Add 'fiscal/' from commit '102ba84500dbd9655a0471288c3e278652593ca9'

git-subtree-dir: fiscal
git-subtree-mainline: d95165fc8f
git-subtree-split: 102ba84500

fiscal/central/app/datasets/ncm.py

@@ -0,0 +1,48 @@
+"""Validated parser for the official Siscomex NCM JSON download."""
+
+from dataclasses import dataclass
+from datetime import datetime
+import hashlib
+import json
+
+
+@dataclass(frozen=True)
+class NcmEntry:
+    code: str
+    description: str
+    valid_from: str
+    valid_to: str
+
+
+@dataclass(frozen=True)
+class NcmPayload:
+    version: str
+    act: str
+    sha256: str
+    entries: tuple[NcmEntry, ...]
+
+
+def parse_ncm_payload(payload: bytes) -> NcmPayload:
+    try:
+        document = json.loads(payload)
+    except (TypeError, json.JSONDecodeError) as error:
+        raise ValueError("payload is not valid JSON") from error
+    if not isinstance(document, dict):
+        raise ValueError("payload root must be an object")
+    nomenclaturas = document.get("Nomenclaturas")
+    version = document.get("Data_Ultima_Atualizacao_NCM")
+    act = document.get("Ato")
+    if not isinstance(nomenclaturas, list) or not nomenclaturas:
+        raise ValueError("Nomenclaturas must be a nonempty list")
+    if not isinstance(version, str) or not isinstance(act, str):
+        raise ValueError("dataset metadata is invalid")
+    entries = []
+    for item in nomenclaturas:
+        if not isinstance(item, dict):
+            raise ValueError("Nomenclaturas item must be an object")
+        values = tuple(item.get(name) for name in ("Codigo", "Descricao", "Data_Inicio", "Data_Fim"))
+        if not all(isinstance(value, str) for value in values):
+            raise ValueError("Nomenclaturas item schema is invalid")
+        code, description, valid_from, valid_to = values
+        entries.append(NcmEntry("".join(char for char in code if char.isdigit()), description, valid_from, valid_to))
+    return NcmPayload(version, act, hashlib.sha256(payload).hexdigest(), tuple(entries))