/*
 *  textbox.c -- implements the text box
 *
 *  AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
 *
 *  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 bool match_string(char *string);
static char *get_line(void);
static char *read_high(int fd, char *buf, size_t size_read);
static int get_search_term(WINDOW *win, char *input, int height, int width);
static int tabize(int val, int pos);
static void back_lines(int n);
static void print_line(WINDOW *win, int row, int width);
static void print_page(WINDOW *win, int height, int width);
static void print_position(WINDOW *win, int height, int width);

static int begin_reached = 1;
static int buffer_first = 1;
static int buffer_len = 0;
static int bytes_read;
static int end_reached = 0;
static int fd;
static int fd_bytes_read;
static int file_size;
static int hscroll = 0;
static int page_length;

static char *buf;
static char *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, dir, temp, temp1;
    int next = 0;
#ifdef NCURSES_VERSION
    int passed_end;
#endif
    char search_term[MAX_LEN + 1], *tempptr;
    WINDOW *dialog, *text;
    bool found;
    bool done = FALSE;
    bool moved = TRUE;
    const char **buttons = dlg_exit_label();

    auto_sizefile(title, file, &height, &width, 2, 12);
    print_size(height, width);
    ctl_size(height, width);

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

    /* Open input file for reading */
    if ((fd = open(file, O_RDONLY)) == -1)
	exiterr("Can't open input file in dialog_textbox().");

    /* 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)
	exiterr("Error getting file size in dialog_textbox().");

    /* Restore file pointer to beginning of file after getting file size */
    if (lseek(fd, 0, SEEK_SET) == -1)
	exiterr("Error moving file pointer in dialog_textbox().");

    if ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
	exiterr("Error reading file in dialog_textbox().");

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

    x = box_x_ordinate(width);
    y = box_y_ordinate(height);

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

    mouse_setbase(x, y);

    /* Create window for text region, used for scrolling text */
    text = subwin(dialog, height - 4, width - 2, y + 1, x + 1);

    keypad(text, TRUE);

    /* register the new window, along with its borders */
    mouse_mkbigregion(0, 0, height - 2, width, 1, 0, 2 /* not normal */ );
    draw_box(dialog, 0, 0, height, width, dialog_attr, border_attr);
    draw_bottom_box(dialog);
    draw_title(dialog, title);

    dlg_draw_buttons(dialog, height - 2, 0, buttons, FALSE, FALSE, width);
    wnoutrefresh(dialog);
    getyx(dialog, cur_y, cur_x);	/* Save cursor position */

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

    while (!done) {

	/*
	 * Update the screen according to whether we shifted up/down by a line
	 * or not.
	 */
	if (moved) {
	    if (next < 0) {
		scrollok(text, TRUE);
		scroll(text);	/* Scroll text region up one line */
		scrollok(text, FALSE);
		print_line(text, height - 5, width - 2);
#ifndef NCURSES_VERSION
		wmove(text, height - 5, 0);
		waddch(text, ' ');
		wmove(text, height - 5, width - 3);
		waddch(text, ' ');
#endif
		wnoutrefresh(text);
	    } else if (next > 0) {
#ifdef NCURSES_VERSION
		/*
		 * 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_line(text, 0, width - 2);		/* print first line of page */
			wnoutrefresh(text);
		    } else
			get_line();	/* Called to update 'end_reached' and 'page' */
		    if (!passed_end)
			page_length++;
		    if (end_reached && !passed_end)
			passed_end = 1;
		}
#else
		print_page(text, height - 4, width - 2);
#endif
	    } else {
		print_page(text, height - 4, width - 2);
	    }
	    print_position(dialog, height, width);
	    wmove(dialog, cur_y, cur_x);	/* Restore cursor position */
	    wrefresh_lock(dialog);
	}
	moved = FALSE;		/* assume we'll not move */
	next = 0;		/* ...but not scroll by a line */

	key = mouse_wgetch(dialog);
	if (dlg_char_to_button(key, buttons) == 0) {
	    key = '\n';
	}
	switch (key) {
	case ESC:
	    done = TRUE;
	    break;
	case M_EVENT + 'E':
	case '\n':
	    done = TRUE;
	    break;
	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)
		    exiterr("Error moving file pointer in dialog_textbox().");

		if (fpos > fd_bytes_read) {	/* Yes, we have to read it in */
		    if (lseek(fd, 0, SEEK_SET) == -1)
			exiterr("Error moving file pointer in dialog_textbox().");

		    if ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
			exiterr("Error reading file in dialog_textbox().");
		}
		page = buf;
		moved = TRUE;
	    }
	    break;
	case 'G':		/* Last page */
	case KEY_LL:
	case KEY_END:
	    end_reached = 1;
	    /* Last page not in buffer? */
	    if ((fpos = lseek(fd, 0, SEEK_CUR)) == -1)
		exiterr("Error moving file pointer in dialog_textbox().");

	    if (fpos < file_size) {	/* Yes, we have to read it in */
		if (lseek(fd, -BUF_SIZE, SEEK_END) == -1)
		    exiterr("Error moving file pointer in dialog_textbox().");

		if ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
		    exiterr("Error reading file in dialog_textbox().");
	    }
	    page = buf + bytes_read;
	    back_lines(height - 4);
	    moved = TRUE;
	    break;
	case 'K':		/* Previous line */
	case 'k':
	case KEY_UP:
	    if (!begin_reached) {
		back_lines(page_length + 1);
		next = 1;
		moved = TRUE;
	    }
	    break;
	case 'B':		/* Previous page */
	case 'b':
	case KEY_PPAGE:
	    if (!begin_reached) {
		back_lines(page_length + height - 4);
		moved = TRUE;
	    }
	    break;
	case 'J':		/* Next line */
	case 'j':
	case KEY_DOWN:
	    if (!end_reached) {
		begin_reached = 0;
		next = -1;
		moved = TRUE;
	    }
	    break;
	case ' ':		/* Next page */
	case KEY_NPAGE:
	    if (!end_reached) {
		begin_reached = 0;
		moved = TRUE;
	    }
	    break;
	case '0':		/* Beginning of line */
	case 'H':		/* Scroll left */
	case 'h':
	case KEY_LEFT:
	    if (hscroll > 0) {
		if (key == '0')
		    hscroll = 0;
		else
		    hscroll--;
		/* Reprint current page to scroll horizontally */
		back_lines(page_length);
		moved = TRUE;
	    }
	    break;
	case 'L':		/* Scroll right */
	case 'l':
	case KEY_RIGHT:
	    if (hscroll < MAX_LEN) {
		hscroll++;
		/* Reprint current page to scroll horizontally */
		back_lines(page_length);
		moved = TRUE;
	    }
	    break;
	case '/':		/* Forward search */
	case 'n':		/* Repeat forward search */
	case '?':		/* Backward search */
	case 'N':		/* Repeat backward search */
	    /* set search direction */
	    dir = (key == '/' || key == 'n') ? 1 : 0;
	    if (dir ? !end_reached : !begin_reached) {
		if (key == 'n' || key == 'N') {
		    if (search_term[0] == '\0') {	/* No search term yet */
			beep();
			break;
		    }
		    /* Get search term from user */
		} else if (get_search_term(text, search_term, height - 4,
			width - 2) == -1) {
		    /* ESC pressed in get_search_term(). Reprint page to clear box */
		    wattrset(text, dialog_attr);
		    back_lines(page_length);
		    moved = TRUE;
		    break;
		}
		/* Save variables for restoring in case search term can't be found */
		tempptr = page;
		temp = begin_reached;
		temp1 = end_reached;
		if ((fpos = lseek(fd, 0, SEEK_CUR)) == -1)
		    exiterr("Error moving file pointer in dialog_textbox().");

		fpos -= fd_bytes_read;
		/* update 'page' to point to next (previous) line before
		   forward (backward) searching */
		back_lines(dir ? page_length - 1 : page_length + 1);
		found = FALSE;
		if (dir) {	/* Forward search */
		    while ((found = match_string(search_term)) == FALSE) {
			if (end_reached)
			    break;
		    }
		} else {	/* Backward search */
		    while ((found = match_string(search_term)) == FALSE) {
			if (begin_reached)
			    break;
			back_lines(2);
		    }
		}
		if (found == FALSE) {	/* not found */
		    beep();
		    /* Restore program state to that before searching */
		    if (lseek(fd, fpos, SEEK_SET) == -1)
			exiterr("Error moving file pointer in dialog_textbox().");

		    if ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
			exiterr("Error reading file in dialog_textbox().");

		    page = tempptr;
		    begin_reached = temp;
		    end_reached = temp1;
		    /* move 'page' to point to start of current page in order to
		       re-print current page. Note that 'page' always points to
		       start of next page, so this is necessary */
		    back_lines(page_length);
		} else {	/* Search term found */
		    back_lines(1);
		}
		/* Reprint page */
		wattrset(text, dialog_attr);
		moved = TRUE;
	    } else {		/* no need to find */
		beep();
	    }
	    break;
	}
    }

    delwin(dialog);
    free(buf);
    close(fd);
    return (key == ESC) ? -1 : 0;
}
/* End of dialog_textbox() */

/*
 * 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, val_to_tabize;

    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)
		exiterr("Error moving file pointer in back_lines().");

	    if (fpos > fd_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 + fd_bytes_read) {
		    /* No, move less then */
		    if (lseek(fd, 0, SEEK_SET) == -1)
			exiterr("Error moving file pointer in back_lines().");

		    val_to_tabize = fpos - fd_bytes_read;
		} else {	/* Move backward BUF_SIZE/2 bytes */
		    if (lseek(fd, -(BUF_SIZE / 2 + fd_bytes_read), SEEK_CUR)
			== -1)
			exiterr("Error moving file pointer in back_lines().");

		    val_to_tabize = BUF_SIZE / 2;
		}
		if ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
		    exiterr("Error reading file in back_lines().");

		page = buf + tabize(val_to_tabize, 0);

	    } else {		/* Beginning of file reached */
		begin_reached = 1;
		return;
	    }
	}
	if (*(--page) != '\n')	/* '--page' here */
	    /* Something's wrong... */
	    exiterr("Internal error in back_lines().");
    }

    /* Go back 'n' lines */
    for (i = 0; i < n; i++)
	do {
	    if (page == buf) {
		if ((fpos = lseek(fd, 0, SEEK_CUR)) == -1)
		    exiterr("Error moving file pointer in back_lines().");

		if (fpos > fd_bytes_read) {
		    /* Really possible to move backward BUF_SIZE/2 bytes? */
		    if (fpos < BUF_SIZE / 2 + fd_bytes_read) {
			/* No, move less then */
			if (lseek(fd, 0, SEEK_SET) == -1)
			    exiterr("Error moving file pointer in back_lines().");

			val_to_tabize = fpos - fd_bytes_read;
		    } else {	/* Move backward BUF_SIZE/2 bytes */
			if (lseek(fd, -(BUF_SIZE / 2 + fd_bytes_read),
				SEEK_CUR) == -1)
			    exiterr("Error moving file pointer in back_lines().");

			val_to_tabize = BUF_SIZE / 2;
		    }
		    if ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
			exiterr("Error reading file in back_lines().");

		    page = buf + tabize(val_to_tabize, 0);

		} else {	/* Beginning of file reached */
		    begin_reached = 1;
		    return;
		}
	    }
	} while (*(--page) != '\n');
    page++;
}
/* End of back_lines() */

/*
 * 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);
}
/* End of print_page() */

/*
 * Print a new line of text. Called by dialog_textbox() and print_page().
 */
static void
print_line(WINDOW *win, int row, int width)
{
    int i, y, x;
    char *line;
    line = get_line();
    line += MIN((int) strlen(line), hscroll);	/* Scroll horizontally */
    wmove(win, row, 0);		/* move cursor to correct line */
    waddch(win, ' ');
#ifdef NCURSES_VERSION
    waddnstr(win, line, MIN((int) strlen(line), width - 2));
#else
    line[MIN(strlen(line), width - 2)] = '\0';
    waddstr(win, line);
#endif

    getyx(win, y, x);
    /* Clear 'residue' of previous line */
    for (i = 0; i < width - x; i++)
	waddch(win, ' ');
}
/* End of print_line() */

/*
 * 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)
		exiterr("Error moving file pointer in get_line().");

	    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 ((buf = read_high(fd, buf, BUF_SIZE)) == NULL)
		    exiterr("Error reading file in get_line().");
		page = buf;
	    } else {
		if (!end_reached)
		    end_reached = 1;
		break;
	    }
	} else if (i < MAX_LEN)
	    line[i++] = *(page++);
	else {
	    if (i == MAX_LEN)	/* Truncate lines longer than MAX_LEN characters */
		line[i++] = '\0';
	    page++;
	}
    }
    if (i <= MAX_LEN)
	line[i] = '\0';
    if (!end_reached)
	page++;			/* move pass '\n' */

    return line;
}
/* End of get_line() */

/*
 * Display a dialog box and get the search term from user
 */
static int
get_search_term(WINDOW *dialog, char *input, int height, int width)
{
    int box_x, box_y, key = 0, box_height = 3, box_width = 30;
    int offset = 0;
    bool first = TRUE;

    box_x = (width - box_width) / 2;
    box_y = (height - box_height) / 2;
#ifdef HAVE_COLOR
    if (use_shadow)
	draw_shadow(dialog, box_y, box_x, box_height, box_width);
#endif
    draw_box(dialog, box_y, box_x, box_height, box_width, dialog_attr, searchbox_border_attr);
    wattrset(dialog, searchbox_title_attr);
    wmove(dialog, box_y, box_x + box_width / 2 - 4);
    waddstr(dialog, " Search ");

    box_y++;
    box_x++;
    box_width -= 2;
    input[0] = '\0';

    for (;;) {
	if (!first) {
	    key = dlg_getc(dialog);
	    if (key == ESC)
		return -1;
	    if (key == '\n' && *input != '\0')
		return 0;
	}
	if (dlg_edit_string(input, &offset, key, first)) {
	    dlg_show_string(dialog, input, offset, searchbox_attr,
		box_y, box_x, box_width, FALSE, first);
	    first = FALSE;
	}
    }
}
/* End of get_search_term() */

static bool
match_string(char *string)
{
    char *match = get_line();
    return strstr(match, string) != 0;
}

/*
 * Print current position
 */
static void
print_position(WINDOW *win, int height, int width)
{
    int fpos, percent;

    if ((fpos = lseek(fd, 0, SEEK_CUR)) == -1)
	exiterr("Error moving file pointer in print_position().");

    wattrset(win, position_indicator_attr);
    percent = !file_size ? 100 : ((fpos - fd_bytes_read + tabize(page - buf,
		1)) * 100) / file_size;
    wmove(win, height - 3, width - 9);
    wprintw(win, "(%3d%%)", percent);
}
/* End of print_position() */

/*
 * read_high() substitutes read() for tab->spaces conversion
 *
 * buffer_len, fd_bytes_read, bytes_read are modified
 * buf is allocated
 *
 * fd_bytes_read is the effective number of bytes read from file
 * bytes_read is the length of buf, that can be different if tab_correct
 */
static char *
read_high(int my_fd, char *my_buf, size_t size_read)
{
    char *buftab, ch;
    int i = 0, j, n, begin_line, tmpint, disp = 0;

    /* Allocate space for read buffer */
    if ((buftab = malloc(size_read + 1)) == NULL)
	exiterr("Can't allocate memory in read_high().");

    if ((fd_bytes_read = read(my_fd, buftab, size_read)) == -1)
	exiterr("Error reading file in read_high().");

    buftab[fd_bytes_read] = '\0';	/* mark end of valid data */

    if (dialog_vars.tab_correct) {

	/* calculate bytes_read by buftab and fd_bytes_read */
	bytes_read = begin_line = 0;
	for (j = 0; j < fd_bytes_read; j++)
	    if (buftab[j] == TAB)
		bytes_read += dialog_vars.tab_len - ((bytes_read -
			begin_line) % dialog_vars.tab_len);
	    else if (buftab[j] == '\n') {
		bytes_read++;
		begin_line = bytes_read;
	    } else
		bytes_read++;

	if (bytes_read > buffer_len) {
	    if (buffer_first)
		buffer_first = 0;	/* disp = 0 */
	    else {
		disp = page - my_buf;
		free(my_buf);
	    }

	    buffer_len = bytes_read;

	    /* Allocate space for read buffer */
	    if ((my_buf = malloc(buffer_len + 1)) == NULL)
		exiterr("Can't allocate memory in read_high().");

	    page = my_buf + disp;
	}

    } else {
	if (buffer_first) {
	    buffer_first = 0;

	    /* Allocate space for read buffer */
	    if ((my_buf = malloc(size_read + 1)) == NULL)
		exiterr("Can't allocate memory in read_high().");
	}

	bytes_read = fd_bytes_read;
    }

    j = 0;
    begin_line = 0;
    while (j < fd_bytes_read)
	if (((ch = buftab[j++]) == TAB) && (dialog_vars.tab_correct)) {
	    tmpint = dialog_vars.tab_len - ((i - begin_line) % dialog_vars.tab_len);
	    for (n = 0; n < tmpint; n++)
		my_buf[i++] = ' ';
	} else {
	    if (ch == '\n')
		begin_line = i + 1;
	    my_buf[i++] = ch;
	}

    my_buf[i] = '\0';		/* mark end of valid data */

    if (bytes_read == -1)
	return NULL;
    else
	return my_buf;
}

int
tabize(int val, int pos)
{
    int fpos, i, count, begin_line;
    char *buftab;

    if (!dialog_vars.tab_correct)
	return val;

    if ((fpos = lseek(fd, 0, SEEK_CUR)) == -1)
	exiterr("Error moving file pointer in tabize().");

    if ((lseek(fd, fpos - fd_bytes_read, SEEK_SET)) == -1)
	exiterr("Error moving file pointer in tabize().");

    /* Allocate space for read buffer */
    if ((buftab = malloc(val + 1)) == NULL)
	exiterr("Can't allocate memory in tabize().");

    if ((read(fd, buftab, val)) == -1)
	exiterr("Error reading file in tabize().");

    begin_line = count = 0;
    for (i = 0; i < val; i++) {
	if (pos && count >= val) {
	    count = i;		/* it's the retval */
	    break;
	}
	if (buftab[i] == TAB)
	    count += dialog_vars.tab_len - ((count - begin_line) % dialog_vars.tab_len);
	else if (buftab[i] == '\n') {
	    count++;
	    begin_line = count;
	} else
	    count++;
    }

    if (lseek(fd, fpos, SEEK_SET) == -1)
	exiterr("Error moving file pointer in tabize().");

    return count;
}