#include "cache.h"
#include "pack.h"
#include "refs.h"
#include "pkt-line.h"
#include "run-command.h"
#include "commit.h"
#include "object.h"

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

static int deny_non_fast_forwards = 0;
static int unpack_limit = 5000;
static int report_status;

static char capabilities[] = "report-status";
static int capabilities_sent;

static int receive_pack_config(const char *var, const char *value)
{
        git_default_config(var, value);

        if (strcmp(var, "receive.denynonfastforwards") == 0)
        {
                deny_non_fast_forwards = git_config_bool(var, value);
                return 0;
        }

        if (strcmp(var, "receive.unpacklimit") == 0)
        {
                unpack_limit = git_config_int(var, value);
                return 0;
        }

        return 0;
}

static int show_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
{
        if (capabilities_sent)
                packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
        else
                packet_write(1, "%s %s%c%s\n",
                             sha1_to_hex(sha1), path, 0, capabilities);
        capabilities_sent = 1;
        return 0;
}

static void write_head_info(void)
{
        for_each_ref(show_ref, NULL);
        if (!capabilities_sent)
                show_ref("capabilities^{}", null_sha1, 0, NULL);

}

struct command {
        struct command *next;
        const char *error_string;
        unsigned char old_sha1[20];
        unsigned char new_sha1[20];
        char ref_name[FLEX_ARRAY]; /* more */
};

static struct command *commands;

static char update_hook[] = "hooks/update";

static int run_update_hook(const char *refname,
                           char *old_hex, char *new_hex)
{
        int code;

        if (access(update_hook, X_OK) < 0)
                return 0;
        code = run_command(update_hook, refname, old_hex, new_hex, NULL);
        switch (code) {
        case 0:
                return 0;
        case -ERR_RUN_COMMAND_FORK:
                return error("hook fork failed");
        case -ERR_RUN_COMMAND_EXEC:
                return error("hook execute failed");
        case -ERR_RUN_COMMAND_WAITPID:
                return error("waitpid failed");
        case -ERR_RUN_COMMAND_WAITPID_WRONG_PID:
                return error("waitpid is confused");
        case -ERR_RUN_COMMAND_WAITPID_SIGNAL:
                return error("%s died of signal", update_hook);
        case -ERR_RUN_COMMAND_WAITPID_NOEXIT:
                return error("%s died strangely", update_hook);
        default:
                error("%s exited with error code %d", update_hook, -code);
                return -code;
        }
}

static int update(struct command *cmd)
{
        const char *name = cmd->ref_name;
        unsigned char *old_sha1 = cmd->old_sha1;
        unsigned char *new_sha1 = cmd->new_sha1;
        char new_hex[41], old_hex[41];
        struct ref_lock *lock;

        cmd->error_string = NULL;
        if (!strncmp(name, "refs/", 5) && check_ref_format(name + 5)) {
                cmd->error_string = "funny refname";
                return error("refusing to create funny ref '%s' locally",
                             name);
        }

        strcpy(new_hex, sha1_to_hex(new_sha1));
        strcpy(old_hex, sha1_to_hex(old_sha1));
        if (!has_sha1_file(new_sha1)) {
                cmd->error_string = "bad pack";
                return error("unpack should have generated %s, "
                             "but I can't find it!", new_hex);
        }
        if (deny_non_fast_forwards && !is_null_sha1(old_sha1)) {
                struct commit *old_commit, *new_commit;
                struct commit_list *bases, *ent;

                old_commit = (struct commit *)parse_object(old_sha1);
                new_commit = (struct commit *)parse_object(new_sha1);
                bases = get_merge_bases(old_commit, new_commit, 1);
                for (ent = bases; ent; ent = ent->next)
                        if (!hashcmp(old_sha1, ent->item->object.sha1))
                                break;
                free_commit_list(bases);
                if (!ent)
                        return error("denying non-fast forward;"
                                     " you should pull first");
        }
        if (run_update_hook(name, old_hex, new_hex)) {
                cmd->error_string = "hook declined";
                return error("hook declined to update %s", name);
        }

        lock = lock_any_ref_for_update(name, old_sha1);
        if (!lock) {
                cmd->error_string = "failed to lock";
                return error("failed to lock %s", name);
        }
        write_ref_sha1(lock, new_sha1, "push");

        fprintf(stderr, "%s: %s -> %s\n", name, old_hex, new_hex);
        return 0;
}

static char update_post_hook[] = "hooks/post-update";

static void run_update_post_hook(struct command *cmd)
{
        struct command *cmd_p;
        int argc;
        const char **argv;

        if (access(update_post_hook, X_OK) < 0)
                return;
        for (argc = 1, cmd_p = cmd; cmd_p; cmd_p = cmd_p->next) {
                if (cmd_p->error_string)
                        continue;
                argc++;
        }
        argv = xmalloc(sizeof(*argv) * (1 + argc));
        argv[0] = update_post_hook;

        for (argc = 1, cmd_p = cmd; cmd_p; cmd_p = cmd_p->next) {
                char *p;
                if (cmd_p->error_string)
                        continue;
                p = xmalloc(strlen(cmd_p->ref_name) + 1);
                strcpy(p, cmd_p->ref_name);
                argv[argc] = p;
                argc++;
        }
        argv[argc] = NULL;
        run_command_v_opt(argc, argv, RUN_COMMAND_NO_STDIO);
}

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

        while (cmd) {
                update(cmd);
                cmd = cmd->next;
        }
        run_update_post_hook(commands);
}

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;
                char *refname;
                int len, reflen;

                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);

                refname = line + 82;
                reflen = strlen(refname);
                if (reflen + 82 < len) {
                        if (strstr(refname + reflen + 1, "report-status"))
                                report_status = 1;
                }
                cmd = xmalloc(sizeof(struct command) + len - 80);
                hashcpy(cmd->old_sha1, old_sha1);
                hashcpy(cmd->new_sha1, new_sha1);
                memcpy(cmd->ref_name, line + 82, len - 81);
                cmd->error_string = "n/a (unpacker error)";
                cmd->next = NULL;
                *p = cmd;
                p = &cmd->next;
        }
}

static const char *parse_pack_header(struct pack_header *hdr)
{
        char *c = (char*)hdr;
        ssize_t remaining = sizeof(struct pack_header);
        do {
                ssize_t r = xread(0, c, remaining);
                if (r <= 0)
                        return "eof before pack header was fully read";
                remaining -= r;
                c += r;
        } while (remaining > 0);
        if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
                return "protocol error (pack signature mismatch detected)";
        if (!pack_version_ok(hdr->hdr_version))
                return "protocol error (pack version unsupported)";
        return NULL;
}

static const char *unpack(void)
{
        struct pack_header hdr;
        const char *hdr_err;
        char hdr_arg[38];
        int code;

        hdr_err = parse_pack_header(&hdr);
        if (hdr_err)
                return hdr_err;
        snprintf(hdr_arg, sizeof(hdr_arg), "--pack_header=%u,%u",
                        ntohl(hdr.hdr_version), ntohl(hdr.hdr_entries));

        if (ntohl(hdr.hdr_entries) < unpack_limit) {
                const char *unpacker[3];
                unpacker[0] = "unpack-objects";
                unpacker[1] = hdr_arg;
                unpacker[2] = NULL;
                code = run_command_v_opt(1, unpacker, RUN_GIT_CMD);
        } else {
                const char *keeper[6];
                char my_host[255], keep_arg[128 + 255];

                if (gethostname(my_host, sizeof(my_host)))
                        strcpy(my_host, "localhost");
                snprintf(keep_arg, sizeof(keep_arg),
                                "--keep=receive-pack %i on %s",
                                getpid(), my_host);

                keeper[0] = "index-pack";
                keeper[1] = "--stdin";
                keeper[2] = "--fix-thin";
                keeper[3] = hdr_arg;
                keeper[4] = keep_arg;
                keeper[5] = NULL;
                code = run_command_v_opt(1, keeper, RUN_GIT_CMD);
                if (!code)
                        reprepare_packed_git();
        }

        switch (code) {
                case 0:
                        return NULL;
                case -ERR_RUN_COMMAND_FORK:
                        return "unpack fork failed";
                case -ERR_RUN_COMMAND_EXEC:
                        return "unpack execute failed";
                case -ERR_RUN_COMMAND_WAITPID:
                        return "waitpid failed";
                case -ERR_RUN_COMMAND_WAITPID_WRONG_PID:
                        return "waitpid is confused";
                case -ERR_RUN_COMMAND_WAITPID_SIGNAL:
                        return "unpacker died of signal";
                case -ERR_RUN_COMMAND_WAITPID_NOEXIT:
                        return "unpacker died strangely";
                default:
                        return "unpacker exited with error code";
        }
}

static void report(const char *unpack_status)
{
        struct command *cmd;
        packet_write(1, "unpack %s\n",
                     unpack_status ? unpack_status : "ok");
        for (cmd = commands; cmd; cmd = cmd->next) {
                if (!cmd->error_string)
                        packet_write(1, "ok %s\n",
                                     cmd->ref_name);
                else
                        packet_write(1, "ng %s %s\n",
                                     cmd->ref_name, cmd->error_string);
        }
        packet_flush(1);
}

int main(int argc, char **argv)
{
        int i;
        char *dir = NULL;

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

                if (*arg == '-') {
                        /* Do flag handling here */
                        usage(receive_pack_usage);
                }
                if (dir)
                        usage(receive_pack_usage);
                dir = arg;
        }
        if (!dir)
                usage(receive_pack_usage);

        if (!enter_repo(dir, 0))
                die("'%s': unable to chdir or not a git archive", dir);

        setup_ident();
        git_config(receive_pack_config);

        write_head_info();

        /* EOF */
        packet_flush(1);

        read_head_info();
        if (commands) {
                const char *unpack_status = unpack();
                if (!unpack_status)
                        execute_commands();
                if (report_status)
                        report(unpack_status);
        }
        return 0;
}