"""
Data structures for step-level reasoning chains with vision-language annotations.
"""

from dataclasses import dataclass, field
from typing import Dict, List, Optional, Any
from enum import Enum
import torch
from torch.utils.data import Dataset
import json

# Special tokens for chain-of-thought reasoning
SPECIAL_TOKENS = [
    # Reasoning structure
    "<|reasoning_start|>", "<|reasoning_end|>",
    
    # Step-level markers
    "<|step_start|>", "<|step_end|>",
    "<|step_type|>",
    
    # Step components
    "<|description_start|>", "<|description_end|>",
    "<|confidence_start|>", "<|confidence_end|>",
    
    # Dependencies
    "<|depends_on|>",
    
    # PRM evaluation tokens (from PRM800K)
    "ки",   # step separator for PRM scoring
    "к+и",  # positive step label
    "к-и",  # negative step label
    
    # Final answer
    "<|answer_start|>", "<|answer_end|>",
    
    # Region tokens (inspired by Chain-of-Sight for visual grounding)
    "<|region|>", "<|bbox|>",  # Region markers and bounding box coordinates
]

SPECIAL_TOKEN_DESCRIPTIONS = [
    "start of reasoning", "end of reasoning",
    "start of step", "end of step",
    "step type indicator",
    "start of description", "end of description",
    "start of confidence", "end of confidence",
    "depends on previous step",
    "step separator for PRM", "positive step", "negative step",
    "start of answer", "end of answer",
    "region reference", "bounding box coordinates",
]

# Generate additional region tokens like <region1>, <region2>, ... <region10>
# for referring to specific visual regions (Chain-of-Sight style)
REGION_TOKENS = [f"<region{i}>" for i in range(1, 11)]
SPECIAL_TOKENS.extend(REGION_TOKENS)
SPECIAL_TOKEN_DESCRIPTIONS.extend([f"visual region {i}" for i in range(1, 11)])


class StepType(Enum):
    """Types of reasoning steps in vision-language tasks."""
    PERCEPTION = "perception"  # Visual understanding
    LOCALIZATION = "localization"  # Spatial reasoning
    COMPARISON = "comparison"  # Comparing visual elements
    COUNTING = "counting"  # Numerical reasoning
    INFERENCE = "inference"  # Logical deduction
    COMPOSITION = "composition"  # Combining information
    VERIFICATION = "verification"  # Checking consistency


@dataclass
class ReasoningStep:
    """
    A single step in the chain of thought reasoning process.
    
    Attributes:
        step_id: Unique identifier for this step
        step_type: Type of reasoning performed
        description: Natural language description of the reasoning
        visual_features: Extracted visual features relevant to this step
        attention_map: Spatial attention weights (H, W)
        confidence: Model's confidence in this step [0, 1]
        reward: Process reward score assigned by PRM [-1, 1]
        dependencies: IDs of previous steps this depends on
        bounding_boxes: List of [x1, y1, x2, y2] bounding boxes (Chain-of-Sight style)
        region_ids: List of region IDs referenced in this step (e.g., [1, 2])
        metadata: Additional step-specific information
    """
    step_id: int
    step_type: StepType
    description: str
    visual_features: Optional[torch.Tensor] = None
    attention_map: Optional[torch.Tensor] = None
    confidence: float = 0.0
    reward: float = 0.0
    dependencies: List[int] = field(default_factory=list)
    bounding_boxes: List[List[float]] = field(default_factory=list)  # [[x1,y1,x2,y2], ...]
    region_ids: List[int] = field(default_factory=list)  # [1, 2, 3]
    metadata: Dict[str, Any] = field(default_factory=dict)
    
    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary for serialization."""
        return {
            'step_id': self.step_id,
            'step_type': self.step_type.value,
            'description': self.description,
            'confidence': self.confidence,
            'reward': self.reward,
            'dependencies': self.dependencies,
            'metadata': self.metadata,
            'has_visual_features': self.visual_features is not None,
            'has_attention_map': self.attention_map is not None,
        }
    
    def format_with_tokens(self) -> str:
        """Format step with special tokens for training (with Chain-of-Sight region support)."""
        parts = ["<|step_start|>"]
        
        # Add step type
        parts.append(f"<|step_type|>{self.step_type.value}")
        
        # Add dependencies if any
        if self.dependencies:
            deps_str = ",".join(map(str, self.dependencies))
            parts.append(f"<|depends_on|>{deps_str}")
        
        # Add region references (Chain-of-Sight style)
        if self.region_ids:
            region_refs = " ".join([f"<region{rid}>" for rid in self.region_ids])
            parts.append(f"<|region|>{region_refs}")
        
        # Add bounding boxes if present
        if self.bounding_boxes:
            bbox_strs = [f"[{b[0]:.3f},{b[1]:.3f},{b[2]:.3f},{b[3]:.3f}]" for b in self.bounding_boxes]
            parts.append(f"<|bbox|>{','.join(bbox_strs)}")
        
        # Add description
        parts.append(f"<|description_start|>{self.description}<|description_end|>")
        
        # Add confidence
        parts.append(f"<|confidence_start|>{self.confidence:.3f}<|confidence_end|>")
        
        # Add PRM separator
        parts.append("ки")
        
        parts.append("<|step_end|>")
        
        return " ".join(parts)
    
    @classmethod
    def from_dict(cls, data: Dict[str, Any]) -> 'ReasoningStep':
        """Create from dictionary."""
        return cls(
            step_id=data['step_id'],
            step_type=StepType(data['step_type']),
            description=data['description'],
            confidence=data.get('confidence', 0.0),
            reward=data.get('reward', 0.0),
            dependencies=data.get('dependencies', []),
            metadata=data.get('metadata', {}),
        )


@dataclass
class ReasoningChain:
    """
    Complete chain of reasoning steps for a vision-language task.
    
    Attributes:
        chain_id: Unique identifier for this reasoning chain
        image_path: Path to the input image
        image: PIL Image object (for streaming datasets)
        prompt: Input text prompt/question
        steps: Ordered list of reasoning steps
        final_answer: Final output/answer
        total_reward: Cumulative reward from PRM
        is_correct: Whether final answer is correct
        metadata: Additional chain-level information
    """
    chain_id: str
    image_path: str = None
    image: Any = None
    prompt: str = ""
    steps: List[ReasoningStep] = field(default_factory=list)
    final_answer: str = ""
    total_reward: float = 0.0
    is_correct: bool = False
    metadata: Dict[str, Any] = field(default_factory=dict)
    
    def __len__(self) -> int:
        """Number of reasoning steps."""
        return len(self.steps)
    
    def get_step_rewards(self) -> List[float]:
        """Extract reward for each step."""
        return [step.reward for step in self.steps]
    
    def get_cumulative_rewards(self) -> List[float]:
        """Calculate cumulative rewards up to each step."""
        cumulative = []
        total = 0.0
        for step in self.steps:
            total += step.reward
            cumulative.append(total)
        return cumulative
    
    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary for serialization."""
        return {
            'chain_id': self.chain_id,
            'image_path': self.image_path,
            'prompt': self.prompt,
            'steps': [step.to_dict() for step in self.steps],
            'final_answer': self.final_answer,
            'total_reward': self.total_reward,
            'is_correct': self.is_correct,
            'metadata': self.metadata
        }
    
    def format_with_tokens(self) -> str:
        """Format entire reasoning chain with special tokens for training."""
        parts = ["<|reasoning_start|>"]
        
        # Add all steps
        for step in self.steps:
            parts.append(step.format_with_tokens())
        
        parts.append("<|reasoning_end|>")
        
        # Add final answer
        parts.append(f"<|answer_start|>{self.final_answer}<|answer_end|>")
        
        return " ".join(parts)
    
    @classmethod
    def from_dict(cls, data: Dict[str, Any]) -> 'ReasoningChain':
        """Create from dictionary."""
        return cls(
            chain_id=data['chain_id'],
            image_path=data['image_path'],
            prompt=data['prompt'],
            steps=[ReasoningStep.from_dict(s) for s in data['steps']],
            final_answer=data['final_answer'],
            total_reward=data.get('total_reward', 0.0),
            is_correct=data.get('is_correct', False),
            metadata=data.get('metadata', {}),
        )
    
    def save_json(self, path: str) -> None:
        """Save reasoning chain to JSON file."""
        with open(path, 'w', encoding='utf-8') as f:
            json.dump(self.to_dict(), f, indent=2, ensure_ascii=False)
    
    @classmethod
    def load_json(cls, path: str) -> 'ReasoningChain':
        """Load reasoning chain from JSON file."""
        with open(path, 'r', encoding='utf-8') as f:
            data = json.load(f)
        return cls.from_dict(data)


class StepDataset(Dataset):
    """
    Dataset for training with step-level reasoning chains.
    
    Supports both supervised fine-tuning and RL training with process rewards.
    """
    
    def __init__(
        self,
        reasoning_chains: List[ReasoningChain],
        tokenizer: Any,
        max_steps: int = 10,
        include_visual_features: bool = True,
        filter_incorrect: bool = False,
    ):
        """
        Initialize step dataset.
        
        Args:
            reasoning_chains: List of annotated reasoning chains
            tokenizer: Tokenizer for text encoding
            max_steps: Maximum number of steps per chain
            include_visual_features: Whether to include visual features
            filter_incorrect: If True, only include correct chains
        """
        self.tokenizer = tokenizer
        self.max_steps = max_steps
        self.include_visual_features = include_visual_features
        
        # Filter chains if needed
        if filter_incorrect:
            self.chains = [c for c in reasoning_chains if c.is_correct]
        else:
            self.chains = reasoning_chains
        
        # Pre-compute statistics
        self.avg_steps = sum(len(c) for c in self.chains) / len(self.chains) if self.chains else 0
        self.total_steps = sum(len(c) for c in self.chains)
    
    def __len__(self) -> int:
        return len(self.chains)
    
    def __getitem__(self, idx: int) -> Dict[str, Any]:
        """
        Get a single reasoning chain with all steps.
        
        Returns:
            Dictionary containing:
                - prompt_ids: Tokenized prompt
                - formatted_input_ids: Tokenized chain with special tokens
                - formatted_text: Raw text with special tokens
                - step_descriptions: List of step descriptions
                - step_types: List of step types
                - step_rewards: List of process rewards
                - visual_features: List of visual features (if enabled)
                - attention_maps: List of attention maps (if available)
                - final_answer: Target answer
                - is_correct: Ground truth correctness
                - chain_metadata: Additional information
        """
        chain = self.chains[idx]
        
        # Format chain with special tokens
        formatted_text = chain.format_with_tokens()
        
        # Tokenize formatted text (for training)
        formatted_encoding = self.tokenizer(
            formatted_text,
            truncation=True,
            max_length=2048,  # Longer for full reasoning chains
            return_tensors='pt',
        )
        
        # Tokenize prompt (for compatibility)
        prompt_encoding = self.tokenizer(
            chain.prompt,
            truncation=True,
            max_length=512,
            return_tensors='pt',
        )
        
        # Prepare step data
        step_descriptions = []
        step_types = []
        step_rewards = []
        visual_features = []
        attention_maps = []
        
        for step in chain.steps[:self.max_steps]:
            step_descriptions.append(step.description)
            step_types.append(step.step_type.value)
            step_rewards.append(step.reward)
            
            if self.include_visual_features:
                if step.visual_features is not None:
                    visual_features.append(step.visual_features)
                else:
                    visual_features.append(torch.zeros(768))  # Default dimension
                
                if step.attention_map is not None:
                    attention_maps.append(step.attention_map)
        
        # Tokenize final answer
        answer_encoding = self.tokenizer(
            chain.final_answer,
            truncation=True,
            max_length=256,
            return_tensors='pt',
        )
        
        result = {
            'prompt_ids': prompt_encoding['input_ids'].squeeze(0),
            'prompt_mask': prompt_encoding['attention_mask'].squeeze(0),
            'formatted_input_ids': formatted_encoding['input_ids'].squeeze(0),
            'formatted_attention_mask': formatted_encoding['attention_mask'].squeeze(0),
            'formatted_text': formatted_text,
            'step_descriptions': step_descriptions,
            'step_types': step_types,
            'step_rewards': torch.tensor(step_rewards, dtype=torch.float32),
            'answer_ids': answer_encoding['input_ids'].squeeze(0),
            'answer_mask': answer_encoding['attention_mask'].squeeze(0),
            'is_correct': torch.tensor(chain.is_correct, dtype=torch.bool),
            'total_reward': torch.tensor(chain.total_reward, dtype=torch.float32),
            'num_steps': len(chain.steps),
            'chain_id': chain.chain_id,
            'image_path': chain.image_path,
        }
        
        if self.include_visual_features and visual_features:
            result['visual_features'] = torch.stack(visual_features)
        
        if attention_maps:
            result['attention_maps'] = attention_maps
        
        return result
    
    @classmethod
    def from_json_dir(
        cls,
        json_dir: str,
        tokenizer: Any,
        **kwargs
    ) -> 'StepDataset':
        """
        Load dataset from directory of JSON files.
        
        Args:
            json_dir: Directory containing reasoning chain JSON files
            tokenizer: Tokenizer for text encoding
            **kwargs: Additional arguments for StepDataset
        """
        from pathlib import Path
        
        json_path = Path(json_dir)
        chains = []
        
        for json_file in json_path.glob('*.json'):
            try:
                chain = ReasoningChain.load_json(str(json_file))
                chains.append(chain)
            except Exception as e:
                print(f"Error loading {json_file}: {e}")
        
        return cls(chains, tokenizer, **kwargs)
    
    def get_statistics(self) -> Dict[str, Any]:
        """Calculate dataset statistics."""
        step_types = {}
        rewards = []
        correct_count = 0
        
        for chain in self.chains:
            if chain.is_correct:
                correct_count += 1
            
            for step in chain.steps:
                step_type = step.step_type.value
                step_types[step_type] = step_types.get(step_type, 0) + 1
                rewards.append(step.reward)
        
        return {
            'num_chains': len(self.chains),
            'total_steps': self.total_steps,
            'avg_steps_per_chain': self.avg_steps,
            'accuracy': correct_count / len(self.chains) if self.chains else 0,
            'step_type_distribution': step_types,
            'avg_step_reward': sum(rewards) / len(rewards) if rewards else 0,
            'min_step_reward': min(rewards) if rewards else 0,
            'max_step_reward': max(rewards) if rewards else 0,
        }