Model.py

import json  
import numpy as np  
import pandas as pd
import tensorflow as tf  
from tensorflow.keras import layers 
import sentencepiece as spm  
import requests

# ⬇️ 파일 다운로드 함수
def download_file(url, save_path):
    response = requests.get(url, stream=True)
    response.raise_for_status()
    with open(save_path, 'wb') as f:
        for chunk in response.iter_content(chunk_size=8192):
            f.write(chunk)
    print(f"✅ 파일 저장됨: {save_path}")

# ⬇️ 데이터와 토크나이저 다운로드
download_file('https://huggingface.co/datasets/Yuchan5386/TinyInst/resolve/main/ko_unigram.model?download=true', 'ko_unigram.model')
download_file('https://huggingface.co/datasets/Yuchan5386/TinyInst/resolve/refs%2Fconvert%2Fparquet/default/train/0000.parquet?download=true', 'dataset.parquet')

# ⬇️ Parquet 데이터 불러오기
df = pd.read_parquet("dataset.parquet", engine="pyarrow")

# ⬇️ <start> 질문 <sep> 답변 <end> 포맷으로 변환
train_sentences = []

for conversations in df["conversations"]:
    for i in range(0, len(conversations) - 1, 2):
        item1, item2 = conversations[i], conversations[i + 1]
        if item1.get("from") == "human" and item2.get("from") == "gpt":
            prompt = item1.get("value", "").strip().replace("\n", " ")
            response = item2.get("value", "").strip().replace("\n", " ")
            full = f"<start> {prompt} <sep> {response} <end>"
            train_sentences.append(full)
train_sentences = train_sentences
print(f"총 문장 개수: {len(train_sentences)}")

# ⬇️ 토크나이저 불러오기
sp = spm.SentencePieceProcessor()
sp.load("ko_unigram.model")

# ⬇️ 특수 토큰 ID 추출
pad_id = sp.piece_to_id("<pad>") if sp.piece_to_id("<pad>") != -1 else 0  
start_id = sp.piece_to_id("<start>")  
sep_id = sp.piece_to_id("<sep>")  
end_id = sp.piece_to_id("<end>")  
unk_id = sp.piece_to_id("<unk>")  

vocab_size = sp.get_piece_size()
print(f"✅ Vocabulary size: {vocab_size}")

# ⬇️ 텍스트 <-> ID 변환 함수
def text_to_ids(text):
    return sp.encode(text, out_type=int)

def ids_to_text(ids):
    return sp.decode(ids)

# ⬇️ 전처리 하이퍼파라미터
max_len = 100
batch_size = 128

# ⬇️ 인풋과 타겟 마스킹 포함된 전처리
encoded_inputs = []
targets = []

for sentence in train_sentences:
    if "<sep>" not in sentence:
        continue

    sep_index = sentence.index("<sep>")
    input_text = sentence[:sep_index + len("<sep>")].strip()
    target_text = sentence[sep_index + len("<sep>"):].strip()

    input_ids = text_to_ids(input_text)
    target_ids = text_to_ids(target_text + " <end>")

    full_input = input_ids + target_ids
    full_input = full_input[:max_len]

    target_mask = [0] * len(input_ids) + [1] * len(target_ids)
    target_mask = target_mask[:max_len]

    if len(full_input) < max_len:
        pad_len = max_len - len(full_input)
        full_input += [pad_id] * pad_len
        target_mask += [0] * pad_len

    encoded_inputs.append(full_input)

    target_seq = full_input[1:] + [end_id]
    target_seq = target_seq[:max_len]

    masked_target = [
        t if m == 1 else pad_id
        for t, m in zip(target_seq, target_mask)
    ]

    targets.append(masked_target)

# ⬇️ 넘파이 변환
encoded_inputs = np.array(encoded_inputs)
targets = np.array(targets)

# ⬇️ TensorFlow Dataset 생성
def data_generator():
    for input_seq, target_seq in zip(encoded_inputs, targets):
        yield input_seq, target_seq

dataset = tf.data.Dataset.from_generator(
    data_generator,
    output_signature=(
        tf.TensorSpec(shape=(max_len,), dtype=tf.int32),
        tf.TensorSpec(shape=(max_len,), dtype=tf.int32)
    )
)

dataset = dataset.shuffle(1000).batch(batch_size).prefetch(tf.data.AUTOTUNE)

print("✅ TF Dataset 생성 완료!")

class Lo(layers.Layer):
    def __init__(self, d_model):
        super().__init__()
        # 내부 계산은 float32로 유지
        self.proj = layers.Dense(d_model, use_bias=True, dtype='float32')
        self.p = layers.Dense(96, use_bias=True, dtype='float32')
        self._out_dtype = 'float32'

    def call(self, x):
        # x may be bfloat16; cast to float32 for stable intermediate computation
        x_f32 = tf.cast(x, tf.float32)
        x = self.proj(x_f32)
        x = tf.nn.gelu(x)
        x = self.p(x)
        # cast back to model dtype for consistency
        return tf.cast(x, self._out_dtype)

class LoSoU(layers.Layer):
    """
    안정화된 LoSoU 레이어
    - 누적합 대신 지수이동평균(EMA) 사용 (alpha: smoothing factor)
    - 내부 계산은 float32로 수행 (TPU bfloat16 안정성 향상)
    - EMA 결과 클리핑 및 작은 epsilon 적용
    - 안전한 split 처리 (짝수 차원 가정; 아니라면 마지막 차원 pad 필요)
    """
    def __init__(self, d_model, alpha=0.15, clip_value=5.0, eps=1e-6):
        super().__init__()
        # 대부분 연산을 float32로 수행
        self.d_model = d_model
        self.alpha = float(alpha)
        self.clip_value = float(clip_value)
        self.eps = float(eps)

        # projection / gating layers in float32
        self.Q = layers.Dense(96, dtype='float32')
        self.K = layers.Dense(96, dtype='float32')
        # V produces d_model so keep it float32 internally
        self.V = Lo(d_model)  # Lo already handles casting to model dtype; we'll cast back to float32
        self.proj = layers.Dense(d_model, use_bias=True, dtype='float32')
        self.O = layers.Dense(d_model, dtype='float32')
        self.norm = layers.LayerNormalization(epsilon=1e-5, dtype='float32')

    def _ema_over_time(self, score):
        # score: (B, L, D) float32 in [0,1] roughly
        alpha = tf.constant(self.alpha, dtype=score.dtype)

        # transpose to (L, B, D) to scan over time steps
        seq = tf.transpose(score, perm=[1, 0, 2])

        def step(prev_ema, x_t):
            # prev_ema: (B, D), x_t: (B, D)
            new = alpha * x_t + (1.0 - alpha) * prev_ema
            return new

        # 초기값을 첫 step 값으로 설정
        init = seq[0]  

        ema_seq = tf.scan(fn=step, elems=seq[1:], initializer=init)
        ema_seq = tf.concat([tf.expand_dims(init, 0), ema_seq], axis=0)  # (L, B, D)

        # transpose back to (B, L, D)
        ema = tf.transpose(ema_seq, perm=[1, 0, 2])
        return ema


    def call(self, x):
        # x: (B, L, d_model) maybe bfloat16 or float32
        # cast to float32 for all internal computations
        x_f32 = tf.cast(x, tf.float32)
        residual = x_f32

        # Q, K, V
        q = self.Q(x_f32)   # (B, L, 128)
        k = self.K(x_f32)   # (B, L, 128)
        V = tf.cast(self.V(x), tf.float32)  # ensure V's output is float32

        # gating signals in (0,1)
        g_q = tf.nn.sigmoid(q)
        g_k = tf.nn.sigmoid(k)

        # elementwise product -> bounded roughly [0,1]
        score = g_q * g_k

        # EMA across time (stable alternative to cumsum)
        score_ema = self._ema_over_time(score)

        # optionally normalize by (mean + eps) across last dim to reduce scale variations
        mean_last = tf.reduce_mean(score_ema, axis=-1, keepdims=True)  # (B, L, 1)
        denom = tf.maximum(mean_last, self.eps)
        score_norm = score_ema / denom

        # clip to avoid extremes
        score_clipped = tf.clip_by_value(score_norm, -self.clip_value, self.clip_value)

        # combine with V
        x_comb = score_clipped * V  # (B, L, d_model)

        out = self.proj(x_comb)  # (B, L, d_model)

        # ensure out dim even for split
        d = out.shape[-1]  # this is an int (static shape)
        if d is not None and d % 2 == 1:
            out = tf.pad(out, [[0,0],[0,0],[0,1]])


        a, b = tf.split(out, 2, axis=-1)
        gated = tf.nn.silu(a) * b
        out = self.O(gated)

        out = self.norm(out + residual)

        # cast back to original dtype for downstream layers
        return tf.cast(out, x.dtype)

class Block(layers.Layer):
    def __init__(self, d_model, r, hyper_n, num_heads, num_groups):
        super().__init__()
        self.losou = [LoSoU(d_model) for _ in range(hyper_n)]

    def call(self, x):
        for losou in self.losou:
            x = losou(x)
        return x

class ReLaM(tf.keras.Model):
    def __init__(self, vocab_size, max_seq_len, d_model, n_layers, dropout_rate=0.1):
        super().__init__()
        self.token_embedding = layers.Embedding(vocab_size, d_model)
        self.pos_embedding = layers.Embedding(max_seq_len, d_model)
        self.blocks = [Block(d_model, r=204, hyper_n=3, num_heads=8, num_groups=2) for _ in range(n_layers)]

        # LayerNormalization은 float32로 해서 정밀도 문제 방지
        self.ln_f = layers.LayerNormalization(epsilon=1e-5, dtype="float32")

    def call(self, x, training=False):
        batch_size, seq_len = tf.shape(x)[0], tf.shape(x)[1]
        positions = tf.range(seq_len)[tf.newaxis, :]

        x = self.token_embedding(x) + self.pos_embedding(positions)
        for block in self.blocks:
            x = block(x)

        x = self.ln_f(x)

        embedding_matrix = tf.cast(self.token_embedding.embeddings, x.dtype)
        logits = tf.matmul(x, embedding_matrix, transpose_b=True)
        return tf.cast(logits, tf.float32)


def masked_loss(y_true, y_pred):
    loss = loss_fn(y_true, y_pred)
    mask = tf.cast(tf.not_equal(y_true, pad_id), tf.float32)
    masked_loss = tf.reduce_sum(loss * mask) / tf.reduce_sum(mask)
    return masked_loss

def masked_perplexity(y_true, y_pred):
    loss = loss_fn(y_true, y_pred)
    mask = tf.cast(tf.not_equal(y_true, pad_id), tf.float32)
    avg_loss = tf.reduce_sum(loss * mask) / tf.reduce_sum(mask)
    return tf.exp(tf.minimum(avg_loss, 10.0))  # 수치 안정성 확보

def create_lr_schedule(initial_lr=5e-5, decay_steps=10000, decay_rate=0.9):
    return tf.keras.optimizers.schedules.ExponentialDecay(
        initial_learning_rate=initial_lr,
        decay_steps=decay_steps,
        decay_rate=decay_rate,
        staircase=False
    )

# 모델 생성
model = ReLaM(
    vocab_size=vocab_size,
    max_seq_len=max_len,
    d_model=256,
    n_layers=1
)

# 옵티마이저 설정
optimizer = tf.keras.optimizers.Adam(
    learning_rate=create_lr_schedule(),
    beta_1=0.9,
    beta_2=0.95,
    epsilon=1e-8,
    clipnorm=1.0
)

# 모델 컴파일
model.compile(
    optimizer=optimizer,
    loss=masked_loss,
    metrics=[
        masked_perplexity
    ]
)

# 더미 인풋으로 모델 초기화
dummy_input = np.zeros((1, max_len), dtype=np.int32)
model(dummy_input)
model.summary()

# 학습 시작
history = model.fit(
    dataset,
    epochs=1,
    steps_per_epoch = encoded_inputs.shape[0] // batch_size,
    verbose=1
)

# 가중치 저장
model.save_weights("Cobra.weights.h5")
print("모델 가중치 저장 완료!")

def generate_text_topp(model, prompt, max_len=100, max_gen=98, p=0.9, temperature=0.8, min_len=20):
    model_input = text_to_ids(f"<start> {prompt} <sep>")
    model_input = model_input[:max_len]
    generated = list(model_input)
    for step in range(max_gen):
        if len(generated) > max_len:
            input_seq = generated[-max_len:]
        else:
            input_seq = generated
        input_padded = np.pad(input_seq, (0, max_len - len(input_seq)), constant_values=pad_id)
        input_tensor = tf.convert_to_tensor([input_padded])
        logits = model(input_tensor, training=False)
        next_token_logits = logits[0, len(input_seq) - 1].numpy()
        next_token_logits[end_id] -= 5.0
        next_token_logits[pad_id] -= 10.0
        probs = tf.nn.softmax(next_token_logits / temperature).numpy()
        sorted_indices = np.argsort(probs)[::-1]
        sorted_probs = probs[sorted_indices]
        cumulative_probs = np.cumsum(sorted_probs)
        cutoff = np.searchsorted(cumulative_probs, p)
        top_indices = sorted_indices[:cutoff + 1]
        top_probs = sorted_probs[:cutoff + 1]
        top_probs /= np.sum(top_probs)
        next_token_id = np.random.choice(top_indices, p=top_probs)
        if next_token_id == end_id and len(generated) >= min_len:
            break
        generated.append(int(next_token_id))
    return ids_to_text(generated)

print("\n\n===== 생성 결과 =====")  
print(generate_text_topp(model, "안녕", p=0.9))