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

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

enum deny_action {
	DENY_UNCONFIGURED,
	DENY_IGNORE,
	DENY_WARN,
	DENY_REFUSE,
};

static int deny_deletes;
static int deny_non_fast_forwards;
static enum deny_action deny_current_branch = DENY_UNCONFIGURED;
static enum deny_action deny_delete_current = DENY_UNCONFIGURED;
static int receive_fsck_objects;
static int receive_unpack_limit = -1;
static int transfer_unpack_limit = -1;
static int unpack_limit = 100;
static int report_status;
static int prefer_ofs_delta = 1;
static const char *head_name;
static char *capabilities_to_send;

static enum deny_action parse_deny_action(const char *var, const char *value)
{
	if (value) {
		if (!strcasecmp(value, "ignore"))
			return DENY_IGNORE;
		if (!strcasecmp(value, "warn"))
			return DENY_WARN;
		if (!strcasecmp(value, "refuse"))
			return DENY_REFUSE;
	}
	if (git_config_bool(var, value))
		return DENY_REFUSE;
	return DENY_IGNORE;
}

static int receive_pack_config(const char *var, const char *value, void *cb)
{
	if (strcmp(var, "receive.denydeletes") == 0) {
		deny_deletes = git_config_bool(var, value);
		return 0;
	}

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

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

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

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

	if (!strcmp(var, "receive.denycurrentbranch")) {
		deny_current_branch = parse_deny_action(var, value);
		return 0;
	}

	if (strcmp(var, "receive.denydeletecurrent") == 0) {
		deny_delete_current = parse_deny_action(var, value);
		return 0;
	}

	if (strcmp(var, "repack.usedeltabaseoffset") == 0) {
		prefer_ofs_delta = git_config_bool(var, value);
		return 0;
	}

	return git_default_config(var, value, cb);
}

static int show_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
{
	if (!capabilities_to_send)
		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_to_send);
	capabilities_to_send = NULL;
	return 0;
}

static void write_head_info(void)
{
	for_each_ref(show_ref, NULL);
	if (capabilities_to_send)
		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 const char pre_receive_hook[] = "hooks/pre-receive";
static const char post_receive_hook[] = "hooks/post-receive";

static int run_receive_hook(const char *hook_name)
{
	static char buf[sizeof(commands->old_sha1) * 2 + PATH_MAX + 4];
	struct command *cmd;
	struct child_process proc;
	const char *argv[2];
	int have_input = 0, code;

	for (cmd = commands; !have_input && cmd; cmd = cmd->next) {
		if (!cmd->error_string)
			have_input = 1;
	}

	if (!have_input || access(hook_name, X_OK) < 0)
		return 0;

	argv[0] = hook_name;
	argv[1] = NULL;

	memset(&proc, 0, sizeof(proc));
	proc.argv = argv;
	proc.in = -1;
	proc.stdout_to_stderr = 1;

	code = start_command(&proc);
	if (code)
		return code;
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (!cmd->error_string) {
			size_t n = snprintf(buf, sizeof(buf), "%s %s %s\n",
				sha1_to_hex(cmd->old_sha1),
				sha1_to_hex(cmd->new_sha1),
				cmd->ref_name);
			if (write_in_full(proc.in, buf, n) != n)
				break;
		}
	}
	close(proc.in);
	return finish_command(&proc);
}

static int run_update_hook(struct command *cmd)
{
	static const char update_hook[] = "hooks/update";
	const char *argv[5];

	if (access(update_hook, X_OK) < 0)
		return 0;

	argv[0] = update_hook;
	argv[1] = cmd->ref_name;
	argv[2] = sha1_to_hex(cmd->old_sha1);
	argv[3] = sha1_to_hex(cmd->new_sha1);
	argv[4] = NULL;

	return run_command_v_opt(argv, RUN_COMMAND_NO_STDIN |
					RUN_COMMAND_STDOUT_TO_STDERR);
}

static int is_ref_checked_out(const char *ref)
{
	if (is_bare_repository())
		return 0;

	if (!head_name)
		return 0;
	return !strcmp(head_name, ref);
}

static char *warn_unconfigured_deny_msg[] = {
	"Updating the currently checked out branch may cause confusion,",
	"as the index and work tree do not reflect changes that are in HEAD.",
	"As a result, you may see the changes you just pushed into it",
	"reverted when you run 'git diff' over there, and you may want",
	"to run 'git reset --hard' before starting to work to recover.",
	"",
	"You can set 'receive.denyCurrentBranch' configuration variable to",
	"'refuse' in the remote repository to forbid pushing into its",
	"current branch."
	"",
	"To allow pushing into the current branch, you can set it to 'ignore';",
	"but this is not recommended unless you arranged to update its work",
	"tree to match what you pushed in some other way.",
	"",
	"To squelch this message, you can set it to 'warn'.",
	"",
	"Note that the default will change in a future version of git",
	"to refuse updating the current branch unless you have the",
	"configuration variable set to either 'ignore' or 'warn'."
};

static void warn_unconfigured_deny(void)
{
	int i;
	for (i = 0; i < ARRAY_SIZE(warn_unconfigured_deny_msg); i++)
		warning("%s", warn_unconfigured_deny_msg[i]);
}

static char *warn_unconfigured_deny_delete_current_msg[] = {
	"Deleting the current branch can cause confusion by making the next",
	"'git clone' not check out any file.",
	"",
	"You can set 'receive.denyDeleteCurrent' configuration variable to",
	"'refuse' in the remote repository to disallow deleting the current",
	"branch.",
	"",
	"You can set it to 'ignore' to allow such a delete without a warning.",
	"",
	"To make this warning message less loud, you can set it to 'warn'.",
	"",
	"Note that the default will change in a future version of git",
	"to refuse deleting the current branch unless you have the",
	"configuration variable set to either 'ignore' or 'warn'."
};

static void warn_unconfigured_deny_delete_current(void)
{
	int i;
	for (i = 0;
	     i < ARRAY_SIZE(warn_unconfigured_deny_delete_current_msg);
	     i++)
		warning("%s", warn_unconfigured_deny_delete_current_msg[i]);
}

static const char *update(struct command *cmd)
{
	const char *name = cmd->ref_name;
	unsigned char *old_sha1 = cmd->old_sha1;
	unsigned char *new_sha1 = cmd->new_sha1;
	struct ref_lock *lock;

	/* only refs/... are allowed */
	if (prefixcmp(name, "refs/") || check_ref_format(name + 5)) {
		error("refusing to create funny ref '%s' remotely", name);
		return "funny refname";
	}

	if (is_ref_checked_out(name)) {
		switch (deny_current_branch) {
		case DENY_IGNORE:
			break;
		case DENY_UNCONFIGURED:
		case DENY_WARN:
			warning("updating the current branch");
			if (deny_current_branch == DENY_UNCONFIGURED)
				warn_unconfigured_deny();
			break;
		case DENY_REFUSE:
			error("refusing to update checked out branch: %s", name);
			return "branch is currently checked out";
		}
	}

	if (!is_null_sha1(new_sha1) && !has_sha1_file(new_sha1)) {
		error("unpack should have generated %s, "
		      "but I can't find it!", sha1_to_hex(new_sha1));
		return "bad pack";
	}

	if (!is_null_sha1(old_sha1) && is_null_sha1(new_sha1)) {
		if (deny_deletes && !prefixcmp(name, "refs/heads/")) {
			error("denying ref deletion for %s", name);
			return "deletion prohibited";
		}

		if (!strcmp(name, head_name)) {
			switch (deny_delete_current) {
			case DENY_IGNORE:
				break;
			case DENY_WARN:
			case DENY_UNCONFIGURED:
				if (deny_delete_current == DENY_UNCONFIGURED)
					warn_unconfigured_deny_delete_current();
				warning("deleting the current branch");
				break;
			case DENY_REFUSE:
				error("refusing to delete the current branch: %s", name);
				return "deletion of the current branch prohibited";
			}
		}
	}

	if (deny_non_fast_forwards && !is_null_sha1(new_sha1) &&
	    !is_null_sha1(old_sha1) &&
	    !prefixcmp(name, "refs/heads/")) {
		struct object *old_object, *new_object;
		struct commit *old_commit, *new_commit;
		struct commit_list *bases, *ent;

		old_object = parse_object(old_sha1);
		new_object = parse_object(new_sha1);

		if (!old_object || !new_object ||
		    old_object->type != OBJ_COMMIT ||
		    new_object->type != OBJ_COMMIT) {
			error("bad sha1 objects for %s", name);
			return "bad ref";
		}
		old_commit = (struct commit *)old_object;
		new_commit = (struct commit *)new_object;
		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) {
			error("denying non-fast forward %s"
			      " (you should pull first)", name);
			return "non-fast forward";
		}
	}
	if (run_update_hook(cmd)) {
		error("hook declined to update %s", name);
		return "hook declined";
	}

	if (is_null_sha1(new_sha1)) {
		if (!parse_object(old_sha1)) {
			warning ("Allowing deletion of corrupt ref.");
			old_sha1 = NULL;
		}
		if (delete_ref(name, old_sha1, 0)) {
			error("failed to delete %s", name);
			return "failed to delete";
		}
		return NULL; /* good */
	}
	else {
		lock = lock_any_ref_for_update(name, old_sha1, 0);
		if (!lock) {
			error("failed to lock %s", name);
			return "failed to lock";
		}
		if (write_ref_sha1(lock, new_sha1, "push")) {
			return "failed to write"; /* error() already called */
		}
		return NULL; /* good */
	}
}

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

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

	for (argc = 0, cmd_p = cmd; cmd_p; cmd_p = cmd_p->next) {
		if (cmd_p->error_string)
			continue;
		argc++;
	}
	if (!argc || access(update_post_hook, X_OK) < 0)
		return;
	argv = xmalloc(sizeof(*argv) * (2 + 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;
	status = run_command_v_opt(argv, RUN_COMMAND_NO_STDIN
			| RUN_COMMAND_STDOUT_TO_STDERR);
}

static void execute_commands(const char *unpacker_error)
{
	struct command *cmd = commands;
	unsigned char sha1[20];

	if (unpacker_error) {
		while (cmd) {
			cmd->error_string = "n/a (unpacker error)";
			cmd = cmd->next;
		}
		return;
	}

	if (run_receive_hook(pre_receive_hook)) {
		while (cmd) {
			cmd->error_string = "pre-receive hook declined";
			cmd = cmd->next;
		}
		return;
	}

	head_name = resolve_ref("HEAD", sha1, 0, NULL);

	while (cmd) {
		cmd->error_string = update(cmd);
		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;
		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 = NULL;
		cmd->next = NULL;
		*p = cmd;
		p = &cmd->next;
	}
}

static const char *parse_pack_header(struct pack_header *hdr)
{
	switch (read_pack_header(0, hdr)) {
	case PH_ERROR_EOF:
		return "eof before pack header was fully read";

	case PH_ERROR_PACK_SIGNATURE:
		return "protocol error (pack signature mismatch detected)";

	case PH_ERROR_PROTOCOL:
		return "protocol error (pack version unsupported)";

	default:
		return "unknown error in parse_pack_header";

	case 0:
		return NULL;
	}
}

static const char *pack_lockfile;

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

	hdr_err = parse_pack_header(&hdr);
	if (hdr_err)
		return hdr_err;
	snprintf(hdr_arg, sizeof(hdr_arg),
			"--pack_header=%"PRIu32",%"PRIu32,
			ntohl(hdr.hdr_version), ntohl(hdr.hdr_entries));

	if (ntohl(hdr.hdr_entries) < unpack_limit) {
		int code, i = 0;
		const char *unpacker[4];
		unpacker[i++] = "unpack-objects";
		if (receive_fsck_objects)
			unpacker[i++] = "--strict";
		unpacker[i++] = hdr_arg;
		unpacker[i++] = NULL;
		code = run_command_v_opt(unpacker, RUN_GIT_CMD);
		if (!code)
			return NULL;
		return "unpack-objects abnormal exit";
	} else {
		const char *keeper[7];
		int s, status, i = 0;
		char keep_arg[256];
		struct child_process ip;

		s = sprintf(keep_arg, "--keep=receive-pack %"PRIuMAX" on ", (uintmax_t) getpid());
		if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
			strcpy(keep_arg + s, "localhost");

		keeper[i++] = "index-pack";
		keeper[i++] = "--stdin";
		if (receive_fsck_objects)
			keeper[i++] = "--strict";
		keeper[i++] = "--fix-thin";
		keeper[i++] = hdr_arg;
		keeper[i++] = keep_arg;
		keeper[i++] = NULL;
		memset(&ip, 0, sizeof(ip));
		ip.argv = keeper;
		ip.out = -1;
		ip.git_cmd = 1;
		status = start_command(&ip);
		if (status) {
			return "index-pack fork failed";
		}
		pack_lockfile = index_pack_lockfile(ip.out);
		close(ip.out);
		status = finish_command(&ip);
		if (!status) {
			reprepare_packed_git();
			return NULL;
		}
		return "index-pack abnormal exit";
	}
}

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);
}

static int delete_only(struct command *cmd)
{
	while (cmd) {
		if (!is_null_sha1(cmd->new_sha1))
			return 0;
		cmd = cmd->next;
	}
	return 1;
}

static int add_refs_from_alternate(struct alternate_object_database *e, void *unused)
{
	char *other;
	size_t len;
	struct remote *remote;
	struct transport *transport;
	const struct ref *extra;

	e->name[-1] = '\0';
	other = xstrdup(make_absolute_path(e->base));
	e->name[-1] = '/';
	len = strlen(other);

	while (other[len-1] == '/')
		other[--len] = '\0';
	if (len < 8 || memcmp(other + len - 8, "/objects", 8))
		return 0;
	/* Is this a git repository with refs? */
	memcpy(other + len - 8, "/refs", 6);
	if (!is_directory(other))
		return 0;
	other[len - 8] = '\0';
	remote = remote_get(other);
	transport = transport_get(remote, other);
	for (extra = transport_get_remote_refs(transport);
	     extra;
	     extra = extra->next) {
		add_extra_ref(".have", extra->old_sha1, 0);
	}
	transport_disconnect(transport);
	free(other);
	return 0;
}

static void add_alternate_refs(void)
{
	foreach_alt_odb(add_refs_from_alternate, NULL);
}

int cmd_receive_pack(int argc, const char **argv, const char *prefix)
{
	int i;
	char *dir = NULL;

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

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

	setup_path();

	if (!enter_repo(dir, 0))
		die("'%s' does not appear to be a git repository", dir);

	if (is_repository_shallow())
		die("attempt to push into a shallow repository");

	git_config(receive_pack_config, NULL);

	if (0 <= transfer_unpack_limit)
		unpack_limit = transfer_unpack_limit;
	else if (0 <= receive_unpack_limit)
		unpack_limit = receive_unpack_limit;

	capabilities_to_send = (prefer_ofs_delta) ?
		" report-status delete-refs ofs-delta " :
		" report-status delete-refs ";

	add_alternate_refs();
	write_head_info();
	clear_extra_refs();

	/* EOF */
	packet_flush(1);

	read_head_info();
	if (commands) {
		const char *unpack_status = NULL;

		if (!delete_only(commands))
			unpack_status = unpack();
		execute_commands(unpack_status);
		if (pack_lockfile)
			unlink_or_warn(pack_lockfile);
		if (report_status)
			report(unpack_status);
		run_receive_hook(post_receive_hook);
		run_update_post_hook(commands);
	}
	return 0;
}