package gorm

import (
	"errors"
	"fmt"
	"reflect"
	"regexp"

	"time"
)

type Model struct {
	data   interface{}
	driver string
}

type Field struct {
	Name           string
	Value          interface{}
	SqlType        string
	DbName         string
	AutoCreateTime bool
	AutoUpdateTime bool
	IsPrimaryKey   bool
	IsBlank        bool
}

func (m *Model) primaryKeyZero() bool {
	return m.primaryKeyValue() <= 0
}

func (m *Model) primaryKeyValue() int64 {
	if m.data == nil {
		return -1
	}

	data := reflect.ValueOf(m.data).Elem()

	switch data.Kind() {
	case reflect.Array, reflect.Chan, reflect.Map, reflect.Ptr, reflect.Slice:
		return 0
	default:
		value := data.FieldByName(m.primaryKey())

		if value.IsValid() {
			switch value.Kind() {
			case reflect.Int, reflect.Int64, reflect.Int32:
				return value.Int()
			default:
				return 0
			}
		} else {
			return 0
		}
	}
}

func (m *Model) primaryKey() string {
	return "Id"
}

func (m *Model) primaryKeyDb() string {
	return toSnake(m.primaryKey())
}

func (m *Model) fields(operation string) (fields []Field) {
	indirect_value := reflect.Indirect(reflect.ValueOf(m.data))
	typ := indirect_value.Type()

	for i := 0; i < typ.NumField(); i++ {
		p := typ.Field(i)
		if !p.Anonymous {
			var field Field
			field.Name = p.Name
			field.DbName = toSnake(p.Name)
			field.IsPrimaryKey = m.primaryKeyDb() == field.DbName
			field.AutoCreateTime = "created_at" == field.DbName
			field.AutoUpdateTime = "updated_at" == field.DbName
			value := indirect_value.FieldByName(p.Name)

			switch value.Kind() {
			case reflect.Int, reflect.Int64, reflect.Int32:
				field.IsBlank = value.Int() == 0
			case reflect.String:
				field.IsBlank = value.String() == ""
			default:
				if value, ok := value.Interface().(time.Time); ok {
					field.IsBlank = value.IsZero()
				}
			}

			if v, ok := value.Interface().(time.Time); ok {
				switch operation {
				case "create":
					if (field.AutoCreateTime || field.AutoUpdateTime) && v.IsZero() {
						value.Set(reflect.ValueOf(time.Now()))
					}
				case "update":
					if field.AutoUpdateTime {
						value.Set(reflect.ValueOf(time.Now()))
					}
				}
			}

			field.Value = value.Interface()

			if field.IsPrimaryKey {
				field.SqlType = getPrimaryKeySqlType(m.driver, field.Value, 0)
			} else {
				field.SqlType = getSqlType(m.driver, field.Value, 0)
			}
			fields = append(fields, field)
		}
	}
	return

}

func (m *Model) columnsHasValue(operation string) (fields []Field) {
	for _, field := range m.fields(operation) {
		if !field.IsBlank {
			fields = append(fields, field)
		}
	}
	return
}

func (m *Model) updatedColumnsAndValues(values map[string]interface{}) (map[string]interface{}, bool) {
	if m.data == nil {
		return values, true
	}

	data := reflect.Indirect(reflect.ValueOf(m.data))
	results := map[string]interface{}{}

	for key, value := range values {
		field := data.FieldByName(snakeToUpperCamel(key))
		if field.IsValid() {
			if field.Interface() != value {
				switch field.Kind() {
				case reflect.Int, reflect.Int32, reflect.Int64:
					field.SetInt(reflect.ValueOf(value).Int())
					if field.Int() != reflect.ValueOf(value).Int() {
						results[key] = value
					}
				default:
					results[key] = value
					field.Set(reflect.ValueOf(value))
				}
			}
		}
	}

	field := data.FieldByName("UpdatedAt")
	if field.IsValid() && values["updated_at"] != nil && len(results) > 0 {
		data.FieldByName("UpdatedAt").Set(reflect.ValueOf(time.Now()))
	}
	result := len(results) > 0
	return map[string]interface{}{}, result
}

func (m *Model) columnsAndValues(operation string) map[string]interface{} {
	if m.data == nil {
		return map[string]interface{}{}
	}

	results := map[string]interface{}{}
	for _, field := range m.fields(operation) {
		if !field.IsPrimaryKey {
			results[field.DbName] = field.Value
		}
	}
	return results
}

func (m *Model) hasColumn(name string) bool {
	if m.data == nil {
		return false
	}

	data := reflect.Indirect(reflect.ValueOf(m.data))
	if data.Kind() == reflect.Slice {
		return reflect.New(data.Type().Elem()).Elem().FieldByName(name).IsValid()
	} else {
		return data.FieldByName(name).IsValid()
	}
}

func (m *Model) tableName() (str string, err error) {
	if m.data == nil {
		err = errors.New("Model haven't been set")
		return
	}

	typ := reflect.Indirect(reflect.ValueOf(m.data)).Type()
	if typ.Kind() == reflect.Slice {
		typ = typ.Elem()
	}

	str = toSnake(typ.Name())
	pluralMap := map[string]string{"ch": "ches", "ss": "sses", "sh": "shes", "day": "days", "y": "ies", "x": "xes", "s?": "s"}
	for key, value := range pluralMap {
		reg := regexp.MustCompile(key + "$")
		if reg.MatchString(str) {
			return reg.ReplaceAllString(str, value), err
		}
	}
	return
}

func (m *Model) callMethod(method string) error {
	if m.data == nil {
		return nil
	}

	fm := reflect.ValueOf(m.data).MethodByName(method)
	if fm.IsValid() {
		v := fm.Call([]reflect.Value{})
		if len(v) > 0 {
			if verr, ok := v[0].Interface().(error); ok {
				return verr
			}
		}
	}
	return nil
}

func (m *Model) returningStr() (str string) {
	if m.driver == "postgres" {
		str = fmt.Sprintf("RETURNING \"%v\"", m.primaryKeyDb())
	}
	return
}

func (m *Model) missingColumns() (results []string) {
	return
}

func (m *Model) setValueByColumn(name string, value interface{}, out interface{}) {
	data := reflect.Indirect(reflect.ValueOf(out))

	field := data.FieldByName(snakeToUpperCamel(name))
	if field.IsValid() {
		field.Set(reflect.ValueOf(value))
	}
}