package service

import (
	"math"
	"strings"
)

// RiskRuleVersion 当前风险规则版本；权重仍沿用试点公式，待数据校准后升版。
const RiskRuleVersion = "risk-v2-2026.08.14"

// RiskInput 风险评分输入。nil 表示未采集，不能按 0 参与归一化。
type RiskInput struct {
	AI           *float64 // AI 异常概率（权重 0.5）
	Env          *float64 // 环境风险系数（权重 0.2）
	Stage        *float64 // 饲养阶段风险系数（权重 0.15）
	Uniformity   *float64 // 群体整齐度偏离度（权重 0.15）
	ModelVersion string
}

// RiskAssessment 可解释风险输出。
type RiskAssessment struct {
	Score        float64             `json:"score"`
	Level        string              `json:"level"`
	Confidence   string              `json:"confidence"`
	ModelVersion string              `json:"modelVersion"`
	RuleVersion  string              `json:"ruleVersion"`
	Components   map[string]*float64 `json:"components"`
	Missing      []string            `json:"missing"`
}

// ComputeRiskScore 按可用权重归一化计算 0~100 风险分，缺失组件返回 null。
// 当前 0.5/0.2/0.15/0.15 是待试点校准规则，不是科学结论。
func ComputeRiskScore(in RiskInput) RiskAssessment {
	defs := []struct {
		key    string
		weight float64
		value  *float64
	}{
		{"aiAbnormalProbability", 0.5, in.AI},
		{"environment", 0.2, in.Env},
		{"stage", 0.15, in.Stage},
		{"uniformity", 0.15, in.Uniformity},
	}
	components := make(map[string]*float64, len(defs))
	missing := make([]string, 0, len(defs))
	weighted := 0.0
	totalWeight := 0.0
	for _, def := range defs {
		if def.value == nil {
			components[def.key] = nil
			missing = append(missing, def.key)
			continue
		}
		value := clamp01(*def.value)
		components[def.key] = &value
		weighted += def.weight * value
		totalWeight += def.weight
	}

	score := 0.0
	if totalWeight > 0 {
		score = math.Round(clamp01(weighted/totalWeight)*10000) / 100
	}
	return RiskAssessment{
		Score:        score,
		Level:        RiskLevel(score),
		Confidence:   RiskConfidence(in),
		ModelVersion: in.ModelVersion,
		RuleVersion:  RiskRuleVersion,
		Components:   components,
		Missing:      missing,
	}
}

// RiskConfidence 当前仅给出 low/medium/unknown，避免把未校准规则描述为 high。
func RiskConfidence(in RiskInput) string {
	if in.AI == nil {
		return "unknown"
	}
	if *in.AI >= 0.25 {
		return "medium"
	}
	return "low"
}

// AbnormalProbability 从 AI 检测结果计算异常概率：healthy/unknown 不贡献风险。
// abnormalClasses 可选；缺省时任一非 healthy/unknown 类别都视为异常类别。
func AbnormalProbability(detections []AIDetection, abnormalClasses ...string) float64 {
	configured := make(map[string]struct{}, len(abnormalClasses))
	for _, class := range abnormalClasses {
		if class = strings.ToLower(strings.TrimSpace(class)); class != "" {
			configured[class] = struct{}{}
		}
	}
	best := 0.0
	for _, d := range detections {
		class := strings.ToLower(strings.TrimSpace(d.ClassName))
		if class == "" || class == "healthy" || class == "unknown" {
			continue
		}
		if len(configured) > 0 {
			if _, ok := configured[class]; !ok {
				continue
			}
		}
		if d.Confidence > best {
			best = d.Confidence
		}
	}
	return clamp01(best)
}

func clamp01(v float64) float64 {
	return math.Max(0, math.Min(1, v))
}

// RiskLevel 按规格书 3.1.4 分级：绿 0-30 / 黄 31-60 / 橙 61-80 / 红 81-100
func RiskLevel(score float64) string {
	switch {
	case score <= 30:
		return "green"
	case score <= 60:
		return "yellow"
	case score <= 80:
		return "orange"
	default:
		return "red"
	}
}

// StageCoefficient 蚕房阶段 → 阶段风险系数（Room.Stage 粗粒度映射；
// 待 #7 蚕匾/批次管理的龄期字段落地后细化）
func StageCoefficient(stage string) float64 {
	switch stage {
	case "pupa":
		return 0.5 // 核型多角体病 5龄后期至蛹期高发
	case "larva":
		return 0.4 // 软化病 5 龄集中暴发等
	case "moth":
		return 0.2
	case "egg":
		return 0.1
	default:
		return 0
	}
}

// EnvCoefficient 由最新温湿度计算环境风险系数（规则取自规格书 3.2.3）
func EnvCoefficient(temp, humidity *float64) float64 {
	coef := 0.0
	if humidity != nil {
		switch {
		case *humidity >= 80:
			coef = math.Max(coef, 0.8) // 白僵病等真菌病高湿条件
		case *humidity >= 75:
			coef = math.Max(coef, 0.5)
		}
	}
	if temp != nil {
		if *temp > 30 || *temp < 20 {
			coef = math.Max(coef, 0.5) // 温度突变诱发核型多角体病
		}
	}
	return coef
}