#include "cache.h"
#include "refs.h"
#include "pkt-line.h"

static const char send_pack_usage[] =
"git-send-pack [--exec=git-receive-pack] [host:]directory [heads]*";
static const char *exec = "git-receive-pack";

struct ref {
        struct ref *next;
        unsigned char old_sha1[20];
        unsigned char new_sha1[20];
        char name[0];
};

static int is_zero_sha1(const unsigned char *sha1)
{
        int i;

        for (i = 0; i < 20; i++) {
                if (*sha1++)
                        return 0;
        }
        return 1;
}

static void exec_pack_objects(void)
{
        static char *args[] = {
                "git-pack-objects",
                "--stdout",
                NULL
        };
        execvp("git-pack-objects", args);
        die("git-pack-objects exec failed (%s)", strerror(errno));
}

static void exec_rev_list(struct ref *refs)
{
        static char *args[1000];
        int i = 0;

        args[i++] = "git-rev-list";     /* 0 */
        args[i++] = "--objects";        /* 1 */
        while (refs) {
                char *buf = malloc(100);
                if (i > 900)
                        die("git-rev-list environment overflow");
                if (!is_zero_sha1(refs->old_sha1)) {
                        args[i++] = buf;
                        snprintf(buf, 50, "^%s", sha1_to_hex(refs->old_sha1));
                        buf += 50;
                }
                if (!is_zero_sha1(refs->new_sha1)) {
                        args[i++] = buf;
                        snprintf(buf, 50, "%s", sha1_to_hex(refs->new_sha1));
                }
                refs = refs->next;
        }
        args[i] = NULL;
        execvp("git-rev-list", args);
        die("git-rev-list exec failed (%s)", strerror(errno));
}

static void rev_list(int fd, struct ref *refs)
{
        int pipe_fd[2];
        pid_t pack_objects_pid;

        if (pipe(pipe_fd) < 0)
                die("rev-list setup: pipe failed");
        pack_objects_pid = fork();
        if (!pack_objects_pid) {
                dup2(pipe_fd[0], 0);
                dup2(fd, 1);
                close(pipe_fd[0]);
                close(pipe_fd[1]);
                close(fd);
                exec_pack_objects();
                die("pack-objects setup failed");
        }
        if (pack_objects_pid < 0)
                die("pack-objects fork failed");
        dup2(pipe_fd[1], 1);
        close(pipe_fd[0]);
        close(pipe_fd[1]);
        close(fd);
        exec_rev_list(refs);
}

static int pack_objects(int fd, struct ref *refs)
{
        pid_t rev_list_pid;

        rev_list_pid = fork();
        if (!rev_list_pid) {
                rev_list(fd, refs);
                die("rev-list setup failed");
        }
        if (rev_list_pid < 0)
                die("rev-list fork failed");
        /*
         * We don't wait for the rev-list pipeline in the parent:
         * we end up waiting for the other end instead
         */
        return 0;
}

static int read_ref(const char *ref, unsigned char *sha1)
{
        int fd, ret;
        char buffer[60];

        fd = open(git_path("%s", ref), O_RDONLY);
        if (fd < 0)
                return -1;
        ret = -1;
        if (read(fd, buffer, sizeof(buffer)) >= 40)
                ret = get_sha1_hex(buffer, sha1);
        close(fd);
        return ret;
}

static int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
{
        if (!has_sha1_file(old_sha1))
                return 0;
        /*
         * FIXME! It is not correct to say that the new one is newer
         * just because we don't have the old one!
         *
         * We should really see if we can reach the old_sha1 commit
         * from the new_sha1 one.
         */
        return 1;
}

static int local_ref_nr_match;
static char **local_ref_match;
static struct ref **local_ref_list;

static int try_to_match(const char *refname, const unsigned char *sha1)
{
        struct ref *ref;
        int len;

        if (!path_match(refname, local_ref_nr_match, local_ref_match))
                return 0;

        len = strlen(refname)+1;
        ref = xmalloc(sizeof(*ref) + len);
        memset(ref->old_sha1, 0, 20);
        memcpy(ref->new_sha1, sha1, 20);
        memcpy(ref->name, refname, len);
        ref->next = NULL;
        *local_ref_list = ref;
        local_ref_list = &ref->next;
        return 0;
}

static int send_pack(int in, int out, int nr_match, char **match)
{
        struct ref *ref_list = NULL, **last_ref = &ref_list;
        struct ref *ref;
        int new_refs;

        /*
         * Read all the refs from the other end
         */
        for (;;) {
                unsigned char old_sha1[20];
                static char buffer[1000];
                char *name;
                int len;

                len = packet_read_line(in, buffer, sizeof(buffer));
                if (!len)
                        break;
                if (buffer[len-1] == '\n')
                        buffer[--len] = 0;

                if (len < 42 || get_sha1_hex(buffer, old_sha1) || buffer[40] != ' ')
                        die("protocol error: expected sha/ref, got '%s'", buffer);
                name = buffer + 41;
                ref = xmalloc(sizeof(*ref) + len - 40);
                memcpy(ref->old_sha1, old_sha1, 20);
                memset(ref->new_sha1, 0, 20);
                memcpy(ref->name, buffer + 41, len - 40);
                ref->next = NULL;
                *last_ref = ref;
                last_ref = &ref->next;
        }

        /*
         * Go through the refs, see if we want to update
         * any of them..
         */
        for (ref = ref_list; ref; ref = ref->next) {
                unsigned char new_sha1[20];
                char *name = ref->name;

                if (nr_match && !path_match(name, nr_match, match))
                        continue;

                if (read_ref(name, new_sha1) < 0)
                        continue;

                if (!memcmp(ref->old_sha1, new_sha1, 20)) {
                        fprintf(stderr, "'%s' unchanged\n", name);
                        continue;
                }

                if (!ref_newer(new_sha1, ref->old_sha1)) {
                        error("remote '%s' points to object I don't have", name);
                        continue;
                }

                /* Ok, mark it for update */
                memcpy(ref->new_sha1, new_sha1, 20);
        }

        /*
         * See if we have any refs that the other end didn't have
         */
        if (nr_match) {
                local_ref_nr_match = nr_match;
                local_ref_match = match;
                local_ref_list = last_ref;
                for_each_ref(try_to_match);
        }

        /*
         * Finally, tell the other end!
         */
        new_refs = 0;
        for (ref = ref_list; ref; ref = ref->next) {
                char old_hex[60], *new_hex;
                if (is_zero_sha1(ref->new_sha1))
                        continue;
                new_refs++;
                strcpy(old_hex, sha1_to_hex(ref->old_sha1));
                new_hex = sha1_to_hex(ref->new_sha1);
                packet_write(out, "%s %s %s", old_hex, new_hex, ref->name);
                fprintf(stderr, "'%s': updating from %s to %s\n", ref->name, old_hex, new_hex);
        }
        
        packet_flush(out);
        if (new_refs)
                pack_objects(out, ref_list);
        close(out);
        return 0;
}

int main(int argc, char **argv)
{
        int i, nr_heads = 0;
        char *dest = NULL;
        char **heads = NULL;
        int fd[2], ret;
        pid_t pid;

        argv++;
        for (i = 1; i < argc; i++) {
                char *arg = *argv++;

                if (*arg == '-') {
                        if (!strncmp(arg, "--exec=", 7)) {
                                exec = arg + 7;
                                continue;
                        }
                        usage(send_pack_usage);
                }
                dest = arg;
                heads = argv;
                nr_heads = argc - i -1;
                break;
        }
        if (!dest)
                usage(send_pack_usage);
        pid = git_connect(fd, dest, exec);
        if (pid < 0)
                return 1;
        ret = send_pack(fd[0], fd[1], nr_heads, heads);
        close(fd[0]);
        close(fd[1]);
        finish_connect(pid);
        return ret;
}