/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"

#include <pwd.h>
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <time.h>

#define BLOCKING (1ul << 14)
#define ORIG_OFFSET (40)

/*
 * Leave space at the beginning to insert the tag
 * once we know how big things are.
 *
 * FIXME! Share the code with "write-tree.c"
 */
static void init_buffer(char **bufp, unsigned int *sizep)
{
        char *buf = malloc(BLOCKING);
        memset(buf, 0, ORIG_OFFSET);
        *sizep = ORIG_OFFSET;
        *bufp = buf;
}

static void add_buffer(char **bufp, unsigned int *sizep, const char *fmt, ...)
{
        char one_line[2048];
        va_list args;
        int len;
        unsigned long alloc, size, newsize;
        char *buf;

        va_start(args, fmt);
        len = vsnprintf(one_line, sizeof(one_line), fmt, args);
        va_end(args);
        size = *sizep;
        newsize = size + len;
        alloc = (size + 32767) & ~32767;
        buf = *bufp;
        if (newsize > alloc) {
                alloc = (newsize + 32767) & ~32767;
                buf = realloc(buf, alloc);
                *bufp = buf;
        }
        *sizep = newsize;
        memcpy(buf + size, one_line, len);
}

static int prepend_integer(char *buffer, unsigned val, int i)
{
        buffer[--i] = '\0';
        do {
                buffer[--i] = '0' + (val % 10);
                val /= 10;
        } while (val);
        return i;
}

static void finish_buffer(char *tag, char **bufp, unsigned int *sizep)
{
        int taglen;
        int offset;
        char *buf = *bufp;
        unsigned int size = *sizep;

        offset = prepend_integer(buf, size - ORIG_OFFSET, ORIG_OFFSET);
        taglen = strlen(tag);
        offset -= taglen;
        buf += offset;
        size -= offset;
        memcpy(buf, tag, taglen);

        *bufp = buf;
        *sizep = size;
}

static void remove_special(char *p)
{
        char c;
        char *dst = p, *src = p;

        for (;;) {
                c = *src;
                src++;
                switch(c) {
                case '\n': case '<': case '>':
                        continue;
                }
                *dst++ = c;
                if (!c)
                        break;
        }

        /*
         * Go back, and remove crud from the end: some people
         * have commas etc in their gecos field
         */
        dst--;
        while (--dst >= p) {
                unsigned char c = *dst;
                switch (c) {
                case ',': case ';': case '.':
                        *dst = 0;
                        continue;
                }
                break;
        }
}

static const char *month_names[] = {
        "Jan", "Feb", "Mar", "Apr", "May", "Jun",
        "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

static const char *weekday_names[] = {
        "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};


static char *skipfws(char *str)
{
        while (isspace(*str))
                str++;
        return str;
}

        
/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
   (i.e. English) day/month names, and it doesn't work correctly with %z. */
static void parse_rfc2822_date(char *date, char *result, int maxlen)
{
        struct tm tm;
        char *p;
        int i, offset;
        time_t then;

        memset(&tm, 0, sizeof(tm));

        /* Skip day-name */
        p = skipfws(date);
        if (!isdigit(*p)) {
                for (i=0; i<7; i++) {
                        if (!strncmp(p,weekday_names[i],3) && p[3] == ',') {
                                p = skipfws(p+4);
                                goto day;
                        }
                }
                return;
        }                                       

        /* day */
 day:
        tm.tm_mday = strtoul(p, &p, 10);

        if (tm.tm_mday < 1 || tm.tm_mday > 31)
                return;

        if (!isspace(*p))
                return;

        p = skipfws(p);

        /* month */

        for (i=0; i<12; i++) {
                if (!strncmp(p, month_names[i], 3) && isspace(p[3])) {
                        tm.tm_mon = i;
                        p = skipfws(p+strlen(month_names[i]));
                        goto year;
                }
        }
        return; /* Error -- bad month */

        /* year */
 year:  
        tm.tm_year = strtoul(p, &p, 10);

        if (!tm.tm_year && !isspace(*p))
                return;

        if (tm.tm_year > 1900)
                tm.tm_year -= 1900;
                
        p=skipfws(p);

        /* hour */
        if (!isdigit(*p))
                return;
        tm.tm_hour = strtoul(p, &p, 10);
        
        if (!tm.tm_hour > 23)
                return;

        if (*p != ':')
                return; /* Error -- bad time */
        p++;

        /* minute */
        if (!isdigit(*p))
                return;
        tm.tm_min = strtoul(p, &p, 10);
        
        if (!tm.tm_min > 59)
                return;

        if (isspace(*p))
                goto zone;

        if (*p != ':')
                return; /* Error -- bad time */
        p++;

        /* second */
        if (!isdigit(*p))
                return;
        tm.tm_sec = strtoul(p, &p, 10);
        
        if (!tm.tm_sec > 59)
                return;

        if (!isspace(*p))
                return;

 zone:
        p = skipfws(p);

        if (*p == '-')
                offset = -60;
        else if (*p == '+')
                offset = 60;
        else
               return;

        if (!isdigit(p[1]) || !isdigit(p[2]) || !isdigit(p[3]) || !isdigit(p[4]))
                return;

        i = strtoul(p+1, NULL, 10);
        offset *= ((i % 100) + ((i / 100) * 60));

        if (*(skipfws(p + 5)))
                return;

        then = mktime(&tm); /* mktime appears to ignore the GMT offset, stupidly */
        if (then == -1)
                return;

        then -= offset;

        snprintf(result, maxlen, "%lu %5.5s", then, p);
}

static void check_valid(unsigned char *sha1, const char *expect)
{
        void *buf;
        char type[20];
        unsigned long size;

        buf = read_sha1_file(sha1, type, &size);
        if (!buf || strcmp(type, expect))
                die("%s is not a valid '%s' object", sha1_to_hex(sha1), expect);
        free(buf);
}

/*
 * Having more than two parents may be strange, but hey, there's
 * no conceptual reason why the file format couldn't accept multi-way
 * merges. It might be the "union" of several packages, for example.
 *
 * I don't really expect that to happen, but this is here to make
 * it clear that _conceptually_ it's ok..
 */
#define MAXPARENT (16)

int main(int argc, char **argv)
{
        int i, len;
        int parents = 0;
        unsigned char tree_sha1[20];
        unsigned char parent_sha1[MAXPARENT][20];
        unsigned char commit_sha1[20];
        char *gecos, *realgecos;
        char *email, realemail[1000];
        char date[20], realdate[20];
        char *audate;
        char comment[1000];
        struct passwd *pw;
        time_t now;
        struct tm *tm;
        char *buffer;
        unsigned int size;

        if (argc < 2 || get_sha1_hex(argv[1], tree_sha1) < 0)
                usage("commit-tree <sha1> [-p <sha1>]* < changelog");

        check_valid(tree_sha1, "tree");
        for (i = 2; i < argc; i += 2) {
                char *a, *b;
                a = argv[i]; b = argv[i+1];
                if (!b || strcmp(a, "-p") || get_sha1_hex(b, parent_sha1[parents]))
                        usage("commit-tree <sha1> [-p <sha1>]* < changelog");
                check_valid(parent_sha1[parents], "commit");
                parents++;
        }
        if (!parents)
                fprintf(stderr, "Committing initial tree %s\n", argv[1]);
        pw = getpwuid(getuid());
        if (!pw)
                die("You don't exist. Go away!");
        realgecos = pw->pw_gecos;
        len = strlen(pw->pw_name);
        memcpy(realemail, pw->pw_name, len);
        realemail[len] = '@';
        gethostname(realemail+len+1, sizeof(realemail)-len-1);
        time(&now);
        tm = localtime(&now);

        strftime(realdate, sizeof(realdate), "%s %z", tm);
        strcpy(date, realdate);

        gecos = getenv("AUTHOR_NAME") ? : realgecos;
        email = getenv("AUTHOR_EMAIL") ? : realemail;
        audate = getenv("AUTHOR_DATE");
        if (audate)
                parse_rfc2822_date(audate, date, sizeof(date));

        remove_special(gecos); remove_special(realgecos);
        remove_special(email); remove_special(realemail);

        init_buffer(&buffer, &size);
        add_buffer(&buffer, &size, "tree %s\n", sha1_to_hex(tree_sha1));

        /*
         * NOTE! This ordering means that the same exact tree merged with a
         * different order of parents will be a _different_ changeset even
         * if everything else stays the same.
         */
        for (i = 0; i < parents; i++)
                add_buffer(&buffer, &size, "parent %s\n", sha1_to_hex(parent_sha1[i]));

        /* Person/date information */
        add_buffer(&buffer, &size, "author %s <%s> %s\n", gecos, email, date);
        add_buffer(&buffer, &size, "committer %s <%s> %s\n\n", realgecos, realemail, realdate);

        /* And add the comment */
        while (fgets(comment, sizeof(comment), stdin) != NULL)
                add_buffer(&buffer, &size, "%s", comment);

        finish_buffer("commit ", &buffer, &size);

        write_sha1_file(buffer, size, commit_sha1);
        printf("%s\n", sha1_to_hex(commit_sha1));
        return 0;
}