|
1
|
|
|
<?php |
|
2
|
|
|
|
|
3
|
|
|
namespace lucidtaz\minimax; |
|
4
|
|
|
|
|
5
|
|
|
use BadMethodCallException; |
|
6
|
|
|
use Closure; |
|
7
|
|
|
use RuntimeException; |
|
8
|
|
|
|
|
9
|
|
|
class Engine |
|
10
|
|
|
{ |
|
11
|
|
|
private $objectivePlayer; |
|
12
|
|
|
|
|
13
|
|
|
private $maxDepth; |
|
14
|
|
|
|
|
15
|
12 |
|
public function __construct(Player $objectivePlayer, int $maxDepth = 3) |
|
16
|
|
|
{ |
|
17
|
12 |
|
$this->objectivePlayer = $objectivePlayer; |
|
18
|
12 |
|
$this->maxDepth = $maxDepth; |
|
19
|
12 |
|
} |
|
20
|
|
|
|
|
21
|
|
|
/** |
|
22
|
|
|
* Evaluate possible decisions and take the best one |
|
23
|
|
|
*/ |
|
24
|
12 |
|
public function decide(GameState $state): Decision |
|
25
|
|
|
{ |
|
26
|
12 |
|
if (!$state->getNextPlayer()->equals($this->objectivePlayer)) { |
|
27
|
1 |
|
throw new BadMethodCallException('It is not this players turn'); |
|
28
|
|
|
} |
|
29
|
11 |
|
$decisionWithScore = $this->decideMax($state, $this->maxDepth); |
|
30
|
11 |
|
if ($decisionWithScore->decision === null) { |
|
31
|
1 |
|
throw new RuntimeException('There are no possible moves'); |
|
32
|
|
|
} |
|
33
|
10 |
|
return $decisionWithScore->decision; |
|
34
|
|
|
} |
|
35
|
|
|
|
|
36
|
11 |
|
private function decideMax(GameState $state, int $depthLeft) |
|
37
|
|
|
{ |
|
38
|
|
|
return $this->decideVar($state, $depthLeft, function (DecisionWithScore $a, DecisionWithScore $b) { |
|
39
|
9 |
|
return $a->isBetterThan($b) ? $a : $b; |
|
40
|
11 |
|
}); |
|
41
|
|
|
} |
|
42
|
|
|
|
|
43
|
|
|
private function decideMin(GameState $state, int $depthLeft) |
|
44
|
|
|
{ |
|
45
|
10 |
|
return $this->decideVar($state, $depthLeft, function (DecisionWithScore $a, DecisionWithScore $b) { |
|
46
|
9 |
|
return $b->isBetterThan($a) ? $a : $b; |
|
47
|
10 |
|
}); |
|
48
|
|
|
} |
|
49
|
|
|
|
|
50
|
11 |
|
private function decideVar(GameState $state, int $depthLeft, Closure $ideal) |
|
51
|
|
|
{ |
|
52
|
11 |
|
if ($depthLeft == 0) { |
|
53
|
9 |
|
$result = new DecisionWithScore; |
|
54
|
9 |
|
$result->age = $depthLeft; |
|
55
|
9 |
|
$result->score = $state->evaluateScore($this->objectivePlayer); |
|
56
|
9 |
|
return $result; |
|
57
|
|
|
} |
|
58
|
|
|
|
|
59
|
|
|
/* @var $possibleMoves Decision[] */ |
|
60
|
11 |
|
$possibleMoves = $state->getDecisions(); |
|
61
|
11 |
|
if (empty($possibleMoves)) { |
|
62
|
9 |
|
$result = new DecisionWithScore; |
|
63
|
9 |
|
$result->age = $depthLeft; |
|
64
|
9 |
|
$result->score = $state->evaluateScore($this->objectivePlayer); |
|
65
|
9 |
|
return $result; |
|
66
|
|
|
} |
|
67
|
|
|
|
|
68
|
10 |
|
$bestDecisionWithScore = null; |
|
69
|
10 |
|
foreach ($possibleMoves as $move) { |
|
70
|
10 |
|
$bestDecisionWithScore = $this->considerMove($move, $state, $depthLeft, $ideal, $bestDecisionWithScore); |
|
71
|
|
|
} |
|
72
|
|
|
|
|
73
|
10 |
|
return $bestDecisionWithScore; |
|
74
|
|
|
} |
|
75
|
|
|
|
|
76
|
10 |
|
private function considerMove(Decision $move, GameState $state, int $depthLeft, Closure $ideal, DecisionWithScore $bestDecisionWithScoreSoFar = null): DecisionWithScore |
|
77
|
|
|
{ |
|
78
|
10 |
|
$newState = $move->apply($state); |
|
79
|
|
|
|
|
80
|
10 |
|
$nextDecisionWithScore = $this->considerNextMove($newState, $depthLeft - 1); |
|
81
|
|
|
|
|
82
|
10 |
|
$replaced = false; |
|
83
|
10 |
|
$bestDecisionWithScore = $this->replaceIfBetter( |
|
84
|
|
|
$ideal, |
|
85
|
|
|
$nextDecisionWithScore, |
|
86
|
|
|
$bestDecisionWithScoreSoFar, |
|
87
|
|
|
$replaced |
|
88
|
|
|
); |
|
89
|
10 |
|
if ($replaced) { |
|
90
|
10 |
|
$bestDecisionWithScore->decision = $move; |
|
91
|
|
|
} |
|
92
|
|
|
|
|
93
|
10 |
|
return $bestDecisionWithScore; |
|
94
|
|
|
} |
|
95
|
|
|
|
|
96
|
10 |
|
private function considerNextMove(GameState $state, $depthLeft): DecisionWithScore |
|
97
|
|
|
{ |
|
98
|
10 |
|
if ($state->getNextPlayer()->isFriendsWith($this->objectivePlayer)) { |
|
99
|
9 |
|
return $this->decideMax($state, $depthLeft); |
|
100
|
|
|
} |
|
101
|
10 |
|
return $this->decideMin($state, $depthLeft); |
|
102
|
|
|
} |
|
103
|
|
|
|
|
104
|
10 |
|
private function replaceIfBetter(Closure $ideal, DecisionWithScore $new, DecisionWithScore $current = null, &$replaced = false): DecisionWithScore |
|
105
|
|
|
{ |
|
106
|
10 |
|
if ($current === null) { |
|
107
|
10 |
|
$replaced = true; |
|
108
|
10 |
|
return $new; |
|
109
|
|
|
} |
|
110
|
|
|
|
|
111
|
9 |
|
$idealDecisionWithScore = $ideal($new, $current); |
|
112
|
9 |
|
if ($idealDecisionWithScore === $new) { |
|
113
|
7 |
|
$replaced = true; |
|
114
|
7 |
|
return $new; |
|
115
|
|
|
} |
|
116
|
|
|
|
|
117
|
9 |
|
$replaced = false; |
|
118
|
9 |
|
return $current; |
|
119
|
|
|
} |
|
120
|
|
|
} |
|
121
|
|
|
|
LucidTaZ /
minimax
