AToTB Chase: add custom AI controlling Muff Toras

(cherry-picked from commit bbb151fa71)

data/campaigns/Two_Brothers/lua/muff_toras_move.lua

@@ -0,0 +1,113 @@
+local M = wesnoth.map
+local AH = wesnoth.require "ai/lua/ai_helper.lua"
+local BC = wesnoth.require "ai/lua/battle_calcs.lua"
+
+local muff_toras_move = {}
+
+function muff_toras_move:evaluation()
+    local muff_toras = wesnoth.get_units { id = 'Muff Toras' }[1]
+
+    if muff_toras and (muff_toras.moves > 0) then
+        return 15000
+    end
+
+    return 0
+end
+
+function muff_toras_move:execution()
+    local muff_toras = wesnoth.get_units { id = 'Muff Toras' }[1]
+    local units = wesnoth.get_units { side = 3, { 'not', { id = 'Muff Toras' } } }
+    local enemies = AH.get_attackable_enemies()
+    local enemy_attack_map = BC.get_attack_map(enemies)
+
+    local go_to = AH.find_best_move(muff_toras, function(x, y)
+        -- Note: we use no_random = false, which adds contribution of up to 0.01.
+        -- This means all differences between deterministic ratings need to be
+        -- larger than that
+
+        local rating = -10000 -- This is the base rating if no other units are left
+
+        -- Main rating is distance from the closest own unit
+        local min_dist
+        for _,unit in ipairs(units) do
+            local dist = M.distance_between(x, y, unit.x, unit.y)
+            if (not min_dist) or (dist < min_dist) then
+                min_dist = dist
+            end
+        end
+        if min_dist then rating = -100 * min_dist end
+
+        -- Enemy threat is next most important. We could put a scaling factor
+        -- in front of this, but using 1 seems to work pretty well
+        local enemy_hp = enemy_attack_map.hitpoints:get(x,y)
+        if enemy_hp then
+           rating = rating - enemy_hp
+        end
+
+        -- All else being equal, go with good terrain
+        local hit_chance = muff_toras:defense(wesnoth.get_terrain(x, y))
+        rating = rating - hit_chance
+
+        -- Finally, we want to run away from enemies if there are no other factors.
+        -- This mostly kicks in after the other AI units have been killed.
+        local closest_enemy_dist
+        for _,enemy in ipairs(enemies) do
+            local dist = M.distance_between(x, y, enemy.x, enemy.y)
+            if (not closest_enemy_dist) or (dist < closest_enemy_dist) then
+                closest_enemy_dist = dist
+            end
+        end
+        rating = rating + closest_enemy_dist
+
+        return rating
+    end)
+
+    if ((go_to[1] ~= muff_toras.x) or (go_to[2] ~= muff_toras.y)) then
+        AH.robust_move_and_attack(ai, muff_toras, go_to)
+    else
+        AH.checked_stopunit_moves(ai, muff_toras)
+    end
+
+    -- Test whether an attack without retaliation or with little damage is possible
+    if (muff_toras.attacks_left <= 0) or (#muff_toras.attacks == 0) then
+        return
+    end
+
+    local targets = AH.get_attackable_enemies { { "filter_adjacent", { id = muff_toras.id } } }
+
+    local max_rating, best_target, best_weapon = -9e99
+    for _,target in ipairs(targets) do
+        for n_weapon,weapon in ipairs(muff_toras.attacks) do
+            local att_stats, def_stats = wesnoth.simulate_combat(muff_toras, n_weapon, target)
+
+            local rating = -9e99
+            -- This is an acceptable attack if:
+            -- 1. There is no counter attack
+            -- 2. Probability of death is >=67% for enemy, 0% for attacker (default values)
+
+            local enemy_death_chance = 0.67
+            local muff_toras_death_chance = 0
+
+            if (att_stats.hp_chance[muff_toras.hitpoints] == 1)
+                or (def_stats.hp_chance[0] >= enemy_death_chance) and (att_stats.hp_chance[0] <= muff_toras_death_chance)
+            then
+                rating = target.max_hitpoints + def_stats.hp_chance[0] * 100 + att_stats.average_hp - def_stats.average_hp
+            end
+
+            if (rating > max_rating) then
+                max_rating, best_target, best_weapon = rating, target, n_weapon
+            end
+        end
+    end
+
+    if best_target then
+        AH.checked_attack(ai, muff_toras, best_target, best_weapon)
+    end
+    if (not muff_toras) or (not muff_toras.valid) then
+        return
+    end
+
+    AH.checked_stopunit_attacks(ai, muff_toras)
+end
+
+return muff_toras_move

data/campaigns/Two_Brothers/scenarios/02_The_Chase.cfg

@@ -176,7 +176,7 @@ Besides... I want my brother back."
         x,y=9,4
 
         [ai]
-            leader_ignores_keep=yes
+            passive_leader=yes
             village_value=0
 
             [modify_ai]
@@ -426,6 +426,16 @@ Besides... I want my brother back."
             hidden=no
         [/modify_side]
 
+        {MODIFY_AI_ADD_CANDIDATE_ACTION 3 main_loop (
+                [candidate_action]
+                        engine=lua
+                        name=muff_toras_move
+                        id=muff_toras_move
+                        max_score=15000
+                        location="campaigns/Two_Brothers/lua/muff_toras_move.lua"
+                [/candidate_action]
+        )}
+
         [remove_shroud]
             side=1
             x=0-20