package msgpack

import (
	"fmt"
	"reflect"
)

var valueEncoders []encoderFunc

func init() {
	valueEncoders = []encoderFunc{
		reflect.Bool: encodeBoolValue,
		reflect.Int: encodeInt64CondValue,
		reflect.Int8: encodeInt8CondValue,
		reflect.Int16: encodeInt16CondValue,
		reflect.Int32: encodeInt32CondValue,
		reflect.Int64: encodeInt64CondValue,
		reflect.Uint: encodeUint64CondValue,
		reflect.Uint8: encodeUint8CondValue,
		reflect.Uint16: encodeUint16CondValue,
		reflect.Uint32: encodeUint32CondValue,
		reflect.Uint64: encodeUint64CondValue,
		reflect.Float32: encodeFloat32Value,
		reflect.Float64: encodeFloat64Value,
		reflect.Complex64: encodeUnsupportedValue,
		reflect.Complex128: encodeUnsupportedValue,
		reflect.Array: encodeArrayValue,
		reflect.Chan: encodeUnsupportedValue,
		reflect.Func: encodeUnsupportedValue,
		reflect.Interface: encodeInterfaceValue,
		reflect.Map: encodeMapValue,
		reflect.Ptr: encodeUnsupportedValue,
		reflect.Slice: encodeSliceValue,
		reflect.String: encodeStringValue,
		reflect.Struct: encodeStructValue,
		reflect.UnsafePointer: encodeUnsupportedValue,
	}
}

func getEncoder(typ reflect.Type) encoderFunc {
	if encoder, ok := typEncMap[typ]; ok {
		return encoder
	}

	if typ.Implements(customEncoderType) {
		return encodeCustomValue
	}
	if typ.Implements(marshalerType) {
		return marshalValue
	}

	kind := typ.Kind()

	// Addressable struct field value.
	if kind != reflect.Ptr {
		ptr := reflect.PtrTo(typ)
		if ptr.Implements(customEncoderType) {
			return encodeCustomValuePtr
		}
		if ptr.Implements(marshalerType) {
			return marshalValuePtr
		}
	}

	if typ == errorType {
		return encodeErrorValue
	}

	switch kind {
	case reflect.Ptr:
		return ptrEncoderFunc(typ)
	case reflect.Slice:
		if typ.Elem().Kind() == reflect.Uint8 {
			return encodeByteSliceValue
		}
	case reflect.Array:
		if typ.Elem().Kind() == reflect.Uint8 {
			return encodeByteArrayValue
		}
	case reflect.Map:
		if typ.Key() == stringType {
			switch typ.Elem() {
			case stringType:
				return encodeMapStringStringValue
			case interfaceType:
				return encodeMapStringInterfaceValue
			}
		}
	}
	return valueEncoders[kind]
}

func ptrEncoderFunc(typ reflect.Type) encoderFunc {
	encoder := getEncoder(typ.Elem())
	return func(e *Encoder, v reflect.Value) error {
		if v.IsNil() {
			return e.EncodeNil()
		}
		return encoder(e, v.Elem())
	}
}

func encodeCustomValuePtr(e *Encoder, v reflect.Value) error {
	if !v.CanAddr() {
		return fmt.Errorf("msgpack: Encode(non-addressable %T)", v.Interface())
	}
	encoder := v.Addr().Interface().(CustomEncoder)
	return encoder.EncodeMsgpack(e)
}

func encodeCustomValue(e *Encoder, v reflect.Value) error {
	switch v.Kind() {
	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
		if v.IsNil() {
			return e.EncodeNil()
		}
	}

	encoder := v.Interface().(CustomEncoder)
	return encoder.EncodeMsgpack(e)
}

func marshalValuePtr(e *Encoder, v reflect.Value) error {
	if !v.CanAddr() {
		return fmt.Errorf("msgpack: Encode(non-addressable %T)", v.Interface())
	}
	return marshalValue(e, v.Addr())
}

func marshalValue(e *Encoder, v reflect.Value) error {
	switch v.Kind() {
	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
		if v.IsNil() {
			return e.EncodeNil()
		}
	}

	marshaler := v.Interface().(Marshaler)
	b, err := marshaler.MarshalMsgpack()
	if err != nil {
		return err
	}
	_, err = e.w.Write(b)
	return err
}

func encodeBoolValue(e *Encoder, v reflect.Value) error {
	return e.EncodeBool(v.Bool())
}

func encodeInterfaceValue(e *Encoder, v reflect.Value) error {
	if v.IsNil() {
		return e.EncodeNil()
	}
	return e.EncodeValue(v.Elem())
}

func encodeErrorValue(e *Encoder, v reflect.Value) error {
	if v.IsNil() {
		return e.EncodeNil()
	}
	return e.EncodeString(v.Interface().(error).Error())
}

func encodeUnsupportedValue(e *Encoder, v reflect.Value) error {
	return fmt.Errorf("msgpack: Encode(unsupported %s)", v.Type())
}