#include "cache.h"
#include "refs.h"
#include "pkt-line.h"
#include <sys/wait.h>

static int quiet;
static int verbose;
static const char fetch_pack_usage[] =
"git-fetch-pack [-q] [-v] [--exec=upload-pack] [host:]directory <refs>...";
static const char *exec = "git-upload-pack";

static int find_common(int fd[2], unsigned char *result_sha1,
                       struct ref *refs)
{
        int fetching;
        static char line[1000];
        int count = 0, flushes = 0, retval;
        FILE *revs;

        revs = popen("git-rev-list $(git-rev-parse --all)", "r");
        if (!revs)
                die("unable to run 'git-rev-list'");

        fetching = 0;
        for ( ; refs ; refs = refs->next) {
                unsigned char *remote = refs->old_sha1;
                unsigned char *local = refs->new_sha1;

                if (!memcmp(remote, local, 20))
                        continue;
                packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
                fetching++;
        }
        packet_flush(fd[1]);
        if (!fetching)
                return 1;
        flushes = 1;
        retval = -1;
        while (fgets(line, sizeof(line), revs) != NULL) {
                unsigned char sha1[20];
                if (get_sha1_hex(line, sha1))
                        die("git-fetch-pack: expected object name, got crud");
                packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
                if (verbose)
                        fprintf(stderr, "have %s\n", sha1_to_hex(sha1));
                if (!(31 & ++count)) {
                        packet_flush(fd[1]);
                        flushes++;

                        /*
                         * We keep one window "ahead" of the other side, and
                         * will wait for an ACK only on the next one
                         */
                        if (count == 32)
                                continue;
                        if (get_ack(fd[0], result_sha1)) {
                                flushes = 0;
                                retval = 0;
                                if (verbose)
                                        fprintf(stderr, "got ack\n");
                                break;
                        }
                        flushes--;
                }
        }
        pclose(revs);
        packet_write(fd[1], "done\n");
        if (verbose)
                fprintf(stderr, "done\n");
        while (flushes) {
                flushes--;
                if (get_ack(fd[0], result_sha1)) {
                        if (verbose)
                                fprintf(stderr, "got ack\n");
                        return 0;
                }
        }
        return retval;
}

static int everything_local(struct ref *refs)
{
        int retval;

        for (retval = 1; refs ; refs = refs->next) {
                const unsigned char *remote = refs->old_sha1;
                unsigned char local[20];

                if (read_ref(git_path("%s", refs->name), local) < 0 ||
                    memcmp(remote, local, 20)) {
                        retval = 0;
                        if (!verbose)
                                continue;
                        fprintf(stderr,
                                "want %s (%s)\n", sha1_to_hex(remote),
                                refs->name);
                        continue;
                }

                memcpy(refs->new_sha1, local, 20);
                if (!verbose)
                        continue;
                fprintf(stderr,
                        "already have %s (%s)\n", sha1_to_hex(remote),
                        refs->name);
        }
        return retval;
}

static int fetch_pack(int fd[2], int nr_match, char **match)
{
        struct ref *ref;
        unsigned char sha1[20];
        int status;
        pid_t pid;

        get_remote_heads(fd[0], &ref, nr_match, match, 1);
        if (!ref) {
                packet_flush(fd[1]);
                die("no matching remote head");
        }
        if (everything_local(ref)) {
                packet_flush(fd[1]);
                goto all_done;
        }
        if (find_common(fd, sha1, ref) < 0)
                fprintf(stderr, "warning: no common commits\n");
        pid = fork();
        if (pid < 0)
                die("git-fetch-pack: unable to fork off git-unpack-objects");
        if (!pid) {
                dup2(fd[0], 0);
                close(fd[0]);
                close(fd[1]);
                execlp("git-unpack-objects", "git-unpack-objects",
                       quiet ? "-q" : NULL, NULL);
                die("git-unpack-objects exec failed");
        }
        close(fd[0]);
        close(fd[1]);
        while (waitpid(pid, &status, 0) < 0) {
                if (errno != EINTR)
                        die("waiting for git-unpack-objects: %s", strerror(errno));
        }
        if (WIFEXITED(status)) {
                int code = WEXITSTATUS(status);
                if (code)
                        die("git-unpack-objects died with error code %d", code);
all_done:
                while (ref) {
                        printf("%s %s\n",
                               sha1_to_hex(ref->old_sha1), ref->name);
                        ref = ref->next;
                }
                return 0;
        }
        if (WIFSIGNALED(status)) {
                int sig = WTERMSIG(status);
                die("git-unpack-objects died of signal %d", sig);
        }
        die("Sherlock Holmes! git-unpack-objects died of unnatural causes %d!", status);
}

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

        nr_heads = 0;
        heads = NULL;
        for (i = 1; i < argc; i++) {
                char *arg = argv[i];

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