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/*

 *  textbox.c -- implements the text box

 *

 *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)

 *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)

 *

 *  This program is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU General Public License

 *  as published by the Free Software Foundation; either version 2

 *  of the License, or (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#include "dialog.h"

static void back_lines (int n);

static void print_page (WINDOW * win, int height, int width);

static void print_line (WINDOW * win, int row, int width);

static char *get_line (void);

static void print_position (WINDOW * win, int height, int width);

static int hscroll = 0, fd, file_size, bytes_read;

static int begin_reached = 1, end_reached = 0, page_length;

static char *buf, *page;

/*

 * Display text from a file in a dialog box.

 */

int

dialog_textbox (const char *title, const char *file, int height, int width)

{

    int i, x, y, cur_x, cur_y, fpos, key = 0;

    int passed_end;

    char search_term[MAX_LEN + 1];

    WINDOW *dialog, *text;

    search_term[0] = '\0';       /* no search term entered yet */

    /* Open input file for reading */

    if ((fd = open (file, O_RDONLY)) == -1) {

        endwin ();

        fprintf (stderr,

                 "\nCan't open input file in dialog_textbox().\n");

        exit (-1);

    }

    /* Get file size. Actually, 'file_size' is the real file size - 1,

       since it's only the last byte offset from the beginning */

    if ((file_size = lseek (fd, 0, SEEK_END)) == -1) {

        endwin ();

        fprintf (stderr, "\nError getting file size in dialog_textbox().\n");

        exit (-1);

    }

    /* Restore file pointer to beginning of file after getting file size */

    if (lseek (fd, 0, SEEK_SET) == -1) {

        endwin ();

        fprintf (stderr, "\nError moving file pointer in dialog_textbox().\n");

        exit (-1);

    }

    /* Allocate space for read buffer */

    if ((buf = malloc (BUF_SIZE + 1)) == NULL) {

        endwin ();

        fprintf (stderr, "\nCan't allocate memory in dialog_textbox().\n");

        exit (-1);

    }

    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {

        endwin ();

        fprintf (stderr, "\nError reading file in dialog_textbox().\n");

        exit (-1);

    }

    buf[bytes_read] = '\0';     /* mark end of valid data */

    page = buf;                 /* page is pointer to start of page to be displayed */

    /* center dialog box on screen */

    x = (COLS - width) / 2;

    y = (LINES - height) / 2;

    draw_shadow (stdscr, y, x, height, width);

    dialog = newwin (height, width, y, x);

    keypad (dialog, TRUE);

    /* Create window for text region, used for scrolling text */

    text = subwin (dialog, height - 4, width - 2, y + 1, x + 1);

    wattrset (text, dialog_attr);

    wbkgdset (text, dialog_attr & A_COLOR);

    keypad (text, TRUE);

    /* register the new window, along with its borders */

    draw_box (dialog, 0, 0, height, width, dialog_attr, border_attr);

    wattrset (dialog, border_attr);

    mvwaddch (dialog, height-3, 0, ACS_LTEE);

    for (i = 0; i < width - 2; i++)

        waddch (dialog, ACS_HLINE);

    wattrset (dialog, dialog_attr);

    wbkgdset (dialog, dialog_attr & A_COLOR);

    waddch (dialog, ACS_RTEE);

    if (title != NULL && strlen(title) >= width-2 ) {

        /* truncate long title -- mec */

        char * title2 = malloc(width-2+1);

        memcpy( title2, title, width-2 );

        title2[width-2] = '\0';

        title = title2;

    }

    if (title != NULL) {

        wattrset (dialog, title_attr);

        mvwaddch (dialog, 0, (width - strlen(title))/2 - 1, ' ');

        waddstr (dialog, (char *)title);

        waddch (dialog, ' ');

    }

    print_button (dialog, " Exit ", height - 2, width / 2 - 4, TRUE);

    wnoutrefresh (dialog);

    getyx (dialog, cur_y, cur_x);       /* Save cursor position */

    /* Print first page of text */

    attr_clear (text, height - 4, width - 2, dialog_attr);

    print_page (text, height - 4, width - 2);

    print_position (dialog, height, width);

    wmove (dialog, cur_y, cur_x);       /* Restore cursor position */

    wrefresh (dialog);

    while ((key != ESC) && (key != '\n')) {

        key = wgetch (dialog);

        switch (key) {

        case 'E':               /* Exit */

        case 'e':

        case 'X':

        case 'x':

            delwin (dialog);

            free (buf);

            close (fd);

            return 0;

        case 'g':               /* First page */

        case KEY_HOME:

            if (!begin_reached) {

                begin_reached = 1;

                /* First page not in buffer? */

                if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {

                    endwin ();

                    fprintf (stderr,

                      "\nError moving file pointer in dialog_textbox().\n");

                    exit (-1);

                }

                if (fpos > bytes_read) {        /* Yes, we have to read it in */

                    if (lseek (fd, 0, SEEK_SET) == -1) {

                        endwin ();

                        fprintf (stderr, "\nError moving file pointer in "

                                 "dialog_textbox().\n");

                        exit (-1);

                    }

                    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {

                        endwin ();

                        fprintf (stderr,

                             "\nError reading file in dialog_textbox().\n");

                        exit (-1);

                    }

                    buf[bytes_read] = '\0';

                }

                page = buf;

                print_page (text, height - 4, width - 2);

                print_position (dialog, height, width);

                wmove (dialog, cur_y, cur_x);   /* Restore cursor position */

                wrefresh (dialog);

            }

            break;

        case 'G':               /* Last page */

        case KEY_END:

            end_reached = 1;

            /* Last page not in buffer? */

            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {

                endwin ();

                fprintf (stderr,

                      "\nError moving file pointer in dialog_textbox().\n");

                exit (-1);

            }

            if (fpos < file_size) {     /* Yes, we have to read it in */

                if (lseek (fd, -BUF_SIZE, SEEK_END) == -1) {

                    endwin ();

                    fprintf (stderr,

                      "\nError moving file pointer in dialog_textbox().\n");

                    exit (-1);

                }

                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {

                    endwin ();

                    fprintf (stderr,

                             "\nError reading file in dialog_textbox().\n");

                    exit (-1);

                }

                buf[bytes_read] = '\0';

            }

            page = buf + bytes_read;

            back_lines (height - 4);

            print_page (text, height - 4, width - 2);

            print_position (dialog, height, width);

            wmove (dialog, cur_y, cur_x);       /* Restore cursor position */

            wrefresh (dialog);

            break;

        case 'K':               /* Previous line */

        case 'k':

        case KEY_UP:

            if (!begin_reached) {

                back_lines (page_length + 1);

                /* We don't call print_page() here but use scrolling to ensure

                   faster screen update. However, 'end_reached' and

                   'page_length' should still be updated, and 'page' should

                   point to start of next page. This is done by calling

                   get_line() in the following 'for' loop. */

                scrollok (text, TRUE);

                wscrl (text, -1);       /* Scroll text region down one line */

                scrollok (text, FALSE);

                page_length = 0;

                passed_end = 0;

                for (i = 0; i < height - 4; i++) {

                    if (!i) {

                        /* print first line of page */

                        print_line (text, 0, width - 2);

                        wnoutrefresh (text);

                    } else

                        /* Called to update 'end_reached' and 'page' */

                        get_line ();

                    if (!passed_end)

                        page_length++;

                    if (end_reached && !passed_end)

                        passed_end = 1;

                }

                print_position (dialog, height, width);

                wmove (dialog, cur_y, cur_x);   /* Restore cursor position */

                wrefresh (dialog);

            }

            break;

        case 'B':               /* Previous page */

        case 'b':

        case KEY_PPAGE:

            if (begin_reached)

                break;

            back_lines (page_length + height - 4);

            print_page (text, height - 4, width - 2);

            print_position (dialog, height, width);

            wmove (dialog, cur_y, cur_x);

            wrefresh (dialog);

            break;

        case 'J':               /* Next line */

        case 'j':

        case KEY_DOWN:

            if (!end_reached) {

                begin_reached = 0;

                scrollok (text, TRUE);

                scroll (text);  /* Scroll text region up one line */

                scrollok (text, FALSE);

                print_line (text, height - 5, width - 2);

                wnoutrefresh (text);

                print_position (dialog, height, width);

                wmove (dialog, cur_y, cur_x);   /* Restore cursor position */

                wrefresh (dialog);

            }

            break;

        case KEY_NPAGE:         /* Next page */

        case ' ':

            if (end_reached)

                break;

            begin_reached = 0;

            print_page (text, height - 4, width - 2);

            print_position (dialog, height, width);

            wmove (dialog, cur_y, cur_x);

            wrefresh (dialog);

            break;

        case '0':               /* Beginning of line */

        case 'H':               /* Scroll left */

        case 'h':

        case KEY_LEFT:

            if (hscroll <= 0)

                break;

            if (key == '0')

                hscroll = 0;

            else

                hscroll--;

            /* Reprint current page to scroll horizontally */

            back_lines (page_length);

            print_page (text, height - 4, width - 2);

            wmove (dialog, cur_y, cur_x);

            wrefresh (dialog);

            break;

        case 'L':               /* Scroll right */

        case 'l':

        case KEY_RIGHT:

            if (hscroll >= MAX_LEN)

                break;

            hscroll++;

            /* Reprint current page to scroll horizontally */

            back_lines (page_length);

            print_page (text, height - 4, width - 2);

            wmove (dialog, cur_y, cur_x);

            wrefresh (dialog);

            break;

        case ESC:

            break;

        }

    }

    delwin (dialog);

    free (buf);

    close (fd);

    return 1;                   /* ESC pressed */

}

/*

 * Go back 'n' lines in text file. Called by dialog_textbox().

 * 'page' will be updated to point to the desired line in 'buf'.

 */

static void

back_lines (int n)

{

    int i, fpos;

    begin_reached = 0;

    /* We have to distinguish between end_reached and !end_reached

       since at end of file, the line is not ended by a '\n'.

       The code inside 'if' basically does a '--page' to move one

       character backward so as to skip '\n' of the previous line */

    if (!end_reached) {

        /* Either beginning of buffer or beginning of file reached? */

        if (page == buf) {

            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {

                endwin ();

                fprintf (stderr, "\nError moving file pointer in "

                         "back_lines().\n");

                exit (-1);

            }

            if (fpos > bytes_read) {    /* Not beginning of file yet */

                /* We've reached beginning of buffer, but not beginning of

                   file yet, so read previous part of file into buffer.

                   Note that we only move backward for BUF_SIZE/2 bytes,

                   but not BUF_SIZE bytes to avoid re-reading again in

                   print_page() later */

                /* Really possible to move backward BUF_SIZE/2 bytes? */

                if (fpos < BUF_SIZE / 2 + bytes_read) {

                    /* No, move less then */

                    if (lseek (fd, 0, SEEK_SET) == -1) {

                        endwin ();

                        fprintf (stderr, "\nError moving file pointer in "

                                 "back_lines().\n");

                        exit (-1);

                    }

                    page = buf + fpos - bytes_read;

                } else {        /* Move backward BUF_SIZE/2 bytes */

                    if (lseek (fd, -(BUF_SIZE / 2 + bytes_read), SEEK_CUR)

                        == -1) {

                        endwin ();

                        fprintf (stderr, "\nError moving file pointer "

                                 "in back_lines().\n");

                        exit (-1);

                    }

                    page = buf + BUF_SIZE / 2;

                }

                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {

                    endwin ();

                    fprintf (stderr, "\nError reading file in back_lines().\n");

                    exit (-1);

                }

                buf[bytes_read] = '\0';

            } else {            /* Beginning of file reached */

                begin_reached = 1;

                return;

            }

        }

        if (*(--page) != '\n') {        /* '--page' here */

            /* Something's wrong... */

            endwin ();

            fprintf (stderr, "\nInternal error in back_lines().\n");

            exit (-1);

        }

    }

    /* Go back 'n' lines */

    for (i = 0; i < n; i++)

        do {

            if (page == buf) {

                if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {

                    endwin ();

                    fprintf (stderr,

                          "\nError moving file pointer in back_lines().\n");

                    exit (-1);

                }

                if (fpos > bytes_read) {

                    /* Really possible to move backward BUF_SIZE/2 bytes? */

                    if (fpos < BUF_SIZE / 2 + bytes_read) {

                        /* No, move less then */

                        if (lseek (fd, 0, SEEK_SET) == -1) {

                            endwin ();

                            fprintf (stderr, "\nError moving file pointer "

                                     "in back_lines().\n");

                            exit (-1);

                        }

                        page = buf + fpos - bytes_read;

                    } else {    /* Move backward BUF_SIZE/2 bytes */

                        if (lseek (fd, -(BUF_SIZE / 2 + bytes_read),

                                   SEEK_CUR) == -1) {

                            endwin ();

                            fprintf (stderr, "\nError moving file pointer"

                                     " in back_lines().\n");

                            exit (-1);

                        }

                        page = buf + BUF_SIZE / 2;

                    }

                    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {

                        endwin ();

                        fprintf (stderr, "\nError reading file in "

                                 "back_lines().\n");

                        exit (-1);

                    }

                    buf[bytes_read] = '\0';

                } else {        /* Beginning of file reached */

                    begin_reached = 1;

                    return;

                }

            }

        } while (*(--page) != '\n');

    page++;

}

/*

 * Print a new page of text. Called by dialog_textbox().

 */

static void

print_page (WINDOW * win, int height, int width)

{

    int i, passed_end = 0;

    page_length = 0;

    for (i = 0; i < height; i++) {

        print_line (win, i, width);

        if (!passed_end)

            page_length++;

        if (end_reached && !passed_end)

            passed_end = 1;

    }

    wnoutrefresh (win);

}

/*

 * Print a new line of text. Called by dialog_textbox() and print_page().

 */

static void

print_line (WINDOW * win, int row, int width)

{

    int y, x;

    char *line;

    line = get_line ();

    line += MIN (strlen (line), hscroll);       /* Scroll horizontally */

    wmove (win, row, 0); /* move cursor to correct line */

    waddch (win, ' ');

    waddnstr (win, line, MIN (strlen (line), width - 2));

    getyx (win, y, x);

    /* Clear 'residue' of previous line */

#if OLD_NCURSES

    {

        int i;

        for (i = 0; i < width - x; i++)

            waddch (win, ' ');

    }

#else

    wclrtoeol(win);

#endif

}

/*

 * Return current line of text. Called by dialog_textbox() and print_line().

 * 'page' should point to start of current line before calling, and will be

 * updated to point to start of next line.

 */

static char *

get_line (void)

{

    int i = 0, fpos;

    static char line[MAX_LEN + 1];

    end_reached = 0;

    while (*page != '\n') {

        if (*page == '\0') {

            /* Either end of file or end of buffer reached */

            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {

                endwin ();

                fprintf (stderr, "\nError moving file pointer in "

                         "get_line().\n");

                exit (-1);

            }

            if (fpos < file_size) {     /* Not end of file yet */

                /* We've reached end of buffer, but not end of file yet,

                   so read next part of file into buffer */

                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {

                    endwin ();

                    fprintf (stderr, "\nError reading file in get_line().\n");

                    exit (-1);

                }

                buf[bytes_read] = '\0';

                page = buf;

            } else {

                if (!end_reached)

                    end_reached = 1;

                break;

            }

        } else if (i < MAX_LEN)

            line[i++] = *(page++);

        else {

            /* Truncate lines longer than MAX_LEN characters */

            if (i == MAX_LEN)

                line[i++] = '\0';

            page++;

        }

    }

    if (i <= MAX_LEN)

        line[i] = '\0';

    if (!end_reached)

        page++;                 /* move pass '\n' */

    return line;

}

/*

 * Print current position

 */

static void

print_position (WINDOW * win, int height, int width)

{

    int fpos, percent;

    if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {

        endwin ();

        fprintf (stderr, "\nError moving file pointer in print_position().\n");

        exit (-1);

    }

    wattrset (win, position_indicator_attr);

    wbkgdset (win, position_indicator_attr & A_COLOR);

    percent = !file_size ?

        100 : ((fpos - bytes_read + page - buf) * 100) / file_size;

    wmove (win, height - 3, width - 9);

    wprintw (win, "(%3d%%)", percent);

}