Initial commit

libs/forms/evidence_pack.py

@@ -0,0 +1,185 @@
+"""Evidence pack generation with manifests and signatures."""
+
+import io
+from typing import Any
+
+import structlog
+
+logger = structlog.get_logger()
+
+
+class EvidencePackGenerator:  # pylint: disable=too-few-public-methods
+    """Generate evidence packs with manifests and signatures"""
+
+    def __init__(self, storage_client: Any) -> None:
+        self.storage = storage_client
+
+    async def create_evidence_pack(  # pylint: disable=too-many-locals
+        self,
+        taxpayer_id: str,
+        tax_year: str,
+        scope: str,
+        evidence_items: list[dict[str, Any]],
+    ) -> dict[str, Any]:
+        """Create evidence pack with manifest and signatures"""
+        # pylint: disable=import-outside-toplevel
+        import hashlib
+        import json
+        import zipfile
+        from datetime import datetime
+
+        try:
+            # Create ZIP buffer
+            zip_buffer = io.BytesIO()
+
+            with zipfile.ZipFile(zip_buffer, "w", zipfile.ZIP_DEFLATED) as zip_file:
+                manifest: dict[str, Any] = {
+                    "taxpayer_id": taxpayer_id,
+                    "tax_year": tax_year,
+                    "scope": scope,
+                    "created_at": datetime.utcnow().isoformat(),
+                    "evidence_items": [],
+                    "signatures": {},
+                }
+
+                # Add evidence files to ZIP
+                for item in evidence_items:
+                    doc_id = item["doc_id"]
+                    page = item.get("page")
+                    bbox = item.get("bbox")
+                    text_hash = item.get("text_hash")
+
+                    # Get document content
+                    doc_content = await self.storage.get_object(
+                        bucket_name="raw-documents",
+                        object_name=f"tenants/{taxpayer_id}/raw/{doc_id}.pdf",
+                    )
+
+                    if doc_content:
+                        # Add to ZIP
+                        zip_filename = f"documents/{doc_id}.pdf"
+                        zip_file.writestr(zip_filename, doc_content)
+
+                        # Calculate file hash
+                        file_hash = hashlib.sha256(doc_content).hexdigest()
+
+                        # Add to manifest
+                        manifest["evidence_items"].append(
+                            {
+                                "doc_id": doc_id,
+                                "filename": zip_filename,
+                                "page": page,
+                                "bbox": bbox,
+                                "text_hash": text_hash,
+                                "file_hash": file_hash,
+                                "file_size": len(doc_content),
+                            }
+                        )
+
+                # Sign manifest
+                manifest_json = json.dumps(manifest, indent=2, sort_keys=True)
+                manifest_hash = hashlib.sha256(manifest_json.encode()).hexdigest()
+
+                manifest["signatures"]["manifest_hash"] = manifest_hash
+                manifest["signatures"]["algorithm"] = "SHA-256"
+
+                # Add manifest to ZIP
+                zip_file.writestr("manifest.json", json.dumps(manifest, indent=2))
+
+            # Get ZIP content
+            zip_content = zip_buffer.getvalue()
+
+            # Store evidence pack
+            pack_filename = f"evidence_pack_{taxpayer_id}_{tax_year}_{scope}.zip"
+            pack_key = f"tenants/{taxpayer_id}/evidence_packs/{pack_filename}"
+
+            success = await self.storage.put_object(
+                bucket_name="evidence-packs",
+                object_name=pack_key,
+                data=io.BytesIO(zip_content),
+                length=len(zip_content),
+                content_type="application/zip",
+            )
+
+            if success:
+                return {
+                    "pack_filename": pack_filename,
+                    "pack_key": pack_key,
+                    "pack_size": len(zip_content),
+                    "evidence_count": len(evidence_items),
+                    "manifest_hash": manifest_hash,
+                    "s3_url": f"s3://evidence-packs/{pack_key}",
+                }
+            raise RuntimeError("Failed to store evidence pack")
+
+        except Exception as e:  # pylint: disable=broad-exception-caught
+            logger.error("Failed to create evidence pack", error=str(e))
+            raise
+
+
+# Form configuration for UK tax forms
+UK_TAX_FORMS = {
+    "SA100": {
+        "name": "Self Assessment Tax Return",
+        "template_path": "forms/templates/SA100.pdf",
+        "boxes": {
+            "1": {"description": "Your name", "type": "text"},
+            "2": {"description": "Your address", "type": "text"},
+            "3": {"description": "Your UTR", "type": "text"},
+            "4": {"description": "Your NI number", "type": "text"},
+        },
+    },
+    "SA103": {
+        "name": "Self-employment (full)",
+        "template_path": "forms/templates/SA103.pdf",
+        "boxes": {
+            "1": {"description": "Business name", "type": "text"},
+            "2": {"description": "Business description", "type": "text"},
+            "3": {"description": "Accounting period start", "type": "date"},
+            "4": {"description": "Accounting period end", "type": "date"},
+            "20": {"description": "Total turnover", "type": "currency"},
+            "31": {
+                "description": "Total allowable business expenses",
+                "type": "currency",
+            },
+            "32": {"description": "Net profit", "type": "currency"},
+            "33": {"description": "Balancing charges", "type": "currency"},
+            "34": {"description": "Goods/services for own use", "type": "currency"},
+            "35": {"description": "Total taxable profits", "type": "currency"},
+        },
+    },
+    "SA105": {
+        "name": "Property income",
+        "template_path": "forms/templates/SA105.pdf",
+        "boxes": {
+            "20": {"description": "Total rents and other income", "type": "currency"},
+            "29": {
+                "description": "Premiums for the grant of a lease",
+                "type": "currency",
+            },
+            "31": {
+                "description": "Rent, rates, insurance, ground rents etc",
+                "type": "currency",
+            },
+            "32": {"description": "Property management", "type": "currency"},
+            "33": {
+                "description": "Services provided, including wages",
+                "type": "currency",
+            },
+            "34": {
+                "description": "Repairs, maintenance and renewals",
+                "type": "currency",
+            },
+            "35": {
+                "description": "Finance costs, including interest",
+                "type": "currency",
+            },
+            "36": {"description": "Professional fees", "type": "currency"},
+            "37": {"description": "Costs of services provided", "type": "currency"},
+            "38": {
+                "description": "Other allowable property expenses",
+                "type": "currency",
+            },
+        },
+    },
+}