write: Improve help text of --writer.

[paraslash.git] / gui.c

/*
 * Copyright (C) 1998 Andre Noll <maan@tuebingen.mpg.de>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file gui.c Curses-based interface for paraslash. */

#include <regex.h>
#include <signal.h>
#include <sys/types.h>
#include <curses.h>
#include <locale.h>
#include <sys/time.h>

#include "gui.cmdline.h"
#include "para.h"
#include "gui.h"
#include "string.h"
#include "ringbuffer.h"
#include "fd.h"
#include "error.h"
#include "list.h"
#include "sched.h"
#include "signal.h"
#include "ggo.h"
#include "version.h"

/** define the array of error lists needed by para_gui */
INIT_GUI_ERRLISTS;
static char *stat_content[NUM_STAT_ITEMS];

static struct gui_window {
        WINDOW *win;
        bool needs_update;
} top, bot, sb, in, sep;

/** How many lines of output to remember. */
#define RINGBUFFER_SIZE 512

struct rb_entry {
        char *msg;
        size_t len;
        int color;
};
static struct ringbuffer *bot_win_rb;

static unsigned scroll_position;

static pid_t exec_pid;

static int exec_fds[2] = {-1, -1};
static struct gui_args_info conf;
static int loglevel;

/** Type of the process currently being executed. */
enum exec_status {
        EXEC_IDLE, /**< No process running. */
        EXEC_DCMD, /**< para or display process running. */
        EXEC_XCMD, /**< External process running. */
};

/**
 * Codes for various colors.
 *
 * Each status item has its own color pair. The ones defined here start at a
 * higher number so that they do not overlap with these.
 */
enum gui_color_pair {
        COLOR_STATUSBAR = NUM_STAT_ITEMS + 1,
        COLOR_COMMAND,
        COLOR_OUTPUT,
        COLOR_MSG,
        COLOR_ERRMSG,
        COLOR_SEPARATOR,
        COLOR_TOP,
        COLOR_BOT,
};

struct gui_command {
        const char *key;
        const char *name;
        const char *description;
        void (*handler)(void);
};

static struct gui_theme theme;

#define GUI_COMMANDS \
        GUI_COMMAND(help, "?", "print help") \
        GUI_COMMAND(enlarge_top_win, "+", "enlarge the top window") \
        GUI_COMMAND(shrink_top_win, "-", "shrink the top window") \
        GUI_COMMAND(reread_conf, "r", "reread configuration file") \
        GUI_COMMAND(quit, "q", "exit para_gui") \
        GUI_COMMAND(refresh, "^L", "redraw the screen") \
        GUI_COMMAND(next_theme, ".", "switch to next theme") \
        GUI_COMMAND(prev_theme, ",", "switch to previous theme") \
        GUI_COMMAND(ll_incr, ">", "increase loglevel (decreases verbosity)") \
        GUI_COMMAND(ll_decr, "<", "decrease loglevel (increases verbosity)") \
        GUI_COMMAND(version, "V", "show the para_gui version") \
        GUI_COMMAND(scroll_up, "<up>", "scroll up one line") \
        GUI_COMMAND(scroll_down, "<down>", "scroll_down") \
        GUI_COMMAND(page_up, "<ppage>", "scroll up one page") \
        GUI_COMMAND(page_down, "<npage>", "scroll down one page") \
        GUI_COMMAND(scroll_top, "<home>", "scroll to top of buffer") \
        GUI_COMMAND(cancel_scroll, "<end>", "deactivate scroll mode") \

/* declare command handlers */
#define GUI_COMMAND(_c, _k, _d) \
        static void com_ ## _c(void);
GUI_COMMANDS

#undef GUI_COMMAND

/* define command array */
#define GUI_COMMAND(_c, _k, _d) \
        { \
                .key = _k, \
                .name = #_c, \
                .description = _d, \
                .handler = com_ ## _c \
        },

static struct gui_command command_list[] = {GUI_COMMANDS {.name = NULL}};

struct input_task {
        struct task *task;
};

struct status_task {
        struct task *task;
        pid_t pid;
        char *buf;
        int bufsize, loaded;
        struct timeval next_exec;
        int fd;
};

/** Stdout/stderr of the executing process is read in chunks of this size. */
#define COMMAND_BUF_SIZE 32768

struct exec_task {
        struct task *task;
        char command_buf[2][COMMAND_BUF_SIZE]; /* stdout/stderr of command */
        int cbo[2]; /* command buf offsets */
        unsigned flags[2]; /* passed to for_each_line() */
};

static int find_cmd_byname(const char *name)
{
        int i;

        for (i = 0; command_list[i].handler; i++)
                if (!strcmp(command_list[i].name, name))
                        return i;
        return -1;
}

/*
 * Even though ncurses provides getmaxx and getmaxy, these functions/macros are
 * not described in the XSI Curses standard.
 */
static int get_num_lines(struct gui_window *w)
{
        int lines;
        __a_unused int cols; /* avoid "set but not used" warnings */

        getmaxyx(w->win, lines, cols);
        return lines;
}

static int get_num_cols(struct gui_window *w)
{
        __a_unused int lines; /* avoid "set but not used" warnings */
        int cols;

        getmaxyx(w->win, lines, cols);
        return cols;
}

/** Number of lines of the window are occupied by an output line. */
#define NUM_LINES(len) (1 + (len) / get_num_cols(&bot))

/* isendwin() returns false before initscr() was called */
static bool curses_active(void)
{
        return top.win && !isendwin();
}

/* taken from mutt */
static char *km_keyname(int c)
{
        static char buf[10];

        if (c == KEY_UP) {
                sprintf(buf, "<up>");
                return buf;
        }
        if (c == KEY_DOWN) {
                sprintf(buf, "<down>");
                return buf;
        }
        if (c == KEY_LEFT) {
                sprintf(buf, "<left>");
                return buf;
        }
        if (c == KEY_RIGHT) {
                sprintf(buf, "<right>");
                return buf;
        }
        if (c == KEY_NPAGE) {
                sprintf(buf, "<npage>");
                return buf;
        }
        if (c == KEY_PPAGE) {
                sprintf(buf, "<ppage>");
                return buf;
        }
        if (c == KEY_HOME) {
                sprintf(buf, "<home>");
                return buf;
        }
        if (c == KEY_END) {
                sprintf(buf, "<end>");
                return buf;
        }
        if (c < 256 && c > -128 && iscntrl((unsigned char) c)) {
                if (c < 0)
                        c += 256;
                if (c < 128) {
                        buf[0] = '^';
                        buf[1] = (c + '@') & 0x7f;
                        buf[2] = 0;
                } else
                        snprintf(buf, sizeof(buf), "\\%d%d%d", c >> 6,
                                (c >> 3) & 7, c & 7);
        } else if (c >= KEY_F0 && c < KEY_F(256))
                sprintf(buf, "<F%d>", c - KEY_F0);
        else if (isprint(c))
                snprintf(buf, sizeof(buf), "%c", (unsigned char) c);
        else
                snprintf(buf, sizeof(buf), "\\x%hx", (unsigned short) c);
        return buf;
}

/* Print given number of spaces to curses window. */
static void add_spaces(WINDOW* win, unsigned int num)
{
        const char space[] = "                                ";
        const unsigned sz = sizeof(space) - 1; /* number of spaces */

        while (num >= sz)  {
                waddstr(win, space);
                num -= sz;
        }
        if (num > 0) {
                assert(num < sz);
                waddstr(win, space + sz - num);
        }
}

/*
 * print aligned string to curses window. This function always prints
 * exactly len chars.
 */
static int align_str(WINDOW* win, const char *str, unsigned int len,
                unsigned int align)
{
        int ret, num; /* of spaces */
        size_t width;
        char *sstr; /* sanitized string */

        if (!win || !str)
                return 0;
        ret = sanitize_str(str, len, &sstr, &width);
        if (ret < 0) {
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                width = 0;
                sstr = para_strdup(NULL);
        }
        assert(width <= len);
        num = len - width;
        if (align == LEFT) {
                waddstr(win, sstr);
                add_spaces(win, num);
        } else if (align == RIGHT) {
                add_spaces(win, num);
                waddstr(win, sstr);
        } else {
                add_spaces(win, num / 2);
                waddstr(win, sstr);
                add_spaces(win, num - num / 2);
        }
        free(sstr);
        return 1;
}

static void refresh_window(struct gui_window *gw)
{
        gw->needs_update = true;
}

static bool window_update_needed(void)
{
        return top.needs_update || bot.needs_update || sb.needs_update ||
                in.needs_update || sep.needs_update;
}

__printf_2_3 static void print_in_bar(int color, const char *fmt,...)
{
        char *msg;
        va_list ap;

        if (!curses_active())
                return;
        wattron(in.win, COLOR_PAIR(color));
        va_start(ap, fmt);
        xvasprintf(&msg, fmt, ap);
        va_end(ap);
        wmove(in.win, 0, 0);
        align_str(in.win, msg, get_num_cols(&in), LEFT);
        free(msg);
        refresh_window(&in);
}

static void print_status_bar(void)
{
        char *tmp;

        tmp = para_strdup("para_gui " PACKAGE_VERSION " (hit ? for help)");
        wmove(sb.win, 0, 0);
        align_str(sb.win, tmp, get_num_cols(&sb), CENTER);
        free(tmp);
}

/*
 * get the number of the oldest rbe that is (partially) visible. On return,
 * lines contains the sum of the number of lines of all visible entries. If the
 * first one is only partially visible, lines is greater than bot.lines.
 */
static int first_visible_rbe(unsigned *lines)
{
        int i, bot_lines = get_num_lines(&bot);

        *lines = 0;
        for (i = scroll_position; i < RINGBUFFER_SIZE; i++) {
                struct rb_entry *rbe = ringbuffer_get(bot_win_rb, i);
                int rbe_lines;
                if (!rbe)
                        return i - 1;
                rbe_lines = NUM_LINES(rbe->len);
                if (rbe_lines > bot_lines)
                        return -1;
                *lines += rbe_lines;
                if (*lines >= bot_lines)
                        return i;
        }
        return RINGBUFFER_SIZE - 1;
}

/*
returns number of first visible rbe, *lines is the number of lines drawn.
 */
static int draw_top_rbe(unsigned *lines)
{
        int bot_cols, bot_lines, ret, fvr = first_visible_rbe(lines);
        struct rb_entry *rbe;
        size_t bytes_to_skip, cells_to_skip, width;

        if (fvr < 0)
                return -1;
        wmove(bot.win, 0, 0);
        rbe = ringbuffer_get(bot_win_rb, fvr);
        if (!rbe)
                return -1;
        getmaxyx(bot.win, bot_lines, bot_cols);
        if (*lines > bot_lines) {
                /* rbe is partially visible multi-line */
                cells_to_skip = (*lines - bot_lines) * bot_cols;
                ret = skip_cells(rbe->msg, cells_to_skip, &bytes_to_skip);
                if (ret < 0)
                        return ret;
                ret = strwidth(rbe->msg + bytes_to_skip, &width);
                if (ret < 0)
                        return ret;
        } else {
                bytes_to_skip = 0;
                width = rbe->len;
        }
        wattron(bot.win, COLOR_PAIR(rbe->color));
        waddstr(bot.win, rbe->msg + bytes_to_skip);
        *lines = NUM_LINES(width);
        return fvr;
}

static void redraw_bot_win(void)
{
        unsigned lines;
        int i, bot_lines = get_num_lines(&bot);

        wmove(bot.win, 0, 0);
        wclear(bot.win);
        i = draw_top_rbe(&lines);
        if (i <= 0)
                goto out;
        while (i > 0 && lines < bot_lines) {
                struct rb_entry *rbe = ringbuffer_get(bot_win_rb, --i);
                if (!rbe) {
                        lines++;
                        waddstr(bot.win, "\n");
                        continue;
                }
                lines += NUM_LINES(rbe->len);
                wattron(bot.win, COLOR_PAIR(rbe->color));
                waddstr(bot.win, "\n");
                waddstr(bot.win, rbe->msg);
        }
out:
        refresh_window(&bot);
}

static void rb_add_entry(int color, char *msg)
{
        struct rb_entry *old, *new;
        int x, y;
        size_t len;

        if (strwidth(msg, &len) < 0)
                return;
        new = para_malloc(sizeof(struct rb_entry));
        new->color = color;
        new->len = len;
        new->msg = msg;
        old = ringbuffer_add(bot_win_rb, new);
        if (old) {
                free(old->msg);
                free(old);
        }
        if (scroll_position) {
                /* discard current scrolling, like xterm does */
                scroll_position = 0;
                redraw_bot_win();
                return;
        }
        wattron(bot.win, COLOR_PAIR(color));
        getyx(bot.win, y, x);
        if (y || x)
                waddstr(bot.win, "\n");
        waddstr(bot.win, msg);
}

/*
 * print formated output to bot win and refresh
 */
__printf_2_3 static void outputf(int color, const char* fmt,...)
{
        char *msg;
        va_list ap;

        if (!curses_active())
                return;
        va_start(ap, fmt);
        xvasprintf(&msg, fmt, ap);
        va_end(ap);
        rb_add_entry(color, msg);
        refresh_window(&bot);
}

static int add_output_line(char *line, void *data)
{
        int color = *(int *)data? COLOR_ERRMSG : COLOR_OUTPUT;

        if (!curses_active())
                return 1;
        rb_add_entry(color, para_strdup(line));
        return 1;
}

static __printf_2_3 void curses_log(int ll, const char *fmt,...)
{
        va_list ap;

        if (ll < loglevel)
                return;
        va_start(ap, fmt);
        if (curses_active()) {
                int color = ll <= LL_NOTICE? COLOR_MSG : COLOR_ERRMSG;
                char *msg;
                unsigned bytes = xvasprintf(&msg, fmt, ap);
                if (bytes > 0 && msg[bytes - 1] == '\n')
                        msg[bytes - 1] = '\0'; /* cut trailing newline */
                rb_add_entry(color, msg);
                refresh_window(&bot);
        } else if (exec_pid <= 0) /* no external command running */
                vfprintf(stderr, fmt, ap);
        va_end(ap);
}
/** The log function of para_gui, always set to curses_log(). */
__printf_2_3 void (*para_log)(int, const char*, ...) = curses_log;

/* Call endwin() to reset the terminal into non-visual mode. */
static void shutdown_curses(void)
{
        /*
         * If para_gui received a terminating signal in external mode, the
         * terminal can be in an unusable state at this point because the child
         * process might not have caught the signal. In this case endwin() has
         * already been called and must not be called again. So we first return
         * to program mode, then call endwin().
         */
        if (!curses_active())
                reset_prog_mode();
        endwin();
}

/* disable curses, print a message, kill running processes and exit */
__noreturn __printf_2_3 static void die(int exit_code, const char* fmt, ...)
{
        va_list argp;

        /* Kill every process in our process group. */
        para_sigaction(SIGTERM, SIG_IGN);
        kill(0, SIGTERM);
        /* Wait up to two seconds for child processes to die. */
        alarm(2);
        while (waitpid(0, NULL, 0) >= 0)
                ; /* nothing */
        alarm(0);
        /* mousemask() exists only in ncurses */
#ifdef NCURSES_MOUSE_VERSION
        mousemask(~(mmask_t)0, NULL); /* Avoid bad terminal state with xterm. */
#endif
        shutdown_curses();
        va_start(argp, fmt);
        vfprintf(stderr, fmt, argp);
        va_end(argp);
        exit(exit_code);
}

/*
 * Print stat item #i to curses window
 */
static void print_stat_item(int i)
{
        char *tmp;
        struct stat_item_data d = theme.data[i];
        char *c = stat_content[i];
        int top_lines = get_num_lines(&top);

        if (!curses_active() || !d.len || !c)
                return;
        tmp = make_message("%s%s%s", d.prefix, c, d.postfix);
        wmove(top.win, d.y * top_lines / 100, d.x * COLS / 100);
        wattron(top.win, COLOR_PAIR(i + 1));
        align_str(top.win, tmp, d.len * COLS / 100, d.align);
        free(tmp);
        refresh_window(&top);
}

static int update_item(int item_num, char *buf)
{
        char **c = stat_content + item_num;

        free(*c);
        if (buf && buf[0])
                goto dup;
        switch (item_num) {
        case SI_ARTIST:
                *c = para_strdup("(artist tag not set)");
                goto print;
        case SI_TITLE:
                *c = para_strdup("(title tag not set)");
                goto print;
        case SI_YEAR:
                *c = para_strdup("????");
                goto print;
        case SI_ALBUM:
                *c = para_strdup("(album tag not set)");
                goto print;
        case SI_COMMENT:
                *c = para_strdup("(comment tag not set)");
                goto print;
        }
dup:
        *c = para_strdup(buf);
print:
        print_stat_item(item_num);
        return 1;
}

static void print_all_items(void)
{
        int i;

        if (!curses_active())
                return;
        FOR_EACH_STATUS_ITEM(i)
                print_stat_item(i);
}

static void clear_all_items(void)
{
        int i;

        FOR_EACH_STATUS_ITEM(i) {
                free(stat_content[i]);
                stat_content[i] = para_strdup("");
        }
}

static void status_pre_select(struct sched *s, void *context)
{
        struct status_task *st = context;

        if (st->fd >= 0)
                para_fd_set(st->fd, &s->rfds, &s->max_fileno);
        if (task_get_notification(st->task) < 0)
                return sched_min_delay(s);
        if (st->fd < 0)
                sched_request_barrier_or_min_delay(&st->next_exec, s);
}

static int status_post_select(struct sched *s, void *context)
{
        struct status_task *st = context;
        size_t sz;
        int ret, ret2;

        ret = task_get_notification(st->task);
        if (ret == -E_GUI_SIGCHLD && st->pid > 0) {
                int exit_status;
                if (waitpid(st->pid, &exit_status, WNOHANG) == st->pid) {
                        st->pid = 0;
                        PARA_ERROR_LOG("stat command exit status: %d",
                                exit_status);
                }
        }
        if (st->fd < 0) {
                int fds[3] = {0, 1, 0};
                if (st->pid > 0)
                        return 0;
                /* Avoid busy loop */
                if (tv_diff(&st->next_exec, now, NULL) > 0)
                        return 0;
                st->next_exec.tv_sec = now->tv_sec + 2;
                ret = para_exec_cmdline_pid(&st->pid, conf.stat_cmd_arg, fds);
                if (ret < 0)
                        return 0;
                ret = mark_fd_nonblocking(fds[1]);
                if (ret < 0) {
                        close(fds[1]);
                        return 0;
                }
                st->fd = fds[1];
                return 0;
        }

        if (st->loaded >= st->bufsize) {
                if (st->bufsize > 1000 * 1000) {
                        st->loaded = 0;
                        return 0;
                }
                st->bufsize += st->bufsize + 1000;
                st->buf = para_realloc(st->buf, st->bufsize);
        }
        assert(st->loaded < st->bufsize);
        ret = read_nonblock(st->fd, st->buf + st->loaded,
                st->bufsize - st->loaded, &s->rfds, &sz);
        st->loaded += sz;
        ret2 = for_each_stat_item(st->buf, st->loaded, update_item);
        if (ret < 0 || ret2 < 0) {
                st->loaded = 0;
                PARA_NOTICE_LOG("closing stat pipe: %s\n",
                        para_strerror(ret < 0? -ret : -ret2));
                close(st->fd);
                st->fd = -1;
                clear_all_items();
                free(stat_content[SI_BASENAME]);
                stat_content[SI_BASENAME] =
                        para_strdup("stat command terminated!?");
                print_all_items();
                return 0;
        }
        sz = ret2; /* what is left */
        if (sz > 0 && sz < st->loaded)
                memmove(st->buf, st->buf + st->loaded - sz, sz);
        st->loaded = sz;
        return 0;
}

/*
 * init all windows
 */
static void init_wins(int top_lines)
{
        int top_y = 0, bot_y = top_lines + 1, sb_y = LINES - 2,
                in_y = LINES - 1, sep_y = top_lines;
        int bot_lines = LINES - top_lines - 3, sb_lines = 1, in_lines = 1,
                sep_lines = 1;

        assume_default_colors(theme.dflt.fg, theme.dflt.bg);
        if (top.win) {
                wresize(top.win, top_lines, COLS);
                mvwin(top.win, top_y, 0);

                wresize(sb.win, sb_lines, COLS);
                mvwin(sb.win, sb_y, 0);

                wresize(sep.win, sep_lines, COLS);
                mvwin(sep.win, sep_y, 0);

                wresize(bot.win, bot_lines, COLS);
                mvwin(bot.win, bot_y, 0);

                wresize(in.win, in_lines, COLS);
                mvwin(in.win, in_y, 0);
        } else {
                sep.win = newwin(sep_lines, COLS, sep_y, 0);
                top.win = newwin(top_lines, COLS, top_y, 0);
                bot.win = newwin(bot_lines, COLS, bot_y, 0);
                sb.win = newwin(sb_lines, COLS, sb_y, 0);
                in.win = newwin(in_lines, COLS, in_y, 0);
                if (!top.win || !bot.win || !sb.win || !in.win || !sep.win)
                        die(EXIT_FAILURE, "Error: Cannot create curses windows\n");
                wclear(bot.win);
                wclear(sb.win);
                wclear(in.win);
                scrollok(bot.win, 1);
                wattron(sb.win, COLOR_PAIR(COLOR_STATUSBAR));
                wattron(sep.win, COLOR_PAIR(COLOR_SEPARATOR));
                wattron(bot.win, COLOR_PAIR(COLOR_BOT));
                wattron(top.win, COLOR_PAIR(COLOR_TOP));
                nodelay(top.win, 1);
                nodelay(bot.win, 1);
                nodelay(sb.win, 1);
                nodelay(in.win, 0);

                keypad(top.win, 1);
                keypad(bot.win, 1);
                keypad(sb.win, 1);
                keypad(in.win, 1);
        }
        wmove(sep.win, 0, 0);
        whline(sep.win, theme.sep_char, COLS);
        wclear(top.win);
        print_all_items();
        //wclear(bot.win);
        wnoutrefresh(top.win);
        wnoutrefresh(bot.win);
        print_status_bar();
        wnoutrefresh(sb.win);
        wnoutrefresh(in.win);
        wnoutrefresh(sep.win);
        doupdate();
}

static void init_pair_or_die(short pair, short f, short b)
{
        if (init_pair(pair, f, b) == ERR)
                die(EXIT_FAILURE, "fatal: init_pair() failed\n");
}

static void init_colors_or_die(void)
{
        int i;

        if (!has_colors())
                die(EXIT_FAILURE, "fatal: No color term\n");
        if (start_color() == ERR)
                die(EXIT_FAILURE, "fatal: failed to start colors\n");
        FOR_EACH_STATUS_ITEM(i)
                if (theme.data[i].len)
                        init_pair_or_die(i + 1, theme.data[i].color.fg,
                                theme.data[i].color.bg);
        init_pair_or_die(COLOR_STATUSBAR, theme.sb.fg, theme.sb.bg);
        init_pair_or_die(COLOR_COMMAND, theme.cmd.fg, theme.cmd.bg);
        init_pair_or_die(COLOR_OUTPUT, theme.output.fg, theme.output.bg);
        init_pair_or_die(COLOR_MSG, theme.msg.fg, theme.msg.bg);
        init_pair_or_die(COLOR_ERRMSG, theme.err_msg.fg, theme.err_msg.bg);
        init_pair_or_die(COLOR_SEPARATOR, theme.sep.fg, theme.sep.bg);
        init_pair_or_die(COLOR_TOP, theme.dflt.fg, theme.dflt.bg);
        init_pair_or_die(COLOR_BOT, theme.dflt.fg, theme.dflt.bg);
}

/* (Re-)initialize the curses library. */
static void init_curses(void)
{
        if (curses_active())
                return;
        if (refresh() == ERR) /* refresh is really needed */
                die(EXIT_FAILURE, "refresh() failed\n");
        if (LINES < theme.lines_min || COLS < theme.cols_min)
                die(EXIT_FAILURE, "Terminal (%dx%d) too small"
                        " (need at least %dx%d)\n", COLS, LINES,
                        theme.cols_min, theme.lines_min);
        curs_set(0); /* make cursor invisible, ignore errors */
        nonl(); /* do not NL->CR/NL on output, always returns OK */
        /* don't echo input */
        if (noecho() == ERR)
                die(EXIT_FAILURE, "fatal: noecho() failed\n");
        /* take input chars one at a time, no wait for \n */
        if (cbreak() == ERR)
                die(EXIT_FAILURE, "fatal: cbreak() failed\n");
        init_colors_or_die();
        clear(); /* ignore non-fatal errors */
        init_wins(theme.top_lines_default);
        // noecho(); /* don't echo input */
}

/*
 * This sucker modifies its first argument. *handler and *arg are
 * pointers to 0-terminated strings (inside line). Crap.
 */
static int split_key_map(char *line, char **handler, char **arg)
{
        if (!(*handler = strchr(line + 1, ':')))
                goto err_out;
        **handler = '\0';
        (*handler)++;
        if (!(*arg = strchr(*handler, ':')))
                goto err_out;
        **arg = '\0';
        (*arg)++;
        return 1;
err_out:
        return 0;
}

static void check_key_map_args_or_die(void)
{
        int i;
        char *tmp = NULL;

        for (i = 0; i < conf.key_map_given; ++i) {
                char *handler, *arg;

                free(tmp);
                tmp = para_strdup(conf.key_map_arg[i]);
                if (!split_key_map(tmp, &handler, &arg))
                        break;
                if (strlen(handler) != 1)
                        break;
                if (*handler != 'x' && *handler != 'd' && *handler != 'i'
                                && *handler != 'p')
                        break;
                if (*handler != 'i')
                        continue;
                if (find_cmd_byname(arg) < 0)
                        break;
        }
        if (i != conf.key_map_given)
                die(EXIT_FAILURE, "invalid key map: %s\n", conf.key_map_arg[i]);
        free(tmp);
}

static void parse_config_file_or_die(bool override)
{
        bool err;
        char *config_file;
        struct gui_cmdline_parser_params params = {
                .override = override,
                .initialize = 0,
                .check_required = !override,
                .check_ambiguity = 0,
                .print_errors = 1,
        };

        if (conf.config_file_given)
                config_file = para_strdup(conf.config_file_arg);
        else {
                char *home = para_homedir();
                config_file = make_message("%s/.paraslash/gui.conf", home);
                free(home);
        }
        if (!file_exists(config_file)) {
                if (!conf.config_file_given)
                        err = false;
                else {
                        PARA_EMERG_LOG("config file %s does not exist\n",
                                config_file);
                        err = true;
                }
                goto out;
        }
        /*
         * When the gengetopt config file parser is called more than once, any
         * key map arguments found in the config file are _appended_ to the old
         * values, even though we turn on ->override. We want the new arguments
         * to replace the old ones, so we must empty the key_map_arg array
         * first. Unfortunately, this also clears any key map arguments given
         * at the command line.
         */
        if (override) {
                int i;
                for (i = 0; i < conf.key_map_given; i++) {
                        free(conf.key_map_arg[i]);
                        conf.key_map_arg[i] = NULL;
                }
                conf.key_map_given = 0;
        }

        gui_cmdline_parser_config_file(config_file, &conf, &params);
        loglevel = get_loglevel_by_name(conf.loglevel_arg);
        check_key_map_args_or_die();
        err = false;
out:
        free(config_file);
        if (err)
                exit(EXIT_FAILURE);
        theme_init(conf.theme_arg, &theme);
}

/* reread configuration, terminate on errors */
static void reread_conf(void)
{
        /*
         * gengetopt might print to stderr and exit on errors. So we have to
         * shutdown curses first.
         */
        shutdown_curses();
        parse_config_file_or_die(true /* override */);
        init_curses();
        print_in_bar(COLOR_MSG, "config file reloaded\n");
}

/*
 * React to various signal-related events
 */
static int signal_post_select(struct sched *s, __a_unused void *context)
{
        int ret = para_next_signal(&s->rfds);

        if (ret <= 0)
                return 0;
        switch (ret) {
        case SIGTERM:
                die(EXIT_FAILURE, "only the good die young (caught SIGTERM)\n");
        case SIGINT:
                return 1;
        case SIGUSR1:
                PARA_NOTICE_LOG("got SIGUSR1, rereading configuration\n");
                reread_conf();
                return 1;
        case SIGCHLD:
                task_notify_all(s, E_GUI_SIGCHLD);
                return 1;
        }
        return 1;
}

static enum exec_status exec_status(void)
{
        if (exec_fds[0] >= 0 || exec_fds[1] >= 0)
                return EXEC_DCMD;
        if (exec_pid > 0)
                return EXEC_XCMD;
        return EXEC_IDLE;
}

static void exec_pre_select(struct sched *s, void *context)
{
        struct exec_task *et = context;
        if (exec_fds[0] >= 0)
                para_fd_set(exec_fds[0], &s->rfds, &s->max_fileno);
        if (exec_fds[1] >= 0)
                para_fd_set(exec_fds[1], &s->rfds, &s->max_fileno);
        if (task_get_notification(et->task) < 0)
                sched_min_delay(s);
}

static int exec_post_select(struct sched *s, void *context)
{
        struct exec_task *ct = context;
        int i, ret;

        ret = task_get_notification(ct->task);
        if (ret == -E_GUI_SIGCHLD && exec_pid > 0) {
                int exit_status;
                if (waitpid(exec_pid, &exit_status, WNOHANG) == exec_pid) {
                        exec_pid = 0;
                        init_curses();
                        PARA_INFO_LOG("command exit status: %d", exit_status);
                        print_in_bar(COLOR_MSG, " ");
                }
        }
        for (i = 0; i < 2; i++) {
                size_t sz;
                if (exec_fds[i] < 0)
                        continue;
                ret = read_nonblock(exec_fds[i],
                        ct->command_buf[i] + ct->cbo[i],
                        COMMAND_BUF_SIZE - 1 - ct->cbo[i], &s->rfds, &sz);
                ct->cbo[i] += sz;
                sz = ct->cbo[i];
                ct->cbo[i] = for_each_line(ct->flags[i], ct->command_buf[i],
                        ct->cbo[i], add_output_line, &i);
                if (sz != ct->cbo[i]) { /* at least one line found */
                        refresh_window(&bot);
                        ct->flags[i] = 0;
                }
                if (ret < 0 || exec_pid == 0) {
                        if (ret < 0)
                                PARA_NOTICE_LOG("closing command fd %d: %s",
                                        i, para_strerror(-ret));
                        close(exec_fds[i]);
                        exec_fds[i] = -1;
                        ct->flags[i] = 0;
                        ct->cbo[i] = 0;
                        if (exec_fds[!i] < 0) /* both fds closed */
                                return 1;
                }
                if (ct->cbo[i] == COMMAND_BUF_SIZE - 1) {
                        PARA_NOTICE_LOG("discarding overlong line");
                        ct->cbo[i] = 0;
                        ct->flags[i] = FELF_DISCARD_FIRST;
                }
        }
        return 0;
}

static void input_pre_select(struct sched *s, __a_unused void *context)
{
        if (exec_status() != EXEC_XCMD)
                para_fd_set(STDIN_FILENO, &s->rfds, &s->max_fileno);
        if (window_update_needed())
                sched_min_delay(s);
}

/* read from command pipe and print data to bot window */
static void exec_and_display(const char *file_and_args)
{
        int ret, fds[3] = {0, 1, 1};

        outputf(COLOR_COMMAND, "%s", file_and_args);
        ret = para_exec_cmdline_pid(&exec_pid, file_and_args, fds);
        if (ret < 0)
                return;
        ret = mark_fd_nonblocking(fds[1]);
        if (ret < 0)
                goto fail;
        ret = mark_fd_nonblocking(fds[2]);
        if (ret < 0)
                goto fail;
        exec_fds[0] = fds[1];
        exec_fds[1] = fds[2];
        print_in_bar(COLOR_MSG, "hit any key to abort\n");
        return;
fail:
        PARA_ERROR_LOG("%s\n", para_strerror(-ret));
        close(exec_fds[0]);
        close(exec_fds[1]);
}

static void exec_para(const char *args)
{
        char *file_and_args;

        file_and_args = make_message(BINDIR "/para_client -- %s", args);
        exec_and_display(file_and_args);
        free(file_and_args);
}

/*
 * shutdown curses and stat pipe before executing external commands
 */
static void exec_external(char *file_and_args)
{
        int fds[3] = {-1, -1, -1};

        if (exec_pid)
                return;
        shutdown_curses();
        para_exec_cmdline_pid(&exec_pid, file_and_args, fds);
}

static void handle_command(int c)
{
        int i;

        /* first check user-defined key bindings */
        for (i = 0; i < conf.key_map_given; ++i) {
                char *tmp, *handler, *arg;

                tmp = para_strdup(conf.key_map_arg[i]);
                if (!split_key_map(tmp, &handler, &arg)) {
                        free(tmp);
                        return;
                }
                if (strcmp(tmp, km_keyname(c))) {
                        free(tmp);
                        continue;
                }
                if (*handler == 'd')
                        exec_and_display(arg);
                else if (*handler == 'x')
                        exec_external(arg);
                else if (*handler == 'p')
                        exec_para(arg);
                else if (*handler == 'i') {
                        int num = find_cmd_byname(arg);
                        if (num >= 0)
                                command_list[num].handler();
                }
                free(tmp);
                return;
        }
        /* not found, check internal key bindings */
        for (i = 0; command_list[i].handler; i++) {
                if (!strcmp(km_keyname(c), command_list[i].key)) {
                        command_list[i].handler();
                        return;
                }
        }
        print_in_bar(COLOR_ERRMSG, "key '%s' is not bound, press ? for help",
                km_keyname(c));
}

static int input_post_select(__a_unused struct sched *s, __a_unused void *context)
{
        int ret;
        enum exec_status exs = exec_status();

        if (exs == EXEC_XCMD)
                return 0;
        if (window_update_needed()) {
                if (top.needs_update)
                        assert(wnoutrefresh(top.win) == OK);
                if (bot.needs_update)
                        assert(wnoutrefresh(bot.win) == OK);
                if (sep.needs_update)
                        assert(wnoutrefresh(sep.win) == OK);
                if (sb.needs_update)
                        assert(wnoutrefresh(sb.win) == OK);
                if (in.needs_update)
                        assert(wnoutrefresh(in.win) == OK);
                doupdate();
                top.needs_update = bot.needs_update = sb.needs_update =
                        in.needs_update = sep.needs_update = false;
        }
        ret = wgetch(top.win);
        if (ret == ERR)
                return 0;
        if (ret == KEY_RESIZE) {
                if (curses_active()) {
                        shutdown_curses();
                        init_curses();
                        redraw_bot_win();
                }
                return 0;
        }
        if (exs == EXEC_IDLE)
                handle_command(ret);
        else if (exec_pid > 0)
                kill(exec_pid, SIGTERM);
        return 0;
}

static void print_scroll_msg(void)
{
        unsigned lines_total, filled = ringbuffer_filled(bot_win_rb);
        int first_rbe = first_visible_rbe(&lines_total);

        print_in_bar(COLOR_MSG, "scrolled view: %d-%d/%d\n", filled - first_rbe,
                filled - scroll_position, ringbuffer_filled(bot_win_rb));
}

static void com_scroll_top(void)
{
        int i = RINGBUFFER_SIZE - 1, bot_lines = get_num_lines(&bot);
        unsigned lines = 0;

        while (i > 0 && !ringbuffer_get(bot_win_rb, i))
                i--;
        /* i is oldest entry */
        for (; lines < bot_lines && i >= 0; i--) {
                struct rb_entry *rbe = ringbuffer_get(bot_win_rb, i);
                if (!rbe)
                        break;
                lines += NUM_LINES(rbe->len);
        }
        i++;
        if (lines > 0 && scroll_position != i) {
                scroll_position = i;
                redraw_bot_win();
                print_scroll_msg();
                return;
        }
        print_in_bar(COLOR_ERRMSG, "top of buffer is shown\n");
}

static void com_cancel_scroll(void)
{

        if (scroll_position == 0) {
                print_in_bar(COLOR_ERRMSG, "bottom of buffer is shown\n");
                return;
        }
        scroll_position = 0;
        redraw_bot_win();
}

static void com_page_down(void)
{
        unsigned lines = 0;
        int i = scroll_position, bot_lines = get_num_lines(&bot);

        while (lines < bot_lines && --i > 0) {
                struct rb_entry *rbe = ringbuffer_get(bot_win_rb, i);
                if (!rbe)
                        break;
                lines += NUM_LINES(rbe->len);
        }
        if (lines) {
                scroll_position = i;
                redraw_bot_win();
                print_scroll_msg();
                return;
        }
        print_in_bar(COLOR_ERRMSG, "bottom of buffer is shown\n");
}

static void com_page_up(void)
{
        unsigned lines;
        int fvr = first_visible_rbe(&lines), bot_lines = get_num_lines(&bot);

        if (fvr < 0 || fvr + 1 >= ringbuffer_filled(bot_win_rb)) {
                print_in_bar(COLOR_ERRMSG, "top of buffer is shown\n");
                return;
        }
        scroll_position = fvr + 1;
        for (; scroll_position > 0; scroll_position--) {
                first_visible_rbe(&lines);
                if (lines == bot_lines)
                        break;
        }
        redraw_bot_win();
        print_scroll_msg();
}

static void com_scroll_down(void)
{
        struct rb_entry *rbe;
        int rbe_lines, bot_lines = get_num_lines(&bot);

        if (!scroll_position) {
                print_in_bar(COLOR_ERRMSG, "bottom of buffer is shown\n");
                return;
        }
        scroll_position--;
        rbe = ringbuffer_get(bot_win_rb, scroll_position);
        rbe_lines = NUM_LINES(rbe->len);
        wscrl(bot.win, rbe_lines);
        wmove(bot.win, bot_lines - rbe_lines, 0);
        wattron(bot.win, COLOR_PAIR(rbe->color));
        waddstr(bot.win, rbe->msg);
        refresh_window(&bot);
        print_scroll_msg();
}

static void com_scroll_up(void)
{
        struct rb_entry *rbe = NULL;
        unsigned lines;
        int i, first_rbe, num_scroll;

        /* the entry that is going to vanish */
        rbe = ringbuffer_get(bot_win_rb, scroll_position);
        if (!rbe)
                goto err_out;
        num_scroll = NUM_LINES(rbe->len);
        first_rbe = first_visible_rbe(&lines);
        if (first_rbe < 0 || (first_rbe == ringbuffer_filled(bot_win_rb) - 1))
                goto err_out;
        scroll_position++;
        wscrl(bot.win, -num_scroll);
        i = draw_top_rbe(&lines);
        if (i < 0)
                goto err_out;
        while (i > 0 && lines < num_scroll) {
                int rbe_lines;
                rbe = ringbuffer_get(bot_win_rb, --i);
                if (!rbe)
                        break;
                rbe_lines = NUM_LINES(rbe->len);
                lines += rbe_lines;
                wattron(bot.win, COLOR_PAIR(rbe->color));
                waddstr(bot.win, "\n");
                waddstr(bot.win, rbe->msg);
                if (!i)
                        break;
                i--;
        }
        refresh_window(&bot);
        print_scroll_msg();
        return;
err_out:
        print_in_bar(COLOR_ERRMSG, "top of buffer is shown\n");
}

static void com_ll_decr(void)
{
        if (loglevel <= LL_DEBUG) {
                print_in_bar(COLOR_ERRMSG,
                        "loglevel already at maximal verbosity\n");
                return;
        }
        loglevel--;
        print_in_bar(COLOR_MSG, "loglevel set to %d\n", loglevel);
}

static void com_ll_incr(void)
{
        if (loglevel >= LL_EMERG) {
                print_in_bar(COLOR_ERRMSG,
                        "loglevel already at minimal verbosity\n");
                return;
        }
        loglevel++;
        print_in_bar(COLOR_MSG, "loglevel set to %d\n", loglevel);
}

static void com_reread_conf(void)
{
        reread_conf();
}

static void com_help(void)
{
        int i;

        for (i = 0; i < conf.key_map_given; ++i) {
                char *handler, *arg, *tmp = para_strdup(conf.key_map_arg[i]);
                const char *handler_text = "???", *desc = NULL;

                if (!split_key_map(tmp, &handler, &arg)) {
                        free(tmp);
                        return;
                }
                switch (*handler) {
                        case 'i':
                                handler_text = "internal";
                                desc = command_list[find_cmd_byname(arg)].description;
                                break;
                        case 'x': handler_text = "external"; break;
                        case 'd': handler_text = "display "; break;
                        case 'p': handler_text = "para    "; break;
                }
                outputf(COLOR_MSG, "%s\t%s\t%s%s\t%s", tmp, handler_text, arg,
                        strlen(arg) < 8? "\t" : "",
                        desc? desc : "");
                free(tmp);
        }
        for (i = 0; command_list[i].handler; i++) {
                struct gui_command gc = command_list[i];

                outputf(COLOR_MSG, "%s\tinternal\t%s\t%s%s", gc.key, gc.name,
                        strlen(gc.name) < 8? "\t" : "",
                        gc.description);
        }
        print_in_bar(COLOR_MSG, "try \"para_gui -h\" or \"para_client help\" "
                "for more info");
}

static void com_shrink_top_win(void)
{
        int top_lines = get_num_lines(&top);

        if (top_lines <= theme.top_lines_min) {
                PARA_WARNING_LOG("can not decrease top window\n");
                return;
        }
        init_wins(top_lines - 1);
        print_in_bar(COLOR_MSG, "%s", "decreased top window");
}

static void com_enlarge_top_win(void)
{
        int top_lines = get_num_lines(&top), bot_lines = get_num_lines(&bot);

        if (bot_lines < 3) {
                PARA_WARNING_LOG("can not increase top window\n");
                return;
        }
        init_wins(top_lines + 1);
        print_in_bar(COLOR_MSG, "increased top window");
}

static void com_version(void)
{
        print_in_bar(COLOR_MSG, "%s", version_single_line("gui"));
}

__noreturn static void com_quit(void)
{
        die(EXIT_SUCCESS, "%s", "");
}

static void com_refresh(void)
{
        shutdown_curses();
        init_curses();
}

static void com_next_theme(void)
{
        theme_next(&theme);
        com_refresh();
}

static void com_prev_theme(void)
{
        theme_prev(&theme);
        com_refresh();
}

__noreturn static void print_help_and_die(void)
{
        struct ggo_help h = DEFINE_GGO_HELP(gui);
        bool d = conf.detailed_help_given;

        ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
        exit(0);
}

static int setup_tasks_and_schedule(void)
{
        int ret;
        struct exec_task exec_task = {.task = NULL};
        struct status_task status_task = {.fd = -1};
        struct input_task input_task = {.task = NULL};
        struct signal_task *signal_task;
        struct sched sched = {
                .default_timeout = {
                        .tv_sec = conf.timeout_arg  / 1000,
                        .tv_usec = (conf.timeout_arg % 1000) * 1000,
                },
        };

        exec_task.task = task_register(&(struct task_info) {
                .name = "exec",
                .pre_select = exec_pre_select,
                .post_select = exec_post_select,
                .context = &exec_task,
        }, &sched);

        status_task.task = task_register(&(struct task_info) {
                .name = "status",
                .pre_select = status_pre_select,
                .post_select = status_post_select,
                .context = &status_task,
        }, &sched);

        input_task.task = task_register(&(struct task_info) {
                .name = "input",
                .pre_select = input_pre_select,
                .post_select = input_post_select,
                .context = &input_task,
        }, &sched);

        signal_task = signal_init_or_die();
        para_install_sighandler(SIGINT);
        para_install_sighandler(SIGTERM);
        para_install_sighandler(SIGCHLD);
        para_install_sighandler(SIGUSR1);
        signal_task->task = task_register(&(struct task_info) {
                .name = "signal",
                .pre_select = signal_pre_select,
                .post_select = signal_post_select,
                .context = signal_task,
        }, &sched);
        ret = schedule(&sched);
        sched_shutdown(&sched);
        signal_shutdown(signal_task);
        return ret;
}

/**
 * The main function of para_gui.
 *
 * \param argc Usual argument count.
 * \param argv Usual argument vector.
 *
 * After initialization para_gui registers the following tasks to the paraslash
 * scheduler: status, exec, signal, input.
 *
 * The status task executes the para_audioc stat command to obtain the status
 * of para_server and para_audiod, and displays this information in the top
 * window of para_gui.
 *
 * The exec task is responsible for printing the output of the currently
 * running executable to the bottom window.
 *
 * The signal task performs various actions according to signals received. For
 * example, it reloads the configuration file on SIGUSR1, and it shuts down the
 * curses system on SIGTERM to restore the terminal settings before exit.
 *
 * The input task reads single key strokes from stdin. For each key pressed, it
 * executes the command handler associated with this key.
 *
 * \return \p EXIT_SUCCESS or \p EXIT_FAILURE.
 */
int main(int argc, char *argv[])
{
        gui_cmdline_parser(argc, argv, &conf); /* exits on errors */
        loglevel = get_loglevel_by_name(conf.loglevel_arg);
        version_handle_flag("gui", conf.version_given);
        if (conf.help_given || conf.detailed_help_given)
                print_help_and_die();
        parse_config_file_or_die(false /* override */);
        bot_win_rb = ringbuffer_new(RINGBUFFER_SIZE);
        setlocale(LC_CTYPE, "");
        initscr(); /* needed only once, always successful */
        init_curses();
        return setup_tasks_and_schedule() < 0? EXIT_FAILURE : EXIT_SUCCESS;
}