/* clectio -- tiny, fast, suckless daily readings.
 *
 * Computes nothing at runtime: the liturgical calendar, its reading citations
 * and the scripture text are all compiled in (see gen/ and the Makefile). For a
 * date it does a table lookup and prints the day and its readings. Configuration
 * is compile-time (config.h), suckless-style: edit and recompile.
 *
 * Copyright (C) 2026 Łukasz Kasprzak.  SPDX-License-Identifier: GPL-3.0-or-later
 *
 * clectio is free software: you may redistribute and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version, and WITHOUT ANY WARRANTY. See the LICENSE file for the full text.
 *
 * The compiled scripture text is a separate work under its own terms; the
 * default Latin Vulgate is public domain (see README).
 */
#define _POSIX_C_SOURCE 200809L /* localtime_r, isatty under -std=c99 */
#define _DEFAULT_SOURCE         /* struct winsize / TIOCGWINSZ under -std=c99 */

#include "config.h"
#include LITURGY /* gen/liturgy_<form>.h: names,parts,cites_*,vpool,readings,rpool,days,cal,EPOCH,NDAYS */
#include "text.lz.h" /* embedded DEFLATE text blob: text_lz[], text_lz_len */
#include "puff.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/ioctl.h>

static char *textbuf;        /* inflated verse text */
static const char **verse;   /* verse[i] -> the text of the i-th key, nul-terminated */
static int usecolor;

static const char *const colname[] = { "green", "white", "red", "violet", "rose", "black" };
static const char *const colansi[] = { "\033[32m", "\033[37m", "\033[31m", "\033[35m", "\033[95m", "\033[90m" };

/* Local calendar overrides: replace one fixed date's name + colour. The colour
 * names below match colname[]/colansi[] above (index order). The user table
 * lives in calendar.h (copied from calendar.def.h); see it for the limits. */
enum { GREEN, WHITE, RED, VIOLET, ROSE, BLACK };
typedef struct { int mon, day, colour; const char *name; } Override;
#include "calendar.h" /* static const Override overrides[]; ends with a {0,...} row */

static const Override *find_override(int mon, int day) {
	const Override *o;
	for (o = overrides; o->mon; o++)
		if (o->mon == mon && o->day == day)
			return o;
	return NULL;
}

/* Days since the civil epoch 1970-01-01 (Howard Hinnant's algorithm). */
static long days_from_civil(long y, unsigned m, unsigned d) {
	y -= m <= 2;
	long era = (y >= 0 ? y : y - 399) / 400;
	unsigned yoe = (unsigned)(y - era * 400);
	unsigned doy = (153u * (m + (m > 2 ? -3u : 9u)) + 2u) / 5u + d - 1;
	unsigned doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
	return era * 146097 + (long)doe - 719468;
}

static void load_text(void) {
	unsigned long rawlen = text_lz[0] | text_lz[1] << 8 | text_lz[2] << 16 | (unsigned long)text_lz[3] << 24;
	unsigned long dstlen = rawlen, srclen = text_lz_len - 4;
	size_t cap = 8192, n = 0;
	char *p;
	textbuf = malloc(rawlen + 1);
	puff((unsigned char *)textbuf, &dstlen, text_lz + 4, &srclen);
	textbuf[dstlen] = 0;
	verse = malloc(cap * sizeof(*verse));
	verse[n++] = textbuf;
	for (p = textbuf; *p; p++)
		if (*p == '\n') {
			*p = 0;
			if (p[1]) {
				if (n == cap) { cap *= 2; verse = realloc(verse, cap * sizeof(*verse)); }
				verse[n++] = p + 1;
			}
		}
}

static const char *citation(int r) {
#ifdef SIGLA_LATIN
	return cites_la[readings_cite_la[r]];
#else
	return cites_en[readings[r].cite];
#endif
}

/* Column width of the terminal on stdout, or 72 if it cannot be determined. */
static int termwidth(void) {
	struct winsize ws;
	if (ioctl(1, TIOCGWINSZ, &ws) == 0 && ws.ws_col > 0)
		return ws.ws_col;
	return 72;
}

/* Print s wrapped at w columns, breaking on spaces (greedy). w <= 0 prints s
 * unwrapped. UTF-8 aware: continuation bytes (0x80-0xBF) do not count as a
 * column, so multibyte letters measure as one. */
static void putwrapped(const char *s, int w) {
	if (w <= 0) {
		printf("%s\n", s);
		return;
	}
	while (*s) {
		const char *p = s, *brk = NULL;
		int col = 0;
		while (*p && col < w) {
			if (*p == ' ')
				brk = p;
			if ((*p & 0xC0) != 0x80)
				col++;
			p++;
		}
		if (!*p) { /* the rest fits on one line */
			printf("%s\n", s);
			return;
		}
		if (!brk) /* a single word longer than w: hard-break at the column */
			brk = p;
		fwrite(s, 1, (size_t)(brk - s), stdout);
		putchar('\n');
		for (s = brk; *s == ' '; s++) /* skip the space(s) we broke on */
			;
	}
}

/* One line per day of month `mon` in year `y`: weekday, day, colour, celebration.
 * Needs no scripture text, so it never touches the text blob. Returns an exit
 * code (1 if the month falls outside the compiled range). */
static int print_month(int y, int mon) {
	static const char *const wd[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
	long base = days_from_civil(EPOCH_Y, EPOCH_M, EPOCH_D);
	long civ1 = days_from_civil(y, (unsigned)mon, 1);
	long nextfirst = days_from_civil(mon == 12 ? y + 1 : y, (unsigned)(mon == 12 ? 1 : mon + 1), 1);
	int dim = (int)(nextfirst - civ1); /* days in the month (leap-correct) */
	long off1 = civ1 - base;
	int day, n;

	if (off1 < 0 || off1 + dim - 1 >= NDAYS) {
		fprintf(stderr, "clectio: %04d-%02d is outside the compiled range %d..%d\n",
		        y, mon, EPOCH_Y, EPOCH_Y + (NDAYS / 366));
		return 1;
	}
	n = printf("%04d-%02d  %s\n", y, mon, FORMNAME) - 1; /* underline that line */
	while (n-- > 0)
		putchar('=');
	putchar('\n');
	for (day = 1; day <= dim; day++) {
		long civ = civ1 + (day - 1);
		const Day *d = &days[cal[off1 + (day - 1)]];
		const Override *ov = find_override(mon, day);
		const char *dname = ov ? ov->name : names[d->name];
		int dcol = ov ? ov->colour : d->colour;
		int w = (int)((civ + 4) % 7); /* 1970-01-01 was Thursday; 0 = Sunday */
		printf("%s %02d  %-6s  ", wd[w], day, colname[dcol]);
		if (usecolor)
			printf("%s%s\033[0m\n", colansi[dcol], dname);
		else
			printf("%s\n", dname);
	}
	return 0;
}

/* Parse a --month spec ("YYYY-MM", or "N" for month N of the current year, or
 * NULL for the current month) and print it. Returns an exit code. */
static int run_month(const char *spec) {
	struct tm tm;
	time_t t = time(NULL);
	int y, mon;
	localtime_r(&t, &tm);
	y = tm.tm_year + 1900;
	mon = tm.tm_mon + 1;
	if (spec) {
		int ok = strchr(spec, '-') ? sscanf(spec, "%d-%d", &y, &mon) == 2
		                           : sscanf(spec, "%d", &mon) == 1;
		if (!ok) {
			fprintf(stderr, "clectio: bad month %s (want YYYY-MM or 1-12)\n", spec);
			return 2;
		}
	}
	if (mon < 1 || mon > 12) {
		fprintf(stderr, "clectio: bad month %s (want YYYY-MM or 1-12)\n", spec ? spec : "");
		return 2;
	}
	return print_month(y, mon);
}

static void print_day(long off, const char *datestr, int mon, int day, int gospel, int wrap) {
	const Day *d = &days[cal[off]];
	const Override *ov = find_override(mon, day);
	const char *dname = ov ? ov->name : names[d->name];
	int dcol = ov ? ov->colour : d->colour;
	unsigned ri;
	int n;
	if (usecolor)
		printf("%s%s\033[0m\n", colansi[dcol], dname);
	else
		printf("%s \xc2\xb7 %s\n", dname, colname[dcol]);
	n = printf("%s for %s\n", FORMNAME, datestr) - 1; /* underline that line */
	while (n-- > 0)
		putchar('=');
	putchar('\n');
	for (ri = 0; ri < d->rlen; ri++) {
		const Reading *r = &readings[rpool[d->roff + ri]];
		unsigned v;
		if (gospel && strcmp(parts[r->part], "Gospel") != 0)
			continue;
		printf("\n%s (%s)\n\n", parts[r->part], citation(rpool[d->roff + ri]));
		for (v = 0; v < r->vlen; v++)
			putwrapped(verse[vpool[r->voff + v]], wrap);
	}
}

int main(int argc, char **argv) {
	struct tm tm;
	long off;
	char datestr[16];
	int y, m, dd, i;
	int gospel = GOSPEL_ONLY;    /* compiled default, overridable per run */
	int istty = isatty(1);
	int wrap, monthmode = 0;
	const char *datearg = NULL;

	usecolor = COLOR && istty;

	for (i = 1; i < argc; i++) {
		if (!strcmp(argv[i], "-h") || !strcmp(argv[i], "--help")) {
			fprintf(stderr,
			        "usage: clectio [-a|--all | -g|--gospel] [YYYY-MM-DD]\n"
			        "       clectio --month [YYYY-MM | N]\n"
			        "  -a, --all      print all readings\n"
			        "  -g, --gospel   print the Gospel only\n"
			        "  --month        list a whole month (default: current month)\n"
			        "  (default: today, %s)\n"
			        "  compiled: %s, %s, wrap %s, range %d-%d\n",
			        READMODE, FORMNAME, SIGLANAME, WRAPNAME, EPOCH_Y, EPOCH_Y + (NDAYS / 366));
			return 0;
		} else if (!strcmp(argv[i], "-a") || !strcmp(argv[i], "--all")) {
			gospel = 0;
		} else if (!strcmp(argv[i], "-g") || !strcmp(argv[i], "--gospel")) {
			gospel = 1;
		} else if (!strcmp(argv[i], "--month")) {
			monthmode = 1;
		} else if (argv[i][0] == '-' && argv[i][1]) {
			fprintf(stderr, "clectio: unknown option %s (try -h)\n", argv[i]);
			return 2;
		} else if (!datearg) {
			datearg = argv[i];
		} else {
			fprintf(stderr, "clectio: unexpected argument %s (try -h)\n", argv[i]);
			return 2;
		}
	}

	if (monthmode)
		return run_month(datearg); /* month overview: no readings, no text loaded */

	if (datearg) {
		if (sscanf(datearg, "%d-%d-%d", &y, &m, &dd) != 3) {
			fprintf(stderr, "clectio: bad date %s (want YYYY-MM-DD)\n", datearg);
			return 2;
		}
		snprintf(datestr, sizeof datestr, "%04d-%02d-%02d", y, m, dd);
	} else {
		time_t t = time(NULL);
		localtime_r(&t, &tm);
		y = tm.tm_year + 1900;
		m = tm.tm_mon + 1;
		dd = tm.tm_mday;
		strftime(datestr, sizeof datestr, "%Y-%m-%d", &tm);
	}

	off = days_from_civil(y, (unsigned)m, (unsigned)dd) -
	      days_from_civil(EPOCH_Y, EPOCH_M, EPOCH_D);
	if (off < 0 || off >= NDAYS) {
		fprintf(stderr, "clectio: %s is outside the compiled range %d..%d\n",
		        datestr, EPOCH_Y, EPOCH_Y + (NDAYS / 366));
		return 1;
	}

	/* WRAP>0: always wrap to that width. WRAP==0: fit the terminal, but leave
	 * piped output as one line per verse (0 -> putwrapped prints unwrapped). */
	if (WRAP > 0)
		wrap = WRAP;
	else
		wrap = istty ? termwidth() : 0;

	load_text();
	print_day(off, datestr, m, dd, gospel, wrap);
	return 0;
}