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

static const char send_pack_usage[] = "git-send-pack [--exec=other] destination [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 struct ref *ref_list = NULL, **last_ref = &ref_list;

static int read_ref(const char *ref, unsigned char *sha1)
{
        int fd, ret;
        static char pathname[PATH_MAX];
        char buffer[60];
        const char *git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;

        snprintf(pathname, sizeof(pathname), "%s/%s", git_dir, ref);
        fd = open(pathname, 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 send_pack(int in, int out)
{
        struct ref *ref;

        for (;;) {
                unsigned char old_sha1[20];
                unsigned char new_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;
                if (read_ref(name, new_sha1) < 0)
                        return error("no such local reference '%s'", name);
                if (!has_sha1_file(old_sha1))
                        return error("remote '%s' points to object I don't have", name);
                if (!memcmp(old_sha1, new_sha1, 20)) {
                        fprintf(stderr, "'%s' unchanged\n", name);
                        continue;
                }
                ref = xmalloc(sizeof(*ref) + len - 40);
                memcpy(ref->old_sha1, old_sha1, 20);
                memcpy(ref->new_sha1, new_sha1, 20);
                memcpy(ref->name, buffer + 41, len - 40);
                ref->next = NULL;
                *last_ref = ref;
                last_ref = &ref->next;
        }

        for (ref = ref_list; ref; ref = ref->next) {
                char old_hex[60], *new_hex;
                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);
        close(out);
        return 0;
}

/*
 * First, make it shell-safe.  We do this by just disallowing any
 * special characters. Somebody who cares can do escaping and let
 * through the rest. But since we're doing to feed this to ssh as
 * a command line, we're going to be pretty damn anal for now.
 */
static char *shell_safe(char *url)
{
        char *n = url;
        unsigned char c;
        static const char flags[256] = {
                ['0'...'9'] = 1,
                ['a'...'z'] = 1,
                ['A'...'Z'] = 1,
                ['.'] = 1, ['/'] = 1,
                ['-'] = 1, ['+'] = 1,
                [':'] = 1
        };

        while ((c = *n++) != 0) {
                if (flags[c] != 1)
                        die("I don't like '%c'. Sue me.", c);
        }
        return url;
}

/*
 * Yeah, yeah, fixme. Need to pass in the heads etc.
 */
static int setup_connection(int fd[2], char *url, char **heads)
{
        char command[1024];
        const char *host, *path;
        char *colon;
        int pipefd[2][2];
        pid_t pid;

        url = shell_safe(url);
        host = NULL;
        path = url;
        colon = strchr(url, ':');
        if (colon) {
                *colon = 0;
                host = url;
                path = colon+1;
        }
        snprintf(command, sizeof(command), "%s %s", exec, path);
        if (pipe(pipefd[0]) < 0 || pipe(pipefd[1]) < 0)
                die("unable to create pipe pair for communication");
        pid = fork();
        if (!pid) {
                dup2(pipefd[1][0], 0);
                dup2(pipefd[0][1], 1);
                close(pipefd[0][0]);
                close(pipefd[0][1]);
                close(pipefd[1][0]);
                close(pipefd[1][1]);
                if (host)
                        execlp("ssh", "ssh", host, command, NULL);
                else
                        execlp("sh", "sh", "-c", command, NULL);
                die("exec failed");
        }               
        fd[0] = pipefd[0][0];
        fd[1] = pipefd[1][1];
        close(pipefd[0][1]);
        close(pipefd[1][0]);
        return pid;
}

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 = setup_connection(fd, dest, heads);
        if (pid < 0)
                return 1;
        ret = send_pack(fd[0], fd[1]);
        close(fd[0]);
        close(fd[1]);
        waitpid(pid, NULL, 0);
        return ret;
}