yday = jd - ymd2jd(y, 1, 1) + 1;
	*isoweek = (yday - w + 10) / 7;
	if (*isoweek < 1)
		jd2ymdwi(ymd2jd(y - 1, 12, 31), &_, &_, &_, &_, isoweek);
	else if (*isoweek == 53 &&
	    ymd2jd(y+1, 1, 1) + (7 - (y+y/4-y/100+y/400+3)%7 - 4) <= jd)
		*isoweek = 1;
}

void
parse_isodate(char *optarg, int *y, int *m, int *d)
{
	*m = *d = 1;

	if (isdigit(optarg[0]) &&
	    isdigit(optarg[1]) &&
	    isdigit(optarg[2]) &&
	    isdigit(optarg[3]) &&
	    (!optarg[4] || optarg[4] == '-')) {
		*y = atoi(optarg);

		if (!optarg[4]) {
			flagy = 1;
		} else if (isdigit(optarg[5]) && isdigit(optarg[6]) &&
		    (!optarg[7] || optarg[7] == '-')) {
			*m = atoi(optarg+5);

			if (isdigit(optarg[8]) && isdigit(optarg[9]) &&
			    (!optarg[10] || optarg[10] == '-'))
				*d = atoi(optarg+8);
		}
	}
}

int
main(int argc, char *argv[])
{
	time_t now = time(0);
	struct tm *tm = localtime(&now);

	int y = tm->tm_year + 1900;
	int m = tm->tm_mon + 1;
	int d = tm->tm_mday;
	int w;
	int i;
	int cw;
	int ci;

	int c;
	while ((c = getopt(argc, argv, "13cCid:y")) != -1)
		switch (c) {
		case '1': flag1 = 1; break;
		case '3': flag3 = 1; break;
		case 'c': flagc = 1; break;
		case 'C': flagC = 1; break;
		case 'y': flagy = 1; break;
		case 'i': flagi = 1; break;
		case 'd': parse_isodate(optarg, &y, &m, &d); break;
		case '?': exit(1);
		}

	long today = ymd2jd(y, m, d);
	jd2ymdwi(today, &y, &m, &d, &cw, &ci);

	int max_weeks = 1;
	int max_months = 0;

	if (flagc) {
		max_weeks = 1;
	} else if (flag3) {
		d = 1; m--; max_weeks = 14;
	} else if (flagy) {
		d = 1; m = 1; max_months = 12; max_weeks = 53;
	} else if (flagi) {
		d = 1;
	} else { /* flag1 is default */
		d = 1; max_months = 1; max_weeks = 6;
	}

	long jd = ymd2jd(y, m, d);

	jd2ymdwi(jd, &y, &m, &d, &w, &i);
	jd -= (w - 1);   // skip back to last monday.
	jd2ymdwi(jd, &y, &m, &d, &w, &i);

	int color = isatty(1) || flagC;

	printf("        ");
	if (color)
		printf("\e[4m");
	for (int wd = 1; wd <= 7; wd++) {
		if (color && wd == cw)
			printf("\e[7m");
		printf("%s", wdayname[wd]);
		if (color && wd == cw)
			printf("\e[27m");
		if (wd < 7)
			printf(" ");
	}
	if (color)
		printf("\e[0m");
	printf("\n");

	for (int weeks = 0, months = 0;
	     flagi || (max_months && months < max_months) || (weeks < max_weeks);
	     weeks++) {
		if (color && i == ci)
			printf("\e[7m");
		printf("%02d", i);
		if (color && i == ci)
			printf("\e[27m");
		printf(" ");

		int ey, em, ed, ew, ei;
		jd2ymdwi(jd + 6, &ey, &em, &ed, &ew, &ei);   /* end of week */

		if (ed <= 7 || weeks == 0) {
			printf("%s ", monthname[em]);
			months++;
		} else if ((em == 1 && ed <= 14) || weeks == 1) {
			printf("%04d", ey);
		} else {
			printf("    ");
		}

		do {
			printf(" %s%2d%s",
			    color && (jd == today) ? "\e[7m" : "",
			    d,
			    color && (jd == today) ? "\e[27m" : "");

			jd++;
			jd2ymdwi(jd, &y, &m, &d, &w, &i);
		} while (w != 1);

		printf("\n");
	}
}