package lxUtil

import (
	"reflect"
	"strings"
)

// IsZeroOfUnderlyingType 判断是否零值对象, 考虑到了model是指针的情况
func IsZeroOfUnderlyingType(model interface{}) bool {
	// ref: https://www.coder.work/article/200965
	rawType := reflect.TypeOf(model)
	if rawType.Kind() == reflect.Ptr { // 指针
		rawType = rawType.Elem()
		return reflect.DeepEqual(model, reflect.New(rawType).Interface())
	}
	return reflect.DeepEqual(model, reflect.Zero(rawType).Interface())
}

// ToSlice 为什么不能被 cast.ToSlice 替代?
func ToSlice1(v interface{}) []interface{} {
	var out []interface{}
	rv := reflect.ValueOf(v)
	if rv.Kind() == reflect.Slice {
		for i := 0; i < rv.Len(); i++ {
			out = append(out, rv.Index(i).Interface())
		}
	} else {
		out = append(out, v)
	}
	return out
}

// FieldToColumn inAmt -> in_amt 结构体属性转成库表字段
func FieldToColumn(s string) string {
	return CamelCaseToSnakeCase(s)
}

// CamelCaseToSnakeCase 小驼峰转下划线
// mesLine -> mes_line
// mesLine-lineCode-lineDesc -> mes_line-line_code-line_desc
func CamelCaseToSnakeCase(s string) string {
	if s = strings.TrimSpace(s); s == "" {
		return ""
	}

	var (
		buf                              strings.Builder
		prevUpper, nextUpper, nextNumber bool
		curUpper                         = s[0] <= 'Z' && s[0] >= 'A'
	)

	for i, r := range s[:len(s)-1] {
		nextUpper = 'A' <= s[i+1] && s[i+1] <= 'Z'
		nextNumber = '0' <= s[i+1] && s[i+1] <= '9'

		if curUpper {
			if prevUpper && (nextUpper || nextNumber) {
				buf.WriteRune(r + 32)
			} else {
				if i > 0 && s[i-1] != '_' && s[i+1] != '_' {
					buf.WriteByte('_')
				}
				buf.WriteRune(r + 32)
			}
		} else {
			buf.WriteRune(r)
		}

		prevUpper = curUpper
		curUpper = nextUpper
	}

	if curUpper {
		if !prevUpper && len(s) > 1 {
			buf.WriteByte('_')
		}
		buf.WriteByte(s[len(s)-1] + 32)
	} else {
		buf.WriteByte(s[len(s)-1])
	}

	return buf.String()
}