/*
   * builtin-help.c
   *
   * Builtin help command
   */

  #include "perf.h"

  #include "util/cache.h"

  #include "builtin.h"

  #include "util/exec_cmd.h"

  #include "common-cmds.h"

  #include "util/parse-options.h"
  #include "util/run-command.h"
  #include "util/help.h"

  
  static struct man_viewer_list {
  	struct man_viewer_list *next;
  	char name[FLEX_ARRAY];
  } *man_viewer_list;
  
  static struct man_viewer_info_list {
  	struct man_viewer_info_list *next;
  	const char *info;
  	char name[FLEX_ARRAY];
  } *man_viewer_info_list;
  
  enum help_format {

  	HELP_FORMAT_NONE,

  	HELP_FORMAT_MAN,
  	HELP_FORMAT_INFO,
  	HELP_FORMAT_WEB,
  };

  static enum help_format parse_help_format(const char *format)
  {
  	if (!strcmp(format, "man"))
  		return HELP_FORMAT_MAN;
  	if (!strcmp(format, "info"))
  		return HELP_FORMAT_INFO;
  	if (!strcmp(format, "web") || !strcmp(format, "html"))
  		return HELP_FORMAT_WEB;

  
  	pr_err("unrecognized help format '%s'", format);
  	return HELP_FORMAT_NONE;

  }
  
  static const char *get_man_viewer_info(const char *name)
  {
  	struct man_viewer_info_list *viewer;

  	for (viewer = man_viewer_info_list; viewer; viewer = viewer->next) {

  		if (!strcasecmp(name, viewer->name))
  			return viewer->info;
  	}
  	return NULL;
  }
  
  static int check_emacsclient_version(void)
  {
  	struct strbuf buffer = STRBUF_INIT;
  	struct child_process ec_process;
  	const char *argv_ec[] = { "emacsclient", "--version", NULL };
  	int version;
  
  	/* emacsclient prints its version number on stderr */
  	memset(&ec_process, 0, sizeof(ec_process));
  	ec_process.argv = argv_ec;
  	ec_process.err = -1;
  	ec_process.stdout_to_stderr = 1;
  	if (start_command(&ec_process)) {
  		fprintf(stderr, "Failed to start emacsclient.
  ");
  		return -1;
  	}
  	strbuf_read(&buffer, ec_process.err, 20);
  	close(ec_process.err);
  
  	/*
  	 * Don't bother checking return value, because "emacsclient --version"
  	 * seems to always exits with code 1.
  	 */
  	finish_command(&ec_process);
  
  	if (prefixcmp(buffer.buf, "emacsclient")) {
  		fprintf(stderr, "Failed to parse emacsclient version.
  ");
  		strbuf_release(&buffer);
  		return -1;
  	}
  
  	strbuf_remove(&buffer, 0, strlen("emacsclient"));
  	version = atoi(buffer.buf);
  
  	if (version < 22) {
  		fprintf(stderr,
  			"emacsclient version '%d' too old (< 22).
  ",
  			version);
  		strbuf_release(&buffer);
  		return -1;
  	}
  
  	strbuf_release(&buffer);
  	return 0;
  }

  static void exec_woman_emacs(const char *path, const char *page)

  {
  	if (!check_emacsclient_version()) {
  		/* This works only with emacsclient version >= 22. */
  		struct strbuf man_page = STRBUF_INIT;
  
  		if (!path)
  			path = "emacsclient";
  		strbuf_addf(&man_page, "(woman \"%s\")", page);
  		execlp(path, "emacsclient", "-e", man_page.buf, NULL);
  		warning("failed to exec '%s': %s", path, strerror(errno));
  	}
  }

  static void exec_man_konqueror(const char *path, const char *page)

  {
  	const char *display = getenv("DISPLAY");
  	if (display && *display) {
  		struct strbuf man_page = STRBUF_INIT;
  		const char *filename = "kfmclient";
  
  		/* It's simpler to launch konqueror using kfmclient. */
  		if (path) {
  			const char *file = strrchr(path, '/');
  			if (file && !strcmp(file + 1, "konqueror")) {
  				char *new = strdup(path);
  				char *dest = strrchr(new, '/');
  
  				/* strlen("konqueror") == strlen("kfmclient") */
  				strcpy(dest + 1, "kfmclient");
  				path = new;
  			}
  			if (file)
  				filename = file;
  		} else
  			path = "kfmclient";
  		strbuf_addf(&man_page, "man:%s(1)", page);
  		execlp(path, filename, "newTab", man_page.buf, NULL);
  		warning("failed to exec '%s': %s", path, strerror(errno));
  	}
  }

  static void exec_man_man(const char *path, const char *page)

  {
  	if (!path)
  		path = "man";
  	execlp(path, "man", page, NULL);
  	warning("failed to exec '%s': %s", path, strerror(errno));
  }
  
  static void exec_man_cmd(const char *cmd, const char *page)
  {
  	struct strbuf shell_cmd = STRBUF_INIT;
  	strbuf_addf(&shell_cmd, "%s %s", cmd, page);
  	execl("/bin/sh", "sh", "-c", shell_cmd.buf, NULL);
  	warning("failed to exec '%s': %s", cmd, strerror(errno));
  }
  
  static void add_man_viewer(const char *name)
  {
  	struct man_viewer_list **p = &man_viewer_list;
  	size_t len = strlen(name);
  
  	while (*p)
  		p = &((*p)->next);

  	*p = zalloc(sizeof(**p) + len + 1);

  	strncpy((*p)->name, name, len);
  }
  
  static int supported_man_viewer(const char *name, size_t len)
  {
  	return (!strncasecmp("man", name, len) ||
  		!strncasecmp("woman", name, len) ||
  		!strncasecmp("konqueror", name, len));
  }
  
  static void do_add_man_viewer_info(const char *name,
  				   size_t len,
  				   const char *value)
  {

  	struct man_viewer_info_list *new = zalloc(sizeof(*new) + len + 1);

  
  	strncpy(new->name, name, len);
  	new->info = strdup(value);
  	new->next = man_viewer_info_list;
  	man_viewer_info_list = new;
  }
  
  static int add_man_viewer_path(const char *name,
  			       size_t len,
  			       const char *value)
  {
  	if (supported_man_viewer(name, len))
  		do_add_man_viewer_info(name, len, value);
  	else
  		warning("'%s': path for unsupported man viewer.
  "
  			"Please consider using 'man.<tool>.cmd' instead.",
  			name);
  
  	return 0;
  }
  
  static int add_man_viewer_cmd(const char *name,
  			      size_t len,
  			      const char *value)
  {
  	if (supported_man_viewer(name, len))
  		warning("'%s': cmd for supported man viewer.
  "
  			"Please consider using 'man.<tool>.path' instead.",
  			name);
  	else
  		do_add_man_viewer_info(name, len, value);
  
  	return 0;
  }
  
  static int add_man_viewer_info(const char *var, const char *value)
  {
  	const char *name = var + 4;
  	const char *subkey = strrchr(name, '.');
  
  	if (!subkey)
  		return error("Config with no key for man viewer: %s", name);
  
  	if (!strcmp(subkey, ".path")) {
  		if (!value)
  			return config_error_nonbool(var);
  		return add_man_viewer_path(name, subkey - name, value);
  	}
  	if (!strcmp(subkey, ".cmd")) {
  		if (!value)
  			return config_error_nonbool(var);
  		return add_man_viewer_cmd(name, subkey - name, value);
  	}
  
  	warning("'%s': unsupported man viewer sub key.", subkey);
  	return 0;
  }
  
  static int perf_help_config(const char *var, const char *value, void *cb)
  {

  	enum help_format *help_formatp = cb;

  	if (!strcmp(var, "help.format")) {
  		if (!value)
  			return config_error_nonbool(var);

  		*help_formatp = parse_help_format(value);
  		if (*help_formatp == HELP_FORMAT_NONE)

  			return -1;

  		return 0;
  	}
  	if (!strcmp(var, "man.viewer")) {
  		if (!value)
  			return config_error_nonbool(var);
  		add_man_viewer(value);
  		return 0;
  	}
  	if (!prefixcmp(var, "man."))
  		return add_man_viewer_info(var, value);
  
  	return perf_default_config(var, value, cb);
  }
  
  static struct cmdnames main_cmds, other_cmds;
  
  void list_common_cmds_help(void)
  {

  	unsigned int i, longest = 0;

  
  	for (i = 0; i < ARRAY_SIZE(common_cmds); i++) {
  		if (longest < strlen(common_cmds[i].name))
  			longest = strlen(common_cmds[i].name);
  	}

  	puts(" The most commonly used perf commands are:");

  	for (i = 0; i < ARRAY_SIZE(common_cmds); i++) {

  		printf("   %-*s   ", longest, common_cmds[i].name);

  		puts(common_cmds[i].help);
  	}
  }
  
  static int is_perf_command(const char *s)
  {
  	return is_in_cmdlist(&main_cmds, s) ||
  		is_in_cmdlist(&other_cmds, s);
  }
  
  static const char *prepend(const char *prefix, const char *cmd)
  {
  	size_t pre_len = strlen(prefix);
  	size_t cmd_len = strlen(cmd);
  	char *p = malloc(pre_len + cmd_len + 1);
  	memcpy(p, prefix, pre_len);
  	strcpy(p + pre_len, cmd);
  	return p;
  }
  
  static const char *cmd_to_page(const char *perf_cmd)
  {
  	if (!perf_cmd)
  		return "perf";
  	else if (!prefixcmp(perf_cmd, "perf"))
  		return perf_cmd;

  	else

  		return prepend("perf-", perf_cmd);

  }
  
  static void setup_man_path(void)
  {
  	struct strbuf new_path = STRBUF_INIT;
  	const char *old_path = getenv("MANPATH");
  
  	/* We should always put ':' after our path. If there is no
  	 * old_path, the ':' at the end will let 'man' to try
  	 * system-wide paths after ours to find the manual page. If
  	 * there is old_path, we need ':' as delimiter. */
  	strbuf_addstr(&new_path, system_path(PERF_MAN_PATH));
  	strbuf_addch(&new_path, ':');
  	if (old_path)
  		strbuf_addstr(&new_path, old_path);
  
  	setenv("MANPATH", new_path.buf, 1);
  
  	strbuf_release(&new_path);
  }
  
  static void exec_viewer(const char *name, const char *page)
  {
  	const char *info = get_man_viewer_info(name);
  
  	if (!strcasecmp(name, "man"))
  		exec_man_man(info, page);
  	else if (!strcasecmp(name, "woman"))
  		exec_woman_emacs(info, page);
  	else if (!strcasecmp(name, "konqueror"))
  		exec_man_konqueror(info, page);
  	else if (info)
  		exec_man_cmd(info, page);
  	else
  		warning("'%s': unknown man viewer.", name);
  }

  static int show_man_page(const char *perf_cmd)

  {
  	struct man_viewer_list *viewer;
  	const char *page = cmd_to_page(perf_cmd);
  	const char *fallback = getenv("PERF_MAN_VIEWER");
  
  	setup_man_path();
  	for (viewer = man_viewer_list; viewer; viewer = viewer->next)

  		exec_viewer(viewer->name, page); /* will return when unable */

  	if (fallback)
  		exec_viewer(fallback, page);
  	exec_viewer("man", page);

  
  	pr_err("no man viewer handled the request");
  	return -1;

  }

  static int show_info_page(const char *perf_cmd)

  {
  	const char *page = cmd_to_page(perf_cmd);
  	setenv("INFOPATH", system_path(PERF_INFO_PATH), 1);
  	execlp("info", "info", "perfman", page, NULL);

  	return -1;

  }

  static int get_html_page_path(struct strbuf *page_path, const char *page)

  {
  	struct stat st;
  	const char *html_path = system_path(PERF_HTML_PATH);
  
  	/* Check that we have a perf documentation directory. */
  	if (stat(mkpath("%s/perf.html", html_path), &st)

  	    || !S_ISREG(st.st_mode)) {
  		pr_err("'%s': not a documentation directory.", html_path);
  		return -1;
  	}

  
  	strbuf_init(page_path, 0);
  	strbuf_addf(page_path, "%s/%s.html", html_path, page);

  
  	return 0;

  }
  
  /*
   * If open_html is not defined in a platform-specific way (see for
   * example compat/mingw.h), we use the script web--browse to display
   * HTML.
   */
  #ifndef open_html

  static void open_html(const char *path)

  {
  	execl_perf_cmd("web--browse", "-c", "help.browser", path, NULL);
  }
  #endif

  static int show_html_page(const char *perf_cmd)

  {
  	const char *page = cmd_to_page(perf_cmd);
  	struct strbuf page_path; /* it leaks but we exec bellow */

  	if (get_html_page_path(&page_path, page) != 0)
  		return -1;

  
  	open_html(page_path.buf);

  
  	return 0;

  }

  int cmd_help(int argc, const char **argv, const char *prefix __maybe_unused)

  {

  	bool show_all = false;

  	enum help_format help_format = HELP_FORMAT_MAN;

  	struct option builtin_help_options[] = {
  	OPT_BOOLEAN('a', "all", &show_all, "print all available commands"),
  	OPT_SET_UINT('m', "man", &help_format, "show man page", HELP_FORMAT_MAN),
  	OPT_SET_UINT('w', "web", &help_format, "show manual in web browser",
  			HELP_FORMAT_WEB),
  	OPT_SET_UINT('i', "info", &help_format, "show info page",
  			HELP_FORMAT_INFO),
  	OPT_END(),
  	};
  	const char * const builtin_help_usage[] = {
  		"perf help [--all] [--man|--web|--info] [command]",
  		NULL
  	};

  	const char *alias;

  	int rc = 0;

  	load_command_list("perf-", &main_cmds, &other_cmds);

  	perf_config(perf_help_config, &help_format);

  
  	argc = parse_options(argc, argv, builtin_help_options,
  			builtin_help_usage, 0);
  
  	if (show_all) {

  		printf("
   usage: %s
  
  ", perf_usage_string);

  		list_commands("perf commands", &main_cmds, &other_cmds);

  		printf(" %s
  
  ", perf_more_info_string);

  		return 0;
  	}
  
  	if (!argv[0]) {

  		printf("
   usage: %s
  
  ", perf_usage_string);

  		list_common_cmds_help();

  		printf("
   %s
  
  ", perf_more_info_string);

  		return 0;
  	}
  
  	alias = alias_lookup(argv[0]);
  	if (alias && !is_perf_command(argv[0])) {
  		printf("`perf %s' is aliased to `%s'
  ", argv[0], alias);
  		return 0;
  	}
  
  	switch (help_format) {
  	case HELP_FORMAT_MAN:

  		rc = show_man_page(argv[0]);

  		break;
  	case HELP_FORMAT_INFO:

  		rc = show_info_page(argv[0]);

  		break;
  	case HELP_FORMAT_WEB:

  		rc = show_html_page(argv[0]);
  		break;
  	case HELP_FORMAT_NONE:
  		/* fall-through */

  	default:

  		rc = -1;

  		break;
  	}

  	return rc;

  }