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

static const char receive_pack_usage[] = "git-receive-pack [--unpack=executable] <git-dir> [heads]";

static const char *unpacker = "git-unpack-objects";

static int path_match(const char *path, int nr, char **match)
{
        int i;
        int pathlen = strlen(path);

        for (i = 0; i < nr; i++) {
                char *s = match[i];
                int len = strlen(s);

                if (!len || len > pathlen)
                        continue;
                if (memcmp(path + pathlen - len, s, len))
                        continue;
                if (pathlen > len && path[pathlen - len - 1] != '/')
                        continue;
                *s = 0;
                return 1;
        }
        return 0;
}

static void show_ref(const char *path, unsigned char *sha1)
{
        packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
}

static int read_ref(const char *path, unsigned char *sha1)
{
        int ret = -1;
        int fd = open(path, O_RDONLY);

        if (fd >= 0) {
                char buffer[60];
                if (read(fd, buffer, sizeof(buffer)) >= 40)
                        ret = get_sha1_hex(buffer, sha1);
                close(fd);
        }
        return ret;
}

static void write_head_info(const char *base, int nr, char **match)
{
        DIR *dir = opendir(base);

        if (dir) {
                struct dirent *de;
                int baselen = strlen(base);
                char *path = xmalloc(baselen + 257);
                memcpy(path, base, baselen);

                while ((de = readdir(dir)) != NULL) {
                        char sha1[20];
                        struct stat st;
                        int namelen;

                        if (de->d_name[0] == '.')
                                continue;
                        namelen = strlen(de->d_name);
                        if (namelen > 255)
                                continue;
                        memcpy(path + baselen, de->d_name, namelen+1);
                        if (lstat(path, &st) < 0)
                                continue;
                        if (S_ISDIR(st.st_mode)) {
                                path[baselen + namelen] = '/';
                                path[baselen + namelen + 1] = 0;
                                write_head_info(path, nr, match);
                                continue;
                        }
                        if (read_ref(path, sha1) < 0)
                                continue;
                        if (nr && !path_match(path, nr, match))
                                continue;
                        show_ref(path, sha1);
                }
                free(path);
                closedir(dir);
        }
}

struct command {
        struct command *next;
        unsigned char old_sha1[20];
        unsigned char new_sha1[20];
        char ref_name[0];
};

struct command *commands = NULL;

/*
 * This gets called after(if) we've successfully
 * unpacked the data payload.
 */
static void execute_commands(void)
{
        struct command *cmd = commands;

        while (cmd) {
                char old_hex[60], *new_hex;
                strcpy(old_hex, sha1_to_hex(cmd->old_sha1));
                new_hex = sha1_to_hex(cmd->new_sha1);
                fprintf(stderr, "%s: %s -> %s\n", cmd->ref_name, old_hex, new_hex);
                cmd = cmd->next;
        }
}

static void read_head_info(void)
{
        struct command **p = &commands;
        for (;;) {
                static char line[1000];
                unsigned char old_sha1[20], new_sha1[20];
                struct command *cmd;
                int len;

                len = packet_read_line(0, line, sizeof(line));
                if (!len)
                        break;
                if (line[len-1] == '\n')
                        line[--len] = 0;
                if (len < 83 ||
                    line[40] != ' ' ||
                    line[81] != ' ' ||
                    get_sha1_hex(line, old_sha1) ||
                    get_sha1_hex(line + 41, new_sha1))
                        die("protocol error: expected old/new/ref, got '%s'", line);
                cmd = xmalloc(sizeof(struct command) + len - 80);
                memcpy(cmd->old_sha1, old_sha1, 20);
                memcpy(cmd->new_sha1, new_sha1, 20);
                memcpy(cmd->ref_name, line + 82, len - 81);
                cmd->next = NULL;
                *p = cmd;
                p = &cmd->next;
        }
}

static void unpack(void)
{
        pid_t pid = fork();

        if (pid < 0)
                die("unpack fork failed");
        if (!pid) {
                setenv("GIT_DIR", ".", 1);
                execlp(unpacker, unpacker, NULL);
                die("unpack execute failed");
        }

        for (;;) {
                int status, code;
                int retval = waitpid(pid, &status, 0);

                if (retval < 0) {
                        if (errno == EINTR)
                                continue;
                        die("waitpid failed (%s)", strerror(retval));
                }
                if (retval != pid)
                        die("waitpid is confused");
                if (WIFSIGNALED(status))
                        die("%s died of signal %d", unpacker, WTERMSIG(status));
                if (!WIFEXITED(status))
                        die("%s died out of really strange complications", unpacker);
                code = WEXITSTATUS(status);
                if (code)
                        die("%s exited with error code %d", unpacker, code);
                return;
        }
}

int main(int argc, char **argv)
{
        int i, nr_heads = 0;
        const char *dir = NULL;
        char **heads = NULL;

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

                if (*arg == '-') {
                        if (!strncmp(arg, "--unpack=", 9)) {
                                unpacker = arg+9;
                                continue;
                        }
                        /* Do flag handling here */
                        usage(receive_pack_usage);
                }
                dir = arg;
                heads = argv;
                nr_heads = argc - i - 1;
                break;
        }
        if (!dir)
                usage(receive_pack_usage);

        /* chdir to the directory. If that fails, try appending ".git" */
        if (chdir(dir) < 0) {
                static char path[PATH_MAX];
                snprintf(path, sizeof(path), "%s.git", dir);
                if (chdir(path) < 0)
                        die("unable to cd to %s", dir);
        }

        /* If we have a ".git" directory, chdir to it */
        chdir(".git");

        if (access("objects", X_OK) < 0 || access("refs/heads", X_OK) < 0)
                die("%s doesn't appear to be a git directory", dir);
        write_head_info("refs/", nr_heads, heads);

        /* EOF */
        packet_flush(1);

        read_head_info();
        if (commands) {
                unpack();
                execute_commands();
        }
        return 0;
}