/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <locale.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stringlist.h>
#include <time.h>
#include <unistd.h>

#include "pathnames.h"
#include "calendar.h"

enum {
        T_OK = 0,
        T_ERR,
        T_PROCESS,
};

const char *calendarFile = "calendar";  /* default calendar file */
static const char *calendarHomes[] = {".calendar", _PATH_INCLUDE_LOCAL, _PATH_INCLUDE}; /* HOME */
static const char *calendarNoMail = "nomail";/* don't sent mail if file exist */

static char path[MAXPATHLEN];
static const char *cal_home;
static const char *cal_dir;
static const char *cal_file;
static int cal_line;

struct fixs neaster, npaskha, ncny, nfullmoon, nnewmoon;
struct fixs nmarequinox, nsepequinox, njunsolstice, ndecsolstice;

static int cal_parse(FILE *in, FILE *out);

static StringList *definitions = NULL;
static struct event *events[MAXCOUNT];
static char *extradata[MAXCOUNT];

static char *
trimlr(char **buf)
{
        char *walk = *buf;
        char *sep;
        char *last;

        while (isspace(*walk))
                walk++;
        *buf = walk;

        sep = walk;
        while (*sep != '\0' && !isspace(*sep))
                sep++;

        if (*sep != '\0') {
                last = sep + strlen(sep) - 1;
                while (last > walk && isspace(*last))
                        last--;
                *(last+1) = 0;
        }

        return (sep);
}

static FILE *
cal_fopen(const char *file)
{
        static int cwdfd = -1;
        FILE *fp;
        char *home = getenv("HOME");
        unsigned int i;
        int fd;
        struct stat sb;
        static bool warned = false;
        static char calendarhome[MAXPATHLEN];

        if (home == NULL || *home == '\0') {
                warnx("Cannot get home directory");
                return (NULL);
        }

        /*
         * On -a runs, we would have done a chdir() earlier on, but we also
         * shouldn't have used the initial cwd anyways lest we bring
         * unpredictable behavior upon us.
         */
        if (!doall && cwdfd == -1) {
                cwdfd = open(".", O_DIRECTORY | O_PATH);
                if (cwdfd == -1)
                        err(1, "open(cwd)");
        }

        /*
         * Check $PWD first as documented.
         */
        if (cwdfd != -1) {
                if ((fd = openat(cwdfd, file, O_RDONLY)) != -1) {
                        if ((fp = fdopen(fd, "r")) == NULL)
                                err(1, "fdopen(%s)", file);

                        cal_home = NULL;
                        cal_dir = NULL;
                        cal_file = file;
                        return (fp);
                } else if (errno != ENOENT && errno != ENAMETOOLONG) {
                        err(1, "open(%s)", file);
                }
        }

        if (chdir(home) != 0) {
                warnx("Cannot enter home directory \"%s\"", home);
                return (NULL);
        }

        for (i = 0; i < nitems(calendarHomes); i++) {
                if (snprintf(calendarhome, sizeof (calendarhome), calendarHomes[i],
                        getlocalbase()) >= (int)sizeof (calendarhome))
                        continue;

                if (chdir(calendarhome) != 0)
                        continue;

                if ((fp = fopen(file, "r")) != NULL) {
                        cal_home = home;
                        cal_dir = calendarhome;
                        cal_file = file;
                        return (fp);
                }
        }

        warnx("can't open calendar file \"%s\"", file);
        if (!warned) {
                snprintf(path, sizeof(path), _PATH_INCLUDE_LOCAL, getlocalbase());
                if (stat(path, &sb) != 0) {
                        warnx("calendar data files now provided by calendar-data pkg.");
                        warned = true;
                }
        }

        return (NULL);
}

static char*
cal_path(void)
{
        static char buffer[MAXPATHLEN + 10];

        if (cal_dir == NULL)
                snprintf(buffer, sizeof(buffer), "%s", cal_file);
        else if (cal_dir[0] == '/')
                snprintf(buffer, sizeof(buffer), "%s/%s", cal_dir, cal_file);
        else
                snprintf(buffer, sizeof(buffer), "%s/%s/%s", cal_home, cal_dir, cal_file);
        return (buffer);
}

#define WARN0(format)              \
        warnx(format " in %s line %d", cal_path(), cal_line)
#define WARN1(format, arg1)                \
        warnx(format " in %s line %d", arg1, cal_path(), cal_line)

static char*
cmptoken(char *line, const char* token)
{
        char len = strlen(token);

        if (strncmp(line, token, len) != 0)
                return NULL;
        return (line + len);
}

static int
token(char *line, FILE *out, int *skip, int *unskip)
{
        char *walk, *sep, a, c;
        const char *this_cal_home;
        const char *this_cal_dir;
        const char *this_cal_file;
        int this_cal_line;

        while (isspace(*line))
                line++;

        if (cmptoken(line, "endif")) {
                if (*skip + *unskip == 0) {
                        WARN0("#endif without prior #ifdef or #ifndef");
                        return (T_ERR);
                }
                if (*skip > 0)
                        --*skip;
                else
                        --*unskip;

                return (T_OK);
        }

        walk = cmptoken(line, "ifdef");
        if (walk != NULL) {
                sep = trimlr(&walk);

                if (*walk == '\0') {
                        WARN0("Expecting arguments after #ifdef");
                        return (T_ERR);
                }
                if (*sep != '\0') {
                        WARN1("Expecting a single word after #ifdef "
                            "but got \"%s\"", walk);
                        return (T_ERR);
                }

                if (*skip != 0 ||
                    definitions == NULL || sl_find(definitions, walk) == NULL)
                        ++*skip;
                else
                        ++*unskip;
                
                return (T_OK);
        }

        walk = cmptoken(line, "ifndef");
        if (walk != NULL) {
                sep = trimlr(&walk);

                if (*walk == '\0') {
                        WARN0("Expecting arguments after #ifndef");
                        return (T_ERR);
                }
                if (*sep != '\0') {
                        WARN1("Expecting a single word after #ifndef "
                            "but got \"%s\"", walk);
                        return (T_ERR);
                }

                if (*skip != 0 ||
                    (definitions != NULL && sl_find(definitions, walk) != NULL))
                        ++*skip;
                else
                        ++*unskip;

                return (T_OK);
        }

        walk = cmptoken(line, "else");
        if (walk != NULL) {
                (void)trimlr(&walk);

                if (*walk != '\0') {
                        WARN0("Expecting no arguments after #else");
                        return (T_ERR);
                }
                if (*skip + *unskip == 0) {
                        WARN0("#else without prior #ifdef or #ifndef");
                        return (T_ERR);
                }

                if (*skip == 0) {
                        ++*skip;
                        --*unskip;
                } else if (*skip == 1) {
                        --*skip;
                        ++*unskip;
                }

                return (T_OK);
        }

        if (*skip != 0)
                return (T_OK);

        walk = cmptoken(line, "include");
        if (walk != NULL) {
                (void)trimlr(&walk);

                if (*walk == '\0') {
                        WARN0("Expecting arguments after #include");
                        return (T_ERR);
                }

                if (*walk != '<' && *walk != '\"') {
                        WARN0("Excecting '<' or '\"' after #include");
                        return (T_ERR);
                }

                a = *walk == '<' ? '>' : '\"';
                walk++;
                c = walk[strlen(walk) - 1];

                if (a != c) {
                        WARN1("Unterminated include expecting '%c'", a);
                        return (T_ERR);
                }
                walk[strlen(walk) - 1] = '\0';

                this_cal_home = cal_home;
                this_cal_dir = cal_dir;
                this_cal_file = cal_file;
                this_cal_line = cal_line;
                if (cal_parse(cal_fopen(walk), out))
                        return (T_ERR);
                cal_home = this_cal_home;
                cal_dir = this_cal_dir;
                cal_file = this_cal_file;
                cal_line = this_cal_line;

                return (T_OK);
        }

        walk = cmptoken(line, "define");
        if (walk != NULL) {
                if (definitions == NULL)
                        definitions = sl_init();
                sep = trimlr(&walk);
                *sep = '\0';

                if (*walk == '\0') {
                        WARN0("Expecting arguments after #define");
                        return (T_ERR);
                }

                if (sl_find(definitions, walk) == NULL)
                        sl_add(definitions, strdup(walk));
                return (T_OK);
        }

        walk = cmptoken(line, "undef");
        if (walk != NULL) {
                if (definitions != NULL) {
                        sep = trimlr(&walk);

                        if (*walk == '\0') {
                                WARN0("Expecting arguments after #undef");
                                return (T_ERR);
                        }
                        if (*sep != '\0') {
                                WARN1("Expecting a single word after #undef "
                                    "but got \"%s\"", walk);
                                return (T_ERR);
                        }

                        walk = sl_find(definitions, walk);
                        if (walk != NULL)
                                walk[0] = '\0';
                }
                return (T_OK);
        }

        walk = cmptoken(line, "warning");
        if (walk != NULL) {
                (void)trimlr(&walk);
                WARN1("Warning: %s", walk);
        }

        walk = cmptoken(line, "error");
        if (walk != NULL) {
                (void)trimlr(&walk);
                WARN1("Error: %s", walk);
                return (T_ERR);
        }

        WARN1("Undefined pre-processor command \"#%s\"", line);
        return (T_ERR);
}

static void
setup_locale(const char *locale)
{
        (void)setlocale(LC_ALL, locale);
#ifdef WITH_ICONV
        if (!doall)
                set_new_encoding();
#endif
        setnnames();
}

#define REPLACE(string, slen, struct_) \
                if (strncasecmp(buf, (string), (slen)) == 0 && buf[(slen)]) { \
                        if (struct_.name != NULL)                             \
                                free(struct_.name);                           \
                        if ((struct_.name = strdup(buf + (slen))) == NULL)    \
                                errx(1, "cannot allocate memory");            \
                        struct_.len = strlen(buf + (slen));                   \
                        continue;                                             \
                }
static int
cal_parse(FILE *in, FILE *out)
{
        char *mylocale = NULL;
        char *line = NULL;
        char *buf, *bufp;
        size_t linecap = 0;
        ssize_t linelen;
        ssize_t l;
        static int count = 0;
        int i;
        int month[MAXCOUNT];
        int day[MAXCOUNT];
        int year[MAXCOUNT];
        int skip = 0;
        int unskip = 0;
        char *pp, p;
        int flags;
        char *c, *cc;
        bool incomment = false;

        if (in == NULL)
                return (1);

        cal_line = 0;
        while ((linelen = getline(&line, &linecap, in)) > 0) {
                cal_line++;
                buf = line;
                if (buf[linelen - 1] == '\n')
                        buf[--linelen] = '\0';

                if (incomment) {
                        c = strstr(buf, "*/");
                        if (c) {
                                c += 2;
                                linelen -= c - buf;
                                buf = c;
                                incomment = false;
                        } else {
                                continue;
                        }
                }
                if (!incomment) {
                        bufp = buf;
                        do {
                                c = strstr(bufp, "//");
                                cc = strstr(bufp, "/*");
                                if (c != NULL && (cc == NULL || c - cc < 0)) {
                                        bufp = c + 2;
                                        /* ignore "//" within string to allow it in an URL */
                                        if (c == buf || isspace(c[-1])) {
                                                /* single line comment */
                                                *c = '\0';
                                                linelen = c - buf;
                                                break;
                                        }
                                } else if (cc != NULL) {
                                        c = strstr(cc + 2, "*/");
                                        if (c != NULL) { // 'a /* b */ c' -- cc=2, c=7+2
                                                /* multi-line comment ending on same line */
                                                c += 2;
                                                memmove(cc, c, buf + linelen + 1 - c);
                                                linelen -= c - cc;
                                                bufp = cc;
                                        } else {
                                                /* multi-line comment */
                                                *cc = '\0';
                                                linelen = cc - buf;
                                                incomment = true;
                                                break;
                                        }
                                }
                        } while (c != NULL || cc != NULL);
                }

                for (l = linelen;
                     l > 0 && isspace((unsigned char)buf[l - 1]);
                     l--)
                        ;
                buf[l] = '\0';
                if (buf[0] == '\0')
                        continue;

                if (buf == line && *buf == '#') {
                        switch (token(buf+1, out, &skip, &unskip)) {
                        case T_ERR:
                                free(line);
                                return (1);
                        case T_OK:
                                continue;
                        case T_PROCESS:
                                break;
                        default:
                                break;
                        }
                }

                if (skip != 0)
                        continue;

                /*
                 * Setting LANG in user's calendar was an old workaround
                 * for 'calendar -a' being run with C locale to properly
                 * print user's calendars in their native languages.
                 * Now that 'calendar -a' does fork with setusercontext(),
                 * and does not run iconv(), this variable has little use.
                 */
                if (strncmp(buf, "LANG=", 5) == 0) {
                        if (mylocale == NULL)
                                mylocale = strdup(setlocale(LC_ALL, NULL));
                        setup_locale(buf + 5);
                        continue;
                }
                /* Parse special definitions: Easter, Paskha etc */
                REPLACE("Easter=", 7, neaster);
                REPLACE("Paskha=", 7, npaskha);
                REPLACE("ChineseNewYear=", 15, ncny);
                REPLACE("NewMoon=", 8, nnewmoon);
                REPLACE("FullMoon=", 9, nfullmoon);
                REPLACE("MarEquinox=", 11, nmarequinox);
                REPLACE("SepEquinox=", 11, nsepequinox);
                REPLACE("JunSolstice=", 12, njunsolstice);
                REPLACE("DecSolstice=", 12, ndecsolstice);
                if (strncmp(buf, "SEQUENCE=", 9) == 0) {
                        setnsequences(buf + 9);
                        continue;
                }

                /*
                 * If the line starts with a tab, the data has to be
                 * added to the previous line
                 */
                if (buf[0] == '\t') {
                        for (i = 0; i < count; i++)
                                event_continue(events[i], buf);
                        continue;
                }

                /* Get rid of leading spaces (non-standard) */
                while (isspace((unsigned char)buf[0]))
                        memcpy(buf, buf + 1, strlen(buf));

                /* No tab in the line, then not a valid line */
                if ((pp = strchr(buf, '\t')) == NULL)
                        continue;

                /* Trim spaces in front of the tab */
                while (isspace((unsigned char)pp[-1]))
                        pp--;

                p = *pp;
                *pp = '\0';
                if ((count = parsedaymonth(buf, year, month, day, &flags,
                    extradata)) == 0)
                        continue;
                *pp = p;
                if (count < 0) {
                        /* Show error status based on return value */
                        if (debug)
                                WARN1("Ignored: \"%s\"", buf);
                        if (count == -1)
                                continue;
                        count = -count + 1;
                }

                /* Find the last tab */
                while (pp[1] == '\t')
                        pp++;

                for (i = 0; i < count; i++) {
                        if (debug)
                                WARN1("got \"%s\"", pp);
                        events[i] = event_add(year[i], month[i], day[i],
                            ((flags &= F_VARIABLE) != 0) ? 1 : 0, pp,
                            extradata[i]);
                }
        }
        while (skip-- > 0 || unskip-- > 0) {
                cal_line++;
                WARN0("Missing #endif assumed");
        }

        free(line);
        fclose(in);
        if (mylocale != NULL) {
                setup_locale(mylocale);
                free(mylocale);
        }

        return (0);
}

void
cal(void)
{
        FILE *fpin;
        FILE *fpout;
        int i;

        for (i = 0; i < MAXCOUNT; i++)
                extradata[i] = (char *)calloc(1, 20);


        if ((fpin = opencalin()) == NULL)
                return;

        if ((fpout = opencalout()) == NULL) {
                fclose(fpin);
                return;
        }

        if (cal_parse(fpin, fpout))
                return;

        event_print_all(fpout);
        closecal(fpout);
}

FILE *
opencalin(void)
{
        struct stat sbuf;
        FILE *fpin;

        /* open up calendar file */
        cal_file = calendarFile;
        if ((fpin = fopen(calendarFile, "r")) == NULL) {
                if (doall) {
                        if (chdir(calendarHomes[0]) != 0)
                                return (NULL);
                        if (stat(calendarNoMail, &sbuf) == 0)
                                return (NULL);
                        if ((fpin = fopen(calendarFile, "r")) == NULL)
                                return (NULL);
                } else {
                        fpin = cal_fopen(calendarFile);
                }
        }
        return (fpin);
}

FILE *
opencalout(void)
{
        int fd;

        /* not reading all calendar files, just set output to stdout */
        if (!doall)
                return (stdout);

        /* set output to a temporary file, so if no output don't send mail */
        snprintf(path, sizeof(path), "%s/_calXXXXXX", _PATH_TMP);
        if ((fd = mkstemp(path)) < 0)
                return (NULL);
        return (fdopen(fd, "w+"));
}

void
closecal(FILE *fp)
{
        struct stat sbuf;
        int nread, pdes[2], status;
        char buf[1024];

        if (!doall)
                return;

        rewind(fp);
        if (fstat(fileno(fp), &sbuf) || !sbuf.st_size)
                goto done;
        if (pipe(pdes) < 0)
                goto done;
        switch (fork()) {
        case -1:                        /* error */
                (void)close(pdes[0]);
                (void)close(pdes[1]);
                goto done;
        case 0:
                /* child -- set stdin to pipe output */
                if (pdes[0] != STDIN_FILENO) {
                        (void)dup2(pdes[0], STDIN_FILENO);
                        (void)close(pdes[0]);
                }
                (void)close(pdes[1]);
                execl(_PATH_SENDMAIL, "sendmail", "-i", "-t", "-F",
                    "\"Reminder Service\"", (char *)NULL);
                warn(_PATH_SENDMAIL);
                _exit(1);
        }
        /* parent -- write to pipe input */
        (void)close(pdes[0]);

        write(pdes[1], "From: \"Reminder Service\" <", 26);
        write(pdes[1], pw->pw_name, strlen(pw->pw_name));
        write(pdes[1], ">\nTo: <", 7);
        write(pdes[1], pw->pw_name, strlen(pw->pw_name));
        write(pdes[1], ">\nSubject: ", 11);
        write(pdes[1], dayname, strlen(dayname));
        write(pdes[1], "'s Calendar\nPrecedence: bulk\n\n", 30);

        while ((nread = read(fileno(fp), buf, sizeof(buf))) > 0)
                (void)write(pdes[1], buf, nread);
        (void)close(pdes[1]);
done:   (void)fclose(fp);
        (void)unlink(path);
        while (wait(&status) >= 0);
}