#include "builtin.h"
#include "exec_cmd.h"
#include "cache.h"
#include "quote.h"
#include "run-command.h"

const char git_usage_string[] =
	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [--html-path] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";

const char git_more_info_string[] =
	"See 'git help COMMAND' for more information on a specific command.";

static int use_pager = -1;
struct pager_config {
	const char *cmd;
	int val;
};

static int pager_command_config(const char *var, const char *value, void *data)
{
	struct pager_config *c = data;
	if (!prefixcmp(var, "pager.") && !strcmp(var + 6, c->cmd))
		c->val = git_config_bool(var, value);
	return 0;
}

/* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
int check_pager_config(const char *cmd)
{
	struct pager_config c;
	c.cmd = cmd;
	c.val = -1;
	git_config(pager_command_config, &c);
	return c.val;
}

static void commit_pager_choice(void) {
	switch (use_pager) {
	case 0:
		setenv("GIT_PAGER", "cat", 1);
		break;
	case 1:
		setup_pager();
		break;
	default:
		break;
	}
}

static int handle_options(const char ***argv, int *argc, int *envchanged)
{
	int handled = 0;

	while (*argc > 0) {
		const char *cmd = (*argv)[0];
		if (cmd[0] != '-')
			break;

		/*
		 * For legacy reasons, the "version" and "help"
		 * commands can be written with "--" prepended
		 * to make them look like flags.
		 */
		if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
			break;

		/*
		 * Check remaining flags.
		 */
		if (!prefixcmp(cmd, "--exec-path")) {
			cmd += 11;
			if (*cmd == '=')
				git_set_argv_exec_path(cmd + 1);
			else {
				puts(git_exec_path());
				exit(0);
			}
		} else if (!strcmp(cmd, "--html-path")) {
			puts(system_path(GIT_HTML_PATH));
			exit(0);
		} else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
			use_pager = 1;
		} else if (!strcmp(cmd, "--no-pager")) {
			use_pager = 0;
			if (envchanged)
				*envchanged = 1;
		} else if (!strcmp(cmd, "--git-dir")) {
			if (*argc < 2) {
				fprintf(stderr, "No directory given for --git-dir.\n" );
				usage(git_usage_string);
			}
			setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
			if (envchanged)
				*envchanged = 1;
			(*argv)++;
			(*argc)--;
			handled++;
		} else if (!prefixcmp(cmd, "--git-dir=")) {
			setenv(GIT_DIR_ENVIRONMENT, cmd + 10, 1);
			if (envchanged)
				*envchanged = 1;
		} else if (!strcmp(cmd, "--work-tree")) {
			if (*argc < 2) {
				fprintf(stderr, "No directory given for --work-tree.\n" );
				usage(git_usage_string);
			}
			setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
			if (envchanged)
				*envchanged = 1;
			(*argv)++;
			(*argc)--;
		} else if (!prefixcmp(cmd, "--work-tree=")) {
			setenv(GIT_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
			if (envchanged)
				*envchanged = 1;
		} else if (!strcmp(cmd, "--bare")) {
			static char git_dir[PATH_MAX+1];
			is_bare_repository_cfg = 1;
			setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 0);
			if (envchanged)
				*envchanged = 1;
		} else {
			fprintf(stderr, "Unknown option: %s\n", cmd);
			usage(git_usage_string);
		}

		(*argv)++;
		(*argc)--;
		handled++;
	}
	return handled;
}

static int handle_alias(int *argcp, const char ***argv)
{
	int envchanged = 0, ret = 0, saved_errno = errno;
	const char *subdir;
	int count, option_count;
	const char **new_argv;
	const char *alias_command;
	char *alias_string;
	int unused_nongit;

	subdir = setup_git_directory_gently(&unused_nongit);

	alias_command = (*argv)[0];
	alias_string = alias_lookup(alias_command);
	if (alias_string) {
		if (alias_string[0] == '!') {
			if (*argcp > 1) {
				struct strbuf buf;

				strbuf_init(&buf, PATH_MAX);
				strbuf_addstr(&buf, alias_string);
				sq_quote_argv(&buf, (*argv) + 1, PATH_MAX);
				free(alias_string);
				alias_string = buf.buf;
			}
			trace_printf("trace: alias to shell cmd: %s => %s\n",
				     alias_command, alias_string + 1);
			ret = system(alias_string + 1);
			if (ret >= 0 && WIFEXITED(ret) &&
			    WEXITSTATUS(ret) != 127)
				exit(WEXITSTATUS(ret));
			die("Failed to run '%s' when expanding alias '%s'",
			    alias_string + 1, alias_command);
		}
		count = split_cmdline(alias_string, &new_argv);
		if (count < 0)
			die("Bad alias.%s string", alias_command);
		option_count = handle_options(&new_argv, &count, &envchanged);
		if (envchanged)
			die("alias '%s' changes environment variables\n"
				 "You can use '!git' in the alias to do this.",
				 alias_command);
		memmove(new_argv - option_count, new_argv,
				count * sizeof(char *));
		new_argv -= option_count;

		if (count < 1)
			die("empty alias for %s", alias_command);

		if (!strcmp(alias_command, new_argv[0]))
			die("recursive alias: %s", alias_command);

		trace_argv_printf(new_argv,
				  "trace: alias expansion: %s =>",
				  alias_command);

		new_argv = xrealloc(new_argv, sizeof(char *) *
				    (count + *argcp));
		/* insert after command name */
		memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);

		*argv = new_argv;
		*argcp += count - 1;

		ret = 1;
	}

	if (subdir && chdir(subdir))
		die_errno("Cannot change to '%s'", subdir);

	errno = saved_errno;

	return ret;
}

const char git_version_string[] = GIT_VERSION;

#define RUN_SETUP	(1<<0)
#define USE_PAGER	(1<<1)
/*
 * require working tree to be present -- anything uses this needs
 * RUN_SETUP for reading from the configuration file.
 */
#define NEED_WORK_TREE	(1<<2)

struct cmd_struct {
	const char *cmd;
	int (*fn)(int, const char **, const char *);
	int option;
};

static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
{
	int status;
	struct stat st;
	const char *prefix;

	prefix = NULL;
	if (p->option & RUN_SETUP)
		prefix = setup_git_directory();

	if (use_pager == -1 && p->option & RUN_SETUP)
		use_pager = check_pager_config(p->cmd);
	if (use_pager == -1 && p->option & USE_PAGER)
		use_pager = 1;
	commit_pager_choice();

	if (p->option & NEED_WORK_TREE)
		setup_work_tree();

	trace_argv_printf(argv, "trace: built-in: git");

	status = p->fn(argc, argv, prefix);
	if (status)
		return status;

	/* Somebody closed stdout? */
	if (fstat(fileno(stdout), &st))
		return 0;
	/* Ignore write errors for pipes and sockets.. */
	if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
		return 0;

	/* Check for ENOSPC and EIO errors.. */
	if (fflush(stdout))
		die_errno("write failure on standard output");
	if (ferror(stdout))
		die("unknown write failure on standard output");
	if (fclose(stdout))
		die_errno("close failed on standard output");
	return 0;
}

static void handle_internal_command(int argc, const char **argv)
{
	const char *cmd = argv[0];
	static struct cmd_struct commands[] = {
		{ "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
		{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
		{ "annotate", cmd_annotate, RUN_SETUP },
		{ "apply", cmd_apply },
		{ "archive", cmd_archive },
		{ "bisect--helper", cmd_bisect__helper, RUN_SETUP | NEED_WORK_TREE },
		{ "blame", cmd_blame, RUN_SETUP },
		{ "branch", cmd_branch, RUN_SETUP },
		{ "bundle", cmd_bundle },
		{ "cat-file", cmd_cat_file, RUN_SETUP },
		{ "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
		{ "checkout-index", cmd_checkout_index,
			RUN_SETUP | NEED_WORK_TREE},
		{ "check-ref-format", cmd_check_ref_format },
		{ "check-attr", cmd_check_attr, RUN_SETUP },
		{ "cherry", cmd_cherry, RUN_SETUP },
		{ "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
		{ "clone", cmd_clone },
		{ "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
		{ "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
		{ "commit-tree", cmd_commit_tree, RUN_SETUP },
		{ "config", cmd_config },
		{ "count-objects", cmd_count_objects, RUN_SETUP },
		{ "describe", cmd_describe, RUN_SETUP },
		{ "diff", cmd_diff },
		{ "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
		{ "diff-index", cmd_diff_index, RUN_SETUP },
		{ "diff-tree", cmd_diff_tree, RUN_SETUP },
		{ "fast-export", cmd_fast_export, RUN_SETUP },
		{ "fetch", cmd_fetch, RUN_SETUP },
		{ "fetch-pack", cmd_fetch_pack, RUN_SETUP },
		{ "fetch--tool", cmd_fetch__tool, RUN_SETUP },
		{ "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
		{ "for-each-ref", cmd_for_each_ref, RUN_SETUP },
		{ "format-patch", cmd_format_patch, RUN_SETUP },
		{ "fsck", cmd_fsck, RUN_SETUP },
		{ "fsck-objects", cmd_fsck, RUN_SETUP },
		{ "gc", cmd_gc, RUN_SETUP },
		{ "get-tar-commit-id", cmd_get_tar_commit_id },
		{ "grep", cmd_grep, RUN_SETUP | USE_PAGER },
		{ "help", cmd_help },
#ifndef NO_CURL
		{ "http-fetch", cmd_http_fetch, RUN_SETUP },
#endif
		{ "init", cmd_init_db },
		{ "init-db", cmd_init_db },
		{ "log", cmd_log, RUN_SETUP | USE_PAGER },
		{ "ls-files", cmd_ls_files, RUN_SETUP },
		{ "ls-tree", cmd_ls_tree, RUN_SETUP },
		{ "ls-remote", cmd_ls_remote },
		{ "mailinfo", cmd_mailinfo },
		{ "mailsplit", cmd_mailsplit },
		{ "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
		{ "merge-base", cmd_merge_base, RUN_SETUP },
		{ "merge-file", cmd_merge_file },
		{ "merge-ours", cmd_merge_ours, RUN_SETUP },
		{ "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
		{ "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
		{ "mktree", cmd_mktree, RUN_SETUP },
		{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
		{ "name-rev", cmd_name_rev, RUN_SETUP },
		{ "pack-objects", cmd_pack_objects, RUN_SETUP },
		{ "peek-remote", cmd_ls_remote },
		{ "pickaxe", cmd_blame, RUN_SETUP },
		{ "prune", cmd_prune, RUN_SETUP },
		{ "prune-packed", cmd_prune_packed, RUN_SETUP },
		{ "push", cmd_push, RUN_SETUP },
		{ "read-tree", cmd_read_tree, RUN_SETUP },
		{ "receive-pack", cmd_receive_pack },
		{ "reflog", cmd_reflog, RUN_SETUP },
		{ "remote", cmd_remote, RUN_SETUP },
		{ "repo-config", cmd_config },
		{ "rerere", cmd_rerere, RUN_SETUP },
		{ "reset", cmd_reset, RUN_SETUP },
		{ "rev-list", cmd_rev_list, RUN_SETUP },
		{ "rev-parse", cmd_rev_parse },
		{ "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
		{ "rm", cmd_rm, RUN_SETUP },
		{ "send-pack", cmd_send_pack, RUN_SETUP },
		{ "shortlog", cmd_shortlog, USE_PAGER },
		{ "show-branch", cmd_show_branch, RUN_SETUP },
		{ "show", cmd_show, RUN_SETUP | USE_PAGER },
		{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
		{ "stripspace", cmd_stripspace },
		{ "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
		{ "tag", cmd_tag, RUN_SETUP },
		{ "tar-tree", cmd_tar_tree },
		{ "unpack-objects", cmd_unpack_objects, RUN_SETUP },
		{ "update-index", cmd_update_index, RUN_SETUP },
		{ "update-ref", cmd_update_ref, RUN_SETUP },
		{ "upload-archive", cmd_upload_archive },
		{ "verify-tag", cmd_verify_tag, RUN_SETUP },
		{ "version", cmd_version },
		{ "whatchanged", cmd_whatchanged, RUN_SETUP | USE_PAGER },
		{ "write-tree", cmd_write_tree, RUN_SETUP },
		{ "verify-pack", cmd_verify_pack },
		{ "show-ref", cmd_show_ref, RUN_SETUP },
		{ "pack-refs", cmd_pack_refs, RUN_SETUP },
	};
	int i;
	static const char ext[] = STRIP_EXTENSION;

	if (sizeof(ext) > 1) {
		i = strlen(argv[0]) - strlen(ext);
		if (i > 0 && !strcmp(argv[0] + i, ext)) {
			char *argv0 = xstrdup(argv[0]);
			argv[0] = cmd = argv0;
			argv0[i] = '\0';
		}
	}

	/* Turn "git cmd --help" into "git help cmd" */
	if (argc > 1 && !strcmp(argv[1], "--help")) {
		argv[1] = argv[0];
		argv[0] = cmd = "help";
	}

	for (i = 0; i < ARRAY_SIZE(commands); i++) {
		struct cmd_struct *p = commands+i;
		if (strcmp(p->cmd, cmd))
			continue;
		exit(run_builtin(p, argc, argv));
	}
}

static void execv_dashed_external(const char **argv)
{
	struct strbuf cmd = STRBUF_INIT;
	const char *tmp;
	int status;

	strbuf_addf(&cmd, "git-%s", argv[0]);

	/*
	 * argv[0] must be the git command, but the argv array
	 * belongs to the caller, and may be reused in
	 * subsequent loop iterations. Save argv[0] and
	 * restore it on error.
	 */
	tmp = argv[0];
	argv[0] = cmd.buf;

	trace_argv_printf(argv, "trace: exec:");

	/*
	 * if we fail because the command is not found, it is
	 * OK to return. Otherwise, we just pass along the status code.
	 */
	status = run_command_v_opt(argv, 0);
	if (status != -ERR_RUN_COMMAND_EXEC) {
		if (IS_RUN_COMMAND_ERR(status))
			die("unable to run '%s'", argv[0]);
		exit(-status);
	}
	errno = ENOENT; /* as if we called execvp */

	argv[0] = tmp;

	strbuf_release(&cmd);
}

static int run_argv(int *argcp, const char ***argv)
{
	int done_alias = 0;

	while (1) {
		/* See if it's an internal command */
		handle_internal_command(*argcp, *argv);

		/* .. then try the external ones */
		execv_dashed_external(*argv);

		/* It could be an alias -- this works around the insanity
		 * of overriding "git log" with "git show" by having
		 * alias.log = show
		 */
		if (done_alias || !handle_alias(argcp, argv))
			break;
		done_alias = 1;
	}

	return done_alias;
}


int main(int argc, const char **argv)
{
	const char *cmd;

	cmd = git_extract_argv0_path(argv[0]);
	if (!cmd)
		cmd = "git-help";

	/*
	 * "git-xxxx" is the same as "git xxxx", but we obviously:
	 *
	 *  - cannot take flags in between the "git" and the "xxxx".
	 *  - cannot execute it externally (since it would just do
	 *    the same thing over again)
	 *
	 * So we just directly call the internal command handler, and
	 * die if that one cannot handle it.
	 */
	if (!prefixcmp(cmd, "git-")) {
		cmd += 4;
		argv[0] = cmd;
		handle_internal_command(argc, argv);
		die("cannot handle %s internally", cmd);
	}

	/* Look for flags.. */
	argv++;
	argc--;
	handle_options(&argv, &argc, NULL);
	commit_pager_choice();
	if (argc > 0) {
		if (!prefixcmp(argv[0], "--"))
			argv[0] += 2;
	} else {
		/* The user didn't specify a command; give them help */
		printf("usage: %s\n\n", git_usage_string);
		list_common_cmds_help();
		printf("\n%s\n", git_more_info_string);
		exit(1);
	}
	cmd = argv[0];

	/*
	 * We use PATH to find git commands, but we prepend some higher
	 * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
	 * environment, and the $(gitexecdir) from the Makefile at build
	 * time.
	 */
	setup_path();

	while (1) {
		static int done_help = 0;
		static int was_alias = 0;
		was_alias = run_argv(&argc, &argv);
		if (errno != ENOENT)
			break;
		if (was_alias) {
			fprintf(stderr, "Expansion of alias '%s' failed; "
				"'%s' is not a git-command\n",
				cmd, argv[0]);
			exit(1);
		}
		if (!done_help) {
			cmd = argv[0] = help_unknown_cmd(cmd);
			done_help = 1;
		} else
			break;
	}

	fprintf(stderr, "Failed to run command '%s': %s\n",
		cmd, strerror(errno));

	return 1;
}
