/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is libguac-client-ssh.
 *
 * The Initial Developer of the Original Code is
 * Michael Jumper.
 * Portions created by the Initial Developer are Copyright (C) 2011
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * James Muehlner <dagger10k@users.sourceforge.net>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include <stdlib.h>
#include <string.h>
#include <pthread.h>

#include <cairo/cairo.h>
#include <pango/pangocairo.h>

#include <guacamole/socket.h>
#include <guacamole/protocol.h>
#include <guacamole/client.h>

#include "types.h"
#include "buffer.h"
#include "common.h"
#include "display.h"
#include "terminal.h"
#include "terminal_handlers.h"

guac_terminal* guac_terminal_create(guac_client* client,
        int width, int height) {

    guac_terminal_char default_char = {
        .value = 0,
        .attributes = {
            .foreground = 7,
            .background = 0,
            .bold       = false,
            .reverse    = false,
            .underscore = false
        }};

    guac_terminal* term = malloc(sizeof(guac_terminal));
    term->client = client;

    /* Init buffer */
    term->buffer = guac_terminal_buffer_alloc(1000, &default_char);
    term->scroll_offset = 0;

    /* Init display */
    term->display = guac_terminal_display_alloc(client,
            default_char.attributes.foreground,
            default_char.attributes.background);

    /* Init terminal state */
    term->current_attributes = default_char.attributes;
    term->default_char = default_char;

    term->cursor_row = term->visible_cursor_row = 0;
    term->cursor_col = term->visible_cursor_col = 0;

    term->term_width   = width  / term->display->char_width;
    term->term_height  = height / term->display->char_height;
    term->char_handler = guac_terminal_echo; 

    term->scroll_start = 0;
    term->scroll_end = term->term_height - 1;

    term->text_selected = false;

    /* Size display */
    guac_terminal_display_resize(term->display,
            term->term_width, term->term_height);

    /* Init terminal lock */
    pthread_mutex_init(&(term->lock), NULL);

    return term;

}

void guac_terminal_free(guac_terminal* term) {
    
    /* Free display */
    guac_terminal_display_free(term->display);

    /* Free buffer */
    guac_terminal_buffer_free(term->buffer);

}

int guac_terminal_set(guac_terminal* term, int row, int col, int codepoint) {

    /* Build character with current attributes */
    guac_terminal_char guac_char;
    guac_char.value = codepoint;
    guac_char.attributes = term->current_attributes;

    guac_terminal_set_columns(term, row, col, col, &guac_char);

    return 0;

}

void guac_terminal_commit_cursor(guac_terminal* term) {

    guac_terminal_char* guac_char;

    guac_terminal_buffer_row* old_row;
    guac_terminal_buffer_row* new_row;

    /* If no change, done */
    if (term->visible_cursor_row == term->cursor_row && term->visible_cursor_col == term->cursor_col)
        return;

    /* Get old and new rows with cursor */
    new_row = guac_terminal_buffer_get_row(term->buffer, term->cursor_row, term->cursor_col+1);
    old_row = guac_terminal_buffer_get_row(term->buffer, term->visible_cursor_row, term->visible_cursor_col+1);

    /* Clear cursor */
    guac_char = &(old_row->characters[term->visible_cursor_col]);
    guac_char->attributes.cursor = false;
    guac_terminal_display_set_columns(term->display, term->visible_cursor_row + term->scroll_offset,
            term->visible_cursor_col, term->visible_cursor_col, guac_char);

    /* Set cursor */
    guac_char = &(new_row->characters[term->cursor_col]);
    guac_char->attributes.cursor = true;
    guac_terminal_display_set_columns(term->display, term->cursor_row + term->scroll_offset,
            term->cursor_col, term->cursor_col, guac_char);

    term->visible_cursor_row = term->cursor_row;
    term->visible_cursor_col = term->cursor_col;

    return;

}

int guac_terminal_write(guac_terminal* term, const char* c, int size) {

    while (size > 0) {
        term->char_handler(term, *(c++));
        size--;
    }

    return 0;

}

int guac_terminal_scroll_up(guac_terminal* term,
        int start_row, int end_row, int amount) {

    /* If scrolling entire display, update scroll offset */
    if (start_row == 0 && end_row == term->term_height - 1) {

        /* Scroll up visibly */
        guac_terminal_display_copy_rows(term->display, start_row + amount, end_row, -amount);

        /* Advance by scroll amount */
        term->buffer->top += amount;
        if (term->buffer->top >= term->buffer->available)
            term->buffer->top -= term->buffer->available;

        term->buffer->length += amount;
        if (term->buffer->length > term->buffer->available)
            term->buffer->length = term->buffer->available;

        /* Update cursor location if within region */
        if (term->visible_cursor_row >= start_row &&
            term->visible_cursor_row <= end_row)
            term->visible_cursor_row -= amount;

    }

    /* Otherwise, just copy row data upwards */
    else
        guac_terminal_copy_rows(term, start_row + amount, end_row, -amount);

    /* Clear new area */
    guac_terminal_clear_range(term,
            end_row - amount + 1, 0,
            end_row, term->term_width - 1);

    return 0;
}

int guac_terminal_scroll_down(guac_terminal* term,
        int start_row, int end_row, int amount) {

    guac_terminal_copy_rows(term, start_row, end_row - amount, amount);

    /* Clear new area */
    guac_terminal_clear_range(term,
            start_row, 0,
            start_row + amount - 1, term->term_width - 1);

    return 0;
}

int guac_terminal_clear_columns(guac_terminal* term,
        int row, int start_col, int end_col) {

    /* Build space */
    guac_terminal_char blank;
    blank.value = 0;
    blank.attributes = term->current_attributes;

    /* Clear */
    guac_terminal_set_columns(term,
        row, start_col, end_col, &blank);

    return 0;

}

int guac_terminal_clear_range(guac_terminal* term,
        int start_row, int start_col,
        int end_row, int end_col) {

    /* If not at far left, must clear sub-region to far right */
    if (start_col > 0) {

        /* Clear from start_col to far right */
        guac_terminal_clear_columns(term,
            start_row, start_col, term->term_width - 1);

        /* One less row to clear */
        start_row++;
    }

    /* If not at far right, must clear sub-region to far left */
    if (end_col < term->term_width - 1) {

        /* Clear from far left to end_col */
        guac_terminal_clear_columns(term, end_row, 0, end_col);

        /* One less row to clear */
        end_row--;

    }

    /* Remaining region now guaranteed rectangular. Clear, if possible */
    if (start_row <= end_row) {

        int row;
        for (row=start_row; row<=end_row; row++) {

            /* Clear entire row */
            guac_terminal_clear_columns(term, row, 0, term->term_width - 1);

        }

    }

    return 0;

}

void guac_terminal_scroll_display_down(guac_terminal* terminal,
        int scroll_amount) {

    int start_row, end_row;
    int dest_row;
    int row, column;

    /* Limit scroll amount by size of scrollback buffer */
    if (scroll_amount > terminal->scroll_offset)
        scroll_amount = terminal->scroll_offset;

    /* If not scrolling at all, don't bother trying */
    if (scroll_amount <= 0)
        return;

    /* Shift screen up */
    if (terminal->term_height > scroll_amount)
        guac_terminal_display_copy_rows(terminal->display,
                scroll_amount, terminal->term_height - 1,
                -scroll_amount);

    /* Advance by scroll amount */
    terminal->scroll_offset -= scroll_amount;

    /* Get row range */
    end_row   = terminal->term_height - terminal->scroll_offset - 1;
    start_row = end_row - scroll_amount + 1;
    dest_row  = terminal->term_height - scroll_amount;

    /* Draw new rows from scrollback */
    for (row=start_row; row<=end_row; row++) {

        /* Get row from scrollback */
        guac_terminal_buffer_row* buffer_row =
            guac_terminal_buffer_get_row(terminal->buffer, row, 0);

        /* Clear row */
        guac_terminal_display_set_columns(terminal->display,
                dest_row, 0, terminal->display->width, &(terminal->default_char));

        /* Draw row */
        guac_terminal_char* current = buffer_row->characters;
        for (column=0; column<buffer_row->length; column++)
            guac_terminal_display_set_columns(terminal->display,
                    dest_row, column, column, current++);

        /* Next row */
        dest_row++;

    }

    guac_terminal_display_flush(terminal->display);
    guac_socket_flush(terminal->client->socket);

}

void guac_terminal_scroll_display_up(guac_terminal* terminal,
        int scroll_amount) {

    int start_row, end_row;
    int dest_row;
    int row, column;


    /* Limit scroll amount by size of scrollback buffer */
    if (terminal->scroll_offset + scroll_amount > terminal->buffer->length - terminal->term_height)
        scroll_amount = terminal->buffer->length - terminal->scroll_offset - terminal->term_height;

    /* If not scrolling at all, don't bother trying */
    if (scroll_amount <= 0)
        return;

    /* Shift screen down */
    if (terminal->term_height > scroll_amount)
        guac_terminal_display_copy_rows(terminal->display,
                0, terminal->term_height - scroll_amount - 1,
                scroll_amount);

    /* Advance by scroll amount */
    terminal->scroll_offset += scroll_amount;

    /* Get row range */
    start_row = -terminal->scroll_offset;
    end_row   = start_row + scroll_amount - 1;
    dest_row  = 0;

    /* Draw new rows from scrollback */
    for (row=start_row; row<=end_row; row++) {

        /* Get row from scrollback */
        guac_terminal_buffer_row* buffer_row = 
            guac_terminal_buffer_get_row(terminal->buffer, row, 0);

        /* Clear row */
        guac_terminal_display_set_columns(terminal->display,
                dest_row, 0, terminal->display->width, &(terminal->default_char));

        /* Draw row */
        guac_terminal_char* current = buffer_row->characters;
        for (column=0; column<buffer_row->length; column++)
            guac_terminal_display_set_columns(terminal->display,
                    dest_row, column, column, current++);

        /* Next row */
        dest_row++;

    }

    guac_terminal_display_flush(terminal->display);
    guac_socket_flush(terminal->client->socket);

}

void guac_terminal_select_redraw(guac_terminal* terminal) {

    guac_terminal_display_select(terminal->display,
            terminal->selection_start_row + terminal->scroll_offset,
            terminal->selection_start_column,
            terminal->selection_end_row + terminal->scroll_offset,
            terminal->selection_end_column);

}

void guac_terminal_select_start(guac_terminal* terminal, int row, int column) {

    terminal->selection_start_row = 
    terminal->selection_end_row   = row;

    terminal->selection_start_column = 
    terminal->selection_end_column   = column;

    terminal->text_selected = true;

    guac_terminal_select_redraw(terminal);

}

void guac_terminal_select_update(guac_terminal* terminal, int row, int column) {

    if (row != terminal->selection_end_row || column != terminal->selection_end_column) {
        terminal->selection_end_row   = row;
        terminal->selection_end_column   = column;

        guac_terminal_select_redraw(terminal);
    }

}

int __guac_terminal_buffer_string(guac_terminal_buffer_row* row, int start, int end, char* string) {

    int length = 0;
    int i;
    for (i=start; i<=end; i++) {

        int codepoint = row->characters[i].value;

        /* If not null (blank), add to string */
        if (codepoint != 0) {
            int bytes = guac_terminal_encode_utf8(codepoint, string);
            string += bytes;
            length += bytes;
        }

    }

    return length;

}

void guac_terminal_select_end(guac_terminal* terminal, char* string) {

    /* Deselect */
    terminal->text_selected = false;
    guac_terminal_display_commit_select(terminal->display);

    guac_terminal_buffer_row* buffer_row;

    int row;

    int start_row, start_col;
    int end_row, end_col;

    /* Ensure proper ordering of start and end coords */
    if (terminal->selection_start_row <= terminal->selection_end_row) {
        start_row = terminal->selection_start_row;
        start_col = terminal->selection_start_column;
        end_row   = terminal->selection_end_row;
        end_col   = terminal->selection_end_column;
    }
    else {
        end_row   = terminal->selection_start_row;
        end_col   = terminal->selection_start_column;
        start_row = terminal->selection_end_row;
        start_col = terminal->selection_end_column;
    }

    /* If only one row, simply copy */
    buffer_row = guac_terminal_buffer_get_row(terminal->buffer, start_row, 0);
    if (end_row == start_row) {
        if (buffer_row->length - 1 < end_col)
            end_col = buffer_row->length - 1;
        string += __guac_terminal_buffer_string(buffer_row, start_col, end_col, string);
    }

    /* Otherwise, copy multiple rows */
    else {

        /* Store first row */
        string += __guac_terminal_buffer_string(buffer_row, start_col, buffer_row->length - 1, string);

        /* Store all middle rows */
        for (row=start_row+1; row<end_row; row++) {

            buffer_row = guac_terminal_buffer_get_row(terminal->buffer, row, 0);

            *(string++) = '\n';
            string += __guac_terminal_buffer_string(buffer_row, 0, buffer_row->length - 1, string);

        }

        /* Store last row */
        buffer_row = guac_terminal_buffer_get_row(terminal->buffer, end_row, 0);
        if (buffer_row->length - 1 < end_col)
            end_col = buffer_row->length - 1;

        *(string++) = '\n';
        string += __guac_terminal_buffer_string(buffer_row, 0, end_col, string);

    }

    /* Null terminator */
    *string = 0;

}

void guac_terminal_copy_columns(guac_terminal* terminal, int row,
        int start_column, int end_column, int offset) {

    guac_terminal_display_copy_columns(terminal->display, row + terminal->scroll_offset,
            start_column, end_column, offset);

    guac_terminal_buffer_copy_columns(terminal->buffer, row,
            start_column, end_column, offset);

    /* Update cursor location if within region */
    if (row == terminal->visible_cursor_row &&
            terminal->visible_cursor_col >= start_column &&
            terminal->visible_cursor_col <= end_column)
        terminal->visible_cursor_col += offset;

}

void guac_terminal_copy_rows(guac_terminal* terminal,
        int start_row, int end_row, int offset) {

    guac_terminal_display_copy_rows(terminal->display,
            start_row + terminal->scroll_offset, end_row + terminal->scroll_offset, offset);

    guac_terminal_buffer_copy_rows(terminal->buffer,
            start_row, end_row, offset);

    /* Update cursor location if within region */
    if (terminal->visible_cursor_row >= start_row &&
        terminal->visible_cursor_row <= end_row)
        terminal->visible_cursor_row += offset;

}

void guac_terminal_set_columns(guac_terminal* terminal, int row,
        int start_column, int end_column, guac_terminal_char* character) {

    guac_terminal_display_set_columns(terminal->display, row + terminal->scroll_offset,
            start_column, end_column, character);

    guac_terminal_buffer_set_columns(terminal->buffer, row,
            start_column, end_column, character);

}

static void __guac_terminal_redraw_rect(guac_terminal* term, int start_row, int start_col, int end_row, int end_col) {

    int row, col;

    /* Redraw region */
    for (row=start_row; row<=end_row; row++) {

        guac_terminal_buffer_row* buffer_row =
            guac_terminal_buffer_get_row(term->buffer, row - term->scroll_offset, 0);

        /* Clear row */
        guac_terminal_display_set_columns(term->display,
                row, start_col, end_col, &(term->default_char));

        /* Copy characters */
        for (col=start_col; col <= end_col && col < buffer_row->length; col++)
            guac_terminal_display_set_columns(term->display, row, col, col,
                    &(buffer_row->characters[col]));

    }

}

void guac_terminal_resize(guac_terminal* term, int width, int height) {

    /* If height is decreasing, shift display up */
    if (height < term->term_height) {

        int shift_amount;

        /* Get number of rows actually occupying terminal space */
        int used_height = term->buffer->length;
        if (used_height > term->term_height)
            used_height = term->term_height;

        shift_amount = used_height - height;

        /* If the new terminal bottom covers N rows, shift up N rows */
        if (shift_amount > 0) {

            guac_terminal_display_copy_rows(term->display,
                    shift_amount, term->display->height - 1, -shift_amount);

            /* Update buffer top and cursor row based on shift */
            term->buffer->top += shift_amount;
            term->cursor_row  -= shift_amount;

            /* Redraw characters within old region */
            __guac_terminal_redraw_rect(term, height - shift_amount, 0, height-1, width-1);

        }

    }

    /* Resize display */
    guac_terminal_display_flush(term->display);
    guac_terminal_display_resize(term->display, width, height);

    /* Reraw any characters on right if widening */
    if (width > term->term_width)
        __guac_terminal_redraw_rect(term, 0, term->term_width-1, height-1, width-1);

    /* If height is increasing, shift display down */
    if (height > term->term_height) {

        /* If undisplayed rows exist in the buffer, shift them into view */
        if (term->term_height < term->buffer->length) {

            /* If the new terminal bottom reveals N rows, shift down N rows */
            int shift_amount = height - term->term_height;

            /* The maximum amount we can shift is the number of undisplayed rows */
            int max_shift = term->buffer->length - term->term_height;

            if (shift_amount > max_shift)
                shift_amount = max_shift;

            /* Update buffer top and cursor row based on shift */
            term->buffer->top -= shift_amount;
            term->cursor_row  += shift_amount;

            /* If scrolled enough, use scroll to fulfill entire resize */
            if (term->scroll_offset >= shift_amount) {

                term->scroll_offset -= shift_amount;

                /* Draw characters from scroll at bottom */
                __guac_terminal_redraw_rect(term, term->term_height, 0, term->term_height + shift_amount - 1, width-1);

            }

            /* Otherwise, fulfill with as much scroll as possible */
            else {

                /* Draw characters from scroll at bottom */
                __guac_terminal_redraw_rect(term, term->term_height, 0, term->term_height + term->scroll_offset - 1, width-1);

                /* Update shift_amount and scroll based on new rows */
                shift_amount -= term->scroll_offset;
                term->scroll_offset = 0;

                /* If anything remains, move screen as necessary */
                if (shift_amount > 0) {

                    guac_terminal_display_copy_rows(term->display,
                            0, term->display->height - shift_amount - 1, shift_amount);

                    /* Draw characters at top from scroll */
                    __guac_terminal_redraw_rect(term, 0, 0, shift_amount - 1, width-1);

                }

            }

        } /* end if undisplayed rows exist */

    }

    /* Commit new dimensions */
    term->term_width = width;
    term->term_height = height;

}