/*
 *  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);

static int hscroll;
static int begin_reached, end_reached, page_length;
static const char *buf;
static const char *page;

/*
 * refresh window content
 */
static void refresh_text_box(WINDOW *dialog, WINDOW *box, int boxh, int boxw,
                                                          int cur_y, int cur_x)
{
        print_page(box, boxh, boxw);
        print_position(dialog);
        wmove(dialog, cur_y, cur_x);    /* Restore cursor position */
        wrefresh(dialog);
}


/*
 * Display text from a file in a dialog box.
 */
int dialog_textbox(const char *title, const char *tbuf,
                   int initial_height, int initial_width)
{
        int i, x, y, cur_x, cur_y, key = 0;
        int height, width, boxh, boxw;
        int passed_end;
        WINDOW *dialog, *box;

        begin_reached = 1;
        end_reached = 0;
        page_length = 0;
        hscroll = 0;
        buf = tbuf;
        page = buf;     /* page is pointer to start of page to be displayed */

do_resize:
        getmaxyx(stdscr, height, width);
        if (height < 8 || width < 8)
                return -ERRDISPLAYTOOSMALL;
        if (initial_height != 0)
                height = initial_height;
        else
                if (height > 4)
                        height -= 4;
                else
                        height = 0;
        if (initial_width != 0)
                width = initial_width;
        else
                if (width > 5)
                        width -= 5;
                else
                        width = 0;

        /* 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 box region, used for scrolling text */
        boxh = height - 4;
        boxw = width - 2;
        box = subwin(dialog, boxh, boxw, y + 1, x + 1);
        wattrset(box, dlg.dialog.atr);
        wbkgdset(box, dlg.dialog.atr & A_COLOR);

        keypad(box, TRUE);

        /* register the new window, along with its borders */
        draw_box(dialog, 0, 0, height, width,
                 dlg.dialog.atr, dlg.border.atr);

        wattrset(dialog, dlg.border.atr);
        mvwaddch(dialog, height - 3, 0, ACS_LTEE);
        for (i = 0; i < width - 2; i++)
                waddch(dialog, ACS_HLINE);
        wattrset(dialog, dlg.dialog.atr);
        wbkgdset(dialog, dlg.dialog.atr & A_COLOR);
        waddch(dialog, ACS_RTEE);

        print_title(dialog, title, width);

        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(box, boxh, boxw, dlg.dialog.atr);
        refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);

        while ((key != KEY_ESC) && (key != '\n')) {
                key = wgetch(dialog);
                switch (key) {
                case 'E':       /* Exit */
                case 'e':
                case 'X':
                case 'x':
                        delwin(box);
                        delwin(dialog);
                        return 0;
                case 'g':       /* First page */
                case KEY_HOME:
                        if (!begin_reached) {
                                begin_reached = 1;
                                page = buf;
                                refresh_text_box(dialog, box, boxh, boxw,
                                                 cur_y, cur_x);
                        }
                        break;
                case 'G':       /* Last page */
                case KEY_END:

                        end_reached = 1;
                        /* point to last char in buf */
                        page = buf + strlen(buf);
                        back_lines(boxh);
                        refresh_text_box(dialog, box, boxh, boxw,
                                         cur_y, cur_x);
                        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(box, TRUE);
                                wscrl(box, -1); /* Scroll box region down one line */
                                scrollok(box, FALSE);
                                page_length = 0;
                                passed_end = 0;
                                for (i = 0; i < boxh; i++) {
                                        if (!i) {
                                                /* print first line of page */
                                                print_line(box, 0, boxw);
                                                wnoutrefresh(box);
                                        } 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);
                                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 + boxh);
                        refresh_text_box(dialog, box, boxh, boxw,
                                         cur_y, cur_x);
                        break;
                case 'J':       /* Next line */
                case 'j':
                case KEY_DOWN:
                        if (!end_reached) {
                                begin_reached = 0;
                                scrollok(box, TRUE);
                                scroll(box);    /* Scroll box region up one line */
                                scrollok(box, FALSE);
                                print_line(box, boxh - 1, boxw);
                                wnoutrefresh(box);
                                print_position(dialog);
                                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;
                        refresh_text_box(dialog, box, boxh, boxw,
                                         cur_y, cur_x);
                        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);
                        refresh_text_box(dialog, box, boxh, boxw,
                                         cur_y, cur_x);
                        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);
                        refresh_text_box(dialog, box, boxh, boxw,
                                         cur_y, cur_x);
                        break;
                case KEY_ESC:
                        key = on_key_esc(dialog);
                        break;
                case KEY_RESIZE:
                        back_lines(height);
                        delwin(box);
                        delwin(dialog);
                        on_key_resize();
                        goto do_resize;
                }
        }
        delwin(box);
        delwin(dialog);
        return key;             /* ESC pressed */
}

/*
 * Go back 'n' lines in text. Called by dialog_textbox().
 * 'page' will be updated to point to the desired line in 'buf'.
 */
static void back_lines(int n)
{
        int i;

        begin_reached = 0;
        /* Go back 'n' lines */
        for (i = 0; i < n; i++) {
                if (*page == '\0') {
                        if (end_reached) {
                                end_reached = 0;
                                continue;
                        }
                }
                if (page == buf) {
                        begin_reached = 1;
                        return;
                }
                page--;
                do {
                        if (page == buf) {
                                begin_reached = 1;
                                return;
                        }
                        page--;
                } 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;
        static char line[MAX_LEN + 1];

        end_reached = 0;
        while (*page != '\n') {
                if (*page == '\0') {
                        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 percent;

        wattrset(win, dlg.position_indicator.atr);
        wbkgdset(win, dlg.position_indicator.atr & A_COLOR);
        percent = (page - buf) * 100 / strlen(buf);
        wmove(win, getmaxy(win) - 3, getmaxx(win) - 9);
        wprintw(win, "(%3d%%)", percent);
}