import base64
import copy
import unittest
from datetime import datetime, timezone
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
from monitor_runtime.licensing import canonical, verify_document, LicenseError

class OfflineLicenseTests(unittest.TestCase):
    def setUp(self):
        self.key = Ed25519PrivateKey.generate()
        self.public = self.key.public_key().public_bytes(serialization.Encoding.PEM,serialization.PublicFormat.SubjectPublicKeyInfo)
        self.now = datetime(2026,8,30,tzinfo=timezone.utc).timestamp()
        self.payload = dict(schema_version=1,product='monitor',license_id='test-id',customer='test',
                            machine_fingerprint='v1:'+'a'*64,issued_at='2026-08-29T00:00:00Z',expires_at=None)

    def sign(self, payload=None):
        payload = payload or self.payload
        return {'payload':payload,'signature':base64.b64encode(self.key.sign(canonical(payload))).decode()}

    def verify(self, document, **kwargs):
        return verify_document(document,kwargs.get('public',self.public),
                               kwargs.get('fingerprint',self.payload['machine_fingerprint']),kwargs.get('now',self.now))

    def test_perpetual_and_dated(self):
        self.assertEqual(self.verify(self.sign())['customer'],'test')
        self.payload['expires_at']='2026-08-31T00:00:00Z'
        self.verify(self.sign())

    def test_expiry_boundary_and_future_issue(self):
        self.payload['expires_at']='2026-08-30T00:00:00Z'
        with self.assertRaises(LicenseError):self.verify(self.sign())
        self.payload['expires_at']=None
        self.payload['issued_at']='2026-09-01T00:00:00Z'
        with self.assertRaises(LicenseError):self.verify(self.sign())

    def test_machine_signature_and_key_mismatch(self):
        doc=self.sign()
        with self.assertRaises(LicenseError):self.verify(doc,fingerprint='another')
        bad=copy.deepcopy(doc);bad['payload']['customer']='tampered'
        with self.assertRaises(LicenseError):self.verify(bad)
        other=Ed25519PrivateKey.generate().public_key().public_bytes(serialization.Encoding.PEM,serialization.PublicFormat.SubjectPublicKeyInfo)
        with self.assertRaises(LicenseError):self.verify(doc,public=other)

    def test_product_version_structure_and_timezone(self):
        for field,value in [('product','other'),('schema_version',2),('issued_at','2026-08-29'),('customer','')]:
            with self.subTest(field=field):
                payload=dict(self.payload);payload[field]=value
                with self.assertRaises(LicenseError):self.verify(self.sign(payload))
        bad=self.sign();bad['unexpected']=1
        with self.assertRaises(LicenseError):self.verify(bad)