package schema

import (
	"database/sql"
	"database/sql/driver"
	"fmt"
	"reflect"
	"strconv"
	"sync"
	"time"

	"github.com/jinzhu/now"
)

type DataType string

const (
	Bool   DataType = "bool"
	Int             = "int"
	Uint            = "uint"
	Float           = "float"
	String          = "string"
	Time            = "time"
	Bytes           = "bytes"
)

type Field struct {
	Name              string
	DBName            string
	BindNames         []string
	DataType          DataType
	DBDataType        string
	PrimaryKey        bool
	AutoIncrement     bool
	Creatable         bool
	Updatable         bool
	HasDefaultValue   bool
	DefaultValue      string
	NotNull           bool
	Unique            bool
	Comment           string
	Size              int
	Precision         int
	FieldType         reflect.Type
	IndirectFieldType reflect.Type
	StructField       reflect.StructField
	Tag               reflect.StructTag
	TagSettings       map[string]string
	Schema            *Schema
	EmbeddedSchema    *Schema
	ReflectValuer     func(reflect.Value) reflect.Value
	Valuer            func(reflect.Value) interface{}
	Setter            func(reflect.Value, interface{}) error
}

func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
	field := &Field{
		Name:              fieldStruct.Name,
		BindNames:         []string{fieldStruct.Name},
		FieldType:         fieldStruct.Type,
		IndirectFieldType: fieldStruct.Type,
		StructField:       fieldStruct,
		Creatable:         true,
		Updatable:         true,
		Tag:               fieldStruct.Tag,
		TagSettings:       ParseTagSetting(fieldStruct.Tag),
		Schema:            schema,
	}

	for field.IndirectFieldType.Kind() == reflect.Ptr {
		field.IndirectFieldType = field.IndirectFieldType.Elem()
	}

	fieldValue := reflect.New(field.IndirectFieldType)
	// if field is valuer, used its value or first fields as data type
	if valuer, isValuer := fieldValue.Interface().(driver.Valuer); isValuer {
		var overrideFieldValue bool
		if v, err := valuer.Value(); v != nil && err == nil {
			overrideFieldValue = true
			fieldValue = reflect.ValueOf(v)
		}

		if field.IndirectFieldType.Kind() == reflect.Struct {
			for i := 0; i < field.IndirectFieldType.NumField(); i++ {
				if !overrideFieldValue {
					newFieldType := field.IndirectFieldType.Field(i).Type
					for newFieldType.Kind() == reflect.Ptr {
						newFieldType = newFieldType.Elem()
					}

					fieldValue = reflect.New(newFieldType)
					overrideFieldValue = true
				}

				// copy tag settings from valuer
				for key, value := range ParseTagSetting(field.IndirectFieldType.Field(i).Tag) {
					if _, ok := field.TagSettings[key]; !ok {
						field.TagSettings[key] = value
					}
				}
			}
		}
	}

	// setup permission
	if _, ok := field.TagSettings["-"]; ok {
		field.Creatable = false
		field.Updatable = false
	}

	if dbName, ok := field.TagSettings["COLUMN"]; ok {
		field.DBName = dbName
	}

	if val, ok := field.TagSettings["PRIMARYKEY"]; ok && checkTruth(val) {
		field.PrimaryKey = true
	}

	if val, ok := field.TagSettings["AUTOINCREMENT"]; ok && checkTruth(val) {
		field.AutoIncrement = true
		field.HasDefaultValue = true
	}

	if v, ok := field.TagSettings["DEFAULT"]; ok {
		field.HasDefaultValue = true
		field.DefaultValue = v
	}

	if num, ok := field.TagSettings["SIZE"]; ok {
		field.Size, _ = strconv.Atoi(num)
	}

	if p, ok := field.TagSettings["PRECISION"]; ok {
		field.Precision, _ = strconv.Atoi(p)
	}

	if val, ok := field.TagSettings["NOT NULL"]; ok && checkTruth(val) {
		field.NotNull = true
	}

	if val, ok := field.TagSettings["UNIQUE"]; ok && checkTruth(val) {
		field.Unique = true
	}

	if val, ok := field.TagSettings["COMMENT"]; ok {
		field.Comment = val
	}

	if val, ok := field.TagSettings["TYPE"]; ok {
		field.DBDataType = val
	}

	switch fieldValue.Elem().Kind() {
	case reflect.Bool:
		field.DataType = Bool
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		field.DataType = Int
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		field.DataType = Uint
	case reflect.Float32, reflect.Float64:
		field.DataType = Float
	case reflect.String:
		field.DataType = String
	case reflect.Struct:
		if _, ok := fieldValue.Interface().(*time.Time); ok {
			field.DataType = Time
		} else if fieldValue.Type().ConvertibleTo(reflect.TypeOf(&time.Time{})) {
			field.DataType = Time
		}
	case reflect.Array, reflect.Slice:
		if fieldValue.Type().Elem() == reflect.TypeOf(uint8(0)) {
			field.DataType = Bytes
		}
	}

	if field.Size == 0 {
		switch fieldValue.Kind() {
		case reflect.Int, reflect.Int64, reflect.Uint, reflect.Uint64, reflect.Float64:
			field.Size = 64
		case reflect.Int8, reflect.Uint8:
			field.Size = 8
		case reflect.Int16, reflect.Uint16:
			field.Size = 16
		case reflect.Int32, reflect.Uint32, reflect.Float32:
			field.Size = 32
		}
	}

	if _, ok := field.TagSettings["EMBEDDED"]; ok || fieldStruct.Anonymous {
		var err error
		field.Creatable = false
		field.Updatable = false
		if field.EmbeddedSchema, err = Parse(fieldValue.Interface(), &sync.Map{}, schema.namer); err != nil {
			schema.err = err
		}
		for _, ef := range field.EmbeddedSchema.Fields {
			ef.Schema = schema
			ef.BindNames = append([]string{fieldStruct.Name}, ef.BindNames...)
			// index is negative means is pointer
			if field.FieldType.Kind() == reflect.Struct {
				ef.StructField.Index = append([]int{fieldStruct.Index[0]}, ef.StructField.Index...)
			} else {
				ef.StructField.Index = append([]int{-fieldStruct.Index[0] - 1}, ef.StructField.Index...)
			}

			if prefix, ok := field.TagSettings["EMBEDDEDPREFIX"]; ok {
				ef.DBName = prefix + ef.DBName
			}

			for k, v := range field.TagSettings {
				ef.TagSettings[k] = v
			}
		}
	}

	return field
}

// ValueOf field value of
func (field *Field) ValueOf(value reflect.Value) interface{} {
	if field != nil {
		return field.Valuer(value)
	}
	return nil
}

func (field *Field) Set(value reflect.Value, v interface{}) error {
	if field != nil {
		return field.Setter(value, v)
	}

	return fmt.Errorf("failed to set field value: %v", field.Name)
}

// create valuer, setter when parse struct
func (field *Field) setupValuerAndSetter() {
	// Valuer
	switch {
	case len(field.StructField.Index) == 1:
		field.Valuer = func(value reflect.Value) interface{} {
			return reflect.Indirect(value).Field(field.StructField.Index[0]).Interface()
		}
	case len(field.StructField.Index) == 2 && field.StructField.Index[0] >= 0:
		field.Valuer = func(value reflect.Value) interface{} {
			return reflect.Indirect(value).Field(field.StructField.Index[0]).Field(field.StructField.Index[1]).Interface()
		}
	default:
		field.Valuer = func(value reflect.Value) interface{} {
			v := reflect.Indirect(value)

			for _, idx := range field.StructField.Index {
				if idx >= 0 {
					v = v.Field(idx)
				} else {
					v = v.Field(-idx - 1)

					if v.Type().Elem().Kind() == reflect.Struct {
						if !v.IsNil() {
							v = v.Elem()
						}
					} else {
						return nil
					}
				}
			}
			return v.Interface()
		}
	}

	// ReflectValuer
	switch {
	case len(field.StructField.Index) == 1:
		if field.FieldType.Kind() == reflect.Ptr {
			field.ReflectValuer = func(value reflect.Value) reflect.Value {
				fieldValue := reflect.Indirect(value).Field(field.StructField.Index[0])
				if fieldValue.IsNil() {
					fieldValue.Set(reflect.New(field.FieldType.Elem()))
				}
				return fieldValue
			}
		} else {
			field.ReflectValuer = func(value reflect.Value) reflect.Value {
				return reflect.Indirect(value).Field(field.StructField.Index[0])
			}
		}
	case len(field.StructField.Index) == 2 && field.StructField.Index[0] >= 0 && field.FieldType.Kind() != reflect.Ptr:
		field.ReflectValuer = func(value reflect.Value) reflect.Value {
			return reflect.Indirect(value).Field(field.StructField.Index[0]).Field(field.StructField.Index[1])
		}
	default:
		field.ReflectValuer = func(value reflect.Value) reflect.Value {
			v := reflect.Indirect(value)
			for _, idx := range field.StructField.Index {
				if idx >= 0 {
					v = v.Field(idx)
				} else {
					v = v.Field(-idx - 1)
				}

				if v.Kind() == reflect.Ptr {
					if v.Type().Elem().Kind() == reflect.Struct {
						if v.IsNil() {
							v.Set(reflect.New(v.Type().Elem()))
						}
					}

					if idx < len(field.StructField.Index)-1 {
						v = v.Elem()
					}
				}
			}
			return v
		}
	}

	recoverFunc := func(value reflect.Value, v interface{}, setter func(reflect.Value, interface{}) error) (err error) {
		reflectV := reflect.ValueOf(v)
		if reflectV.Type().ConvertibleTo(field.FieldType) {
			field.ReflectValuer(value).Set(reflectV.Convert(field.FieldType))
		} else if valuer, ok := v.(driver.Valuer); ok {
			if v, err = valuer.Value(); err == nil {
				return setter(value, v)
			}
		} else if field.FieldType.Kind() == reflect.Ptr && reflectV.Type().ConvertibleTo(field.FieldType.Elem()) {
			field.ReflectValuer(value).Elem().Set(reflectV.Convert(field.FieldType.Elem()))
		} else if reflectV.Kind() == reflect.Ptr {
			return field.Setter(value, reflectV.Elem().Interface())
		} else {
			return fmt.Errorf("failed to set value %+v to field %v", v, field.Name)
		}
		return err
	}

	// Setter
	switch field.FieldType.Kind() {
	case reflect.Bool:
		field.Setter = func(value reflect.Value, v interface{}) error {
			switch data := v.(type) {
			case bool:
				field.ReflectValuer(value).SetBool(data)
			case *bool:
				field.ReflectValuer(value).SetBool(*data)
			default:
				return recoverFunc(value, v, field.Setter)
			}
			return nil
		}
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		field.Setter = func(value reflect.Value, v interface{}) (err error) {
			switch data := v.(type) {
			case int64:
				field.ReflectValuer(value).SetInt(data)
			case int:
				field.ReflectValuer(value).SetInt(int64(data))
			case int8:
				field.ReflectValuer(value).SetInt(int64(data))
			case int16:
				field.ReflectValuer(value).SetInt(int64(data))
			case int32:
				field.ReflectValuer(value).SetInt(int64(data))
			case uint:
				field.ReflectValuer(value).SetInt(int64(data))
			case uint8:
				field.ReflectValuer(value).SetInt(int64(data))
			case uint16:
				field.ReflectValuer(value).SetInt(int64(data))
			case uint32:
				field.ReflectValuer(value).SetInt(int64(data))
			case uint64:
				field.ReflectValuer(value).SetInt(int64(data))
			case float32:
				field.ReflectValuer(value).SetInt(int64(data))
			case float64:
				field.ReflectValuer(value).SetInt(int64(data))
			case []byte:
				return field.Setter(value, string(data))
			case string:
				if i, err := strconv.ParseInt(data, 0, 64); err == nil {
					field.ReflectValuer(value).SetInt(i)
				} else {
					return err
				}
			default:
				return recoverFunc(value, v, field.Setter)
			}
			return err
		}
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		field.Setter = func(value reflect.Value, v interface{}) (err error) {
			switch data := v.(type) {
			case uint64:
				field.ReflectValuer(value).SetUint(data)
			case uint:
				field.ReflectValuer(value).SetUint(uint64(data))
			case uint8:
				field.ReflectValuer(value).SetUint(uint64(data))
			case uint16:
				field.ReflectValuer(value).SetUint(uint64(data))
			case uint32:
				field.ReflectValuer(value).SetUint(uint64(data))
			case int64:
				field.ReflectValuer(value).SetUint(uint64(data))
			case int:
				field.ReflectValuer(value).SetUint(uint64(data))
			case int8:
				field.ReflectValuer(value).SetUint(uint64(data))
			case int16:
				field.ReflectValuer(value).SetUint(uint64(data))
			case int32:
				field.ReflectValuer(value).SetUint(uint64(data))
			case float32:
				field.ReflectValuer(value).SetUint(uint64(data))
			case float64:
				field.ReflectValuer(value).SetUint(uint64(data))
			case []byte:
				return field.Setter(value, string(data))
			case string:
				if i, err := strconv.ParseUint(data, 0, 64); err == nil {
					field.ReflectValuer(value).SetUint(i)
				} else {
					return err
				}
			default:
				return recoverFunc(value, v, field.Setter)
			}
			return err
		}
	case reflect.Float32, reflect.Float64:
		field.Setter = func(value reflect.Value, v interface{}) (err error) {
			switch data := v.(type) {
			case float64:
				field.ReflectValuer(value).SetFloat(data)
			case float32:
				field.ReflectValuer(value).SetFloat(float64(data))
			case int64:
				field.ReflectValuer(value).SetFloat(float64(data))
			case int:
				field.ReflectValuer(value).SetFloat(float64(data))
			case int8:
				field.ReflectValuer(value).SetFloat(float64(data))
			case int16:
				field.ReflectValuer(value).SetFloat(float64(data))
			case int32:
				field.ReflectValuer(value).SetFloat(float64(data))
			case uint:
				field.ReflectValuer(value).SetFloat(float64(data))
			case uint8:
				field.ReflectValuer(value).SetFloat(float64(data))
			case uint16:
				field.ReflectValuer(value).SetFloat(float64(data))
			case uint32:
				field.ReflectValuer(value).SetFloat(float64(data))
			case uint64:
				field.ReflectValuer(value).SetFloat(float64(data))
			case []byte:
				return field.Setter(value, string(data))
			case string:
				if i, err := strconv.ParseFloat(data, 64); err == nil {
					field.ReflectValuer(value).SetFloat(i)
				} else {
					return err
				}
			default:
				return recoverFunc(value, v, field.Setter)
			}
			return err
		}
	case reflect.String:
		field.Setter = func(value reflect.Value, v interface{}) (err error) {
			switch data := v.(type) {
			case string:
				field.ReflectValuer(value).SetString(data)
			case []byte:
				field.ReflectValuer(value).SetString(string(data))
			case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
				field.ReflectValuer(value).SetString(fmt.Sprint(data))
			case float64, float32:
				field.ReflectValuer(value).SetString(fmt.Sprintf("%."+strconv.Itoa(field.Precision)+"f", data))
			default:
				return recoverFunc(value, v, field.Setter)
			}
			return err
		}
	default:
		fieldValue := reflect.New(field.FieldType)
		switch fieldValue.Elem().Interface().(type) {
		case time.Time:
			field.Setter = func(value reflect.Value, v interface{}) error {
				switch data := v.(type) {
				case time.Time:
					field.ReflectValuer(value).Set(reflect.ValueOf(v))
				case *time.Time:
					field.ReflectValuer(value).Set(reflect.ValueOf(v).Elem())
				case string:
					if t, err := now.Parse(data); err == nil {
						field.ReflectValuer(value).Set(reflect.ValueOf(t))
					} else {
						return fmt.Errorf("failed to set string %v to time.Time field %v, failed to parse it as time, got error %v", v, field.Name, err)
					}
				default:
					return recoverFunc(value, v, field.Setter)
				}
				return nil
			}
		case *time.Time:
			field.Setter = func(value reflect.Value, v interface{}) error {
				switch data := v.(type) {
				case time.Time:
					field.ReflectValuer(value).Elem().Set(reflect.ValueOf(v))
				case *time.Time:
					field.ReflectValuer(value).Set(reflect.ValueOf(v))
				case string:
					if t, err := now.Parse(data); err == nil {
						field.ReflectValuer(value).Elem().Set(reflect.ValueOf(t))
					} else {
						return fmt.Errorf("failed to set string %v to time.Time field %v, failed to parse it as time, got error %v", v, field.Name, err)
					}
				default:
					return recoverFunc(value, v, field.Setter)
				}
				return nil
			}
		default:
			if _, ok := fieldValue.Interface().(sql.Scanner); ok {
				// struct scanner
				field.Setter = func(value reflect.Value, v interface{}) (err error) {
					reflectV := reflect.ValueOf(v)
					if reflectV.Type().ConvertibleTo(field.FieldType) {
						field.ReflectValuer(value).Set(reflectV.Convert(field.FieldType))
					} else if valuer, ok := v.(driver.Valuer); ok {
						if v, err = valuer.Value(); err == nil {
							err = field.ReflectValuer(value).Addr().Interface().(sql.Scanner).Scan(v)
						}
					} else {
						err = field.ReflectValuer(value).Addr().Interface().(sql.Scanner).Scan(v)
					}
					return
				}
			} else if _, ok := fieldValue.Elem().Interface().(sql.Scanner); ok {
				// pointer scanner
				field.Setter = func(value reflect.Value, v interface{}) (err error) {
					reflectV := reflect.ValueOf(v)
					if reflectV.Type().ConvertibleTo(field.FieldType) {
						field.ReflectValuer(value).Set(reflectV.Convert(field.FieldType))
					} else if reflectV.Type().ConvertibleTo(field.FieldType.Elem()) {
						field.ReflectValuer(value).Elem().Set(reflectV.Convert(field.FieldType.Elem()))
					} else if valuer, ok := v.(driver.Valuer); ok {
						if v, err = valuer.Value(); err == nil {
							err = field.ReflectValuer(value).Interface().(sql.Scanner).Scan(v)
						}
					} else {
						err = field.ReflectValuer(value).Interface().(sql.Scanner).Scan(v)
					}
					return
				}
			} else {
				field.Setter = func(value reflect.Value, v interface{}) (err error) {
					return recoverFunc(value, v, field.Setter)
				}
			}
		}
	}
}