#include "cache.h"

static int check_valid_sha1(unsigned char *sha1)
{
        char *filename = sha1_file_name(sha1);
        int ret;

        /* If we were anal, we'd check that the sha1 of the contents actually matches */
        ret = access(filename, R_OK);
        if (ret)
                perror(filename);
        return ret;
}

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;
}

#define ORIG_OFFSET (40)        /* Enough space to add the header of "tree <size>\0" */

int main(int argc, char **argv)
{
        unsigned long size, offset, val;
        int i, entries = read_cache();
        char *buffer;

        if (entries <= 0) {
                fprintf(stderr, "No file-cache to create a tree of\n");
                exit(1);
        }

        /* Guess at an initial size */
        size = entries * 40 + 400;
        buffer = malloc(size);
        offset = ORIG_OFFSET;

        for (i = 0; i < entries; i++) {
                struct cache_entry *ce = active_cache[i];
                if (check_valid_sha1(ce->sha1) < 0)
                        exit(1);
                if (offset + ce->namelen + 60 > size) {
                        size = alloc_nr(offset + ce->namelen + 60);
                        buffer = realloc(buffer, size);
                }
                offset += sprintf(buffer + offset, "%o %s", ce->st_mode, ce->name);
                buffer[offset++] = 0;
                memcpy(buffer + offset, ce->sha1, 20);
                offset += 20;
        }

        i = prepend_integer(buffer, offset - ORIG_OFFSET, ORIG_OFFSET);
        i -= 5;
        memcpy(buffer+i, "tree ", 5);

        buffer += i;
        offset -= i;

        write_sha1_file(buffer, offset);
        return 0;
}