- Monster chase range updates (bugreport:7637)

  * Updated monster_chase_range in monster.conf from 1 to 3; I originally thought official value is 1, but doing some in-depth tests myself I realized it's 3 for the most important situations
  * When a monster cannot issue new "move" commands because it was affected by a status change, but is still moving due to knockback immunity, it will no longer unlock its target and stop
  * Fixed a bug that always caused the chase path monsters calculated to be 1 cell too short causing them to recalculate their path one cell before their goal every single time
- Fixed the direction calculation once again and optimized it at the same time (bugreport:9373)
  * Now the calculated direction is 100% official, really truly, checked it myself with every single cell and various skills
  * Added a new function map_calc_dir_xy that allows to check for a direction between two cells without the need of a block_list
  * map_calc_dir will now just use map_calc_dir_xy to avoid duplicate code
* Improved Icewall walk block implementation
- Moved the configuration setting "icewall_walk_block" to monster.conf
- Split the configuration into mob_icewall_walk_block and boss_icewall_walk_block so it can be configured for bosses separately
- Expanded the configuration
  * If the value is set to 1, monsters on an ice wall cell will behave like trapped monsters, that means they won't be able to move at all, they will use idle skills and if they are attacked while nobody is in their attack range, they will use their rudeattacked skills; this is equal to official behavior of bosses
  * If the value is set to 2-255, it will behave as before but monsters in the AI loop now use both idle and chase skills, but will no longer use their rudeattacked skills even if attacked from range; this is equal to official behavior of normal monsters
  * Official values would be "220" for normal monsters (loop until Icewall expiration) and "1" for bosses (behave like trapped monster) on most official servers, but as some official servers have a less exploitable implementation (from looping AI only a limited amount of times up to outright blocking Icewall on all maps with bosses)
- Cleaned up the rudeattacked code a little so it's easier to read
- Fire Pillar is no longer a trap and can no longer be hit or knocked back in renewal

Thanks to Playtester (rathena b43b855d2, 902c920b734cd)

7 files changed, 68 insertions, 36 deletions

diff --git a/conf/battle/monster.conf b/conf/battle/monster.conf
index 9ca8df825..6f63f55be 100644
--- a/conf/battle/monster.conf
+++ b/conf/battle/monster.conf
@@ -52,14 +52,14 @@ monster_ai: 0
 
 // How often should a monster rethink its chase?
 // 0: Every 100ms (MIN_MOBTHINKTIME)
-// 1: Every cell moved (official)
+// 1: Every cell moved
 // 2: Every 2 cells moved
-// 3: Every 3 cells moved (previous setting)
+// 3: Every 3 cells moved (official)
 // x: Every x cells moved
 // Regardless of this setting, a monster will always rethink its chase if it has 
 // reached its target. Increase this value if you want to make monsters continue
 // moving after they lost their target (hide, loot picked, etc.).
-monster_chase_refresh: 1
+monster_chase_refresh: 3
 
 // Should mobs be able to be warped (add as needed)?
 // 0: Disable.
@@ -216,3 +216,19 @@ mvp_tomb_enabled: yes
 // This is only invoked under the 'monster' command, @monsterbig, and @monstersmall. (Note 1)
 // Default: no
 mob_size_influence: no
+
+// How should a monster be trapped by an icewall casted directly on it?
+// On official servers, monsters can only leave an icewall to the west and south. If their target is north or east of
+// them they will continously try to chase it but fail doing so. This brings them into a loop during which they will use
+// idle and chase skills. Boss monsters on the other hand will behave like a trapped monster, do not move and will use
+// idle and rudeattacked skills (when attacked).
+// 0: Monster won't be stuck in icewall at all.
+// 1: Monster will behave like a trapped monster.
+// 2-255: Number of loops a monster will go through the behavior described above before it frees itself from icewall.
+// NOTE: On some servers, normal monsters can free themselves after 15-35 second depending on their speed. On other
+// servers, they will be stuck inside icewall until it expires. Also, many official servers (e.g. iRO) have casting
+// icewall completely blocked on all maps that have boss monsters on them.
+// Default (least exploitable): mob - 75, boss - 0
+// Default (most official): mob - 220, boss - 1
+mob_icewall_walk_block: 220
+boss_icewall_walk_block: 1
\ No newline at end of file
diff --git a/conf/battle/skill.conf b/conf/battle/skill.conf
index 1bb58211a..e6828749b 100644
--- a/conf/battle/skill.conf
+++ b/conf/battle/skill.conf
@@ -293,13 +293,4 @@ mob_max_skilllvl: 100
 // 1: Gutter line system without demi gutter bug
 // 2-20: Area around caster (2 = 5x5, 3 = 7x7, 4 = 9x9, ..., 20 = 41x41)
 // Note: If you knock the target out of the area it will only be hit once and won't do splash damage
-bowling_bash_area: 0
-
-// How many attempts should a monster need until it can escape from an icewall casted directly on it?
-// On official servers, monsters can only leave an icewall to the west and south. If their target is north or east of them
-// they will continously try to chase it but fail doing so. This brings them into a loop during which they will cast idle
-// and rudeattacked skills (if attacked). Official servers have a safety system that eventually allows monsters to escape
-// when their walk routine failed many times in row so they won't stay on the loop endlessly. The time for this seems to be
-// around 15 seconds for fast monsters and 35 seconds for slow monsters, this equals about 75 attempts.
-// Set this to 0 if you don't want monsters to be stuck in icewalls at all.
-icewall_walk_block: 75
\ No newline at end of file
+bowling_bash_area: 0
\ No newline at end of file
diff --git a/db/re/skill_db.txt b/db/re/skill_db.txt
index 5f1e7c2f2..34639425e 100644
--- a/db/re/skill_db.txt
+++ b/db/re/skill_db.txt
@@ -124,7 +124,7 @@
 77,5,6,1,6,0x28,0,10,1,yes,0,0,0,magic,0,	PR_TURNUNDEAD,Turn Undead
 78,9,6,1,0,0x1,0,1,0,yes,0,0,0,magic,0,		PR_LEXAETERNA,Lex Aeterna
 79,9,8,2,6,0,0,10,1:2:3:4:5:6:7:8:9:10,yes,0,0,0,magic,0,	PR_MAGNUS,Magnus Exorcismus
-80,9,8,2,3,0x20,1:1:1:1:1:2:2:2:2:2:2,10,3:4:5:6:7:8:9:10:11:12:12,yes,0,0x80,5,magic,0,	WZ_FIREPILLAR,Fire Pillar
+80,9,8,2,3,0x20,1:1:1:1:1:2:2:2:2:2:2,10,3:4:5:6:7:8:9:10:11:12:12,yes,0,0,5,magic,0,	WZ_FIREPILLAR,Fire Pillar
 81,0,6,4,3,0,3,10,1,yes,0,0,0,magic,5,		WZ_SIGHTRASHER,Sightrasher
 83,9,8,2,3,0,3:3:3:3:3:3:3:3:3:3:14,10,1:1:2:2:3:3:4:4:5:5:15,yes,0,0,0,magic,0,	WZ_METEOR,Meteor Storm
 84,9,8,1,4,0,0,10,3:4:5:6:7:8:9:10:11:12,yes,0,0,0,magic,2:3:3:4:4:5:5:6:6:7,	WZ_JUPITEL,Jupitel Thunder
diff --git a/src/map/battle.c b/src/map/battle.c
index 88d83f91b..40ef15191 100644
--- a/src/map/battle.c
+++ b/src/map/battle.c
@@ -6838,7 +6838,8 @@ static const struct battle_data {
 	{ "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,             },
-	{ "icewall_walk_block",                 &battle_config.icewall_walk_block,              75,     0,      255,            }
+	{ "mob_icewall_walk_block",             &battle_config.mob_icewall_walk_block,          75,     0,      255,            },
+	{ "boss_icewall_walk_block",            &battle_config.boss_icewall_walk_block,         0,      0,      255,            },
 };
 #ifndef STATS_OPT_OUT
 /**
diff --git a/src/map/battle.h b/src/map/battle.h
index 6ac2df391..1b6321cbf 100644
--- a/src/map/battle.h
+++ b/src/map/battle.h
@@ -452,7 +452,8 @@ 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]
+	int mob_icewall_walk_block; //How a normal monster should be trapped in icewall [Playtester]
+	int boss_icewall_walk_block; //How a boss monster should be trapped in icewall [Playtester]
 
 	/** Hercules **/
 	int skill_trap_type;
diff --git a/src/map/mob.c b/src/map/mob.c
index eaf8c8468..23706d293 100644
--- a/src/map/mob.c
+++ b/src/map/mob.c
@@ -1429,7 +1429,7 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 			//No valid target
 			if (mob->warpchase(md, tbl))
 				return true; //Chasing this target.
-			if(md->ud.walktimer != INVALID_TIMER && md->ud.walkpath.path_pos <= battle_config.mob_chase_refresh)
+			if(md->ud.walktimer != INVALID_TIMER && (!can_move || md->ud.walkpath.path_pos <= battle_config.mob_chase_refresh))
 				return true; //Walk at least "mob_chase_refresh" cells before dropping the target
 			mob_unlocktarget(md, tick); //Unlock target
 			tbl = NULL;
@@ -1442,13 +1442,14 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 		if( md->attacked_id == md->target_id )
 		{	//Rude attacked check.
 			if( !battle->check_range(&md->bl, tbl, md->status.rhw.range)
-			   &&  ( //Can't attack back and can't reach back.
+			&&  ( //Can't attack back and can't reach back.
 					(!can_move && DIFF_TICK(tick, md->ud.canmove_tick) > 0 && (battle_config.mob_ai&0x2 || (md->sc.data[SC_SPIDERWEB] && md->sc.data[SC_SPIDERWEB]->val1)
-					|| 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->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.
+						|| md->walktoxy_fail_count > 0)
 					)
+					|| !mob->can_reach(md, tbl, md->min_chase, MSS_RUSH)
+				)
 			&&  md->state.attacked_count++ >= RUDE_ATTACKED_COUNT
 			&&  !mob->skill_use(md, tick, MSC_RUDEATTACKED) // If can't rude Attack
 			&&  can_move && unit->escape(&md->bl, tbl, rnd()%10 +1)) // Attempt escape
@@ -1466,11 +1467,12 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 			 || (battle_config.mob_ai&0x2 && !status->check_skilluse(&md->bl, abl, 0, 0)) // Cannot normal attack back to Attacker
 			 || (!battle->check_range(&md->bl, abl, md->status.rhw.range) // Not on Melee Range and ...
 			    && ( // Reach check
-			         (!can_move && DIFF_TICK(tick, md->ud.canmove_tick) > 0 && (battle_config.mob_ai&0x2 || (md->sc.data[SC_SPIDERWEB] && md->sc.data[SC_SPIDERWEB]->val1)
-			       || 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
+					(!can_move && DIFF_TICK(tick, md->ud.canmove_tick) > 0 && (battle_config.mob_ai&0x2 || (md->sc.data[SC_SPIDERWEB] && md->sc.data[SC_SPIDERWEB]->val1)
+						|| 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.
+						|| md->walktoxy_fail_count > 0)
+					)
+					   || !mob->can_reach(md, abl, dist+md->db->range3, MSS_RUSH)
 			       )
 			    )
 			) {
@@ -1636,6 +1638,9 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 	if(battle->check_range(&md->bl, tbl, md->status.rhw.range))
 		return true;
 
+	//Only update target cell / drop target after having moved at least "mob_chase_refresh" cells
+	if(md->ud.walktimer != INVALID_TIMER && (!can_move || md->ud.walkpath.path_pos <= battle_config.mob_chase_refresh))
+		return true;
 
 	//Out of range...
 	if (!(mode&MD_CANMOVE) || (!can_move && DIFF_TICK(tick, md->ud.canmove_tick) > 0))
@@ -1655,10 +1660,6 @@ bool mob_ai_sub_hard(struct mob_data *md, int64 tick) {
 	)) //Current target tile is still within attack range.
 		return true;
 
-	//Only update target cell after having moved at least "mob_chase_refresh" cells
-	if(md->ud.walktimer != INVALID_TIMER && md->ud.walkpath.path_pos <= battle_config.mob_chase_refresh)
-		return true;
-
 	//Follow up if possible.
 	//Hint: Chase skills are handled in the walktobl routine
 	if(!mob->can_reach(md, tbl, md->min_chase, MSS_RUSH) ||
diff --git a/src/map/unit.c b/src/map/unit.c
index 849e9348f..76a5853df 100644
--- a/src/map/unit.c
+++ b/src/map/unit.c
@@ -108,11 +108,11 @@ int unit_walktoxy_sub(struct block_list *bl)
 		uint8 dir;
 		//Trim the last part of the path to account for range,
 		//but always move at least one cell when requested to move.
-		for (i = ud->chaserange*10; i > 0 && ud->walkpath.path_len>1;) {
+		for (i = (ud->chaserange*10)-10; i > 0 && ud->walkpath.path_len>1;) {
 		   ud->walkpath.path_len--;
 			dir = ud->walkpath.path[ud->walkpath.path_len];
 			if(dir&1)
-				i -= MOVE_DIAGONAL_COST;
+				i -= MOVE_COST*20; //When chasing, units will target a diamond-shaped area in range [Playtester]
 			else
 				i -= MOVE_COST;
 			ud->to_x -= dirx[dir];
@@ -211,6 +211,7 @@ int unit_step_timer(int tid, int64 tick, int id, intptr_t data)
 int unit_walktoxy_timer(int tid, int64 tick, int id, intptr_t data) {
 	int i;
 	int x,y,dx,dy;
+	unsigned char icewall_walk_block;
 	uint8 dir;
 	struct block_list       *bl;
 	struct map_session_data *sd;
@@ -249,19 +250,29 @@ int unit_walktoxy_timer(int tid, int64 tick, int id, intptr_t data) {
 	dx = dirx[(int)dir];
 	dy = diry[(int)dir];
 
+	//Get icewall walk block depending on boss mode (players can't be trapped)
+	if(md && md->status.mode&MD_BOSS)
+		icewall_walk_block = battle_config.boss_icewall_walk_block;
+	else if(md)
+		icewall_walk_block = battle_config.mob_icewall_walk_block;
+	else
+		icewall_walk_block = 0;
+
 	//Monsters will walk into an icewall from the west and south if they already started walking
 	if(map->getcell(bl->m,x+dx,y+dy,CELL_CHKNOPASS)
-	&& (battle_config.icewall_walk_block == 0 || !map->getcell(bl->m,x+dx,y+dy,CELL_CHKICEWALL) || dx < 0 || dy < 0))
+	&& (icewall_walk_block == 0 || !map->getcell(bl->m,x+dx,y+dy,CELL_CHKICEWALL) || dx < 0 || dy < 0))
 		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)) {
+	if(md && md->walktoxy_fail_count < 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);
+		//Monsters in this situation first use a chase skill, then unlock target and then use an idle skill
+		if (!(++ud->walk_count%WALK_SKILL_INTERVAL))
+			mob->skill_use(md, tick, -1);
 		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;
@@ -1060,6 +1071,17 @@ int unit_can_move(struct block_list *bl) {
 			return 0;
 
 	}
+
+	// Icewall walk block special trapped monster mode
+	if(bl->type == BL_MOB) {
+		struct mob_data *md = BL_CAST(BL_MOB, bl);
+		if(md && ((md->status.mode&MD_BOSS && battle_config.boss_icewall_walk_block == 1 && map->getcell(bl->m,bl->x,bl->y,CELL_CHKICEWALL))
+			|| (!(md->status.mode&MD_BOSS) && battle_config.mob_icewall_walk_block == 1 && map->getcell(bl->m,bl->x,bl->y,CELL_CHKICEWALL)))) {
+			md->walktoxy_fail_count = 1; //Make sure rudeattacked skills are invoked
+			return 0;
+		}
+	}
+
 	return 1;
 }