/*
 * Samba Unix/Linux SMB client library
 * Registry Editor
 * Copyright (C) Christopher Davis 2012
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include "includes.h"
#include "regedit_hexedit.h"

/*
 offset    hex1         hex2         ascii
 00000000  FF FF FF FF  FF FF FF FF  ........
*/

#define HEX_COL1 10
#define HEX_COL1_END 21
#define HEX_COL2 23
#define HEX_COL2_END 34
#define ASCII_COL 36
#define ASCII_COL_END LINE_WIDTH
#define BYTES_PER_LINE 8

struct hexedit {
	size_t offset;
	size_t len;
	size_t alloc_size;
	int cursor_y;
	int cursor_x;
	size_t cursor_offset;
	size_t cursor_line_offset;
	int nibble;
	uint8_t *data;
	WINDOW *win;
};

static int max_rows(WINDOW *win)
{
	int maxy;

	maxy = getmaxy(win);

	return maxy - 1;
}

struct hexedit *hexedit_new(TALLOC_CTX *ctx, WINDOW *parent, const void *data,
			    size_t sz)
{
	WERROR rv;
	struct hexedit *buf;

	buf = talloc_zero(ctx, struct hexedit);
	if (buf == NULL) {
		return NULL;
	}

	buf->win = parent;

	rv = hexedit_set_buf(buf, data, sz);
	if (!W_ERROR_IS_OK(rv)) {
		goto fail;
	}

	return buf;

fail:
	talloc_free(buf);

	return NULL;
}

WERROR hexedit_set_buf(struct hexedit *buf, const void *data, size_t sz)
{
	TALLOC_FREE(buf->data);

	buf->data = talloc_zero_array(buf, uint8_t, sz);
	if (buf->data == NULL) {
		return WERR_NOT_ENOUGH_MEMORY;
	}

	if (data != NULL) {
		memcpy(buf->data, data, sz);
	}

	buf->len = sz;
	buf->alloc_size = sz;
	buf->cursor_x = HEX_COL1;
	buf->cursor_y = 0;
	buf->cursor_offset = 0;
	buf->cursor_line_offset = 0;
	buf->nibble = 0;

	return WERR_OK;
}

const void *hexedit_get_buf(struct hexedit *buf)
{
	return buf->data;
}

size_t hexedit_get_buf_len(struct hexedit *buf)
{
	return buf->len;
}

static size_t bytes_per_screen(WINDOW *win)
{
	return max_rows(win) * BYTES_PER_LINE;
}

void hexedit_set_cursor(struct hexedit *buf)
{
	wmove(buf->win, max_rows(buf->win), 0);
	wattron(buf->win, A_REVERSE | A_STANDOUT);
	wclrtoeol(buf->win);
	if (buf->cursor_offset < buf->len) {
		wprintw(buf->win, "Len:%lu Off:%lu Val:0x%X", buf->len,
			buf->cursor_offset, buf->data[buf->cursor_offset]);
	} else {
		wprintw(buf->win, "Len:%lu Off:%lu", buf->len,
			buf->cursor_offset);
	}
	wattroff(buf->win, A_REVERSE | A_STANDOUT);
	wmove(buf->win, buf->cursor_y, buf->cursor_x);
	wcursyncup(buf->win);
	wsyncup(buf->win);
	untouchwin(buf->win);
}

void hexedit_refresh(struct hexedit *buf)
{
	size_t end;
	size_t lineno;
	size_t off;

	werase(buf->win);
	if (buf->len == 0) {
		mvwprintw(buf->win, 0, 0, "%08X", 0);
		return;
	}

	end = buf->offset + bytes_per_screen(buf->win);
	if (end > buf->len) {
		end = buf->len;
	}

	for (off = buf->offset, lineno = 0;
	     off < end;
	     off += BYTES_PER_LINE, ++lineno) {
		uint8_t *line = buf->data + off;
		size_t i, endline;

		wmove(buf->win, lineno, 0);
		wprintw(buf->win, "%08zX  ", off);

		endline = BYTES_PER_LINE;

		if (off + BYTES_PER_LINE > buf->len) {
			endline = buf->len - off;
		}

		for (i = 0; i < endline; ++i) {
			wprintw(buf->win, "%02X", line[i]);
			if (i + 1 < endline) {
				if (i == 3) {
					wprintw(buf->win, "  ");
				} else {
					wprintw(buf->win, " ");
				}
			}
		}

		wmove(buf->win, lineno, ASCII_COL);
		for (i = 0; i < endline; ++i) {
			if (isprint(line[i])) {
				waddch(buf->win, line[i]);
			} else {
				waddch(buf->win, '.');
			}
		}
	}
}

static void calc_cursor_offset(struct hexedit *buf)
{
	buf->cursor_offset = buf->offset + buf->cursor_y * BYTES_PER_LINE +
				buf->cursor_line_offset;
}

static int offset_to_hex_col(size_t pos)
{
	switch (pos) {
	case 0:
		return HEX_COL1;
	case 1:
		return HEX_COL1 + 3;
	case 2:
		return HEX_COL1 + 6;
	case 3:
		return HEX_COL1 + 9;

	case 4:
		return HEX_COL2;
	case 5:
		return HEX_COL2 + 3;
	case 6:
		return HEX_COL2 + 6;
	case 7:
		return HEX_COL2 + 9;
	}

	return -1;
}

static bool scroll_up(struct hexedit *buf)
{
	if (buf->offset == 0) {
		return false;
	}

	buf->offset -= BYTES_PER_LINE;

	return true;
}

static void cursor_down(struct hexedit *buf)
{
	size_t space;
	bool need_refresh = false;

	space = buf->offset + (buf->cursor_y + 1) * BYTES_PER_LINE;
	if (space > buf->len) {
		return;
	}

	if (buf->cursor_y + 1 == max_rows(buf->win)) {
		buf->offset += BYTES_PER_LINE;
		need_refresh = true;
	} else {
		buf->cursor_y++;
	}

	if (buf->cursor_offset + BYTES_PER_LINE > buf->len) {
		buf->nibble = 0;
		buf->cursor_offset = buf->len;
		buf->cursor_line_offset = buf->len - space;
		if (buf->cursor_x >= ASCII_COL) {
			buf->cursor_x = ASCII_COL + buf->cursor_line_offset;
		} else {
			buf->cursor_x = offset_to_hex_col(buf->cursor_line_offset);
		}
	}
	if (need_refresh) {
		hexedit_refresh(buf);
	}
	calc_cursor_offset(buf);
}

static void cursor_up(struct hexedit *buf)
{
	if (buf->cursor_y == 0) {
		if (scroll_up(buf)) {
			hexedit_refresh(buf);
		}
	} else {
		buf->cursor_y--;
	}

	calc_cursor_offset(buf);
}

static bool is_over_gap(struct hexedit *buf)
{
	int col;

	if (buf->cursor_x < ASCII_COL) {
		if (buf->cursor_x >= HEX_COL2) {
			col = buf->cursor_x - HEX_COL2;
		} else {
			col = buf->cursor_x - HEX_COL1;
		}

		switch (col) {
		case 2:
		case 5:
		case 8:
			return true;
		}
	}

	return false;
}

static void cursor_left(struct hexedit *buf)
{
	if (buf->cursor_x == HEX_COL1) {
		return;
	}
	if (buf->cursor_x == HEX_COL2) {
		buf->cursor_x = HEX_COL1_END - 1;
		buf->cursor_line_offset = 3;
		buf->nibble = 1;
	} else if (buf->cursor_x == ASCII_COL) {
		size_t off = buf->offset + buf->cursor_y * BYTES_PER_LINE;
		if (off + 7 >= buf->len) {
			size_t lastpos = buf->len - off;
			buf->cursor_x = offset_to_hex_col(lastpos) + 1;
			buf->cursor_line_offset = lastpos;
		} else {
			buf->cursor_x = HEX_COL2_END - 1;
			buf->cursor_line_offset = 7;
		}
		buf->nibble = 1;
	} else {
		if (buf->cursor_x > ASCII_COL || buf->nibble == 0) {
			buf->cursor_line_offset--;
		}
		buf->cursor_x--;
		buf->nibble = !buf->nibble;
	}

	if (is_over_gap(buf)) {
		buf->cursor_x--;
	}

	calc_cursor_offset(buf);
}

static void cursor_right(struct hexedit *buf)
{
	int new_x = buf->cursor_x + 1;

	if (new_x == ASCII_COL_END) {
		return;
	}
	if ((buf->cursor_x >= ASCII_COL || buf->nibble == 1) &&
	    buf->cursor_offset == buf->len) {
		if (buf->cursor_x < ASCII_COL) {
			new_x = ASCII_COL;
			buf->cursor_line_offset = 0;
			buf->nibble = 0;
		} else {
			return;
		}
	}
	if (new_x == HEX_COL1_END) {
		new_x = HEX_COL2;
		buf->cursor_line_offset = 4;
		buf->nibble = 0;
	} else if (new_x == HEX_COL2_END) {
		new_x = ASCII_COL;
		buf->cursor_line_offset = 0;
		buf->nibble = 0;
	} else {
		if (buf->cursor_x >= ASCII_COL || buf->nibble == 1) {
			buf->cursor_line_offset++;
		}
		buf->nibble = !buf->nibble;
	}

	buf->cursor_x = new_x;

	if (is_over_gap(buf)) {
		buf->cursor_x++;
	}

	calc_cursor_offset(buf);
}

static void do_edit(struct hexedit *buf, int c)
{
	uint8_t *byte;

	if (buf->cursor_offset == buf->len) {
		hexedit_resize_buffer(buf, buf->len + 1);
	}

	byte = buf->data + buf->cursor_offset;

	if (buf->cursor_x >= ASCII_COL) {
		*byte = (uint8_t)c;

		mvwprintw(buf->win, buf->cursor_y,
			  offset_to_hex_col(buf->cursor_line_offset), "%X", c);
		if (!isprint(c)) {
			c = '.';
		}
		mvwaddch(buf->win, buf->cursor_y,
			 ASCII_COL + buf->cursor_line_offset, c);
		if (buf->cursor_x + 1 != ASCII_COL_END) {
			cursor_right(buf);
		} else {
			cursor_down(buf);
		}
	} else {
		if (!isxdigit(c)) {
			return;
		}
		c = toupper(c);
		waddch(buf->win, c);

		if (isdigit(c)) {
			c = c - '0';
		} else {
			c = c - 'A' + 10;
		}
		if (buf->nibble == 0) {
			*byte = (*byte & 0x0f) | c << 4;
		} else {
			*byte = (*byte & 0xf0) | c;
		}

		c = *byte;
		if (!isprint(c)) {
			c = '.';
		}
		mvwaddch(buf->win, buf->cursor_y,
			 ASCII_COL + buf->cursor_line_offset, c);

		if (buf->cursor_x + 1 != HEX_COL2_END) {
			cursor_right(buf);
		} else {
			cursor_down(buf);
		}
	}

	hexedit_refresh(buf);
}

static void erase_at(struct hexedit *buf, size_t pos)
{
	if (pos >= buf->len) {
		return;
	}

	if (pos < buf->len - 1) {
		/* squeeze the character out of the buffer */
		uint8_t *p = buf->data + pos;
		uint8_t *end = buf->data + buf->len;
		memmove(p, p + 1, end - p - 1);
	}

	buf->len--;
	hexedit_refresh(buf);
}

static void do_backspace(struct hexedit *buf)
{
	size_t off;
	bool do_erase = true;

	if (buf->cursor_offset == 0) {
		return;
	}

	off = buf->cursor_offset;
	if (buf->cursor_x == ASCII_COL) {
		cursor_up(buf);
		buf->cursor_line_offset = 7;
		buf->cursor_x = ASCII_COL_END - 1;
		calc_cursor_offset(buf);
	} else if (buf->cursor_x == HEX_COL1) {
		cursor_up(buf);
		buf->cursor_line_offset = 7;
		buf->cursor_x = HEX_COL2_END - 1;
		buf->nibble = 1;
		calc_cursor_offset(buf);
	} else {
		if (buf->cursor_x < ASCII_COL && buf->nibble) {
			do_erase = false;
		}
		cursor_left(buf);
	}
	if (do_erase) {
		erase_at(buf, off - 1);
	}
}

static void do_delete(struct hexedit *buf)
{
	erase_at(buf, buf->cursor_offset);
}

void hexedit_driver(struct hexedit *buf, int c)
{
	switch (c) {
	case HE_CURSOR_UP:
		cursor_up(buf);
		break;
	case HE_CURSOR_DOWN:
		cursor_down(buf);
		break;
	case HE_CURSOR_LEFT:
		cursor_left(buf);
		break;
	case HE_CURSOR_RIGHT:
		cursor_right(buf);
		break;
	case HE_CURSOR_PGUP:
		break;
	case HE_CURSOR_PGDN:
		break;
	case HE_BACKSPACE:
		do_backspace(buf);
		break;
	case HE_DELETE:
		do_delete(buf);
		break;
	default:
		do_edit(buf, c & 0xff);
		break;
	}

	hexedit_set_cursor(buf);
}

WERROR hexedit_resize_buffer(struct hexedit *buf, size_t newsz)
{
	/* reset the cursor if it'll be out of bounds
	   after the resize */
	if (buf->cursor_offset > newsz) {
		buf->cursor_y = 0;
		buf->cursor_x = HEX_COL1;
		buf->offset = 0;
		buf->cursor_offset = 0;
		buf->cursor_line_offset = 0;
		buf->nibble = 0;
	}

	if (newsz > buf->len) {
		if (newsz > buf->alloc_size) {
			uint8_t *d;
			buf->alloc_size *= 2;
			if (newsz > buf->alloc_size) {
				buf->alloc_size = newsz;
			}
			d = talloc_realloc(buf, buf->data, uint8_t,
					   buf->alloc_size);
			if (d == NULL) {
				return WERR_NOT_ENOUGH_MEMORY;
			}
			buf->data = d;
		}
		memset(buf->data + buf->len, '\0', newsz - buf->len);
		buf->len = newsz;
	} else {
		buf->len = newsz;
	}

	return WERR_OK;
}