Fix bug:7454

* Official Icewall implementation and other fixes
- Reverted all the icewall-related changes done in SVN r15777 and following as testing shows they aren't official and are actually pretty exploitable (bugreport:7412)
- Instead implemented the official icewall characteristic that monsters can only leave an icewall cell to the west or south, the changes include:
  * The "sight" path check no longer checks for the current cell so standing on an icewall allows you to see/attack into any direction
  * The path finding will still ignore the current cell as before but the walk routine will not allow to walk east or north while standing on an icewall cell
  * This leads monsters in the situation where they go through an AI loop not allowing them to escape the icewall (if their target is north or east of them)
  * Monster in this situation will use idle skills and if they get attacked will use their rudeattacked skills if available, similar to traps like Spiderweb
  * Added a configuration icewall_walk_block that allows to configure how long a monster should go through the AI loop before the server allows it any movement, this "safety" system is official and seems to equal about 75 AI loops; if you want to disable the whole icewall system so that monsters don't get stuck in icewall at all, just set this to 0
  * Here are videos from jRO showing how this system works: http://ragdo.blog56.fc2.com/blog-entry-763.html
- Implemented the official calculation for "direction"; now you will be considered horizontal/vertical/diagonally aligned with a target cell in the exact same way as on official servers, this is for example used to determine whether an icewall or a firewall should be horizontal, vertical or diagonal; the only thing that is still unofficial is the default direction (officially always "west"); effectively now there are more situations considered diagonal than before
- Further cleanups on the idle skill use code for immobile monsters and monsters near a player but without a target (now skill using will always go via mob_unlocktarget)
  * This also fixes that monsters switched to idle mode and start to use idle skills one second too late

Mega thanks to Playtester (rathena 5540d89cb0e)

10 files changed, 46 insertions, 75 deletions

diff --git a/src/map/battle.c b/src/map/battle.c
index 3b50d3507..6844d8bda 100644
--- a/src/map/battle.c
+++ b/src/map/battle.c
@@ -6830,7 +6830,8 @@ static const struct battle_data {
 	{ "guild_castle_expulsion",				&battle_config.guild_castle_expulsion,			0,		0,		1,				},
 	{ "song_timer_reset",                   &battle_config.song_timer_reset,                0,      0,      1,              },
 	{ "snap_dodge",                         &battle_config.snap_dodge,                      0,      0,      1,              },
-	{ "monster_chase_refresh",              &battle_config.mob_chase_refresh,               1,      0,      30,             }
+	{ "monster_chase_refresh",              &battle_config.mob_chase_refresh,               1,      0,      30,             },
+	{ "icewall_walk_block",                 &battle_config.icewall_walk_block,              75,     0,      255,            }
 };
 #ifndef STATS_OPT_OUT
 /**
diff --git a/src/map/battle.h b/src/map/battle.h
index 966fa073e..6ac2df391 100644
--- a/src/map/battle.h
+++ b/src/map/battle.h
@@ -452,6 +452,7 @@ struct Battle_Config {
 	int mob_size_influence; // Enable modifications on earned experience, drop rates and monster status depending on monster size. [mkbu95]
 	int bowling_bash_area;
 	int mob_chase_refresh; //How often a monster should refresh its chase [Playtester]
+	int icewall_walk_block; //How long a monster should stay trapped in icewall [Playtester]
 
 	/** Hercules **/
 	int skill_trap_type;
diff --git a/src/map/map.c b/src/map/map.c
index 14af392b7..5fa8779eb 100644
--- a/src/map/map.c
+++ b/src/map/map.c
@@ -2420,28 +2420,27 @@ uint8 map_calc_dir(struct block_list* src, int16 x, int16 y)
 	}
 	else if( dx >= 0 && dy >=0 )
 	{	// upper-right
-		if( dx*2 <= dy )      dir = 0;	// up
-		else if( dx > dy*2 )  dir = 6;	// right
-		else                  dir = 7;	// up-right
+		if( dx*2 < dy || dx == 0 )         dir = 0;	// up
+		else if( dx > dy*2+1 || dy == 0 )  dir = 6;	// right
+		else                               dir = 7;	// up-right
 	}
 	else if( dx >= 0 && dy <= 0 )
 	{	// lower-right
-		if( dx*2 <= -dy )     dir = 4;	// down
-		else if( dx > -dy*2 ) dir = 6;	// right
-		else                  dir = 5;	// down-right
+		if( dx*2 < -dy || dx == 0 )        dir = 4;	// down
+		else if( dx > -dy*2+1 || dy == 0 ) dir = 6;	// right
+		else                               dir = 5;	// down-right
 	}
 	else if( dx <= 0 && dy <= 0 )
 	{	// lower-left
-		if( dx*2 >= dy )      dir = 4;	// down
-		else if( dx < dy*2 )  dir = 2;	// left
-		else                  dir = 3;	// down-left
+		if( dx*2 > dy || dx == 0 )         dir = 4;	// down
+		else if( dx < dy*2-1 || dy == 0 )  dir = 2;	// left
+		else                               dir = 3;	// down-left
 	}
 	else
 	{	// upper-left
-		if( -dx*2 <= dy )     dir = 0;	// up
-		else if( -dx > dy*2 ) dir = 2;	// left
-		else                  dir = 1;	// up-left
-
+		if( -dx*2 < dy || dx == 0 )        dir = 0;	// up
+		else if( -dx > dy*2+1 || dy == 0)  dir = 2;	// left
+		else                               dir = 1;	// up-left
 	}
 	return dir;
 }
diff --git a/src/map/map.h b/src/map/map.h
index dba565cc0..751fef67e 100644
--- a/src/map/map.h
+++ b/src/map/map.h
@@ -658,13 +658,7 @@ struct map_data {
 	int jexp;	// map experience multiplicator
 	int bexp;	// map experience multiplicator
 	int nocommand; //Blocks @/# commands for non-gms. [Skotlex]
-	/**
-	* Ice wall reference counter for bugreport:3574
-	* - since there are a thousand mobs out there in a lot of maps checking on,
-	* - every targeting for icewall on attack path would just be a waste, so,
-	* - this counter allows icewall checking be only run when there is a actual ice wall on the map
-	**/
-	int icewall_num;
+
 	// Instance Variables
 	int instance_id;
 	int instance_src_map;
diff --git a/src/map/mob.c b/src/map/mob.c
index 122cc91aa..d0a65315a 100644
--- a/src/map/mob.c
+++ b/src/map/mob.c
@@ -1076,15 +1076,6 @@ int mob_ai_sub_hard_activesearch(struct block_list *bl,va_list ap)
 				((*target) == NULL || !check_distance_bl(&md->bl, *target, dist)) &&
 				battle->check_range(&md->bl,bl,md->db->range2)
 			) { //Pick closest target?
-
-				if( map->list[bl->m].icewall_num &&
-					!path->search_long(NULL,bl->m,md->bl.x,md->bl.y,bl->x,bl->y,CELL_CHKICEWALL) ) {
-
-					if( !check_distance_bl(&md->bl, bl, status_get_range(&md->bl) ) )
-						return 0;
-
-				}
-
 				(*target) = bl;
 				md->target_id=bl->id;
 				md->min_chase= dist + md->db->range3;
@@ -1288,8 +1279,7 @@ int mob_unlocktarget(struct mob_data *md, int64 tick) {
 		md->state.skillstate = MSS_IDLE;
 	case MSS_IDLE:
 		// Idle skill.
-		if ((md->target_id || !(++md->ud.walk_count%IDLE_SKILL_INTERVAL)) &&
-			mob->skill_use(md, tick, -1))
+		if (!(++md->ud.walk_count%IDLE_SKILL_INTERVAL) && mob->skill_use(md, tick, -1))
 			break;
 		//Random walk.
 		if (!md->master_id &&
@@ -1457,6 +1447,7 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 					|| md->sc.data[SC_WUGBITE] || md->sc.data[SC_VACUUM_EXTREME] || md->sc.data[SC_THORNS_TRAP]
 					|| md->sc.data[SC__MANHOLE])) // Not yet confirmed if boss will teleport once it can't reach target.
 					|| !mob->can_reach(md, tbl, md->min_chase, MSS_RUSH)
+					|| md->walktoxy_fail_count > 0
 					)
 			&&  md->state.attacked_count++ >= RUDE_ATTACKED_COUNT
 			&&  !mob->skill_use(md, tick, MSC_RUDEATTACKED) // If can't rude Attack
@@ -1479,6 +1470,7 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 			       || md->sc.data[SC_WUGBITE] || md->sc.data[SC_VACUUM_EXTREME] || md->sc.data[SC_THORNS_TRAP]
 			       || md->sc.data[SC__MANHOLE])) // Not yet confirmed if boss will teleport once it can't reach target.
 			       || !mob->can_reach(md, abl, dist+md->db->range3, MSS_RUSH)
+			       || md->walktoxy_fail_count > 0
 			       )
 			    )
 			) {
@@ -1551,7 +1543,7 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 			}
 		}
 
-		//This handles triggering idle walk/skill.
+		//This handles triggering idle/walk skill.
 		mob->unlocktarget(md, tick);
 		return true;
 	}
@@ -1634,12 +1626,11 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 
 	//Out of range...
 	if (!(mode&MD_CANMOVE) || (!can_move && DIFF_TICK(tick, md->ud.canmove_tick) > 0))
-	{	//Can't chase. Immobile and trapped mobs should unlock target and use an idle skill on next interval.
-		if ((md->ud.target != tbl->id || md->ud.attacktimer == INVALID_TIMER)) 
-		{ //Only unlock target to use idle skill if no more attack left
-			md->ud.walk_count = (md->ud.walk_count+1)%250;
-			if (!(md->ud.walk_count%IDLE_SKILL_INTERVAL))
-				mob_unlocktarget(md,tick);
+	{	//Can't chase. Immobile and trapped mobs should unlock target and use an idle skill.
+		if (md->ud.attacktimer == INVALID_TIMER)
+		{ //Only unlock target if no more attack delay left
+			//This handles triggering idle/walk skill.
+			mob->unlocktarget(md,tick);
 		}
 		return true;
  	}
diff --git a/src/map/mob.h b/src/map/mob.h
index 4df96d7f8..848bfbb2f 100644
--- a/src/map/mob.h
+++ b/src/map/mob.h
@@ -171,6 +171,7 @@ struct mob_data {
 	short move_fail_count;
 	short lootitem_count;
 	short min_chase;
+	unsigned char walktoxy_fail_count; //Pathfinding succeeds but the actual walking failed (e.g. Icewall lock)
 
 	int deletetimer;
 	int master_id,master_dist;
diff --git a/src/map/path.c b/src/map/path.c
index 681dfcb06..d8096ad43 100644
--- a/src/map/path.c
+++ b/src/map/path.c
@@ -129,9 +129,6 @@ bool path_search_long(struct shootpath_data *spd,int16 m,int16 x0,int16 y0,int16
 	spd->x[0] = x0;
 	spd->y[0] = y0;
 
-	if (md->getcellp(md,x1,y1,cell))
-		return false;
-
 	if (dx > abs(dy)) {
 		weight = dx;
 		spd->ry = 1;
@@ -142,8 +139,6 @@ bool path_search_long(struct shootpath_data *spd,int16 m,int16 x0,int16 y0,int16
 
 	while (x0 != x1 || y0 != y1)
 	{
-		if (md->getcellp(md,x0,y0,cell))
-			return false;
 		wx += dx;
 		wy += dy;
 		if (wx >= weight) {
@@ -163,6 +158,8 @@ bool path_search_long(struct shootpath_data *spd,int16 m,int16 x0,int16 y0,int16
 			spd->y[spd->len] = y0;
 			spd->len++;
 		}
+		if (md->getcellp(md,x0,y0,cell))
+			return false;
 	}
 
 	return true;
diff --git a/src/map/skill.c b/src/map/skill.c
index 51e266559..414ca74d3 100644
--- a/src/map/skill.c
+++ b/src/map/skill.c
@@ -10782,28 +10782,6 @@ bool skill_dance_switch(struct skill_unit* su, int flag) {
 
 	return true;
 }
-/**
- * Upon Ice Wall cast it checks all nearby mobs to find any who may be blocked by the IW
- **/
-int skill_icewall_block(struct block_list *bl,va_list ap) {
-	struct block_list *target = NULL;
-	struct mob_data *md = ((TBL_MOB*)bl);
-
-	nullpo_ret(bl);
-	nullpo_ret(md);
-	if( !md->target_id || ( target = map->id2bl(md->target_id) ) == NULL )
-		return 0;
-
-	if( path->search_long(NULL,bl->m,bl->x,bl->y,target->x,target->y,CELL_CHKICEWALL) )
-		return 0;
-
-	if( !check_distance_bl(bl, target, status_get_range(bl) ) ) {
-		mob->unlocktarget(md,timer->gettick());
-		mob_stop_walking(md,1);
-	}
-
-	return 0;
-}
 /*==========================================
  * Initializes and sets a ground skill.
  * flag&1 is used to determine when the skill 'morphs' (Warp portal becomes active, or Fire Pillar becomes active)
@@ -11303,9 +11281,6 @@ struct skill_unit_group* skill_unitsetting(struct block_list *src, uint16 skill_
 
 	//success, unit created.
 	switch( skill_id ) {
-		case WZ_ICEWALL:
-			map->foreachinrange(skill->icewall_block, src, AREA_SIZE, BL_MOB);
-			break;
 		case NJ_TATAMIGAESHI: //Store number of tiles.
 			group->val1 = group->alive_count;
 			break;
@@ -15599,7 +15574,6 @@ struct skill_unit *skill_initunit (struct skill_unit_group *group, int idx, int
 			map->setgatcell(su->bl.m,su->bl.x,su->bl.y,5);
 			clif->changemapcell(0,su->bl.m,su->bl.x,su->bl.y,5,AREA);
 			skill->unitsetmapcell(su,WZ_ICEWALL,group->skill_lv,CELL_ICEWALL,true);
-			map->list[su->bl.m].icewall_num++;
 			break;
 		case SA_LANDPROTECTOR:
 			skill->unitsetmapcell(su,SA_LANDPROTECTOR,group->skill_lv,CELL_LANDPROTECTOR,true);
@@ -15651,7 +15625,6 @@ int skill_delunit (struct skill_unit* su) {
 			map->setgatcell(su->bl.m,su->bl.x,su->bl.y,su->val2);
 			clif->changemapcell(0,su->bl.m,su->bl.x,su->bl.y,su->val2,ALL_SAMEMAP); // hack to avoid clientside cell bug
 			skill->unitsetmapcell(su,WZ_ICEWALL,group->skill_lv,CELL_ICEWALL,false);
-			map->list[su->bl.m].icewall_num--;
 			// AS_CLOAKING in low levels requires a wall to be cast, thus it needs to be
 			// checked again when a wall disapears! issue:8182 [Panikon]
 			map->foreachinarea(skill->check_cloaking_end, su->bl.m,
@@ -18803,7 +18776,6 @@ void skill_defaults(void) {
 	skill->frostjoke_scream = skill_frostjoke_scream;
 	skill->greed = skill_greed;
 	skill->destroy_trap = skill_destroy_trap;
-	skill->icewall_block = skill_icewall_block;
 	skill->unitgrouptickset_search = skill_unitgrouptickset_search;
 	skill->dance_switch = skill_dance_switch;
 	skill->check_condition_char_sub = skill_check_condition_char_sub;
diff --git a/src/map/skill.h b/src/map/skill.h
index 6373d9275..4ec742bd0 100644
--- a/src/map/skill.h
+++ b/src/map/skill.h
@@ -1984,7 +1984,6 @@ struct skill_interface {
 	int (*frostjoke_scream) (struct block_list *bl, va_list ap);
 	int (*greed) (struct block_list *bl, va_list ap);
 	int (*destroy_trap) ( struct block_list *bl, va_list ap );
-	int (*icewall_block) (struct block_list *bl,va_list ap);
 	struct skill_unit_group_tickset *(*unitgrouptickset_search) (struct block_list *bl, struct skill_unit_group *group, int64 tick);
 	bool (*dance_switch) (struct skill_unit* su, int flag);
 	int (*check_condition_char_sub) (struct block_list *bl, va_list ap);
diff --git a/src/map/unit.c b/src/map/unit.c
index f823a3fed..2d8fd530d 100644
--- a/src/map/unit.c
+++ b/src/map/unit.c
@@ -250,6 +250,19 @@ int unit_walktoxy_timer(int tid, int64 tick, int id, intptr_t data) {
 	if(map->getcell(bl->m,x+dx,y+dy,CELL_CHKNOPASS))
 		return unit->walktoxy_sub(bl);
 
+	//Monsters can only leave icewalls to the west and south
+	//But if movement fails more than icewall_walk_block times, they can ignore this rule
+	if(md && md->walktoxy_fail_count < battle_config.icewall_walk_block && map->getcell(bl->m,x,y,CELL_CHKICEWALL) && (dx > 0 || dy > 0)) {
+		//Needs to be done here so that rudeattack skills are invoked
+		md->walktoxy_fail_count++;
+		clif->fixpos(bl);
+		mob->unlocktarget(md, tick);
+		//Use idle skill at this point
+		if (!(++ud->walk_count%WALK_SKILL_INTERVAL))
+			mob->skill_use(md, tick, -1);
+		return 0;
+	}
+
 	//Refresh view for all those we lose sight
 	map->foreachinmovearea(clif->outsight, bl, AREA_SIZE, dx, dy, sd?BL_ALL:BL_PC, bl);
 
@@ -300,6 +313,8 @@ int unit_walktoxy_timer(int tid, int64 tick, int id, intptr_t data) {
 				sd->hd->masterteleport_timer = 0;
 		}
 	} else if (md) {
+		//Movement was successful, reset walktoxy_fail_count
+		md->walktoxy_fail_count = 0;
 		if( map->getcell(bl->m,x,y,CELL_CHKNPC) ) {
 			if( npc->touch_areanpc2(md) ) return 0; // Warped
 		} else
@@ -2010,8 +2025,9 @@ int unit_attack_timer_sub(struct block_list* src, int tid, int64 tick) {
 	sstatus = status->get_status_data(src);
 	range = sstatus->rhw.range;
 
-	if( unit->is_walking(target) )
-		range++; //Extra range when chasing
+	if( unit->is_walking(target) && (target->type == BL_PC || !map->getcell(target->m,target->x,target->y,CELL_CHKICEWALL)) )
+		range++; // Extra range when chasing (does not apply to mobs locked in an icewall)
+
 	if(sd && !check_distance_client_bl(src,target,range)) {
 		// Player tries to attack but target is too far, notify client
 		clif->movetoattack(sd,target);