/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */

/*
 * Prompting and other messages.
 * There are three flavors of prompts, SHORT, MEDIUM and LONG,
 * selected by the -m/-M options.
 * There is also the "equals message", printed by the = command.
 * A prompt is a message composed of various pieces, such as the
 * name of the file being viewed, the percentage into the file, etc.
 */

#include "less.h"
#include "position.h"

extern int pr_type;
extern int new_file;
extern int sc_width;
extern int so_s_width, so_e_width;
extern int linenums;
extern int hshift;
extern int sc_height;
extern int jump_sline;
extern int less_is_more;
extern IFILE curr_ifile;
extern char *editor;
extern char *editproto;

/*
 * Prototypes for the three flavors of prompts.
 * These strings are expanded by pr_expand().
 */
static const char s_proto[] =
        "?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\\: %x..%t";
static const char m_proto[] =
        "?n?f%f .?m(%T %i of %m) ..?e(END) "
        "?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t";
static const char M_proto[] =
        "?f%f .?n?m(%T %i of %m) ..?"
        "ltlines %lt-%lb?L/%L. :byte %bB?s/%s. .?e(END)"
        " ?x- Next\\: %x.:?pB%pB\\%..%t";
static const char e_proto[] =
        "?f%f .?m(%T %i of %m) .?ltlines "
        "%lt-%lb?L/%L. .byte %bB?s/%s. ?e(END) :?pB%pB\\%..%t";
static const char h_proto[] =
        "HELP -- ?eEND -- Press g to see it again:"
        "Press RETURN for more., or q when done";
static const char w_proto[] =
        "Waiting for data";
static const char more_proto[] =
        "%f (?eEND ?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t)";
static const char more_M_proto[] =
        "%f (?eEND ?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t)"
        "[Press space to continue, q to quit, h for help]";

char *prproto[3];
char const *eqproto = e_proto;
char const *hproto = h_proto;
char const *wproto = w_proto;

static char message[PROMPT_SIZE];
static char *mp;

/*
 * Initialize the prompt prototype strings.
 */
void
init_prompt(void)
{
        prproto[0] = estrdup(s_proto);
        prproto[1] = estrdup(less_is_more ? more_proto : m_proto);
        prproto[2] = estrdup(less_is_more ? more_M_proto : M_proto);
        eqproto = estrdup(e_proto);
        hproto = estrdup(h_proto);
        wproto = estrdup(w_proto);
}

/*
 * Append a string to the end of the message.
 */
static void
ap_str(char *s)
{
        int len;

        len = strlen(s);
        if (mp + len >= message + PROMPT_SIZE)
                len = message + PROMPT_SIZE - mp - 1;
        (void) strncpy(mp, s, len);
        mp += len;
        *mp = '\0';
}

/*
 * Append a character to the end of the message.
 */
static void
ap_char(char c)
{
        char buf[2];

        buf[0] = c;
        buf[1] = '\0';
        ap_str(buf);
}

/*
 * Append a off_t (as a decimal integer) to the end of the message.
 */
static void
ap_pos(off_t pos)
{
        char buf[23];

        postoa(pos, buf, sizeof(buf));
        ap_str(buf);
}

/*
 * Append an integer to the end of the message.
 */
static void
ap_int(int num)
{
        char buf[13];

        inttoa(num, buf, sizeof buf);
        ap_str(buf);
}

/*
 * Append a question mark to the end of the message.
 */
static void
ap_quest(void)
{
        ap_str("?");
}

/*
 * Return the "current" byte offset in the file.
 */
static off_t
curr_byte(int where)
{
        off_t pos;

        pos = position(where);
        while (pos == -1 && where >= 0 && where < sc_height-1)
                pos = position(++where);
        if (pos == -1)
                pos = ch_length();
        return (pos);
}

/*
 * Return the value of a prototype conditional.
 * A prototype string may include conditionals which consist of a
 * question mark followed by a single letter.
 * Here we decode that letter and return the appropriate boolean value.
 */
static int
cond(char c, int where)
{
        off_t len;

        switch (c) {
        case 'a':       /* Anything in the message yet? */
                return (*message != '\0');
        case 'b':       /* Current byte offset known? */
                return (curr_byte(where) != -1);
        case 'c':
                return (hshift != 0);
        case 'e':       /* At end of file? */
                return (eof_displayed());
        case 'f':       /* Filename known? */
                return (strcmp(get_filename(curr_ifile), "-") != 0);
        case 'l':       /* Line number known? */
        case 'd':       /* Same as l */
                return (linenums);
        case 'L':       /* Final line number known? */
        case 'D':       /* Final page number known? */
                return (linenums && ch_length() != -1);
        case 'm':       /* More than one file? */
                return (ntags() ? (ntags() > 1) : (nifile() > 1));
        case 'n':       /* First prompt in a new file? */
                return (ntags() ? 1 : new_file);
        case 'p':       /* Percent into file (bytes) known? */
                return (curr_byte(where) != -1 && ch_length() > 0);
        case 'P':       /* Percent into file (lines) known? */
                return (currline(where) != 0 &&
                    (len = ch_length()) > 0 && find_linenum(len) != 0);
        case 's':       /* Size of file known? */
        case 'B':
                return (ch_length() != -1);
        case 'x':       /* Is there a "next" file? */
                if (ntags())
                        return (0);
                return (next_ifile(curr_ifile) != NULL);
        }
        return (0);
}

/*
 * Decode a "percent" prototype character.
 * A prototype string may include various "percent" escapes;
 * that is, a percent sign followed by a single letter.
 * Here we decode that letter and take the appropriate action,
 * usually by appending something to the message being built.
 */
static void
protochar(int c, int where)
{
        off_t pos;
        off_t len;
        int n;
        off_t linenum;
        off_t last_linenum;
        IFILE h;

#undef  PAGE_NUM
#define PAGE_NUM(linenum)  ((((linenum) - 1) / (sc_height - 1)) + 1)

        switch (c) {
        case 'b':       /* Current byte offset */
                pos = curr_byte(where);
                if (pos != -1)
                        ap_pos(pos);
                else
                        ap_quest();
                break;
        case 'c':
                ap_int(hshift);
                break;
        case 'd':       /* Current page number */
                linenum = currline(where);
                if (linenum > 0 && sc_height > 1)
                        ap_pos(PAGE_NUM(linenum));
                else
                        ap_quest();
                break;
        case 'D':       /* Final page number */
                /* Find the page number of the last byte in the file (len-1). */
                len = ch_length();
                if (len == -1) {
                        ap_quest();
                } else if (len == 0) {
                        /* An empty file has no pages. */
                        ap_pos(0);
                } else {
                        linenum = find_linenum(len - 1);
                        if (linenum <= 0)
                                ap_quest();
                        else
                                ap_pos(PAGE_NUM(linenum));
                }
                break;
        case 'E':       /* Editor name */
                ap_str(editor);
                break;
        case 'f':       /* File name */
                ap_str(get_filename(curr_ifile));
                break;
        case 'F':       /* Last component of file name */
                ap_str(last_component(get_filename(curr_ifile)));
                break;
        case 'i':       /* Index into list of files */
                if (ntags())
                        ap_int(curr_tag());
                else
                        ap_int(get_index(curr_ifile));
                break;
        case 'l':       /* Current line number */
                linenum = currline(where);
                if (linenum != 0)
                        ap_pos(linenum);
                else
                        ap_quest();
                break;
        case 'L':       /* Final line number */
                len = ch_length();
                if (len == -1 || len == ch_zero() ||
                    (linenum = find_linenum(len)) <= 0)
                        ap_quest();
                else
                        ap_pos(linenum-1);
                break;
        case 'm':       /* Number of files */
                n = ntags();
                if (n)
                        ap_int(n);
                else
                        ap_int(nifile());
                break;
        case 'p':       /* Percent into file (bytes) */
                pos = curr_byte(where);
                len = ch_length();
                if (pos != -1 && len > 0)
                        ap_int(percentage(pos, len));
                else
                        ap_quest();
                break;
        case 'P':       /* Percent into file (lines) */
                linenum = currline(where);
                if (linenum == 0 ||
                    (len = ch_length()) == -1 || len == ch_zero() ||
                    (last_linenum = find_linenum(len)) <= 0)
                        ap_quest();
                else
                        ap_int(percentage(linenum, last_linenum));
                break;
        case 's':       /* Size of file */
        case 'B':
                len = ch_length();
                if (len != -1)
                        ap_pos(len);
                else
                        ap_quest();
                break;
        case 't':       /* Truncate trailing spaces in the message */
                while (mp > message && mp[-1] == ' ')
                        mp--;
                *mp = '\0';
                break;
        case 'T':       /* Type of list */
                if (ntags())
                        ap_str("tag");
                else
                        ap_str("file");
                break;
        case 'x':       /* Name of next file */
                h = next_ifile(curr_ifile);
                if (h != NULL)
                        ap_str(get_filename(h));
                else
                        ap_quest();
                break;
        }
}

/*
 * Skip a false conditional.
 * When a false condition is found (either a false IF or the ELSE part
 * of a true IF), this routine scans the prototype string to decide
 * where to resume parsing the string.
 * We must keep track of nested IFs and skip them properly.
 */
static const char *
skipcond(const char *p)
{
        int iflevel;

        /*
         * We came in here after processing a ? or :,
         * so we start nested one level deep.
         */
        iflevel = 1;

        for (;;) {
                switch (*++p) {
                case '?':
                        /*
                         * Start of a nested IF.
                         */
                        iflevel++;
                        break;
                case ':':
                        /*
                         * Else.
                         * If this matches the IF we came in here with,
                         * then we're done.
                         */
                        if (iflevel == 1)
                                return (p);
                        break;
                case '.':
                        /*
                         * Endif.
                         * If this matches the IF we came in here with,
                         * then we're done.
                         */
                        if (--iflevel == 0)
                                return (p);
                        break;
                case '\\':
                        /*
                         * Backslash escapes the next character.
                         */
                        ++p;
                        break;
                case '\0':
                        /*
                         * Whoops.  Hit end of string.
                         * This is a malformed conditional, but just treat it
                         * as if all active conditionals ends here.
                         */
                        return (p-1);
                }
        }
}

/*
 * Decode a char that represents a position on the screen.
 */
static const char *
wherechar(const char *p, int *wp)
{
        switch (*p) {
        case 'b': case 'd': case 'l': case 'p': case 'P':
                switch (*++p) {
                case 't':   *wp = TOP;                  break;
                case 'm':   *wp = MIDDLE;               break;
                case 'b':   *wp = BOTTOM;               break;
                case 'B':   *wp = BOTTOM_PLUS_ONE;      break;
                case 'j':   *wp = adjsline(jump_sline); break;
                default:    *wp = TOP; p--;             break;
                }
        }
        return (p);
}

/*
 * Construct a message based on a prototype string.
 */
char *
pr_expand(const char *proto, int maxwidth)
{
        const char *p;
        int c;
        int where;

        mp = message;

        if (*proto == '\0')
                return ("");

        for (p = proto; *p != '\0'; p++) {
                switch (*p) {
                default:        /* Just put the character in the message */
                        ap_char(*p);
                        break;
                case '\\':      /* Backslash escapes the next character */
                        p++;
                        ap_char(*p);
                        break;
                case '?':       /* Conditional (IF) */
                        if ((c = *++p) == '\0') {
                                --p;
                        } else {
                                where = 0;
                                p = wherechar(p, &where);
                                if (!cond(c, where))
                                        p = skipcond(p);
                        }
                        break;
                case ':':       /* ELSE */
                        p = skipcond(p);
                        break;
                case '.':       /* ENDIF */
                        break;
                case '%':       /* Percent escape */
                        if ((c = *++p) == '\0') {
                                --p;
                        } else {
                                where = 0;
                                p = wherechar(p, &where);
                                protochar(c, where);
                        }
                        break;
                }
        }

        if (*message == '\0')
                return ("");
        if (maxwidth > 0 && mp >= message + maxwidth) {
                /*
                 * Message is too long.
                 * Return just the final portion of it.
                 */
                return (mp - maxwidth);
        }
        return (message);
}

/*
 * Return a message suitable for printing by the "=" command.
 */
char *
eq_message(void)
{
        return (pr_expand(eqproto, 0));
}

/*
 * Return a prompt.
 * This depends on the prompt type (SHORT, MEDIUM, LONG), etc.
 * If we can't come up with an appropriate prompt, return NULL
 * and the caller will prompt with a colon.
 */
char *
prompt_string(void)
{
        char *prompt;
        int type;

        type = pr_type;
        prompt = pr_expand((ch_getflags() & CH_HELPFILE) ?
            hproto : prproto[type], sc_width-so_s_width-so_e_width-2);
        new_file = 0;
        return (prompt);
}

/*
 * Return a message suitable for printing while waiting in the F command.
 */
char *
wait_message(void)
{
        return (pr_expand(wproto, sc_width-so_s_width-so_e_width-2));
}