package transformer

// Qwen2ForCausalLM 为生成模型入口
type Qwen2ForCausalLM struct {
	*Qwen2PreTrainedModel
	Model  *Qwen2Model
	LMHead interface{}
}

func (m *Qwen2ForCausalLM) Forward(inputIDs []int, pastKV [][]interface{}) (interface{}, error) {
	outputs, err := m.Model.Forward(inputIDs, nil, nil, pastKV)
	if err != nil {
		return nil, err
	}
	// 根据主干网络输出生成 logits
	hiddenStates := outputs.(struct {
		LastHiddenState interface{}
		PastKeyValues   [][]interface{}
	}).LastHiddenState
	logits := m.lmHeadForward(hiddenStates)
	return struct {
		Logits        interface{}
		PastKeyValues [][]interface{}
	}{Logits: logits, PastKeyValues: outputs.(struct {
		LastHiddenState interface{}
		PastKeyValues   [][]interface{}
	}).PastKeyValues}, nil
}

func (m *Qwen2ForCausalLM) PrepareInputsForGeneration(inputIDs []int, pastKV [][]interface{}) map[string]interface{} {
	if pastKV != nil && len(inputIDs) > 0 {
		// 仅保留最后一个 token
		inputIDs = inputIDs[len(inputIDs)-1:]
	}
	return map[string]interface{}{
		"input_ids":       inputIDs,
		"past_key_values": pastKV,
		"use_cache":       true,
	}
}

// lmHeadForward 模拟 lm_head 的前向传播
func (m *Qwen2ForCausalLM) lmHeadForward(hiddenStates interface{}) interface{} {
	// 实现将 hiddenStates 投影到词表维度的逻辑
	return nil
}
