package sql

import (
	"errors"
	"github.com/iancoleman/strcase"
	"reflect"
	"strings"
)

const (
	sqlResultTagPartSeparator         = ";"
	sqlResultTagPartKeyValueSeparator = ":"
)

const (
	sqlResultTagKey    = "sqlresult"
	sqlResultIgnore    = "-"
	sqlResultColumn    = "column"
	sqlResultParseTime = "parseTime"
	sqlResultAes       = "aes"
)

type Result struct {
	ColumnMap map[string]ResultColumn
}

func ParseSqlResult(e any) (*Result, error) {
	if e == nil {
		return nil, errors.New("没有传递实体")
	}

	entityType := reflect.TypeOf(e)
	if entityType.Kind() == reflect.Ptr {
		entityType = entityType.Elem()
	}

	if entityType.Kind() != reflect.Struct {
		return nil, errors.New("传递的实体不是结构类型")
	}

	entityValue := reflect.ValueOf(e)
	if entityValue.Kind() == reflect.Ptr {
		entityValue = entityValue.Elem()
	}

	sqlResult := new(Result)
	sqlResult.ColumnMap = make(map[string]ResultColumn)

	fieldNum := entityType.NumField()
	for i := 0; i < fieldNum; i++ {
		field := entityType.Field(i)
		fieldValue := entityValue.Field(i)

		column, err := parseSqlResultColumn(field, fieldValue)
		if err != nil {
			return nil, err
		}

		if column == nil {
			continue
		}

		sqlResult.ColumnMap[field.Name] = *column
	}

	return sqlResult, nil
}

type ResultColumn struct {
	Name      string
	ParseTime string
	AESKey    string

	// 原字段的反射结构
	OriginFieldType  reflect.Type
	OriginFieldValue reflect.Value

	// 值类型的反射结构
	FieldTypeElem  reflect.Type
	FieldValueElem reflect.Value
}

func parseSqlResultColumn(field reflect.StructField, fieldValue reflect.Value) (*ResultColumn, error) {
	valueFieldType := field.Type
	valueFieldValue := fieldValue

	if valueFieldType.Kind() == reflect.Ptr {
		valueFieldType = valueFieldType.Elem()

		if !valueFieldValue.IsValid() || valueFieldValue.IsNil() || valueFieldValue.IsZero() {
			valueFieldValue = reflect.Zero(valueFieldType)
		} else {
			valueFieldValue = fieldValue.Elem()
		}
	}

	sqlColumn := &ResultColumn{
		Name:             strcase.ToSnake(field.Name),
		ParseTime:        "",
		AESKey:           "",
		OriginFieldType:  field.Type,
		OriginFieldValue: fieldValue,
		FieldTypeElem:    valueFieldType,
		FieldValueElem:   valueFieldValue,
	}

	sqlResultTag, ok := field.Tag.Lookup(sqlResultTagKey)
	if !ok {
		return sqlColumn, nil
	}

	if sqlResultTag == sqlResultIgnore {
		return nil, nil
	}

	sqlResultParts := strings.Split(sqlResultTag, sqlResultTagPartSeparator)
	if sqlResultParts != nil || len(sqlResultParts) != 0 {
		for _, sqlResultPart := range sqlResultParts {
			sqlPartKeyValue := strings.SplitN(strings.TrimSpace(sqlResultPart), sqlResultTagPartKeyValueSeparator, 2)
			switch sqlPartKeyValue[0] {
			case sqlResultColumn:
				sqlColumn.Name = strings.TrimSpace(sqlPartKeyValue[1])
			case sqlResultParseTime:
				sqlColumn.ParseTime = strings.TrimSpace(sqlPartKeyValue[1])
			case sqlResultAes:
				if len(strings.TrimSpace(sqlPartKeyValue[1])) != 32 {
					return nil, errors.New("AES密钥长度应该为32个字节")
				}

				sqlColumn.AESKey = strings.TrimSpace(sqlPartKeyValue[1])
			default:
				continue
			}
		}
	}

	return sqlColumn, nil
}