/*

  tt 1.0 - Time Tracker

    (Instructions using -h)

  Copyright (C) 2010 Lluís Batlle i Rossell

  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 2

  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, write to the Free Software

  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

*/

#define _POSIX_C_SOURCE 1

#define _XOPEN_SOURCE 500

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

#include <string.h>

#include <errno.h>

/* For debug messages */

static line_counter;

void parsing_error()

{

    fprintf(stderr, "Parsing error at line %i\n", line_counter);

    exit(1);

}

static FILE *

open_file(const char *attr)

{

    char *name = getenv("TT_PROJECT");

    if (name)

    {

        name = strdup(name);

    }

    else

    {

        const char *home = getenv("HOME");

        const char *filename = "/.tt";

        int len;

        if (!home)

        {

            fprintf(stderr, "You should have $HOME or $TT_PROJECT set.\n");

            exit(1);

        }

        len = strlen(filename) + strlen(home) + 1;

        name = malloc(len);

        snprintf(name, len, "%s%s", home, filename);

    }

    FILE *f;

    f = fopen(name, attr);

    if (!f)

    {

        fprintf(stderr, "Could not open the file: %s (%s)\n", name,

                strerror(errno));

        free(name);

        exit(1);

    }

    free(name);

    return f;

}

static int

get_current_time()

{

    time_t current_time = time(0);

    return (int) current_time;

}

static char *

get_time_str(int d)

{

    time_t seconds = (time_t) d;

    struct tm t;

    localtime_r(&seconds, &t);

    char *str = malloc(100);

    snprintf(str, 100, "%04i-%02i-%02i %02i:%02i:%02i",

             1900+t.tm_year, t.tm_mon+1, t.tm_mday,

             t.tm_hour, t.tm_min, t.tm_sec);

    return str;

}

char *

seconds2hms(int t)

{

    int hours, minutes;

    hours = t / 3600;

    t = t % 3600;

    minutes = t / 60;

    t = t % 60;

    char *str = malloc(100);

    snprintf(str, 100, "%02i:%02i:%02i",

             hours, minutes, t);

    return str;

}

static int

str2time(const char *str)

{

    struct tm t;

    time_t seconds;

    char *str2 = strdup(str);

    char *ptr_begin = str2;

    char *ptr_end;

    ptr_end = strchr(ptr_begin, '-');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &t.tm_year);

    t.tm_year -= 1900;

    ptr_begin = ptr_end + 1;

    ptr_end = strchr(ptr_begin, '-');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &t.tm_mon);

    /* starting at 0 */

    t.tm_mon -= 1;

    ptr_begin = ptr_end + 1;

    ptr_end = strchr(ptr_begin, ' ');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &t.tm_mday);

    ptr_begin = ptr_end + 1;

    ptr_end = strchr(ptr_begin, ':');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &t.tm_hour);

    ptr_begin = ptr_end + 1;

    ptr_end = strchr(ptr_begin, ':');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &t.tm_min);

    ptr_begin = ptr_end + 1;

    sscanf(ptr_begin, "%d", &t.tm_sec);

    free(str2);

    /* We don't know, we had or not DST at that time */

    t.tm_isdst = -1;

    seconds = mktime(&t);

    return (int) seconds;

}

static void

new_task(const char *task)

{

    char *time_str = get_time_str(get_current_time());

    FILE *f = open_file("a");

    fprintf(f, "%s\t%s\n", time_str, task);

    free(time_str);

}

static void

list_task_switches()

{

    FILE *f = open_file("r");

    char buf[1000];

    int n;

    do {

        n = fread(buf, 1, sizeof(buf), f);

        while(n > 0)

        {

            int ret;

            ret = fwrite(buf, 1, n, stdout);

            n -= ret;

            memcpy(buf, buf+ret, n);

        }

    }

    while(!feof(f));

    fclose(f);

}

static void

list_task_times(int show_only_last)

{

    FILE *f = open_file("r");

    int is_prev_time_read = 0;

    int prev_time;

    char *prev_task = 0;

    char *prev_time_str = 0;

    line_counter = 1;

    /* Read lines */

    do {

        /* Read a line */

        char buf[1000];

        int n = 0;

        int c;

        do

        {

            buf[n] = fgetc(f);

            if(buf[n] == '\n' || feof(f))

                break;

            ++n;

        } while(!feof(f) && n <= sizeof(buf));

        buf[n] = 0;

        if(n > 0 && buf[0] != '#')

        {

            char *end_date, *start_task;

            int time;

            end_date = strchr(buf, '\t');

            if (!end_date)

                parsing_error();

            *end_date = 0;

            start_task = end_date + 1;

            time = str2time(buf);

            if (is_prev_time_read && !show_only_last)

            {

                int diff = time - prev_time;

                char *hms = seconds2hms(diff);

                char *prevtimestr2 = get_time_str(prev_time);

                printf("%s %s (%s)\n", hms, prev_task, prevtimestr2);

                free(prevtimestr2);

                free(hms);

            }

            prev_time = time;

            free(prev_task);

            prev_task = strdup(start_task);

            free(prev_time_str);

            prev_time_str = strdup(buf);

            is_prev_time_read = 1;

        }

        else if (n == 0) /* eof */

        {

            /* Time until now, for the last switch */

            int diff = get_current_time() - prev_time;

            char *hms = seconds2hms(diff);

            printf("%s %s (%s)\n", hms, prev_task, prev_time_str);

            free(hms);

            free(prev_task);

            free(prev_time_str);

        }

        line_counter++;

    }

    while(!feof(f));

    fclose(f);

}

char *

str_until_space(const char *str)

{

    while(*str != '\0' && !isspace(*str))

    {

        ++str;

    }

    if (*str == '\0')

        return 0;

    /* We get rid of the const */

    return (char *) str;

}

double

hms2time(const char *str)

{

    int hours, minutes, seconds;

    char *str2 = strdup(str);

    char *ptr_begin = str2;

    char *ptr_end;

    ptr_end = strchr(ptr_begin, ':');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &hours);

    ptr_begin = ptr_end + 1;

    ptr_end = strchr(ptr_begin, ':');

    if (!ptr_end)

        parsing_error();

    *ptr_end = '\0';

    sscanf(ptr_begin, "%d", &minutes);

    ptr_begin = ptr_end + 1;

    sscanf(ptr_begin, "%d", &seconds);

    free(str2);

    return hours * 3600 + minutes * 60 + seconds;

}

static void

sum_times()

{

    int accum_time = 0;

    char *str_hms;

    line_counter = 1;

    /* Read lines */

    do {

        /* Read a line */

        char buf[1000];

        int n = 0;

        int c;

        do

        {

            buf[n] = fgetc(stdin);

            if(buf[n] == '\n' || feof(stdin))

                break;

            ++n;

        } while(!feof(stdin) && n <= sizeof(buf));

        buf[n] = 0;

        if(n > 0)

        {

            char *end;

            int time;

            end = str_until_space(buf);

            if (!end)

                parsing_error();

            *end = 0;

            time = hms2time(buf);

            accum_time += time;

        }

        ++line_counter;

    }

    while(!feof(stdin));

    str_hms = seconds2hms(accum_time);

    printf("%s\n", str_hms);

    free(str_hms);

}

void show_help(const char *prog)

{

    printf(

	    "Usage: %s <-s|-l|-t|-h>\n"

        "       %s <task>\n"

        "Manual:\n"

        "  Switch to a task         :  tt mytask\n"

        "  List task switches       :  tt -l\n"

        "  List time spent per task :  tt -t\n"

        "  Sum times given with -t  :  tt -t | grep ... | tt -s\n"

        "  List what is tracked     :  tt\n"

        "  $TT_PROJECT or ~/.tt stores the tracking.\n"

        , prog, prog);

}

int main(int argc, char **argv)

{

    if (argc >= 2)

        if (strcmp(argv[1], "-t") == 0)

            list_task_times(/* show only last */ 0);

        else if (strcmp(argv[1], "-s") == 0)

            sum_times();

        else if (strcmp(argv[1], "-l") == 0)

            list_task_switches();

        else if (strcmp(argv[1], "-h") == 0)

            show_help(argv[0]);

        else

            new_task(argv[1]);

    else

        list_task_times(/* show only last */ 1);

    return 0;

}