"""
AAM Diffusion LLM — Data Pipeline

Orchestrates data preparation: from raw graph data and narratives
to tokenized, batched training data.

The pipeline handles:
1. Loading raw graph→narrative pairs
2. Generating synthetic data if real data isn't available
3. Tokenizing all data
4. Creating train/val splits
5. Building DataLoaders

Analogi: Seperti proses persiapan sebelum Jin Soun berlatih —
mengumpulkan semua kasus, mengorganisirnya, dan menyiapkan
data latihan yang terstruktur.
"""

from __future__ import annotations

import logging
from pathlib import Path
from typing import Optional

from torch.utils.data import DataLoader

from diffusion_llm.config.model_config import AamDiffusionConfig
from diffusion_llm.tokenizer.aam_tokenizer import AamTokenizer
from diffusion_llm.training.dataset import GraphNarrativeDataset, collate_fn
from diffusion_llm.data.synthetic_generator import SyntheticDataGenerator

logger = logging.getLogger(__name__)


class DataPipeline:
    """Data preparation pipeline for AAM Diffusion LLM training.

    Orchestrates the entire data preparation process:
    1. Check for existing data
    2. Generate synthetic data if needed
    3. Train tokenizer on the data
    4. Create datasets and dataloaders

    Usage:
        pipeline = DataPipeline(config)
        tokenizer, train_loader, val_loader = pipeline.prepare()
    """

    def __init__(self, config: AamDiffusionConfig):
        self.config = config
        self.output_dir = Path(config.output_dir) / "data"
        self.output_dir.mkdir(parents=True, exist_ok=True)

    def prepare(
        self,
        tokenizer: Optional[AamTokenizer] = None,
        force_regenerate: bool = False,
    ) -> tuple[AamTokenizer, DataLoader, Optional[DataLoader]]:
        """Prepare all data for training.

        Args:
            tokenizer: Optional pre-trained tokenizer.
            force_regenerate: Whether to regenerate synthetic data.

        Returns:
            Tuple of (tokenizer, train_loader, val_loader).
        """
        train_path = Path(self.config.training.train_data_path) if self.config.training.train_data_path else None
        val_path = Path(self.config.training.val_data_path) if self.config.training.val_data_path else None

        # Step 1: Generate synthetic data if no real data
        if not train_path or not train_path.exists() or force_regenerate:
            logger.info("Generating synthetic training data...")
            train_path, val_path = SyntheticDataGenerator.generate_training_split(
                output_dir=self.output_dir,
                n_train=10000,
                n_val=500,
                language=self.config.inference.language,
                seed=self.config.seed,
            )

        # Step 2: Train tokenizer if not provided
        if tokenizer is None or not tokenizer.is_trained:
            logger.info("Training tokenizer...")
            tokenizer = AamTokenizer()
            # Read training texts for tokenizer training
            texts = self._read_texts(train_path)
            tokenizer.train(texts, vocab_size=self.config.tokenizer.bpe_vocab_size)
            tokenizer.save(self.output_dir / "tokenizer.json")
            logger.info("Tokenizer trained and saved. Vocab size: %d", tokenizer.vocab_size)

        # Step 3: Create datasets
        logger.info("Creating datasets...")
        train_dataset = GraphNarrativeDataset(
            data_path=train_path,
            tokenizer=tokenizer,
            max_seq_len=self.config.model.max_seq_len,
            max_evidence=self.config.graph_encoder.max_evidence_nodes,
            max_anomalies=self.config.graph_encoder.max_anomalies,
            max_reasoning=self.config.graph_encoder.max_reasoning_steps,
        )

        val_dataset = None
        if val_path and val_path.exists():
            val_dataset = GraphNarrativeDataset(
                data_path=val_path,
                tokenizer=tokenizer,
                max_seq_len=self.config.model.max_seq_len,
                max_evidence=self.config.graph_encoder.max_evidence_nodes,
                max_anomalies=self.config.graph_encoder.max_anomalies,
                max_reasoning=self.config.graph_encoder.max_reasoning_steps,
                augment=False,  # No augmentation for validation
            )

        # Step 4: Create dataloaders
        train_loader = DataLoader(
            train_dataset,
            batch_size=self.config.training.batch_size,
            shuffle=True,
            num_workers=self.config.training.num_workers,
            collate_fn=collate_fn,
            pin_memory=True,
        )

        val_loader = None
        if val_dataset:
            val_loader = DataLoader(
                val_dataset,
                batch_size=self.config.training.batch_size,
                shuffle=False,
                num_workers=self.config.training.num_workers,
                collate_fn=collate_fn,
                pin_memory=True,
            )

        logger.info(
            "Data pipeline ready: %d training examples, %s validation examples",
            len(train_dataset),
            len(val_dataset) if val_dataset else 0,
        )

        return tokenizer, train_loader, val_loader

    def _read_texts(self, path: Path) -> list[str]:
        """Read narrative texts from JSONL file for tokenizer training.

        Args:
            path: Path to JSONL data file.

        Returns:
            List of narrative texts.
        """
        import json
        texts = []
        if not path.exists():
            return texts

        with open(path, "r", encoding="utf-8") as f:
            for line in f:
                line = line.strip()
                if not line:
                    continue
                try:
                    data = json.loads(line)
                    # Collect both narratives and evidence for richer tokenizer
                    if data.get("narrative"):
                        texts.append(data["narrative"])
                    if data.get("trigger"):
                        texts.append(data["trigger"])
                    for ev in data.get("evidence_nodes", []):
                        texts.append(ev)
                    for anom in data.get("anomalies", []):
                        texts.append(anom)
                    for step in data.get("reasoning_steps", []):
                        texts.append(step)
                except json.JSONDecodeError:
                    continue

        return texts