# Copyright (c) 2022-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
#
# See LICENSE for license information.
"""Encoder training on single GPU"""
import argparse
import unittest
from functools import partial

import flax
import jax
import jax.numpy as jnp
import nltk
import numpy as np
import optax
from datasets import load_dataset
from flax import linen as nn
from flax.training import train_state

from common import (
    is_bf16_supported,
    get_quantization_recipe_from_name_string,
    unpack_cached_datasets_if_available,
)
import transformer_engine.jax as te
import transformer_engine.jax.flax as te_flax
from transformer_engine.jax.quantize import is_scaling_mode_supported, ScalingMode

unpack_cached_datasets_if_available()

PARAMS_KEY = "params"
DROPOUT_KEY = "dropout"
SR_KEY = "sr_rng"
INPUT_KEY = "input_rng"


class Net(nn.Module):
    """NLP Encoder"""

    num_embed: int

    @nn.compact
    def __call__(self, x, mask, disable_dropout=False):
        x = nn.Embed(num_embeddings=self.num_embed, features=256, dtype=jnp.bfloat16)(x)

        te_Encoder = partial(
            te_flax.TransformerLayer,
            hidden_size=256,
            mlp_hidden_size=1024,
            num_attention_heads=8,
            hidden_dropout=0.1,
            attention_dropout=0.1,
            dropout_rng_name=DROPOUT_KEY,
            layer_type=te_flax.TransformerLayerType.ENCODER,
            self_attn_mask_type="padding",
            enable_relative_embedding=False,
        )
        x = te_Encoder()(x, attention_mask=mask, deterministic=disable_dropout)

        x = x.reshape(x.shape[0], -1)

        x = te_flax.DenseGeneral(features=256)(x)

        x = te_flax.DenseGeneral(features=256)(x)

        x = nn.Dense(features=2)(x)
        return x


@jax.jit
def train_step(state, inputs, masks, labels, var_collect, rngs):
    """Computes gradients, loss and accuracy for a single batch."""

    def loss_fn(var_collect, disable_dropout=False):
        logits = state.apply_fn(var_collect, inputs, masks, disable_dropout, rngs=rngs)
        one_hot = jax.nn.one_hot(labels.astype(jnp.int32), 2)
        loss = jnp.mean(optax.softmax_cross_entropy(logits=logits, labels=one_hot))
        return loss, logits

    var_collect = {**var_collect, PARAMS_KEY: state.params}
    grad_fn = jax.value_and_grad(loss_fn, has_aux=True)
    (loss, logits), grads = grad_fn(var_collect)
    accuracy = jnp.mean(jnp.argmax(logits, -1) == labels)

    var_collect, grads = flax.core.pop(grads, PARAMS_KEY)
    state = state.apply_gradients(grads=grads)

    return state, loss, accuracy, var_collect


def train_epoch(state, train_ds, batch_size, rngs, var_collect):
    """Train for a single epoch."""
    train_ds_size = len(train_ds["sentence"])
    steps_per_epoch = train_ds_size // batch_size
    perms = jax.random.permutation(rngs[INPUT_KEY], train_ds_size)
    perms = perms[: steps_per_epoch * batch_size]  # skip incomplete batch
    perms = perms.reshape((steps_per_epoch, batch_size))
    epoch_loss = []
    epoch_accuracy = []

    for perm in perms:
        # Split and reassign to 'rngs' to ensure unique rng for each step
        rngs = {key: jax.random.split(rngs[key])[1] for key in rngs}
        batch_inputs = train_ds["sentence"][perm, ...]
        batch_masks = train_ds["mask"][perm, ...]
        batch_labels = train_ds["label"][perm, ...]
        state, loss, accuracy, var_collect = train_step(
            state, batch_inputs, batch_masks, batch_labels, var_collect, rngs
        )
        epoch_loss.append(loss)
        epoch_accuracy.append(accuracy)

    avg_loss = np.mean(epoch_loss)
    avg_accuracy = np.mean(epoch_accuracy)
    return state, avg_loss, avg_accuracy, var_collect


@jax.jit
def eval_step(state, inputs, masks, labels, var_collect, rngs):
    """Computes loss and accuracy for a single batch."""

    def loss_fn(var_collect, disable_dropout=False):
        logits = state.apply_fn(var_collect, inputs, masks, disable_dropout, rngs=rngs)
        one_hot = jax.nn.one_hot(labels.astype(jnp.int32), 2)
        loss = jnp.mean(optax.softmax_cross_entropy(logits=logits, labels=one_hot))
        return loss, logits

    var_collect = {**var_collect, PARAMS_KEY: state.params}
    loss, logits = loss_fn(var_collect, disable_dropout=True)
    accuracy = jnp.mean(jnp.argmax(logits, -1) == labels)
    return loss, accuracy


def eval_model(state, test_ds, batch_size, var_collect, rngs):
    """Evaluation loop."""
    test_ds_size = len(test_ds["sentence"])
    num_steps = test_ds_size // batch_size
    valid_size = num_steps * batch_size
    all_loss = []
    all_accuracy = []

    for batch_start in range(0, valid_size, batch_size):
        # Split and reassign to 'rngs' to ensure unique rng for each step
        rngs = {key: jax.random.split(rngs[key])[1] for key in rngs}
        batch_end = batch_start + batch_size
        batch_inputs = test_ds["sentence"][batch_start:batch_end]
        batch_masks = test_ds["mask"][batch_start:batch_end]
        batch_labels = test_ds["label"][batch_start:batch_end]
        loss, accuracy = eval_step(
            state, batch_inputs, batch_masks, batch_labels, var_collect, rngs
        )
        all_loss.append(loss)
        all_accuracy.append(accuracy)

    avg_loss = np.mean(all_loss)
    avg_accuracy = np.mean(all_accuracy)
    return avg_loss, avg_accuracy


def data_preprocess(dataset, vocab, word_id, max_seq_len):
    """Convert tokens to numbers."""
    nltk.download("punkt_tab")
    dataset_size = len(dataset["sentence"])
    output = np.zeros((dataset_size, max_seq_len), dtype=np.int32)
    mask_3d = np.ones((dataset_size, max_seq_len, max_seq_len), dtype=np.uint8)

    for j, sentence in enumerate(dataset["sentence"]):
        tokens = nltk.word_tokenize(sentence)
        tensor = output[j]

        for i, word in enumerate(tokens):
            if i >= max_seq_len:
                break

            if word not in vocab:
                vocab[word] = word_id
                tensor[i] = word_id
                word_id = word_id + 1
            else:
                tensor[i] = vocab[word]

        seq_len = min(len(tokens), max_seq_len)
        mask_2d = mask_3d[j]
        mask_2d[:seq_len, :seq_len] = 0

    new_dataset = {
        "sentence": output,
        "label": dataset["label"].astype(np.float32),
        "mask": mask_3d.reshape((dataset_size, 1, max_seq_len, max_seq_len)),
    }
    return new_dataset, vocab, word_id


def get_datasets(max_seq_len):
    """Load GLUE train and test datasets into memory."""
    vocab = {}
    word_id = 0

    train_ds = load_dataset("glue", "cola", split="train")
    train_ds.set_format(type="np")
    train_ds, vocab, word_id = data_preprocess(train_ds, vocab, word_id, max_seq_len)

    test_ds = load_dataset("glue", "cola", split="validation")
    test_ds.set_format(type="np")
    test_ds, vocab, word_id = data_preprocess(test_ds, vocab, word_id, max_seq_len)
    return train_ds, test_ds, word_id


def check_fp8(state, var_collect, inputs, masks, labels):
    "Check if model includes FP8."
    rngs = {DROPOUT_KEY: jax.random.PRNGKey(0), SR_KEY: jax.random.PRNGKey(0)}
    func_jaxpr = str(jax.make_jaxpr(train_step)(state, inputs, masks, labels, var_collect, rngs))
    assert "f8_e5m2" in func_jaxpr or "f8_e4m3" in func_jaxpr


def train_and_evaluate(args):
    """Execute model training and evaluation loop."""
    print(args)
    train_ds, test_ds, num_embed = get_datasets(args.max_seq_len)

    rng = jax.random.PRNGKey(args.seed)
    rng, params_rng = jax.random.split(rng)
    rng, dropout_rng = jax.random.split(rng)
    rng, sr_rng = jax.random.split(rng)
    init_rngs = {PARAMS_KEY: params_rng, DROPOUT_KEY: dropout_rng, SR_KEY: sr_rng}

    input_shape = [args.batch_size, args.max_seq_len]
    mask_shape = [args.batch_size, 1, args.max_seq_len, args.max_seq_len]
    label_shape = [args.batch_size]

    if args.use_fp8:
        fp8_recipe = get_quantization_recipe_from_name_string(args.fp8_recipe)
    else:
        fp8_recipe = None

    with te.autocast(
        enabled=args.use_fp8, recipe=fp8_recipe, mesh_resource=te.sharding.MeshResource()
    ):
        encoder = Net(num_embed)
        # We use nn.Embed, thus inputs need to be in int
        inputs = jnp.zeros(input_shape, dtype=jnp.int32)
        masks = jnp.zeros(mask_shape, dtype=jnp.uint8)
        var_collect = encoder.init(init_rngs, inputs, masks)
        tx = optax.adamw(args.lr)
        state = train_state.TrainState.create(
            apply_fn=encoder.apply, params=var_collect[PARAMS_KEY], tx=tx
        )

        if args.use_fp8:
            labels = jnp.zeros(label_shape, dtype=jnp.bfloat16)
            check_fp8(state, var_collect, inputs, masks, labels)

        if args.dry_run:
            labels = jnp.zeros(label_shape, dtype=jnp.bfloat16)
            rngs = {DROPOUT_KEY: dropout_rng, SR_KEY: sr_rng}
            train_step(state, inputs, masks, labels, var_collect, rngs)
            print("PASSED")
            return None

        for epoch in range(1, args.epochs + 1):
            # Split and reassign to 'rng' to ensure unique rng for each step
            rng, input_rng = jax.random.split(rng)
            rng, dropout_rng = jax.random.split(rng)
            rng, sr_rng = jax.random.split(rng)
            rngs = {INPUT_KEY: input_rng, DROPOUT_KEY: dropout_rng, SR_KEY: sr_rng}

            state, train_loss, train_accuracy, var_collect = train_epoch(
                state, train_ds, args.batch_size, rngs, var_collect
            )

            test_loss, test_accuracy = eval_model(
                state, test_ds, args.test_batch_size, var_collect, rngs
            )

            print(
                f"Epoch: {epoch:>2} "
                f"Train Loss: {train_loss:.6f} "
                f"Train Accuracy: {train_accuracy:.6f} "
                f"Test Loss: {test_loss:.6f} "
                f"Test Accuracy: {test_accuracy:.6f} "
            )

    return [train_loss, train_accuracy, test_loss, test_accuracy]


def encoder_parser(args):
    """Training settings."""
    parser = argparse.ArgumentParser(description="JAX Encoder Example")
    parser.add_argument(
        "--batch-size",
        type=int,
        default=64,
        metavar="N",
        help="input batch size for training (default: 64)",
    )
    parser.add_argument(
        "--test-batch-size",
        type=int,
        default=64,
        metavar="N",
        help="input batch size for testing (default: 64)",
    )
    parser.add_argument(
        "--max-seq-len",
        type=int,
        default=32,
        metavar="N",
        help="maximum sequence length (default: 32)",
    )
    parser.add_argument(
        "--epochs",
        type=int,
        default=3,
        metavar="N",
        help="number of epochs to train (default: 3)",
    )
    parser.add_argument(
        "--lr",
        type=float,
        default=0.0001,
        metavar="LR",
        help="learning rate (default: 0.0001)",
    )
    parser.add_argument(
        "--dry-run",
        action="store_true",
        default=False,
        help="quickly check a single pass",
    )
    parser.add_argument("--seed", type=int, default=0, metavar="S", help="random seed (default: 0)")
    parser.add_argument(
        "--use-fp8",
        action="store_true",
        default=False,
        help="Use FP8 for inference and training without recalibration",
    )
    parser.add_argument(
        "--fp8-recipe",
        action="store_true",
        default="DelayedScaling",
        help="Use FP8 recipe (default: DelayedScaling)",
    )

    return parser.parse_args(args)


class TestEncoder(unittest.TestCase):
    """Encoder unittests"""

    is_fp8_supported, fp8_reason = is_scaling_mode_supported(ScalingMode.DELAYED_TENSOR_SCALING)
    is_mxfp8_supported, mxfp8_reason = is_scaling_mode_supported(ScalingMode.MXFP8_1D_SCALING)
    is_nvfp4_supported, nvfp4_reason = is_scaling_mode_supported(ScalingMode.NVFP4_1D_SCALING)

    def setUp(self):
        """Run 3 epochs for testing"""
        self.args = encoder_parser(["--epochs", "3"])

    @unittest.skipIf(not is_bf16_supported(), "Device compute capability 8.0+ is required for BF16")
    def test_te_bf16(self):
        """Test Transformer Engine with BF16"""
        actual = train_and_evaluate(self.args)
        assert actual[0] < 0.452 and actual[1] > 0.788

    @unittest.skipIf(not is_fp8_supported, fp8_reason)
    def test_te_delayed_scaling_fp8(self):
        """Test Transformer Engine with DelayedScaling FP8"""
        self.args.use_fp8 = True
        self.args.fp8_recipe = "DelayedScaling"
        actual = train_and_evaluate(self.args)
        assert actual[0] < 0.457 and actual[1] > 0.784

    @unittest.skipIf(not is_fp8_supported, fp8_reason)
    def test_te_current_scaling_fp8(self):
        """Test Transformer Engine with CurrentScaling FP8"""
        self.args.use_fp8 = True
        self.args.fp8_recipe = "Float8CurrentScaling"
        actual = train_and_evaluate(self.args)
        assert actual[0] < 0.461 and actual[1] > 0.784

    @unittest.skipIf(not is_mxfp8_supported, mxfp8_reason)
    def test_te_mxfp8(self):
        """Test Transformer Engine with MXFP8"""
        self.args.use_fp8 = True
        self.args.fp8_recipe = "MXFP8BlockScaling"
        actual = train_and_evaluate(self.args)
        assert actual[0] < 0.457 and actual[1] > 0.784

    @unittest.skipIf(not is_nvfp4_supported, nvfp4_reason)
    def test_te_nvfp4(self):
        """Test Transformer Engine with NVFP4"""
        self.args.use_fp8 = True
        self.args.fp8_recipe = "NVFP4BlockScaling"
        actual = train_and_evaluate(self.args)
        assert actual[0] < 0.477 and actual[1] > 0.769


if __name__ == "__main__":
    train_and_evaluate(encoder_parser(None))
