package model

import (
	"errors"
	"path/filepath"
	"strings"
)

const maxSpectrumSize = 5 << 20 // 5MB

// ValidDetectionMethod 检测方式枚举
func ValidDetectionMethod(method string) bool {
	switch method {
	case "lamp", "qpcr", "sers", "hyperspectral":
		return true
	default:
		return false
	}
}

// JudgeQPCR qPCR Ct 值自动判读：任一 Ct < threshold 判阳性，无 Ct 判阴性
func JudgeQPCR(cts []float64, threshold float64) (string, string) {
	if threshold <= 0 {
		threshold = 35
	}
	if len(cts) == 0 {
		return "negative", "未检出 Ct 值，判为阴性"
	}
	for _, ct := range cts {
		if ct < threshold {
			return "positive", "存在 Ct 值低于阈值，判为阳性"
		}
	}
	return "negative", "全部 Ct 值不低于阈值，判为阴性"
}

// ValidateSpectrumFile 光谱数据文件校验（csv/txt/json，≤5MB）
func ValidateSpectrumFile(filename string, size int64) error {
	if size <= 0 || size > maxSpectrumSize {
		return errors.New("光谱文件大小需在 1B~5MB 之间")
	}
	ext := strings.ToLower(filepath.Ext(filename))
	switch ext {
	case ".csv", ".txt", ".json":
		return nil
	default:
		return errors.New("仅支持 csv/txt/json 光谱数据文件")
	}
}