package validate

import (
	"fmt"
	"strings"
)

// ValidationError 用于收集多个字段错误，同时实现 error 接口
type ValidationError struct {
	Errors map[string]string
}

// Error 实现 error 接口
func (v *ValidationError) Error() string {
	msgs := make([]string, 0, len(v.Errors))
	for field, err := range v.Errors {
		msgs = append(msgs, fmt.Sprintf("%s: %s", field, err))
	}
	return strings.Join(msgs, "; ")
}

// NotEmpty 校验 map[string]interface{} 中指定字段不能为空
func NotEmpty(data map[string]interface{}, fields ...string) error {
	errs := make(map[string]string)

	for _, field := range fields {
		collectErrors(data[field], field, errs)
	}

	if len(errs) > 0 {
		return &ValidationError{Errors: errs}
	}
	return nil
}

// collectErrors 递归收集字段错误
func collectErrors(v interface{}, path string, errs map[string]string) {
	if v == nil {
		errs[path] = "字段不能为空"
		return
	}

	switch val := v.(type) {
	case string:
		if strings.TrimSpace(val) == "" {
			errs[path] = "字段不能为空"
		}
	case []interface{}:
		if len(val) == 0 {
			errs[path] = "字段不能为空"
		}
		for i, elem := range val {
			collectErrors(elem, fmt.Sprintf("%s[%d]", path, i), errs)
		}
	case map[string]interface{}:
		if len(val) == 0 {
			errs[path] = "字段不能为空"
		}
		for k, elem := range val {
			collectErrors(elem, fmt.Sprintf("%s.%s", path, k), errs)
		}
	default:
		// 其他类型暂不校验
	}
}