package sql_mapping

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

const (
	sqlMappingTagPartSeparator         = ";"
	sqlMappingTagPartKeyValueSeparator = ":"
)

const (
	sqlMappingTagKey                 = "sqlmapping"
	sqlMappingIgnore                 = "-"
	sqlMappingColumn                 = "column"
	sqlMappingKey                    = "key"
	sqlMappingNotUpdate              = "notUpdate"
	sqlMappingUpdateClear            = "updateClear"
	sqlMappingNotQuery               = "notQuery"
	sqlMappingQueryConditionCallback = "queryConditionCallback"
)

type SqlMapping struct {
	ColumnMap map[string]SqlColumn
}

func ParseSqlMapping(e any) (*SqlMapping, 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("传递的不是实体结构")
	}

	sqlMapping := new(SqlMapping)
	sqlMapping.ColumnMap = make(map[string]SqlColumn)

	fieldNum := entityType.NumField()
	for i := 0; i < fieldNum; i++ {
		sqlColumn, err := parseSqlColumn(entityType.Field(i))
		if err != nil {
			return nil, err
		}

		if sqlColumn == nil {
			continue
		}

		sqlMapping.ColumnMap[sqlColumn.Name] = *sqlColumn
	}

	return sqlMapping, nil
}

type SqlColumn struct {
	Name                       string
	IsKey                      bool
	CanUpdate                  bool
	CanUpdateClear             bool
	CanQuery                   bool
	NeedQueryConditionCallback bool
}

func parseSqlColumn(field reflect.StructField) (*SqlColumn, error) {
	sqlColumn := &SqlColumn{
		Name:                       strcase.ToSnake(field.Name),
		IsKey:                      false,
		CanUpdate:                  true,
		CanUpdateClear:             false,
		CanQuery:                   true,
		NeedQueryConditionCallback: false,
	}

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

	if sqlMappingTag == sqlMappingIgnore {
		return nil, nil
	}

	sqlMappingParts := strings.Split(sqlMappingTag, sqlMappingTagPartSeparator)
	if sqlMappingParts != nil || len(sqlMappingParts) != 0 {
		for _, sqlMappingPart := range sqlMappingParts {
			sqlPartKeyValue := strings.Split(strings.TrimSpace(sqlMappingPart), sqlMappingTagPartKeyValueSeparator)
			switch sqlPartKeyValue[0] {
			case sqlMappingColumn:
				sqlColumn.Name = strings.TrimSpace(sqlPartKeyValue[1])
			case sqlMappingKey:
				sqlColumn.IsKey = true
				sqlColumn.CanUpdate = false
			case sqlMappingNotUpdate:
				sqlColumn.CanUpdate = false
			case sqlMappingUpdateClear:
				sqlColumn.CanUpdateClear = true
			case sqlMappingNotQuery:
				sqlColumn.CanQuery = false
			case sqlMappingQueryConditionCallback:
				sqlColumn.NeedQueryConditionCallback = true
			default:
				continue
			}
		}
	}

	return sqlColumn, nil
}