package ssob

import (
	"encoding/binary"
	"errors"
	"reflect"
)

func marshalString(in string) (ret []byte) {
	l := int64(len(in))
	b := marshalInt64(l)
	b = append(b, []byte(in)...)
	return b
}

func marshalInt8(in int8) (ret []byte) {
	return []byte{byte(in)}
}

func marshalUint8(in uint8) (ret []byte) {
	return []byte{byte(in)}
}

func marshalInt16(in int16) (ret []byte) {
	out := make([]byte, 2)

	binary.BigEndian.PutUint16(out, uint16(in))
	return out
}

func marshalUint16(in uint16) (ret []byte) {
	out := make([]byte, 2)

	binary.BigEndian.PutUint16(out, in)
	return out
}

func marshalInt32(in int32) (ret []byte) {
	out := make([]byte, 4)

	binary.BigEndian.PutUint32(out, uint32(in))
	return out
}

func marshalUint32(in uint32) (ret []byte) {
	out := make([]byte, 4)

	binary.BigEndian.PutUint32(out, in)
	return out
}

func marshalFloat32(in float32) (ret []byte) {
	out := make([]byte, 4)

	binary.BigEndian.PutUint32(out, uint32(in))
	return out
}

func marshalInt64(in int64) (ret []byte) {
	out := make([]byte, 8)

	binary.BigEndian.PutUint64(out, uint64(in))
	return out
}

func marshalUint64(in uint64) (ret []byte) {
	out := make([]byte, 8)

	binary.BigEndian.PutUint64(out, in)
	return out
}

func marshalFloat64(in float64) (ret []byte) {
	out := make([]byte, 8)

	binary.BigEndian.PutUint64(out, uint64(in))
	return out
}

type marshalFunc func(e interface{}) (ret []byte, err error)

var encoderCache map[string]marshalFunc

func init() {
	encoderCache = make(map[string]marshalFunc)
	encRegister(int8(0))
	encRegister(uint8(0))
	encRegister(int16(0))
	encRegister(uint16(0))
	encRegister(int32(0))
	encRegister(uint32(0))
	encRegister(float32(0))
	encRegister(int64(0))
	encRegister(uint64(0))
	encRegister(float64(0))
	encRegister(string(""))
}

func encRegister(e interface{}) (err error) {
	v := reflect.ValueOf(e)
	t := reflect.TypeOf(e)
	switch t.Kind() {
	case reflect.Invalid:
		return errors.New("ssob: Invalid type")
	case reflect.Slice:
		f := func(e interface{}) (ret []byte, err error) {
			v := reflect.ValueOf(e)
			l := v.Len()
			ret, err = marshal(int64(l))
			if err != nil {
				return nil, err
			}
			for i := 0; i < l; i++ {
				b, err := marshal(v.Index(i).Interface())
				if err != nil {
					return nil, err
				}
				ret = append(ret, b...)
			}

			return ret, nil
		}
		encoderCache[string(t.Kind())] = f
	case reflect.Struct:
		f := func(e interface{}) (ret []byte, err error) {
			n := v.NumField()
			ret = []byte{}
			for i := 0; i < n; i++ {
				b, err := marshal(v.Field(i).Interface())
				if err != nil {
					return nil, err
				}
				ret = append(ret, b...)
			}
			return ret, nil
		}
		encoderCache[t.Name()] = f
	case reflect.Int8:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(int8); ok {
				return marshalInt8(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected int8")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Uint8:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(uint8); ok {
				return marshalUint8(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected uint8")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Int16:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(int16); ok {
				return marshalInt16(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected int16")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Uint16:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(uint16); ok {
				return marshalUint16(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected uint16")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Int32:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(int32); ok {
				return marshalInt32(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected int32")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Uint32:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(uint32); ok {
				return marshalUint32(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected uint32")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Float32:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(float32); ok {
				return marshalFloat32(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected float32")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Int64:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(int64); ok {
				return marshalInt64(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected int64")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Uint64:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(uint64); ok {
				return marshalUint64(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected uint64")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.Float64:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(float64); ok {
				return marshalFloat64(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected float64")
		}
		encoderCache[string(v.Kind())] = f
	case reflect.String:
		f := func(e interface{}) (ret []byte, err error) {
			if i, ok := e.(string); ok {
				return marshalString(i), nil
			}
			return nil, errors.New("ssob: Incompatible type " + string(v.Kind()) + " - expected string")
		}
		encoderCache[string(v.Kind())] = f
	default:
		return errors.New("ssob: Unknown type " + string(v.Kind()))
	}

	return nil
}

func marshal(e interface{}) (ret []byte, err error) {
	var key string
	t := reflect.TypeOf(e)
	v := reflect.ValueOf(e)
	if t.Kind() == reflect.Ptr {
		if v.IsNil() {
			return nil, errors.New("ssob: Cannot marshal nil pointer")
		}
		p := reflect.Indirect(v)
		return marshal(p.Interface())
	}
	if t.Kind() == reflect.Struct {
		key = reflect.TypeOf(e).Name()
	} else {
		key = string(t.Kind())
	}

	if f, ok := encoderCache[key]; ok {
		return f(e)
	} else {
		err = encRegister(e)
		if err != nil {
			return nil, err
		}
	}

	return marshal(e)
}