package ai

import (
	"math/rand"

	"nl-game-api-gin/internal/gamecore/xiangqi"
)

// ruleChessAI 本地规则象棋 AI：极大极小搜索，深度随难度提升
type ruleChessAI struct {
	difficulty string // 难度：easy=1层+随机扰动 medium=2层 hard=3层
	name       string // 显示名
}

// Name AI 显示名
func (a *ruleChessAI) Name() string { return a.name }

// searchDepth 难度对应的搜索深度
func (a *ruleChessAI) searchDepth() int {
	switch a.difficulty {
	case DiffEasy:
		return 1
	case DiffHard:
		return 3
	default:
		return 2
	}
}

// DecideMove 走子：搜索最优着法；简单难度 40% 概率走随机合法着法（模拟新手失误）
func (a *ruleChessAI) DecideMove(b *xiangqi.Board, side int) (xiangqi.Move, string) {
	if a.difficulty == DiffEasy && rand.Float64() < 0.4 {
		if m, ok := b.RandomMove(side); ok {
			return m, ""
		}
	}
	move, score := b.BestMove(side, a.searchDepth())
	say := ""
	// 分数大幅领先时补一句台词增加氛围
	if score > 800 {
		say = "这步棋你可要小心了。"
	}
	return move, say
}