trunk/src/map_edit.c

/*
 * Copyright (C) 2008 Till Harbaum <till@harbaum.org>.
 *
 * This file is part of OSM2Go.
 *
 * OSM2Go 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.
 *
 * OSM2Go 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 OSM2Go.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "appdata.h"

/* --------------------- misc local helper functions ---------------- */

static void transfer_relations(osm_t *osm, way_t *dst, way_t *src) {

  /* transfer relation memberships from the src way to the dst one */
  relation_chain_t *rchain = osm_way_to_relation(osm, src);
    
  while(rchain) {
    relation_chain_t *next = rchain->next;
    printf("way #%ld is part of relation #%ld\n", src->id, 
           rchain->relation->id);
      
    /* make new member of the same relation */
    
    /* walk member chain. save role of way if its being found. */
    member_t **member = &rchain->relation->member;
    char *role = NULL;
    while(*member) { 
      /* save role of way */
      if(((*member)->type == WAY) && ((*member)->way == src))
        role = (*member)->role;
      member = &(*member)->next;
    }
    
    printf("  adding way #%ld to relation\n", dst->id);
    *member = g_new0(member_t, 1);
    (*member)->type = WAY;
    (*member)->way = dst;
    if(role) (*member)->role = g_strdup(role);
    member = &(*member)->next;
    
    rchain->relation->flags |= OSM_FLAG_DIRTY;
    
    g_free(rchain);
    rchain = next;
  }
}
    

/* combine tags from src to dst and combine them in a useful manner */
/* erase all source tags */
static gboolean combine_tags(tag_t **dst, tag_t *src) {
  gboolean conflict = FALSE;
  tag_t *dst_orig = *dst;

  /* ---------- transfer tags from way[1] to way[0] ----------- */
  while(*dst) dst = &((*dst)->next);  /* find end of target tag list */
  while(src) {
    /* check if same key but with different value is present, */
    /* ignoring the created_by tags */
    if(!osm_is_creator_tag(src) && 
       osm_tag_key_other_value_present(dst_orig, src))
      conflict = TRUE;

    /* don't copy "created_by" and "source" tag or tags that already */
    /* exist in identical form */
    if(osm_is_creator_tag(src) || 
       osm_tag_key_and_value_present(dst_orig, src)) {
      tag_t *next = src->next;
      osm_tag_free(src);
      src = next;
    } else {
      *dst = src;
      src = src->next;
      dst = &((*dst)->next);
      *dst = NULL;
    }
  }
  return conflict;
}

/* -------------------------- way_add ----------------------- */

void map_edit_way_add_begin(map_t *map, way_t *way_sel) {
  if(way_sel) printf("previously selected way is #%ld\n", way_sel->id);

  g_assert(!map->action.way);
  map->action.way = osm_way_new();
  map->action.extending = NULL;
}

void map_edit_way_add_segment(map_t *map, gint x, gint y) {

  /* convert mouse position to canvas (world) position */
  canvas_window2world(map->canvas, x, y, &x, &y);
  
  /* check if this was a double click. This is the case if */
  /* the last node placed is less than 5 pixels from the current */
  /* position */
  node_t *lnode = osm_way_get_last_node(map->action.way);
  if(lnode && (map->state->zoom * sqrt((lnode->lpos.x-x)*(lnode->lpos.x-x)+ 
                       (lnode->lpos.y-y)*(lnode->lpos.y-y))) < 5) {
#if 0
    printf("detected double click -> simulate ok click\n");
    map_hl_touchnode_clear(map);
    map_action_ok(map->appdata);
#else
    printf("detected double click -> ignore it as accidential\n");
#endif
  } else {
    
    /* use the existing node if one was touched */    
    node_t *node = map_hl_touchnode_get_node(map);
    if(node) {
      printf("  re-using node #%ld\n", node->id);
      map_hl_touchnode_clear(map);

      g_assert(map->action.way);

      /* check whether this node is first or last one of a different way */
      way_t *touch_way = NULL;
      way_chain_t *way_chain = osm_node_to_way(map->appdata->osm, node);
      while(way_chain) {
        way_chain_t *next = way_chain->next;
        
        if(node == osm_way_get_last_node(way_chain->way)) {
          printf("  way #%ld ends with this node\n", way_chain->way->id);
          if(!touch_way) touch_way = way_chain->way;
        }
        
        if(node == osm_way_get_first_node(way_chain->way)) {
          printf("  way #%ld starts with this node\n", way_chain->way->id);
          if(!touch_way) touch_way = way_chain->way;
        }
        
        g_free(way_chain);
        way_chain = next;
      }
 
      /* remeber this way as this may be the last node placed */
      /* and we might want to join this with this other way */
      map->action.ends_on = touch_way;
     
      /* is this the first node the user places? */
      if(!map->action.way->node_chain) {
        map->action.extending = touch_way;
        
        if(map->action.extending) {
          if(!yes_no_f(GTK_WIDGET(map->appdata->window), 
               map->appdata, MISC_AGAIN_ID_EXTEND_WAY, 0,
               _("Extend way?"), 
               _("Do you want to extend the way present at this location?")))
            map->action.extending = NULL;
          else
            /* there are immediately enough nodes for a valid way */
            icon_bar_map_cancel_ok(map->appdata, TRUE, TRUE);
        }
      }
      
    } else {
      /* the current way doesn't end on another way if we are just placing */
      /* a new node */
      map->action.ends_on = NULL;

      if(!osm_position_within_bounds(map->appdata->osm, x, y)) 
        map_outside_error(map->appdata);
      else 
        node = osm_node_new(map->appdata->osm, x, y);
    }
    
    if(node) {
      g_assert(map->action.way);
      osm_way_append_node(map->action.way, node);
      
      switch(osm_node_chain_length(map->action.way->node_chain)) {
      case 1:
        /* replace "place first node..." message */
        statusbar_set(map->appdata, _("Place next node of way"), FALSE);
        break;
        
      case 2:
        /* two nodes are enough for a valid way */
        icon_bar_map_cancel_ok(map->appdata, TRUE, TRUE);
        break;
        
      default:
        break;
      }
      
      /* remove prior version of this way */
      map_item_chain_destroy(&map->action.way->map_item_chain);
      
      /* draw current way */
      josm_elemstyles_colorize_way(map->style, map->action.way);
      map_way_draw(map, map->action.way);
    }
  }
}

void map_edit_way_add_cancel(map_t *map) {

  printf("  removing temporary way\n");
  g_assert(map->action.way);

  /* remove all nodes that have been created for this way */
  /* (their way count will be 0 after removing the way) */
  node_chain_t *chain = map->action.way->node_chain;
  while(chain) {
    node_chain_t *next = chain->next;
    
    printf("    node #%ld (used by %d)\n", 
           chain->node->id, chain->node->ways);
    
    chain->node->ways--;
    if(!chain->node->ways && (chain->node->id == ID_ILLEGAL)) {
      printf("      -> freeing temp node\n");
      osm_node_free(&map->appdata->icon, chain->node);
    }
    g_free(chain);
    chain = next;
  }
  map->action.way->node_chain = NULL;
  
  /* remove ways visual representation */
  map_item_chain_destroy(&map->action.way->map_item_chain);
  
  osm_way_free(map->action.way);
  map->action.way = NULL;
}

void map_edit_way_add_ok(map_t *map) {
  g_assert(map->action.way);
    
  /* transfer all nodes that have been created for this way */
  /* into the node chain */
  
  /* (their way count will be 0 after removing the way) */
  node_chain_t *chain = map->action.way->node_chain;
  while(chain) {
    printf("    node #%ld (used by %d)\n", 
           chain->node->id, chain->node->ways);
    
    /* a node may have been a stand-alone node before, so remove its */
    /* visual representation as its now drawn as part of the way */
    /* (if at all) */
    if(chain->node->id != ID_ILLEGAL) 
      map_item_chain_destroy(&chain->node->map_item_chain);
    
    map_node_draw(map, chain->node);
    
    /* we can be sure that no node gets inserted twice (even if twice in */
    /* the ways chain) because it gets assigned a non-ID_ILLEGAL id when */
    /* being moved to the osm node chain */
    if(chain->node->id == ID_ILLEGAL) 
      osm_node_attach(map->appdata->osm, chain->node);
    
    chain = chain->next;
  }

  /* attach to existing way if the user requested so */
  gboolean revert = FALSE;
  if(map->action.extending) {
    node_t *nfirst = map->action.way->node_chain->node;

    printf("  request to extend way #%ld\n", map->action.extending->id);

    if(osm_way_get_first_node(map->action.extending) == nfirst) {
      printf("  need to prepend\n");
      osm_way_revert(map->action.extending);
      revert = TRUE;
    } else if(osm_way_get_last_node(map->action.extending) == nfirst) 
      printf("  need to append\n");
    
    /* search end of way to be extended */
    node_chain_t *chain = map->action.extending->node_chain;
    g_assert(chain);
    while(chain->next) chain = chain->next;

    /* skip first node of new way as its the same as the last one of the */
    /* way we are attaching it to */
    chain->next = map->action.way->node_chain->next;

    /* terminate new way afer first node */
    map->action.way->node_chain->next = NULL;

    /* erase and free new way (now only containing the first node anymore) */
    map_item_chain_destroy(&map->action.way->map_item_chain);
    osm_way_free(map->action.way);

    map->action.way = map->action.extending;
    map->action.way->flags |= OSM_FLAG_DIRTY;

    /* and undo reversion of required */
    if(revert)
      osm_way_revert(map->action.way);

  } else {
    /* now move the way itself into the main data structure */
    osm_way_attach(map->appdata->osm, map->action.way);
  }

  /* we might already be working on the "ends_on" way as we may */
  /* be extending it. Joining the same way doesn't make sense. */
  if(map->action.ends_on && (map->action.ends_on == map->action.way)) {
    printf("  the new way ends on itself -> don't join itself\n");
    map->action.ends_on = NULL;
  }

  if(map->action.ends_on) 
    if(!yes_no_f(GTK_WIDGET(map->appdata->window), 
                 map->appdata, MISC_AGAIN_ID_EXTEND_WAY_END, 0,
                 _("Join way?"), 
                 _("Do you want to join the way present at this location?")))
      map->action.ends_on = NULL;
  
  if(map->action.ends_on) {
    printf("  this new way ends on another way\n");

    /* if revert is true the node in question is the first one */
    /* of the newly created way. thus is it revertes again before */
    /* attaching and the result is finally reverted once more */

    /* this is slightly more complex as this time two full tagged */
    /* ways may be involved as the new way may be an extended existing */
    /* way being connected to another way. This happens if you connect */
    /* two existing ways using a new way between them */
    
    if(revert) osm_way_revert(map->action.way);

    /* and open dialog to resolve tag collisions if necessary */
    if(combine_tags(&map->action.way->tag, map->action.ends_on->tag))
      messagef(GTK_WIDGET(map->appdata->window), _("Way tag conflict"), 
               _("The resulting way contains some conflicting tags. "
                 "Please solve these."));
    
    map->action.ends_on->tag = NULL;
    
    /* make way member of all relations ends_on already is */
    transfer_relations(map->appdata->osm, map->action.way, map->action.ends_on);

    /* check if we have to revert (again?) to match the way order */
    if(osm_way_get_last_node(map->action.ends_on) == 
       osm_way_get_last_node(map->action.way)) {

      printf("  need to prepend ends_on\n");

      /* need to revert ends_on way */
      osm_way_revert(map->action.ends_on);
      revert = !revert;
    }

    /* search end of node chain */
    node_chain_t *chain = map->action.way->node_chain;
    g_assert(chain);
    while(chain->next) chain = chain->next;

    /* attach ends_on way to way but omit first node */
    chain->next = map->action.ends_on->node_chain->next;
    map->action.ends_on->node_chain->next = NULL;

    /* erase and free ends_on (now only containing the first node anymore) */
    map_way_delete(map->appdata, map->action.ends_on);
    
    if(revert) osm_way_revert(map->action.way);
  }

  /* remove prior version of this way */
  map_item_chain_destroy(&map->action.way->map_item_chain);
    
  /* draw the updated way */
  map_way_draw(map, map->action.way);
      
  map_way_select(map->appdata, map->action.way);

  map->action.way = NULL;
  
  /* let the user specify some tags for the new way */
  info_dialog(GTK_WIDGET(map->appdata->window), map->appdata, NULL);
}

/* -------------------------- way_node_add ----------------------- */

void map_edit_way_node_add_highlight(map_t *map, map_item_t *item, 
                                     gint x, gint y) {
  if(map_item_is_selected_way(map, item)) {
    gint nx, ny;
    canvas_window2world(map->canvas, x, y, &nx, &ny);
    if(canvas_item_get_segment(item->item, nx, ny) >= 0) 
      map_hl_cursor_draw(map, x, y, FALSE, map->style->node.radius);
  }
}

void map_edit_way_node_add(map_t *map, gint x, gint y) {
  /* check if we are still hovering above the selected way */
  map_item_t *item = map_real_item_at(map, x, y);
  if(item && map_item_is_selected_way(map, item)) {
    /* convert mouse position to canvas (world) position */
    canvas_window2world(map->canvas, x, y, &x, &y);
    gint insert_after = canvas_item_get_segment(item->item, x, y)+1;
    if(insert_after > 0) {
      /* create new node */
      node_t* node = osm_node_new(map->appdata->osm, x, y);
      osm_node_attach(map->appdata->osm, node);
      
      /* insert it into ways chain of nodes */
      way_t *way = item->way;
      
      /* search correct position */
      node_chain_t **chain = &way->node_chain;
      while(insert_after--) {
        g_assert(*chain);
        chain = &(*chain)->next;
      }
      
      /* and actually do the insertion */
      node_chain_t *new_chain_item = g_new0(node_chain_t, 1);
      new_chain_item->node = node;
      new_chain_item->next = *chain;
      *chain = new_chain_item;
      
      /* clear selection */
      map_item_deselect(map->appdata);
      
      /* remove prior version of this way */
      map_item_chain_destroy(&way->map_item_chain);
      
      /* draw the updated way */
      map_way_draw(map, way);
      
      /* remember that this node is contained in one way */
      node->ways=1;
      
      /* and that the way needs to be uploaded */
      way->flags |= OSM_FLAG_DIRTY;
      
      /* put gui into idle state */
      map_action_set(map->appdata, MAP_ACTION_IDLE);
      
      /* and redo it */
      map_way_select(map->appdata, way);
    }
  }
}  

/* -------------------------- way_node_cut ----------------------- */

void map_edit_way_cut_highlight(map_t *map, map_item_t *item, gint x, gint y) {

  if(map_item_is_selected_way(map, item)) {
    gint nx, ny, seg;
    canvas_window2world(map->canvas, x, y, &nx, &ny);
    seg = canvas_item_get_segment(item->item, nx, ny);
    if(seg >= 0) {
      gint x0, y0, x1, y1;
      canvas_item_get_segment_pos(item->item, seg, &x0, &y0, &x1, &y1);
      
      gint width = (item->way->draw.flags & 
                    OSM_DRAW_FLAG_BG)?
        2*item->way->draw.bg.width:
        3*item->way->draw.width;
      map_hl_segment_draw(map, width, x0, y0, x1, y1);
    }
  } else if(map_item_is_selected_node(map, item)) {
    node_t *nfirst = osm_way_get_first_node(map->selected.way);
    node_t *nlast = osm_way_get_last_node(map->selected.way);

    /* cutting a way at its first or last node doesn't make much sense ... */
    if((nfirst != item->node) && (nlast != item->node)) 
      map_hl_cursor_draw(map, item->node->lpos.x, item->node->lpos.y, 
                         TRUE, 2*map->style->node.radius);
  }
}

/* cut the currently selected way at the current cursor position */
void map_edit_way_cut(map_t *map, gint x, gint y) {

  /* check if we are still hovering above the selected way */
  map_item_t *item = map_real_item_at(map, x, y);
  if(item && (map_item_is_selected_way(map, item) || 
              map_item_is_selected_node(map, item))) {
    gboolean cut_at_node = map_item_is_selected_node(map, item);
    
    /* convert mouse position to canvas (world) position */
    canvas_window2world(map->canvas, x, y, &x, &y);
    
    gint cut_at = -1;
    way_t *way = NULL;
    if(cut_at_node) {
      printf("  cut at node\n");
      
      /* node must not be first or last node of way */
      g_assert(map->selected.type == MAP_TYPE_WAY);
      
      if((osm_way_get_first_node(map->selected.way) != item->node) &&
         (osm_way_get_last_node(map->selected.way) != item->node)) {
        way = map->selected.way;

        cut_at = 0;
        node_chain_t *chain = way->node_chain;
        while(chain && chain->node != item->node) {
          chain = chain->next;
          cut_at++;
        }

      } else
        printf("  won't cut as it's last or first node\n");
      
    } else {
      printf("  cut at segment\n");
      cut_at = canvas_item_get_segment(item->item, x, y);
      if(cut_at >= 0) way = item->way;
    }
    
    if(way) {
      /* create a duplicate of the currently selected way */
      way_t *new = osm_way_new();
      
      /* if this is a closed way, reorder (rotate) it, so the */
      /* place to cut is adjecent to the begin/end of the way. */
      /* this prevents a cut polygon to be split into two ways */
      g_assert(way->node_chain);
      if(way->node_chain->node == osm_way_get_last_node(way)) {
        printf("CLOSED WAY -> rotate by %d\n", cut_at);
        osm_way_rotate(way, cut_at);
        cut_at = 0;
      }
      
      /* ------------  copy all tags ------------- */
      new->tag = osm_tags_copy(way->tag, TRUE);
      
      /* ---- transfer relation membership from way to new ----- */
      transfer_relations(map->appdata->osm, new, way);
      
      /* move parts of node_chain to the new way */
      printf("  moving everthing after segment %d to new way\n", cut_at);

      node_chain_t *chain = way->node_chain;
      while(cut_at--) {
        g_assert(chain);
        chain = chain->next;
      }
      
      /* attach remaining nodes to new way */
      new->node_chain = chain->next;
      
      /* terminate remainig chain on old way */
      chain->next = NULL;
      
      /* if we cut at a node, this node is now part of both ways. so */
      /* create a copy of the last node of the old way and prepend it to */
      /* the new way */
      if(cut_at_node) {
        node_chain_t *first = g_new0(node_chain_t, 1);
        first->next = new->node_chain;
        first->node = osm_way_get_last_node(way);
        first->node->ways++;
        new->node_chain = first;
      }

      /* now move the way itself into the main data structure */
      osm_way_attach(map->appdata->osm, new);
      
      /* clear selection */
      map_item_deselect(map->appdata);
      
      /* remove prior version of this way */
      printf("remove visible version of way #%ld\n", way->id);
      map_item_chain_destroy(&way->map_item_chain);
      
      /* swap chains of the old way is to be destroyed due to a lack */
      /* of nodes */
      if(osm_way_number_of_nodes(way) < 2) {
        printf("swapping ways to avoid destruction of original way\n");
        node_chain_t *tmp = way->node_chain;
        way->node_chain = new->node_chain;
        new->node_chain = tmp;
      }

      /* the way may still only consist of a single node. */
      /* remove it then */
      if(osm_way_number_of_nodes(way) < 2) {
        printf("original way has less than 2 nodes left, deleting it\n");
        map_way_delete(map->appdata, way);
        item = NULL;
      } else {
        printf("original way still has %d nodes\n",
               osm_way_number_of_nodes(way));
        
        /* draw the updated old way */
        josm_elemstyles_colorize_way(map->style, way);
        map_way_draw(map, way);
        
        /* remember that the way needs to be uploaded */
        way->flags |= OSM_FLAG_DIRTY;
      }
      
      if(osm_way_number_of_nodes(new) < 2) {
        printf("new way has less than 2 nodes, deleting it\n");
        map_way_delete(map->appdata, new);
        new = NULL;
      } else {
        
        /* colorize the new way before drawing */
        josm_elemstyles_colorize_way(map->style, new);
        map_way_draw(map, new);
      }
      
      /* put gui into idle state */
      map_action_set(map->appdata, MAP_ACTION_IDLE);      
      
      /* and redo selection if way still exists */
      if(item) 
        map_way_select(map->appdata, way);
      else if(new)
        map_way_select(map->appdata, new);
    }
  }
}

void map_edit_node_move(appdata_t *appdata, map_item_t *map_item, 
                          gint ex, gint ey) {

  map_t *map = appdata->map;
  osm_t *osm = appdata->osm;

  g_assert(map_item->type == MAP_TYPE_NODE);
  node_t *node = map_item->node;

  printf("released dragged node #%ld\n", node->id);
  printf("  was at %d %d (%f %f)\n", 
         node->lpos.x, node->lpos.y,
         node->pos.lat, node->pos.lon);


  /* check if it was dropped onto another node */
  node_t *touchnode = map_hl_touchnode_get_node(map);
  if(touchnode) {
    map_hl_touchnode_clear(map);

    printf("  dropped onto node #%ld\n", touchnode->id);

    if(yes_no_f(GTK_WIDGET(appdata->window), 
                appdata, MISC_AGAIN_ID_JOIN_NODES, 0,
                _("Join nodes?"),
                _("Do you want to join the dragged node with the one "
                  "you dropped it on?"))) {

      /* the touchnode vanishes and is replaced by the node the */
      /* user dropped onto it */

      /* use touchnodes position */
      node->lpos = touchnode->lpos;
      node->pos = touchnode->pos;

      way_t *way = appdata->osm->way;
      while(way) {
        node_chain_t *chain = way->node_chain;
        while(chain) {
          if(chain->node == touchnode) {
            printf("  found node in way #%ld\n", way->id);
            
            /* replace by node */
            chain->node = node;
            
            /* and adjust way references of both nodes */
            node->ways++;
            touchnode->ways--;
            
            way->flags |= OSM_FLAG_DIRTY;
          }
          chain = chain->next;
        }
        way = way->next;
      }
      
      /* replace node in relations */
      relation_t *relation = appdata->osm->relation;
      while(relation) {
        member_t *member = relation->member;
        while(member) {
          if(member->type == NODE && member->node == touchnode) {
            printf("  found node in relation #%ld\n", relation->id);
            
            /* replace by node */
            member->node = node;

            relation->flags |= OSM_FLAG_DIRTY;
          }
          member = member->next;
        }
        relation = relation->next;
      }

      gboolean conflict = combine_tags(&node->tag, touchnode->tag);
      touchnode->tag = NULL;

      /* touchnode must not have any references to ways anymore */
      g_assert(!touchnode->ways);

      /* delete touchnode */
      /* remove it visually from the screen */
      map_item_chain_destroy(&touchnode->map_item_chain);

      /* and remove it from the data structures */
      osm_node_remove_from_relation(appdata->osm, touchnode);
      osm_node_delete(appdata->osm, &appdata->icon, touchnode, FALSE, TRUE);
      
      /* and open dialog to resolve tag collisions if necessary */
      if(conflict)
        messagef(GTK_WIDGET(appdata->window), _("Node tag conflict"), 
                 _("The resulting node contains some conflicting tags. "
                   "Please solve these."));
    
      /* check whether this will also join two ways */
      printf("  checking if node is end of way\n");
      guint ways2join_cnt = 0;
      way_t *ways2join[2] = { NULL, NULL };
      way = appdata->osm->way;
      while(way) {
        if(osm_way_ends_with_node(way, node)) {
          if(ways2join_cnt < 2) 
            ways2join[ways2join_cnt] = way;

          printf("  way #%ld ends with this node\n", way->id);
          ways2join_cnt++;
        }
        way = way->next;
      }

      if(ways2join_cnt > 2) {
        messagef(GTK_WIDGET(appdata->window), _("Too many ways to join"), 
                 _("More than two ways now end on this node. Joining more "
                   "than two ways is not yet implemented, sorry"));
        
      } else if(ways2join_cnt == 2) {
        if(yes_no_f(GTK_WIDGET(appdata->window), 
                    appdata, MISC_AGAIN_ID_JOIN_WAYS, 0,
                    _("Join ways?"),
                    _("Do you want to join the dragged way with the one "
                      "you dropped it on?"))) {

          printf("  about to join ways #%ld and #%ld\n",
                 ways2join[0]->id, ways2join[1]->id);

          /* way[1] gets destroyed and attached to way[0] */
          /* so check if way[1] is selected and exchainge ways then */
          /* so that way may stay selected */
          if((map->selected.type == MAP_TYPE_WAY) && 
             (map->selected.way == ways2join[1])) {
            printf("  swapping ways to keep selected one alive\n");
            way_t *tmp = ways2join[1];
            ways2join[1] = ways2join[0];
            ways2join[0] = tmp;
          }

          /* take all nodes from way[1] and append them to way[0] */
          /* check if we have to append or prepend to way[0] */
          gboolean revert = FALSE;
          if(ways2join[0]->node_chain->node == node) {
            /* make "prepend" to be "append" by reverting way[0] */
            printf("  target prepend -> revert\n");         
            revert = TRUE;
            osm_way_revert(ways2join[0]);
          } 
          
          /* verify the common node is last in the target way */
          node_chain_t *chain = ways2join[0]->node_chain;
          while(chain->next) chain = chain->next;
          g_assert(chain->node == node);
          g_assert(!chain->next);
          
          /* common node must be first in the chain to attach */
          if(ways2join[1]->node_chain->node != node) {
            printf("  source revert\n");            
            osm_way_revert(ways2join[1]);
          }
          
          /* verify the common node is first in the source way */
          g_assert(ways2join[1]->node_chain->node == node);

          /* finally append source chain to target */
          g_assert(!chain->next);
          chain->next = ways2join[1]->node_chain->next;

          ways2join[1]->node_chain->next = NULL;

          /* transfer tags from touchnode to node */

          /* ---------- transfer tags from way[1] to way[0] ----------- */
          gboolean conflict = 
            combine_tags(&ways2join[0]->tag, ways2join[1]->tag);
          ways2join[1]->tag = NULL;

          /* ---- transfer relation membership from way[1] to way[0] ----- */
          relation_chain_t *rchain = 
            osm_way_to_relation(appdata->osm, ways2join[1]);

          while(rchain) {
            relation_chain_t *next = rchain->next;
            printf("way[1] is part of relation #%ld\n", rchain->relation->id);

            /* make way[0] member of the same relation */

            /* walk member chain. save role of way[1] if its being found. */
            /* end search either at end of chain or if way[0] was foind */
            /* as it's already a member of that relation */
            member_t **member = &rchain->relation->member;
            char *role = NULL;
            while(*member && 
                  !(((*member)->type == WAY) && 
                    ((*member)->way == ways2join[0]))) {

              /* save role of way[1] */
              if(((*member)->type == WAY) && ((*member)->way == ways2join[0]))
                role = (*member)->role;

              member = &(*member)->next;
            }

            if(*member) 
              printf("  both ways were members of this relation\n");
            else {
              printf("  adding way[0] to relation\n");
              *member = g_new0(member_t, 1);
              (*member)->type = WAY;
              (*member)->way = ways2join[0];
              if(role) (*member)->role = g_strdup(role);
              member = &(*member)->next;

              rchain->relation->flags |= OSM_FLAG_DIRTY;
            }

            g_free(rchain);
            rchain = next;
          }

          
          /* and open dialog to resolve tag collisions if necessary */
          if(conflict) 
            messagef(GTK_WIDGET(appdata->window), _("Way tag conflict"), 
                     _("The resulting way contains some conflicting tags. "
                       "Please solve these."));
          
          ways2join[0]->flags |= OSM_FLAG_DIRTY;
          map_way_delete(appdata, ways2join[1]);
        }
      }
    }
  } else {

    /* finally update dragged nodes position */
    
    /* convert mouse position to canvas (world) position */
    gint x, y;
    canvas_window2world(map->canvas, ex, ey, &x, &y);
    if(!osm_position_within_bounds(appdata->osm, x, y)) {
      map_outside_error(appdata);
      return;
    }
    
    node->lpos.x = x;
    node->lpos.y = y;
    
    /* convert screen position back to ll */
    lpos2pos(osm->bounds, &node->lpos, &node->pos);

    printf("  now at %d %d (%f %f)\n", 
           node->lpos.x, node->lpos.y, node->pos.lat, node->pos.lon);
  }
  
  /* now update the visual representation of the node */
  
  map_item_chain_destroy(&node->map_item_chain);
  map_node_draw(map, node);

  /* visually update ways, node is part of */
  way_t *way = osm->way;
  while(way) {
    if(osm_node_in_way(way, node)) {
      printf("  node is part of way #%ld, redraw!\n", way->id);
      
      /* remove prior version of this way */
      map_item_chain_destroy(&way->map_item_chain);

      /* draw current way */
      josm_elemstyles_colorize_way(map->style, way);
      map_way_draw(map, way);
    }
    
    way = way->next;
  }
  
  /* and mark the node as dirty */
  node->flags |= OSM_FLAG_DIRTY;

  /* update highlight */
  map_highlight_refresh(appdata);
}
                          
/* -------------------------- way_reverse ----------------------- */

/* called from the "reverse" icon */
void map_edit_way_reverse(appdata_t *appdata) {
  /* work on local copy since de-selecting destroys the selection */
  map_item_t item = appdata->map->selected;

  /* deleting the selected item de-selects it ... */
  map_item_deselect(appdata);

  g_assert(item.type == MAP_TYPE_WAY);

  osm_way_revert(item.way);
  item.way->flags |= OSM_FLAG_DIRTY;

  map_way_select(appdata, item.way);
}
