package conversion

import "nex/backend/internal/conversion/canonical"

// StreamDecoder 流式解码器接口
type StreamDecoder interface {
	ProcessChunk(rawChunk []byte) []canonical.CanonicalStreamEvent
	Flush() []canonical.CanonicalStreamEvent
}

// StreamEncoder 流式编码器接口
type StreamEncoder interface {
	EncodeEvent(event canonical.CanonicalStreamEvent) [][]byte
	Flush() [][]byte
}

// StreamConverter 流式转换器接口
type StreamConverter interface {
	ProcessChunk(rawChunk []byte) [][]byte
	Flush() [][]byte
}

// PassthroughStreamConverter 同协议透传流式转换器
type PassthroughStreamConverter struct{}

// NewPassthroughStreamConverter 创建透传流式转换器
func NewPassthroughStreamConverter() *PassthroughStreamConverter {
	return &PassthroughStreamConverter{}
}

// ProcessChunk 直接传递原始字节
func (c *PassthroughStreamConverter) ProcessChunk(rawChunk []byte) [][]byte {
	return [][]byte{rawChunk}
}

// Flush 无缓冲数据
func (c *PassthroughStreamConverter) Flush() [][]byte {
	return nil
}

// CanonicalStreamConverter 跨协议规范流式转换器
type CanonicalStreamConverter struct {
	decoder  StreamDecoder
	encoder  StreamEncoder
	chain    *MiddlewareChain
	ctx      ConversionContext
	clientProtocol  string
	providerProtocol string
}

// NewCanonicalStreamConverter 创建规范流式转换器
func NewCanonicalStreamConverter(decoder StreamDecoder, encoder StreamEncoder) *CanonicalStreamConverter {
	return &CanonicalStreamConverter{
		decoder: decoder,
		encoder: encoder,
	}
}

// NewCanonicalStreamConverterWithMiddleware 创建带中间件的规范流式转换器
func NewCanonicalStreamConverterWithMiddleware(decoder StreamDecoder, encoder StreamEncoder, chain *MiddlewareChain, ctx ConversionContext, clientProtocol, providerProtocol string) *CanonicalStreamConverter {
	return &CanonicalStreamConverter{
		decoder:         decoder,
		encoder:         encoder,
		chain:           chain,
		ctx:             ctx,
		clientProtocol:  clientProtocol,
		providerProtocol: providerProtocol,
	}
}

// ProcessChunk 解码 → 中间件 → 编码管道
func (c *CanonicalStreamConverter) ProcessChunk(rawChunk []byte) [][]byte {
	events := c.decoder.ProcessChunk(rawChunk)
	var result [][]byte
	for i := range events {
		if c.chain != nil {
			processed, err := c.chain.ApplyStreamEvent(&events[i], c.clientProtocol, c.providerProtocol, &c.ctx)
			if err != nil {
				continue
			}
			events[i] = *processed
		}
		chunks := c.encoder.EncodeEvent(events[i])
		result = append(result, chunks...)
	}
	return result
}

// Flush 刷新解码器和编码器缓冲区
func (c *CanonicalStreamConverter) Flush() [][]byte {
	events := c.decoder.Flush()
	var result [][]byte
	for i := range events {
		if c.chain != nil {
			processed, err := c.chain.ApplyStreamEvent(&events[i], c.clientProtocol, c.providerProtocol, &c.ctx)
			if err != nil {
				continue
			}
			events[i] = *processed
		}
		chunks := c.encoder.EncodeEvent(events[i])
		result = append(result, chunks...)
	}
	encoderChunks := c.encoder.Flush()
	result = append(result, encoderChunks...)
	return result
}