package binary

import (
	"bytes"
	"encoding/binary"
	"math"
)

type DynamicProtoMessage map[uint64]interface{}

type encoder struct {
	bytes.Buffer
}

func (msg DynamicProtoMessage) Encode() []byte {
	en := &encoder{}
	for id, value := range msg {
		key := id << 3
		switch v := value.(type) {
		case bool:
			en.uvarint(key | 0)
			vi := uint64(0)
			if v {
				vi = 1
			}
			en.uvarint(vi)
		case int:
			en.uvarint(key | 0)
			en.svarint(int64(v))
		case int32:
			en.uvarint(key | 0)
			en.svarint(int64(v))
		case int64:
			en.uvarint(key | 0)
			en.svarint(v)
		case uint32:
			en.uvarint(key | 0)
			en.uvarint(uint64(v))
		case uint64:
			en.uvarint(key | 0)
			en.uvarint(v)
		case float32:
			en.uvarint(key | 5)
			en.u32(math.Float32bits(v))
		case float64:
			en.uvarint(key | 1)
			en.u64(math.Float64bits(v))
		case string:
			en.uvarint(key | 2)
			b := []byte(v)
			en.uvarint(uint64(len(b)))
			_, _ = en.Write(b)
		case DynamicProtoMessage:
			en.uvarint(key | 2)
			b := v.Encode()
			en.uvarint(uint64(len(b)))
			_, _ = en.Write(b)
		}
	}
	return en.Bytes()
}

func (en *encoder) uvarint(v uint64) {
	var b [binary.MaxVarintLen64]byte
	n := binary.PutUvarint(b[:], v)
	_, _ = en.Write(b[:n])
}

func (en *encoder) svarint(v int64) {
	if v >= 0 {
		en.uvarint(uint64(v) << 1)
	} else {
		en.uvarint(^uint64(v << 1))
	}
}

func (en *encoder) u32(v uint32) {
	var b [4]byte
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	_, _ = en.Write(b[:])
}

func (en *encoder) u64(v uint64) {
	var b [8]byte
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	b[4] = byte(v >> 32)
	b[5] = byte(v >> 40)
	b[6] = byte(v >> 48)
	b[7] = byte(v >> 56)
	_, _ = en.Write(b[:])
}