File size: 34,337 Bytes
aeb53bb
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
"""
Legal-BERT Model Architecture - Fully Learning-Based
Includes Hierarchical BERT for document-level understanding
"""
import torch
import torch.nn as nn
import torch.nn.functional as F
from transformers import AutoModel, AutoTokenizer
from typing import Dict, List, Any, Optional, Tuple

class FullyLearningBasedLegalBERT(nn.Module):
    """
    Legal-BERT model that learns from discovered risk patterns.
    NO hardcoded risk categories!
    """
    
    def __init__(self, config, num_discovered_risks: int = 7):
        super().__init__()
        self.config = config
        self.num_discovered_risks = num_discovered_risks
        
        # Load BERT model
        try:
            self.bert = AutoModel.from_pretrained(config.bert_model_name)
            # Configure BERT dropout
            self.bert.config.hidden_dropout_prob = config.dropout_rate
            self.bert.config.attention_probs_dropout_prob = config.dropout_rate
        except:
            # Fallback for testing without transformers
            print("⚠️ Warning: Using mock BERT model (transformers not available)")
            self.bert = None
        
        # Multi-task heads
        hidden_size = 768  # BERT-base hidden size
        
        # Risk classification head (for discovered risk patterns)
        self.risk_classifier = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_size, hidden_size // 2),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_size // 2, num_discovered_risks)
        )
        
        # Severity regression head (0-10 scale)
        self.severity_regressor = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_size, hidden_size // 4),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_size // 4, 1),
            nn.Sigmoid()  # Output between 0-1, will be scaled to 0-10
        )
        
        # Importance regression head (0-10 scale)
        self.importance_regressor = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_size, hidden_size // 4),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_size // 4, 1),
            nn.Sigmoid()  # Output between 0-1, will be scaled to 0-10
        )
        
        # Temperature scaling for calibration
        self.temperature = nn.Parameter(torch.ones(1))
        
    def forward(self, input_ids: torch.Tensor, attention_mask: torch.Tensor, 
                output_attentions: bool = False) -> Dict[str, torch.Tensor]:
        """Forward pass through the model
        
        Args:
            input_ids: Token IDs from tokenizer
            attention_mask: Attention mask for valid tokens
            output_attentions: If True, return attention weights for analysis
        """
        
        if self.bert is not None:
            # Real BERT forward pass
            outputs = self.bert(
                input_ids=input_ids, 
                attention_mask=attention_mask,
                output_attentions=output_attentions
            )
            pooled_output = outputs.pooler_output
            attentions = outputs.attentions if output_attentions else None
        else:
            # Mock output for testing
            batch_size = input_ids.size(0)
            pooled_output = torch.randn(batch_size, 768)
            if input_ids.is_cuda:
                pooled_output = pooled_output.cuda()
            attentions = None
        
        # Multi-task predictions
        risk_logits = self.risk_classifier(pooled_output)
        severity_score = self.severity_regressor(pooled_output).squeeze(-1) * 10  # Scale to 0-10
        importance_score = self.importance_regressor(pooled_output).squeeze(-1) * 10  # Scale to 0-10
        
        # Apply temperature scaling to classification logits
        calibrated_logits = risk_logits / self.temperature
        
        result = {
            'risk_logits': risk_logits,
            'calibrated_logits': calibrated_logits,
            'severity_score': severity_score,
            'importance_score': importance_score,
            'pooled_output': pooled_output
        }
        
        if output_attentions and attentions is not None:
            result['attentions'] = attentions
        
        return result
    
    def predict_risk_pattern(self, input_ids: torch.Tensor, attention_mask: torch.Tensor,
                            return_attentions: bool = False) -> Dict[str, Any]:
        """Make predictions and return interpretable results
        
        Args:
            input_ids: Token IDs from tokenizer
            attention_mask: Attention mask for valid tokens
            return_attentions: If True, include attention weights for analysis
        """
        self.eval()
        
        with torch.no_grad():
            outputs = self.forward(input_ids, attention_mask, output_attentions=return_attentions)
            
            # Get predictions
            risk_probs = torch.softmax(outputs['calibrated_logits'], dim=-1)
            predicted_risk = torch.argmax(risk_probs, dim=-1)
            confidence = torch.max(risk_probs, dim=-1)[0]
            
            result = {
                'predicted_risk_id': predicted_risk.cpu().numpy(),
                'risk_probabilities': risk_probs.cpu().numpy(),
                'confidence': confidence.cpu().numpy(),
                'severity_score': outputs['severity_score'].cpu().numpy(),
                'importance_score': outputs['importance_score'].cpu().numpy()
            }
            
            if return_attentions and 'attentions' in outputs:
                result['attentions'] = outputs['attentions']
            
            return result
    
    def analyze_attention(self, input_ids: torch.Tensor, attention_mask: torch.Tensor,
                         tokenizer: Optional['LegalBertTokenizer'] = None) -> Dict[str, Any]:
        """Analyze attention patterns to identify important tokens for risk assessment
        
        This method extracts and analyzes BERT attention weights to determine which
        tokens/words contribute most to the risk prediction. Useful for interpretability.
        
        Args:
            input_ids: Token IDs from tokenizer
            attention_mask: Attention mask for valid tokens
            tokenizer: Tokenizer to decode tokens (optional)
        
        Returns:
            Dictionary containing:
                - token_importance: Per-token importance scores
                - top_tokens: Most important tokens for prediction
                - attention_weights: Raw attention weights from last layer
                - layer_analysis: Attention analysis per layer
        """
        self.eval()
        
        with torch.no_grad():
            outputs = self.forward(input_ids, attention_mask, output_attentions=True)
            
            if 'attentions' not in outputs or outputs['attentions'] is None:
                return {'error': 'Attention weights not available'}
            
            attentions = outputs['attentions']  # Tuple of (batch, num_heads, seq_len, seq_len)
            batch_size, seq_len = input_ids.shape
            
            # Average attention across all heads and layers for each token
            # Shape: (num_layers, batch, num_heads, seq_len, seq_len)
            all_attentions = torch.stack(attentions)  # Stack all layers
            
            # Get attention to [CLS] token (index 0) which is used for classification
            # Average across layers and heads
            cls_attention = all_attentions[:, :, :, 0, :].mean(dim=[0, 2])  # (batch, seq_len)
            
            # Also get average attention from all tokens (global importance)
            global_attention = all_attentions.mean(dim=[0, 2, 3])  # (batch, seq_len)
            
            # Combine CLS attention and global attention for final importance score
            token_importance = (cls_attention + global_attention) / 2
            
            # Mask out padding tokens
            token_importance = token_importance * attention_mask
            
            # Get top-k most important tokens per sample
            k = min(10, seq_len)
            top_values, top_indices = torch.topk(token_importance, k, dim=1)
            
            result = {
                'token_importance': token_importance.cpu().numpy(),
                'top_token_indices': top_indices.cpu().numpy(),
                'top_token_scores': top_values.cpu().numpy(),
                'attention_weights': {
                    'cls_attention': cls_attention.cpu().numpy(),
                    'global_attention': global_attention.cpu().numpy()
                }
            }
            
            # Add layer-wise analysis
            layer_attentions = []
            for layer_idx, layer_attn in enumerate(attentions):
                # Average across heads and get attention to CLS token
                layer_cls_attn = layer_attn[:, :, 0, :].mean(dim=1)  # (batch, seq_len)
                layer_attentions.append({
                    'layer': layer_idx,
                    'cls_attention': layer_cls_attn.cpu().numpy()
                })
            result['layer_analysis'] = layer_attentions
            
            # Decode tokens if tokenizer provided
            if tokenizer is not None and tokenizer.tokenizer is not None:
                tokens = tokenizer.tokenizer.convert_ids_to_tokens(input_ids[0])
                top_tokens = [tokens[idx] for idx in top_indices[0].cpu().numpy()]
                result['tokens'] = tokens
                result['top_tokens'] = top_tokens
            
            return result

class LegalBertTokenizer:
    """Tokenizer wrapper for Legal-BERT"""
    
    def __init__(self, model_name: str = "bert-base-uncased"):
        try:
            self.tokenizer = AutoTokenizer.from_pretrained(model_name)
        except:
            print("⚠️ Warning: Using mock tokenizer (transformers not available)")
            self.tokenizer = None
    
    def tokenize_clauses(self, clauses: List[str], max_length: int = 512) -> Dict[str, torch.Tensor]:
        """Tokenize legal clauses for model input"""
        
        if self.tokenizer is None:
            # Mock tokenization for testing
            batch_size = len(clauses)
            return {
                'input_ids': torch.randint(0, 1000, (batch_size, max_length)),
                'attention_mask': torch.ones(batch_size, max_length)
            }
        
        # Real tokenization
        encoded = self.tokenizer(
            clauses,
            padding=True,
            truncation=True,
            max_length=max_length,
            return_tensors='pt'
        )
        
        return {
            'input_ids': encoded['input_ids'],
            'attention_mask': encoded['attention_mask']
        }
    
    def decode_tokens(self, token_ids: torch.Tensor) -> List[str]:
        """Decode token IDs back to text"""
        if self.tokenizer is None:
            return ["Mock decoded text"] * token_ids.size(0)
        
        return self.tokenizer.batch_decode(token_ids, skip_special_tokens=True)


# ============================================================================
# HIERARCHICAL BERT FOR DOCUMENT-LEVEL UNDERSTANDING
# ============================================================================

class HierarchicalLegalBERT(nn.Module):
    """
    Hierarchical BERT for document-level contract understanding
    
    **Key Innovation**: Processes documents hierarchically to maintain context
    
    Architecture:
        Clause Encoding (BERT) β†’ Section Aggregation (LSTM+Attention) β†’ Document
    
    Solves the context problem:
        - Your current model: Each clause processed independently ❌
        - This model: Clauses processed WITH section context βœ…
    
    Usage:
        # Training: Same as current model (clause-level labels)
        # Inference: Processes full documents with context
        
        document = [
            ['clause1', 'clause2'],  # Section 1
            ['clause3', 'clause4'],  # Section 2
        ]
        results = model.predict_document(document)
    """
    
    def __init__(
        self,
        config,
        num_discovered_risks: int = 7,
        hidden_dim: int = 256,
        num_lstm_layers: int = 2
    ):
        super().__init__()
        self.config = config
        self.num_discovered_risks = num_discovered_risks
        self.hidden_dim = hidden_dim
        
        # Load BERT for clause encoding
        try:
            self.bert = AutoModel.from_pretrained(config.bert_model_name)
            self.bert.config.hidden_dropout_prob = config.dropout_rate
            self.bert.config.attention_probs_dropout_prob = config.dropout_rate
            self.bert_hidden_size = self.bert.config.hidden_size  # 768
        except:
            print("⚠️ Warning: Using mock BERT model")
            self.bert = None
            self.bert_hidden_size = 768
        
        # Hierarchical LSTM layers
        # Level 1: Clause-to-Section (captures context within a section)
        self.clause_to_section = nn.LSTM(
            input_size=self.bert_hidden_size,
            hidden_size=hidden_dim,
            num_layers=num_lstm_layers,
            bidirectional=True,
            dropout=config.dropout_rate if num_lstm_layers > 1 else 0,
            batch_first=True
        )
        
        # Level 2: Section-to-Document (captures context across sections)
        self.section_to_document = nn.LSTM(
            input_size=hidden_dim * 2,  # Bidirectional
            hidden_size=hidden_dim,
            num_layers=num_lstm_layers,
            bidirectional=True,
            dropout=config.dropout_rate if num_lstm_layers > 1 else 0,
            batch_first=True
        )
        
        # Attention mechanisms for interpretability
        self.clause_attention = nn.Sequential(
            nn.Linear(hidden_dim * 2, hidden_dim),
            nn.Tanh(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim, 1)
        )
        
        self.section_attention = nn.Sequential(
            nn.Linear(hidden_dim * 2, hidden_dim),
            nn.Tanh(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim, 1)
        )
        
        # Task-specific prediction heads (same as your current model)
        # These operate on context-aware clause representations
        self.risk_classifier = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim * 2, hidden_dim),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim, num_discovered_risks)
        )
        
        self.severity_regressor = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim * 2, hidden_dim // 2),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim // 2, 1),
            nn.Sigmoid()
        )
        
        self.importance_regressor = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim * 2, hidden_dim // 2),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(hidden_dim // 2, 1),
            nn.Sigmoid()
        )
        
        self.temperature = nn.Parameter(torch.ones(1))
    
    def encode_clause(self, input_ids: torch.Tensor, attention_mask: torch.Tensor) -> torch.Tensor:
        """Encode a single clause with BERT"""
        if self.bert is not None:
            outputs = self.bert(input_ids=input_ids, attention_mask=attention_mask)
            return outputs.pooler_output  # [batch, 768]
        else:
            batch_size = input_ids.size(0)
            return torch.randn(batch_size, self.bert_hidden_size).to(input_ids.device)
    
    def forward_single_clause(
        self, 
        input_ids: torch.Tensor, 
        attention_mask: torch.Tensor
    ) -> Dict[str, torch.Tensor]:
        """
        Forward pass for SINGLE clause (for training compatibility)
        
        This maintains compatibility with your current training pipeline
        where clauses are processed one at a time during training.
        """
        # Encode clause with BERT
        clause_embedding = self.encode_clause(input_ids, attention_mask)
        
        # Since we don't have section context during single-clause training,
        # pass through LSTM with single timestep to maintain architecture
        lstm_out, _ = self.clause_to_section(clause_embedding.unsqueeze(1))
        context_aware_repr = lstm_out.squeeze(1)  # [batch, hidden_dim*2]
        
        # Make predictions
        risk_logits = self.risk_classifier(context_aware_repr)
        severity_score = self.severity_regressor(context_aware_repr).squeeze(-1) * 10
        importance_score = self.importance_regressor(context_aware_repr).squeeze(-1) * 10
        calibrated_logits = risk_logits / self.temperature
        
        return {
            'risk_logits': risk_logits,
            'calibrated_logits': calibrated_logits,
            'severity_score': severity_score,
            'importance_score': importance_score,
            'pooled_output': context_aware_repr
        }
    
    def forward_document(
        self,
        document_structure: List[List[Dict[str, torch.Tensor]]]
    ) -> Dict[str, Any]:
        """
        Forward pass for FULL DOCUMENT (for inference with context)
        
        Args:
            document_structure: List of sections, each containing list of clause inputs
                Example: [
                    [  # Section 1
                        {'input_ids': tensor, 'attention_mask': tensor},
                        {'input_ids': tensor, 'attention_mask': tensor}
                    ],
                    [  # Section 2
                        {'input_ids': tensor, 'attention_mask': tensor}
                    ]
                ]
        
        Returns:
            Document-level predictions with full context
        """
        device = next(self.parameters()).device
        section_vectors = []
        all_clause_predictions = []
        attention_weights = {'clause': [], 'section': None}
        
        # Process each section
        for section_idx, section_clauses in enumerate(document_structure):
            if not section_clauses:
                continue
            
            # Encode all clauses in this section
            clause_embeddings = []
            for clause_input in section_clauses:
                input_ids = clause_input['input_ids'].unsqueeze(0).to(device)
                attention_mask = clause_input['attention_mask'].unsqueeze(0).to(device)
                clause_emb = self.encode_clause(input_ids, attention_mask)
                clause_embeddings.append(clause_emb)
            
            # Stack: [num_clauses, 768]
            clause_hidden = torch.cat(clause_embeddings, dim=0)
            
            # LSTM over clauses β†’ context-aware representations
            clause_lstm_out, _ = self.clause_to_section(clause_hidden.unsqueeze(0))
            # clause_lstm_out: [1, num_clauses, hidden_dim*2]
            
            # Attention over clauses β†’ section representation
            attention_logits = self.clause_attention(clause_lstm_out)
            clause_attn = F.softmax(attention_logits, dim=1)
            section_vec = torch.sum(clause_lstm_out * clause_attn, dim=1)
            
            section_vectors.append(section_vec)
            attention_weights['clause'].append(clause_attn.squeeze(0))
            
            # Predict for each clause using context-aware representation
            for i in range(len(section_clauses)):
                clause_repr = clause_lstm_out[0, i, :]  # Context-aware!
                
                risk_logits = self.risk_classifier(clause_repr)
                severity = self.severity_regressor(clause_repr).squeeze() * 10
                importance = self.importance_regressor(clause_repr).squeeze() * 10
                calibrated_logits = risk_logits / self.temperature
                
                all_clause_predictions.append({
                    'risk_logits': risk_logits,
                    'calibrated_logits': calibrated_logits,
                    'severity_score': severity,
                    'importance_score': importance,
                    'section_idx': section_idx,
                    'clause_idx': i
                })
        
        # Aggregate sections β†’ document
        if section_vectors:
            section_hidden = torch.cat(section_vectors, dim=0)
            section_lstm_out, _ = self.section_to_document(section_hidden.unsqueeze(0))
            
            attention_logits = self.section_attention(section_lstm_out)
            section_attn = F.softmax(attention_logits, dim=1)
            document_vec = torch.sum(section_lstm_out * section_attn, dim=1)
            
            attention_weights['section'] = section_attn.squeeze(0)
        else:
            document_vec = torch.zeros(1, self.hidden_dim * 2).to(device)
        
        return {
            'document_embedding': document_vec,
            'clause_predictions': all_clause_predictions,
            'attention_weights': attention_weights
        }
    
    def predict_document(
        self,
        document_structure: List[List[Dict[str, torch.Tensor]]]
    ) -> Dict[str, Any]:
        """Inference mode with formatted output"""
        self.eval()
        
        with torch.no_grad():
            outputs = self.forward_document(document_structure)
        
        # Format predictions
        predictions = []
        for pred in outputs['clause_predictions']:
            risk_probs = F.softmax(pred['calibrated_logits'], dim=0).cpu().numpy()
            predicted_risk = int(risk_probs.argmax())
            
            predictions.append({
                'section_idx': pred['section_idx'],
                'clause_idx': pred['clause_idx'],
                'predicted_risk_id': predicted_risk,
                'risk_probabilities': risk_probs.tolist(),
                'confidence': float(risk_probs[predicted_risk]),
                'severity_score': pred['severity_score'].item(),
                'importance_score': pred['importance_score'].item()
            })
        
        return {
            'clauses': predictions,
            'attention_weights': {
                'clause': [attn.cpu().numpy().tolist() for attn in outputs['attention_weights']['clause']],
                'section': outputs['attention_weights']['section'].cpu().numpy().tolist() 
                          if outputs['attention_weights']['section'] is not None else None
            },
            'summary': {
                'num_sections': len(document_structure),
                'num_clauses': len(predictions),
                'avg_severity': sum(p['severity_score'] for p in predictions) / len(predictions) if predictions else 0,
                'high_risk_count': sum(1 for p in predictions if p['severity_score'] > 7)
            }
        }


# ============================================================================
# ROBERTA-BASE MODEL FOR LEGAL RISK ANALYSIS
# ============================================================================

class RoBERTaLegalBERT(nn.Module):
    """
    Simplified Legal Risk Analysis Model using RoBERTa-base
    
    **Architecture:**
        RoBERTa-base (125M params) β†’ Multi-task heads (risk, severity, importance)
    
    **Key Features:**
        - Pre-trained RoBERTa-base for better contextual understanding
        - Multi-task learning: Risk classification + Severity + Importance
        - Temperature scaling for calibrated confidence scores
        - Focal Loss support for handling class imbalance
        - Compatible with all existing training infrastructure
    
    **Why RoBERTa over BERT:**
        βœ… Better pre-training (10x more data, longer sequences)
        βœ… Dynamic masking (better generalization)
        βœ… No NSP task (focuses on MLM)
        βœ… Byte-level BPE (better handling of legal terminology)
        βœ… State-of-the-art performance on legal benchmarks
    
    **Usage:**
        config = LegalBertConfig(bert_model_name='roberta-base')
        model = RoBERTaLegalBERT(config, num_discovered_risks=7)
        
        # Training (single clause)
        outputs = model(input_ids, attention_mask)
        
        # Inference with predictions
        predictions = model.predict_risk_pattern(input_ids, attention_mask)
    """
    
    def __init__(self, config, num_discovered_risks: int = 7):
        super().__init__()
        self.config = config
        self.num_discovered_risks = num_discovered_risks
        
        # Load RoBERTa model
        try:
            self.roberta = AutoModel.from_pretrained(config.bert_model_name)
            # Configure RoBERTa dropout
            self.roberta.config.hidden_dropout_prob = config.dropout_rate
            self.roberta.config.attention_probs_dropout_prob = config.dropout_rate
            self.hidden_size = self.roberta.config.hidden_size  # 768 for roberta-base
            print(f"βœ… Loaded {config.bert_model_name} (hidden_size={self.hidden_size})")
        except Exception as e:
            print(f"⚠️ Warning: Could not load RoBERTa model: {e}")
            print("   Using mock model for testing")
            self.roberta = None
            self.hidden_size = 768
        
        # Multi-task prediction heads
        # Head 1: Risk Classification (discovered patterns)
        self.risk_classifier = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(self.hidden_size, self.hidden_size // 2),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(self.hidden_size // 2, num_discovered_risks)
        )
        
        # Head 2: Severity Regression (0-10 scale)
        self.severity_regressor = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(self.hidden_size, self.hidden_size // 4),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(self.hidden_size // 4, 1),
            nn.Sigmoid()  # Output 0-1, will be scaled to 0-10
        )
        
        # Head 3: Importance Regression (0-10 scale)
        self.importance_regressor = nn.Sequential(
            nn.Dropout(config.dropout_rate),
            nn.Linear(self.hidden_size, self.hidden_size // 4),
            nn.ReLU(),
            nn.Dropout(config.dropout_rate),
            nn.Linear(self.hidden_size // 4, 1),
            nn.Sigmoid()  # Output 0-1, will be scaled to 0-10
        )
        
        # Temperature parameter for calibration
        self.temperature = nn.Parameter(torch.ones(1))
        
    def forward(self, input_ids: torch.Tensor, attention_mask: torch.Tensor,
                output_attentions: bool = False) -> Dict[str, torch.Tensor]:
        """
        Forward pass through RoBERTa and task-specific heads
        
        Args:
            input_ids: Token IDs [batch_size, seq_len]
            attention_mask: Attention mask [batch_size, seq_len]
            output_attentions: Whether to return attention weights
        
        Returns:
            Dictionary with:
                - risk_logits: Classification logits [batch_size, num_risks]
                - calibrated_logits: Temperature-scaled logits
                - severity_score: Severity predictions [batch_size]
                - importance_score: Importance predictions [batch_size]
                - pooled_output: RoBERTa pooled representation [batch_size, 768]
                - attentions: (optional) Attention weights for analysis
        """
        if self.roberta is not None:
            # Real RoBERTa forward pass
            outputs = self.roberta(
                input_ids=input_ids,
                attention_mask=attention_mask,
                output_attentions=output_attentions
            )
            # RoBERTa uses <s> token (first token) as sentence representation
            pooled_output = outputs.last_hidden_state[:, 0, :]  # [batch, hidden_size]
            attentions = outputs.attentions if output_attentions else None
        else:
            # Mock output for testing
            batch_size = input_ids.size(0)
            pooled_output = torch.randn(batch_size, self.hidden_size, device=input_ids.device)
            attentions = None
        
        # Multi-task predictions
        risk_logits = self.risk_classifier(pooled_output)
        severity_score = self.severity_regressor(pooled_output).squeeze(-1) * 10  # Scale to 0-10
        importance_score = self.importance_regressor(pooled_output).squeeze(-1) * 10  # Scale to 0-10
        
        # Apply temperature scaling for calibrated probabilities
        calibrated_logits = risk_logits / self.temperature
        
        result = {
            'risk_logits': risk_logits,
            'calibrated_logits': calibrated_logits,
            'severity_score': severity_score,
            'importance_score': importance_score,
            'pooled_output': pooled_output
        }
        
        if output_attentions and attentions is not None:
            result['attentions'] = attentions
        
        return result
    
    def predict_risk_pattern(self, input_ids: torch.Tensor, attention_mask: torch.Tensor,
                            return_attentions: bool = False) -> Dict[str, Any]:
        """
        Make predictions with interpretable outputs
        
        Args:
            input_ids: Token IDs [batch_size, seq_len]
            attention_mask: Attention mask [batch_size, seq_len]
            return_attentions: Whether to include attention weights
        
        Returns:
            Dictionary with predictions, probabilities, and confidence scores
        """
        self.eval()
        
        with torch.no_grad():
            outputs = self.forward(input_ids, attention_mask, output_attentions=return_attentions)
            
            # Get predictions
            risk_probs = torch.softmax(outputs['calibrated_logits'], dim=-1)
            predicted_risk = torch.argmax(risk_probs, dim=-1)
            confidence = torch.max(risk_probs, dim=-1)[0]
            
            result = {
                'predicted_risk_id': predicted_risk.cpu().numpy(),
                'risk_probabilities': risk_probs.cpu().numpy(),
                'confidence': confidence.cpu().numpy(),
                'severity_score': outputs['severity_score'].cpu().numpy(),
                'importance_score': outputs['importance_score'].cpu().numpy()
            }
            
            if return_attentions and 'attentions' in outputs:
                result['attentions'] = outputs['attentions']
            
            return result
    
    def analyze_attention(self, input_ids: torch.Tensor, attention_mask: torch.Tensor,
                         tokenizer: Optional['LegalBertTokenizer'] = None) -> Dict[str, Any]:
        """
        Analyze RoBERTa attention patterns to identify important tokens
        
        Args:
            input_ids: Token IDs [batch_size, seq_len]
            attention_mask: Attention mask [batch_size, seq_len]
            tokenizer: Tokenizer for decoding tokens
        
        Returns:
            Dictionary with token importance scores and top tokens
        """
        self.eval()
        
        with torch.no_grad():
            outputs = self.forward(input_ids, attention_mask, output_attentions=True)
            
            if 'attentions' not in outputs or outputs['attentions'] is None:
                return {'error': 'Attention weights not available'}
            
            attentions = outputs['attentions']  # Tuple of (batch, num_heads, seq_len, seq_len)
            batch_size, seq_len = input_ids.shape
            
            # Stack all layers: (num_layers, batch, num_heads, seq_len, seq_len)
            all_attentions = torch.stack(attentions)
            
            # Get attention to <s> token (index 0) - RoBERTa's classification token
            # Average across layers and heads
            cls_attention = all_attentions[:, :, :, 0, :].mean(dim=[0, 2])  # (batch, seq_len)
            
            # Get global attention (average from all tokens)
            global_attention = all_attentions.mean(dim=[0, 2, 3])  # (batch, seq_len)
            
            # Combine for final importance score
            token_importance = (cls_attention + global_attention) / 2
            token_importance = token_importance * attention_mask  # Mask padding
            
            # Get top-k important tokens
            k = min(10, seq_len)
            top_values, top_indices = torch.topk(token_importance, k, dim=1)
            
            result = {
                'token_importance': token_importance.cpu().numpy(),
                'top_token_indices': top_indices.cpu().numpy(),
                'top_token_scores': top_values.cpu().numpy(),
                'attention_weights': {
                    'cls_attention': cls_attention.cpu().numpy(),
                    'global_attention': global_attention.cpu().numpy()
                }
            }
            
            # Add layer-wise analysis
            layer_attentions = []
            for layer_idx, layer_attn in enumerate(attentions):
                layer_cls_attn = layer_attn[:, :, 0, :].mean(dim=1)  # (batch, seq_len)
                layer_attentions.append({
                    'layer': layer_idx,
                    'cls_attention': layer_cls_attn.cpu().numpy()
                })
            result['layer_analysis'] = layer_attentions
            
            # Decode tokens if tokenizer provided
            if tokenizer is not None and tokenizer.tokenizer is not None:
                tokens = tokenizer.tokenizer.convert_ids_to_tokens(input_ids[0])
                top_tokens = [tokens[idx] for idx in top_indices[0].cpu().numpy()]
                result['tokens'] = tokens
                result['top_tokens'] = top_tokens
            
            return result