/* Conky, a system monitor, based on torsmo
 *
 * Any original torsmo code is licensed under the BSD license
 *
 * All code written since the fork of torsmo is licensed under the GPL
 *
 * Please see COPYING for details
 *
 * Copyright (c) 2006 Marco Candrian <mac@calmar.ws>
 * Copyright (c) 2005-2008 Brenden Matthews, Philip Kovacs, et. al.
 *	(see AUTHORS)
 * All rights reserved.
 *
 * This program is free software: you can redistribute it 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * $Id$ */

#include "conky.h"
#include <sys/stat.h>
#include <sys/time.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mboxscan.h"

#define FROM_WIDTH 10
#define SUBJECT_WIDTH 22
#define PRINT_MAILS 5
#define TIME_DELAY 5

struct ring_list {
	char *from;
	char *subject;
	struct ring_list *previous;
	struct ring_list *next;
};

static time_t last_ctime;	/* needed for mutt at least */
static time_t last_mtime;	/* not sure what to test: testing both now */
static double last_update;

static int args_ok = 0;
static int from_width;
static int subject_width;
static int print_mails;
static int time_delay;

static char mbox_mail_spool[DEFAULT_TEXT_BUFFER_SIZE];

void mbox_scan(char *args, char *output, size_t max_len)
{
	int i, u, flag;
	int force_rescan = 0;
	char buf[text_buffer_size];
	struct stat statbuf;
	struct ring_list *curr = 0, *prev = 0, *startlist = 0;
	FILE *fp;

	/* output was set to 1 after malloc'ing in conky.c */
	/* -> beeing able to test it here for catching SIGUSR1 */
	if (output[0] == 1) {
		force_rescan = 1;
		output[0] = '\0';
	}

	if (!args_ok || force_rescan) {

		char *substr = strstr(args, "-n");

		if (substr) {
			if (sscanf(substr, "-n %i", &print_mails) != 1) {
				print_mails = PRINT_MAILS;
			}
		} else {
			print_mails = PRINT_MAILS;
		}
		if (print_mails < 1) {
			print_mails = 1;
		}

		substr = strstr(args, "-t");
		if (substr) {
			if (sscanf(substr, "-t %i", &time_delay) != 1) {
				time_delay = TIME_DELAY;
			}
		} else {
			time_delay = TIME_DELAY;
		}

		substr = strstr(args, "-fw");
		if (substr) {
			if (sscanf(substr, "-fw %i", &from_width) != 1) {
				from_width = FROM_WIDTH;
			}
		} else {
			from_width = FROM_WIDTH;
		}

		substr = strstr(args, "-sw");
		if (substr) {
			if (sscanf(substr, "-sw %i", &subject_width) != 1) {
				subject_width = SUBJECT_WIDTH;
			}
		} else {
			subject_width = SUBJECT_WIDTH;
		}
		/* encapsulated with "'s find first occurrence of " */
		if (args[strlen(args) - 1] == '"') {
			char *start;
			strncpy(mbox_mail_spool, args, DEFAULT_TEXT_BUFFER_SIZE);
			start = strchr(mbox_mail_spool, '"') + 1;

			start[(long) (strrchr(mbox_mail_spool, '"') - start)] = '\0';
			strncpy(mbox_mail_spool, start, DEFAULT_TEXT_BUFFER_SIZE);
		} else {
			char *copy_args = strndup(args, text_buffer_size);
			char *tmp = strtok(copy_args, " ");
			char *start = tmp;

			while (tmp) {
				tmp = strtok(NULL, " ");
				if (tmp) {
					start = tmp;
				}
			}
			strncpy(mbox_mail_spool, start, DEFAULT_TEXT_BUFFER_SIZE);
			free(copy_args);
		}
		if (strlen(mbox_mail_spool) < 1) {
			CRIT_ERR("Usage: ${mboxscan [-n <number of messages to print>] "
				"[-fw <from width>] [-sw <subject width>] "
				"[-t <delay in sec> mbox]}");
		}

		/* allowing $MAIL in the config */
		if (!strcmp(mbox_mail_spool, "$MAIL")) {
			strcpy(mbox_mail_spool, current_mail_spool);
		}

		if (stat(mbox_mail_spool, &statbuf)) {
			CRIT_ERR("can't stat %s: %s", mbox_mail_spool, strerror(errno));
		}
		args_ok = 1;	/* args-computing necessary only once */
	}

	/* if time_delay not yet reached, then return */
	if (current_update_time - last_update < time_delay && !force_rescan) {
		return;
	}

	last_update = current_update_time;

	/* mbox still exists? and get stat-infos */
	if (stat(mbox_mail_spool, &statbuf)) {
		ERR("can't stat %s: %s", mbox_mail_spool, strerror(errno));
		output[0] = '\0';	/* delete any output */
		return;
	}

	/* modification time has not changed, so skip scanning the box */
	if (statbuf.st_ctime == last_ctime && statbuf.st_mtime == last_mtime
			&& !force_rescan) {
		return;
	}

	last_ctime = statbuf.st_ctime;
	last_mtime = statbuf.st_mtime;

	/* build up double-linked ring-list to hold data, while scanning down the
	 * mbox */
	for (i = 0; i < print_mails; i++) {
		curr = (struct ring_list *) malloc(sizeof(struct ring_list));
		curr->from = (char *) malloc(sizeof(char[from_width + 1]));
		curr->subject = (char *) malloc(sizeof(char[subject_width + 1]));
		curr->from[0] = '\0';
		curr->subject[0] = '\0';

		if (i == 0) {
			startlist = curr;
		}
		if (i > 0) {
			curr->previous = prev;
			prev->next = curr;
		}
		prev = curr;
	}

	/* connect end to start for an endless loop-ring */
	startlist->previous = curr;
	curr->next = startlist;

	/* mbox */
	fp = fopen(mbox_mail_spool, "r");
	if (!fp) {
		return;
	}

	/* first find a "From " to set it to 0 for header-sarchings */
	flag = 1;
	while (!feof(fp)) {
		if (fgets(buf, text_buffer_size, fp) == NULL) {
			break;
		}

		if (strncmp(buf, "From ", 5) == 0) {
			curr = curr->next;

			/* skip until \n */
			while (strchr(buf, '\n') == NULL && !feof(fp)) {
				fgets(buf, text_buffer_size, fp);
			}

			flag = 0;	/* in the headers now */
			continue;
		}

		if (flag == 1) {	/* in the body, so skip */
			continue;
		}

		if (buf[0] == '\n') {
			/* beyond the headers now (empty line), skip until \n */
			/* then search for new mail ("From ") */

			while (strchr(buf, '\n') == NULL && !feof(fp)) {
				fgets(buf, text_buffer_size, fp);
			}
			flag = 1;	/* in the body now */
			continue;
		}

		if ((strncmp(buf, "X-Status: ", 10) == 0)
				|| (strncmp(buf, "Status: R", 9) == 0)) {

			/* Mail was read or something, so skip that message */
			flag = 1;	/* search for next From */
			curr->subject[0] = '\0';
			curr->from[0] = '\0';
			/* (will get current again on new 'From ' finding) */
			curr = curr->previous;
			/* Skip until \n */
			while (strchr(buf, '\n') == NULL && !feof(fp)) {
				fgets(buf, text_buffer_size, fp);
			}
			continue;
		}

		/* that covers ^From: and ^from: ^From:<tab> */
		if (strncmp(buf + 1, "rom:", 4) == 0) {

			i = 0;
			u = 6;	/* no "From: " string needed, so skip */
			while (1) {

				if (buf[u] == '"') {	/* no quotes around names */
					u++;
					continue;
				}

				/* some are: From: <foo@bar.com> */
				if (buf[u] == '<' && i > 1) {

					curr->from[i] = '\0';
					/* skip until \n */
					while (strchr(buf, '\n') == NULL && !feof(fp)) {
						fgets(buf, text_buffer_size, fp);
					}
					break;
				}

				if (buf[u] == '\n') {
					curr->from[i] = '\0';
					break;
				}

				if (buf[u] == '\0') {
					curr->from[i] = '\0';
					break;
				}

				if (i >= from_width) {
					curr->from[i] = '\0';
					/* skip until \n */
					while (strchr(buf, '\n') == NULL && !feof(fp)) {
						fgets(buf, text_buffer_size, fp);
					}
					break;
				}

				/* nothing special so just set it */
				curr->from[i++] = buf[u++];
			}
		}

		/* that covers ^Subject: and ^subject: and ^Subjec:<tab> */
		if (strncmp(buf + 1, "ubject:", 7) == 0) {

			i = 0;
			u = 9;	/* no "Subject: " string needed, so skip */
			while (1) {

				if (buf[u] == '\n') {
					curr->subject[i] = '\0';
					break;
				}
				if (buf[u] == '\0') {
					curr->subject[i] = '\0';
					break;
				}
				if (i >= subject_width) {
					curr->subject[i] = '\0';

					/* skip until \n */
					while (strchr(buf, '\n') == NULL && !feof(fp)) {
						fgets(buf, text_buffer_size, fp);
					}
					break;
				}

				/* nothing special so just set it */
				curr->subject[i++] = buf[u++];
			}
		}
	}

	fclose(fp);

	output[0] = '\0';

	i = print_mails;
	while (i) {
		struct ring_list *tmp;
		if (curr->from[0] != '\0') {
			if (i != print_mails) {
				snprintf(buf, text_buffer_size, "\nF: %-*s S: %-*s", from_width,
					curr->from, subject_width, curr->subject);
			} else {	/* first time - no \n in front */
				snprintf(buf, text_buffer_size, "F: %-*s S: %-*s", from_width,
					curr->from, subject_width, curr->subject);
			}
		} else {
			snprintf(buf, text_buffer_size, "\n");
		}
		strncat(output, buf, max_len - strlen(output));

		tmp = curr;
		curr = curr->previous;
		free(tmp->from);
		free(tmp->subject);
		free(tmp);

		i--;
	}
}