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

static int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
{
        int len = len1 < len2 ? len1 : len2;
        int cmp;

        cmp = memcmp(name1, name2, len);
        if (cmp)
                return cmp;
        if (len1 < len2)
                return -1;
        if (len1 > len2)
                return 1;
        return 0;
}

static int cache_name_pos(const char *name, int namelen)
{
        int first, last;

        first = 0;
        last = active_nr;
        while (last > first) {
                int next = (last + first) >> 1;
                struct cache_entry *ce = active_cache[next];
                int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
                if (!cmp)
                        return -next-1;
                if (cmp < 0) {
                        last = next;
                        continue;
                }
                first = next+1;
        }
        return first;
}

static int remove_file_from_cache(char *path)
{
        int pos = cache_name_pos(path, strlen(path));
        if (pos < 0) {
                pos = -pos-1;
                active_nr--;
                if (pos < active_nr)
                        memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos - 1) * sizeof(struct cache_entry *));
        }
        return 0;
}

static int add_cache_entry(struct cache_entry *ce)
{
        int pos;

        pos = cache_name_pos(ce->name, ce->namelen);

        /* existing match? Just replace it */
        if (pos < 0) {
                active_cache[-pos-1] = ce;
                return 0;
        }

        /* Make sure the array is big enough .. */
        if (active_nr == active_alloc) {
                active_alloc = alloc_nr(active_alloc);
                active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
        }

        /* Add it in.. */
        active_nr++;
        if (active_nr > pos)
                memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
        active_cache[pos] = ce;
        return 0;
}

static int index_fd(const char *path, int namelen, struct cache_entry *ce, int fd, struct stat *st)
{
        z_stream stream;
        int max_out_bytes = namelen + st->st_size + 200;
        void *out = malloc(max_out_bytes);
        void *metadata = malloc(namelen + 200);
        void *in = mmap(NULL, st->st_size, PROT_READ, MAP_PRIVATE, fd, 0);
        SHA_CTX c;

        close(fd);
        if (!out || (int)(long)in == -1)
                return -1;

        memset(&stream, 0, sizeof(stream));
        deflateInit(&stream, Z_BEST_COMPRESSION);

        /*
         * ASCII size + nul byte
         */     
        stream.next_in = metadata;
        stream.avail_in = 1+sprintf(metadata, "blob %lu", (unsigned long) st->st_size);
        stream.next_out = out;
        stream.avail_out = max_out_bytes;
        while (deflate(&stream, 0) == Z_OK)
                /* nothing */;

        /*
         * File content
         */
        stream.next_in = in;
        stream.avail_in = st->st_size;
        while (deflate(&stream, Z_FINISH) == Z_OK)
                /*nothing */;

        deflateEnd(&stream);
        
        SHA1_Init(&c);
        SHA1_Update(&c, out, stream.total_out);
        SHA1_Final(ce->sha1, &c);

        return write_sha1_buffer(ce->sha1, out, stream.total_out);
}

static int add_file_to_cache(char *path)
{
        int size, namelen;
        struct cache_entry *ce;
        struct stat st;
        int fd;

        fd = open(path, O_RDONLY);
        if (fd < 0) {
                if (errno == ENOENT)
                        return remove_file_from_cache(path);
                return -1;
        }
        if (fstat(fd, &st) < 0) {
                close(fd);
                return -1;
        }
        namelen = strlen(path);
        size = cache_entry_size(namelen);
        ce = malloc(size);
        memset(ce, 0, size);
        memcpy(ce->name, path, namelen);
        ce->ctime.sec = st.st_ctime;
        ce->ctime.nsec = st.st_ctim.tv_nsec;
        ce->mtime.sec = st.st_mtime;
        ce->mtime.nsec = st.st_mtim.tv_nsec;
        ce->st_dev = st.st_dev;
        ce->st_ino = st.st_ino;
        ce->st_mode = st.st_mode;
        ce->st_uid = st.st_uid;
        ce->st_gid = st.st_gid;
        ce->st_size = st.st_size;
        ce->namelen = namelen;

        if (index_fd(path, namelen, ce, fd, &st) < 0)
                return -1;

        return add_cache_entry(ce);
}

static int write_cache(int newfd, struct cache_entry **cache, int entries)
{
        SHA_CTX c;
        struct cache_header hdr;
        int i;

        hdr.signature = CACHE_SIGNATURE;
        hdr.version = 1;
        hdr.entries = entries;

        SHA1_Init(&c);
        SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
        for (i = 0; i < entries; i++) {
                struct cache_entry *ce = cache[i];
                int size = ce_size(ce);
                SHA1_Update(&c, ce, size);
        }
        SHA1_Final(hdr.sha1, &c);

        if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
                return -1;

        for (i = 0; i < entries; i++) {
                struct cache_entry *ce = cache[i];
                int size = ce_size(ce);
                if (write(newfd, ce, size) != size)
                        return -1;
        }
        return 0;
}               

/*
 * We fundamentally don't like some paths: we don't want
 * dot or dot-dot anywhere, and in fact, we don't even want
 * any other dot-files (.dircache or anything else). They
 * are hidden, for chist sake.
 *
 * Also, we don't want double slashes or slashes at the
 * end that can make pathnames ambiguous. 
 */
static int verify_path(char *path)
{
        char c;

        goto inside;
        for (;;) {
                if (!c)
                        return 1;
                if (c == '/') {
inside:
                        c = *path++;
                        if (c != '/' && c != '.' && c != '\0')
                                continue;
                        return 0;
                }
                c = *path++;
        }
}

int main(int argc, char **argv)
{
        int i, newfd, entries;

        entries = read_cache();
        if (entries < 0) {
                perror("cache corrupted");
                return -1;
        }

        newfd = open(".dircache/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600);
        if (newfd < 0) {
                perror("unable to create new cachefile");
                return -1;
        }
        for (i = 1 ; i < argc; i++) {
                char *path = argv[i];
                if (!verify_path(path)) {
                        fprintf(stderr, "Ignoring path %s\n", argv[i]);
                        continue;
                }
                if (add_file_to_cache(path)) {
                        fprintf(stderr, "Unable to add %s to database\n", path);
                        goto out;
                }
        }
        if (!write_cache(newfd, active_cache, active_nr) && !rename(".dircache/index.lock", ".dircache/index"))
                return 0;
out:
        unlink(".dircache/index.lock");
        return 0;
}