/* -*- c-basic-offset:2; tab-width:2; indent-tabs-mode:nil -*- */

#include "vt_edit_scroll.h"

#include <pobl/bl_util.h>

#include "vt_edit_util.h"

/* --- static functions --- */

/*
 * src and dst may overlap
 */
static int copy_lines(vt_edit_t *edit, int dst_row, int src_row, u_int size, int mark_changed) {
  int count;
  vt_line_t *src_line;
  vt_line_t *dst_line;

  if (size == 0 || dst_row == src_row) {
    return 1;
  }

  if (src_row + size > edit->model.num_rows) {
#ifdef DEBUG
    bl_warn_printf(BL_DEBUG_TAG " copying %d lines from %d row is over edit->model.num_rows(%d)",
                   size, src_row, edit->model.num_rows);
#endif

    size = edit->model.num_rows - src_row;

#ifdef DEBUG
    bl_msg_printf(" ... size modified -> %d.\n", size);
#endif
  }

  if (dst_row + size > edit->model.num_rows) {
#ifdef DEBUG
    bl_warn_printf(BL_DEBUG_TAG " copying %d lines to %d row is over edit->model.num_rows(%d)",
                   size, dst_row, edit->model.num_rows);
#endif

    size = edit->model.num_rows - dst_row;

#ifdef DEBUG
    bl_msg_printf(" ... size modified -> %d.\n", size);
#endif
  }

  if (dst_row < src_row) {
    for (count = 0; count < size; count++) {
      dst_line = vt_model_get_line(&edit->model, dst_row + count);
      src_line = vt_model_get_line(&edit->model, src_row + count);

      vt_line_swap(dst_line, src_line);
      if (mark_changed) {
        vt_line_set_modified_all(dst_line);
      }
    }
  } else {
    for (count = size - 1; count >= 0; count--) {
      dst_line = vt_model_get_line(&edit->model, dst_row + count);
      src_line = vt_model_get_line(&edit->model, src_row + count);

      vt_line_swap(dst_line, src_line);
      if (mark_changed) {
        vt_line_set_modified_all(dst_line);
      }
    }
  }

  return 1;
}

static int clear_lines_to_eol(vt_edit_t *edit, int beg_row, u_int size) {
  int count;

  vt_edit_clear_lines(edit, beg_row, size);

  for (count = 0; count < size; count++) {
    vt_line_set_modified_all(vt_model_get_line(&edit->model, beg_row + count));
  }

  return 1;
}

static int scroll_upward_region(vt_edit_t *edit, int boundary_beg, int boundary_end, u_int size) {
  int count;
  int window_is_scrolled;

  if (boundary_beg + size > boundary_end) {
    /*
     * all lines within boundary are scrolled out.
     */

    if (edit->is_logging) {
      for (count = boundary_beg; count < boundary_end; count++) {
        (*edit->scroll_listener->receive_scrolled_out_line)(edit->scroll_listener->self,
                                                            vt_model_get_line(&edit->model, count));
      }
    }

    edit->cursor.row = boundary_beg;
    edit->cursor.col = 0;
    edit->cursor.char_index = 0;

    (*edit->scroll_listener->scrolled_out_lines_finished)(edit->scroll_listener->self);

    return clear_lines_to_eol(edit, boundary_beg, boundary_end - boundary_beg + 1);
  }

/*
 * scrolling up in window.
 *
 * !! Notice !!
 * This should be done before vt_edit_t data structure is chanegd
 * for the listener object to clear existing cache.
 */
#if 0
  bl_debug_printf(" SCROLL UP region %d %d size %d\n", boundary_beg, boundary_end, size);
#endif
  window_is_scrolled = (*edit->scroll_listener->window_scroll_upward_region)(
      edit->scroll_listener->self, boundary_beg, boundary_end, size);

  /*
   * handing over scrolled out lines , and calculating scrolling beg/end y
   * positions.
   */

  if (edit->is_logging) {
    for (count = boundary_beg; count < boundary_beg + size; count++) {
      (*edit->scroll_listener->receive_scrolled_out_line)(edit->scroll_listener->self,
                                                          vt_model_get_line(&edit->model, count));
    }
  }

  /*
   * resetting cursor position.
   */

  if (boundary_beg <= edit->cursor.row && edit->cursor.row <= boundary_end) {
    if (edit->cursor.row < boundary_beg + size) {
      edit->cursor.row = boundary_beg;
      edit->cursor.char_index = 0;
      edit->cursor.col = 0;
    } else {
      edit->cursor.row -= size;
    }
  }

  /*
   * scrolling up in edit.
   */

  if (boundary_beg == 0 && boundary_end == vt_model_end_row(&edit->model)) {
    vt_model_scroll_upward(&edit->model, size);
  } else {
    copy_lines(edit, boundary_beg, boundary_beg + size, boundary_end - (boundary_beg + size) + 1,
               0);
  }

  if (!window_is_scrolled) {
    int count;

    vt_edit_clear_lines(edit, boundary_end - size + 1, size);

    for (count = boundary_beg; count <= boundary_end; count++) {
      vt_line_set_modified_all(vt_model_get_line(&edit->model, count));
    }
  } else {
    clear_lines_to_eol(edit, boundary_end - size + 1, size);
  }

  /*
   * This must be called after vt_model_scroll_upward() because
   * scrolled_out_lines_finished()
   * can change vt_model_t.
   */
  (*edit->scroll_listener->scrolled_out_lines_finished)(edit->scroll_listener->self);

  return 1;
}

static int scroll_downward_region(vt_edit_t *edit, int boundary_beg, int boundary_end, u_int size) {
  int window_is_scrolled;

  if (boundary_beg + size > boundary_end) {
    /*
     * all lines within boundary are scrolled out.
     */

    edit->cursor.row = boundary_end;
    edit->cursor.col = 0;
    edit->cursor.char_index = 0;

    return clear_lines_to_eol(edit, boundary_beg, boundary_end - boundary_beg + 1);
  }

/*
 * scrolling down in window.
 *
 * !! Notice !!
 * This should be done before vt_edit_t data structure is chanegd
 * for the listener object to clear existing cache.
 */
#if 0
  bl_debug_printf(" SCROLL DOWN region %d %d size %d\n", boundary_beg, boundary_end, size);
#endif
  window_is_scrolled = (*edit->scroll_listener->window_scroll_downward_region)(
      edit->scroll_listener->self, boundary_beg, boundary_end, size);

  /*
   * resetting cursor position.
   */
  if (boundary_beg <= edit->cursor.row && edit->cursor.row <= boundary_end) {
    if (edit->cursor.row + size >= boundary_end + 1) {
      edit->cursor.row = boundary_end;
      edit->cursor.char_index = 0;
      edit->cursor.col = 0;
    } else {
      edit->cursor.row += size;
    }
  }

  /*
   * scrolling down in edit.
   */

  if (boundary_beg == 0 && boundary_end == vt_model_end_row(&edit->model)) {
    vt_model_scroll_downward(&edit->model, size);
  } else {
    copy_lines(edit, boundary_beg + size, boundary_beg, (boundary_end - size) - boundary_beg + 1,
               0);
  }

  if (!window_is_scrolled) {
    int count;

    vt_edit_clear_lines(edit, boundary_beg, size);

    for (count = boundary_beg; count <= boundary_end; count++) {
      vt_line_set_modified_all(vt_model_get_line(&edit->model, count));
    }
  } else {
    clear_lines_to_eol(edit, boundary_beg, size);
  }

  return 1;
}

/* --- global functions --- */

int vt_edsl_scroll_upward(vt_edit_t *edit, u_int size) {
#if 0
  /*
   * XXX
   * Can this cause unexpected result ?
   */
  if (edit->vmargin_beg > edit->cursor.row || edit->cursor.row > edit->vmargin_end) {
    return 0;
  }
#endif

  return scroll_upward_region(edit, edit->vmargin_beg, edit->vmargin_end, size);
}

int vt_edsl_scroll_downward(vt_edit_t *edit, u_int size) {
#if 0
  /*
   * XXX
   * Can this cause unexpected result ?
   */
  if (edit->vmargin_beg > edit->cursor.row || edit->cursor.row > edit->vmargin_end) {
    return 0;
  }
#endif

  return scroll_downward_region(edit, edit->vmargin_beg, edit->vmargin_end, size);
}

/*
 * XXX
 * not used for now.
 */
#if 0
int vt_edsl_scroll_upward_in_all(vt_edit_t *edit, u_int size) {
  return scroll_upward_region(edit, 0, edit->model.num_rows - 1, size);
}

int vt_edsl_scroll_downward_in_all(vt_edit_t *edit, u_int size) {
  return scroll_downward_region(edit, 0, edit->model.num_rows - 1, size);
}
#endif

int vt_is_scroll_upperlimit(vt_edit_t *edit, int row) { return (row == edit->vmargin_beg); }

int vt_is_scroll_lowerlimit(vt_edit_t *edit, int row) { return (row == edit->vmargin_end); }

int vt_edsl_insert_new_line(vt_edit_t *edit) {
  int start_row;
  int start_col;
  int end_row;

  if (edit->cursor.row < edit->vmargin_beg || edit->vmargin_end < edit->cursor.row) {
    return 0;
  }

  start_row = edit->cursor.row;
  start_col = edit->cursor.col;
  end_row = edit->vmargin_end;

  scroll_downward_region(edit, start_row, end_row, 1);
  vt_cursor_goto_by_col(&edit->cursor, start_col, start_row);
  vt_edit_clear_line_to_right(edit);

  return 1;
}

int vt_edsl_delete_line(vt_edit_t *edit) {
  int start_row;
  int start_col;
  int end_row;
  int is_logging;

  if (edit->cursor.row < edit->vmargin_beg || edit->vmargin_end < edit->cursor.row) {
    return 0;
  }

  is_logging = edit->is_logging;
  edit->is_logging = 0;

  start_row = edit->cursor.row;
  start_col = edit->cursor.col;
  end_row = edit->vmargin_end;

  scroll_upward_region(edit, start_row, end_row, 1);
  vt_edit_clear_lines(edit, end_row, 1);
  vt_cursor_goto_by_col(&edit->cursor, start_col, start_row);

  edit->is_logging = is_logging;

  return 1;
}