From e980d6c0b969c84a3500a565f2ef50091493379a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20Mur=C3=A9?= <batolettre@gmail.com>
Date: Wed, 20 Nov 2024 12:34:24 +0100
Subject: [PATCH] various sanding everywhere towards building the tookit

---
 pkg/args/args.go                              | 43 +++++++++++++++++++
 pkg/args/readonly.go                          | 23 ++++++++++
 pkg/container/reader.go                       |  6 ++-
 pkg/meta/meta.go                              | 19 ++++----
 pkg/policy/policy_test.go                     | 31 +++++++++++++
 token/delegation/delegation.go                |  2 +-
 token/delegation/delegationtest/token.go      | 13 +++---
 token/delegation/delegationtest/token_test.go |  6 +--
 token/delegation/loader.go                    | 17 ++++++++
 token/internal/nonce/nonce.go                 | 19 +++++++-
 token/invocation/invocation.go                | 28 ++++++------
 token/invocation/invocation_test.go           | 11 ++---
 token/invocation/proof.go                     |  6 ---
 13 files changed, 176 insertions(+), 48 deletions(-)
 create mode 100644 pkg/args/readonly.go
 create mode 100644 token/delegation/loader.go

diff --git a/pkg/args/args.go b/pkg/args/args.go
index 4ac9d94..d046d93 100644
--- a/pkg/args/args.go
+++ b/pkg/args/args.go
@@ -6,11 +6,13 @@ package args
 import (
 	"fmt"
 	"sort"
+	"strings"
 
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/datamodel"
 	"github.com/ipld/go-ipld-prime/fluent/qp"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/ipld/go-ipld-prime/printer"
 
 	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
 )
@@ -70,6 +72,7 @@ func (a *Args) Include(other *Args) {
 // ToIPLD wraps an instance of an Args with an ipld.Node.
 func (a *Args) ToIPLD() (ipld.Node, error) {
 	sort.Strings(a.Keys)
+
 	return qp.BuildMap(basicnode.Prototype.Any, int64(len(a.Keys)), func(ma datamodel.MapAssembler) {
 		for _, key := range a.Keys {
 			qp.MapEntry(ma, key, qp.Node(a.Values[key]))
@@ -92,3 +95,43 @@ func (a *Args) Equals(other *Args) bool {
 	}
 	return true
 }
+
+func (a *Args) String() string {
+	sort.Strings(a.Keys)
+
+	buf := strings.Builder{}
+	buf.WriteString("{")
+
+	for _, key := range a.Keys {
+		buf.WriteString("\n\t")
+		buf.WriteString(key)
+		buf.WriteString(": ")
+		buf.WriteString(strings.ReplaceAll(printer.Sprint(a.Values[key]), "\n", "\n\t"))
+		buf.WriteString(",")
+	}
+
+	if len(a.Keys) > 0 {
+		buf.WriteString("\n")
+	}
+	buf.WriteString("}")
+
+	return buf.String()
+}
+
+// ReadOnly returns a read-only version of Args.
+func (a *Args) ReadOnly() ReadOnly {
+	return ReadOnly{args: a}
+}
+
+// Clone makes a deep copy.
+func (a *Args) Clone() *Args {
+	res := &Args{
+		Keys:   make([]string, len(a.Keys)),
+		Values: make(map[string]ipld.Node, len(a.Values)),
+	}
+	copy(res.Keys, a.Keys)
+	for k, v := range a.Values {
+		res.Values[k] = v
+	}
+	return res
+}
diff --git a/pkg/args/readonly.go b/pkg/args/readonly.go
new file mode 100644
index 0000000..a708807
--- /dev/null
+++ b/pkg/args/readonly.go
@@ -0,0 +1,23 @@
+package args
+
+import "github.com/ipld/go-ipld-prime"
+
+type ReadOnly struct {
+	args *Args
+}
+
+func (r ReadOnly) ToIPLD() (ipld.Node, error) {
+	return r.args.ToIPLD()
+}
+
+func (r ReadOnly) Equals(other *Args) bool {
+	return r.args.Equals(other)
+}
+
+func (r ReadOnly) String() string {
+	return r.args.String()
+}
+
+func (r ReadOnly) WriteableClone() *Args {
+	return r.args.Clone()
+}
diff --git a/pkg/container/reader.go b/pkg/container/reader.go
index db1e145..984b152 100644
--- a/pkg/container/reader.go
+++ b/pkg/container/reader.go
@@ -2,6 +2,7 @@ package container
 
 import (
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
 	"iter"
@@ -34,13 +35,16 @@ func (ctn Reader) GetToken(cid cid.Cid) (token.Token, error) {
 // GetDelegation is the same as GetToken but only return a delegation.Token, with the right type.
 func (ctn Reader) GetDelegation(cid cid.Cid) (*delegation.Token, error) {
 	tkn, err := ctn.GetToken(cid)
+	if errors.Is(err, ErrNotFound) {
+		return nil, delegation.ErrDelegationNotFound
+	}
 	if err != nil {
 		return nil, err
 	}
 	if tkn, ok := tkn.(*delegation.Token); ok {
 		return tkn, nil
 	}
-	return nil, fmt.Errorf("not a delegation token")
+	return nil, delegation.ErrDelegationNotFound
 }
 
 // GetAllDelegations returns all the delegation.Token in the container.
diff --git a/pkg/meta/meta.go b/pkg/meta/meta.go
index a08d97c..913530f 100644
--- a/pkg/meta/meta.go
+++ b/pkg/meta/meta.go
@@ -12,9 +12,7 @@ import (
 	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
 )
 
-var ErrUnsupported = errors.New("failure adding unsupported type to meta")
-
-var ErrNotFound = errors.New("key-value not found in meta")
+var ErrNotFound = errors.New("key not found in meta")
 
 var ErrNotEncryptable = errors.New("value of this type cannot be encrypted")
 
@@ -193,18 +191,19 @@ func (m *Meta) String() string {
 	buf := strings.Builder{}
 	buf.WriteString("{")
 
-	var i int
 	for key, node := range m.Values {
-		if i > 0 {
-			buf.WriteString(", ")
-		}
-		i++
+		buf.WriteString("\n\t")
 		buf.WriteString(key)
-		buf.WriteString(":")
-		buf.WriteString(printer.Sprint(node))
+		buf.WriteString(": ")
+		buf.WriteString(strings.ReplaceAll(printer.Sprint(node), "\n", "\n\t"))
+		buf.WriteString(",")
 	}
 
+	if len(m.Values) > 0 {
+		buf.WriteString("\n")
+	}
 	buf.WriteString("}")
+
 	return buf.String()
 }
 
diff --git a/pkg/policy/policy_test.go b/pkg/policy/policy_test.go
index 26ed239..c7f8e9f 100644
--- a/pkg/policy/policy_test.go
+++ b/pkg/policy/policy_test.go
@@ -37,6 +37,37 @@ func ExamplePolicy() {
 	// ]
 }
 
+func ExamplePolicy_accumulate() {
+	var statements []policy.Constructor
+
+	statements = append(statements, policy.Equal(".status", literal.String("draft")))
+
+	statements = append(statements, policy.All(".reviewer",
+		policy.Like(".email", "*@example.com"),
+	))
+
+	statements = append(statements, policy.Any(".tags", policy.Or(
+		policy.Equal(".", literal.String("news")),
+		policy.Equal(".", literal.String("press")),
+	)))
+
+	pol := policy.MustConstruct(statements...)
+
+	fmt.Println(pol)
+
+	// Output:
+	// [
+	//   ["==", ".status", "draft"],
+	//   ["all", ".reviewer",
+	//     ["like", ".email", "*@example.com"]],
+	//   ["any", ".tags",
+	//     ["or", [
+	//       ["==", ".", "news"],
+	//       ["==", ".", "press"]]]
+	//     ]
+	// ]
+}
+
 func TestConstruct(t *testing.T) {
 	pol, err := policy.Construct(
 		policy.Equal(".status", literal.String("draft")),
diff --git a/token/delegation/delegation.go b/token/delegation/delegation.go
index 1f19f42..6ab32c6 100644
--- a/token/delegation/delegation.go
+++ b/token/delegation/delegation.go
@@ -48,7 +48,7 @@ type Token struct {
 
 // New creates a validated Token from the provided parameters and options.
 //
-// When creating a delegated token, the Issuer's (iss) DID is assembed
+// When creating a delegated token, the Issuer's (iss) DID is assembled
 // using the public key associated with the private key sent as the first
 // parameter.
 func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
diff --git a/token/delegation/delegationtest/token.go b/token/delegation/delegationtest/token.go
index 07c27e6..47a77fd 100644
--- a/token/delegation/delegationtest/token.go
+++ b/token/delegation/delegationtest/token.go
@@ -2,14 +2,13 @@ package delegationtest
 
 import (
 	"embed"
-	"fmt"
 	"path/filepath"
 	"sync"
 
 	"github.com/ipfs/go-cid"
+
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/token/invocation"
 )
 
 const (
@@ -41,11 +40,11 @@ var fs embed.FS
 
 var (
 	once sync.Once
-	ldr  invocation.DelegationLoader
+	ldr  delegation.Loader
 	err  error
 )
 
-var _ invocation.DelegationLoader = (*delegationLoader)(nil)
+var _ delegation.Loader = (*delegationLoader)(nil)
 
 type delegationLoader struct {
 	tokens map[cid.Cid]*delegation.Token
@@ -54,7 +53,7 @@ type delegationLoader struct {
 // GetDelegationLoader returns a singleton instance of a test
 // DelegationLoader containing all the tokens present in the data/
 // directory.
-func GetDelegationLoader() (invocation.DelegationLoader, error) {
+func GetDelegationLoader() (delegation.Loader, error) {
 	once.Do(func() {
 		ldr, err = loadDelegations()
 	})
@@ -66,13 +65,13 @@ func GetDelegationLoader() (invocation.DelegationLoader, error) {
 func (l *delegationLoader) GetDelegation(id cid.Cid) (*delegation.Token, error) {
 	tkn, ok := l.tokens[id]
 	if !ok {
-		return nil, fmt.Errorf("%w: CID %s", invocation.ErrMissingDelegation, id.String())
+		return nil, delegation.ErrDelegationNotFound
 	}
 
 	return tkn, nil
 }
 
-func loadDelegations() (invocation.DelegationLoader, error) {
+func loadDelegations() (delegation.Loader, error) {
 	dirEntries, err := fs.ReadDir("data")
 	if err != nil {
 		return nil, err
diff --git a/token/delegation/delegationtest/token_test.go b/token/delegation/delegationtest/token_test.go
index e9518ac..fde6749 100644
--- a/token/delegation/delegationtest/token_test.go
+++ b/token/delegation/delegationtest/token_test.go
@@ -6,8 +6,9 @@ import (
 	"github.com/ipfs/go-cid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/token/delegation"
 	"github.com/ucan-wg/go-ucan/token/delegation/delegationtest"
-	"github.com/ucan-wg/go-ucan/token/invocation"
 )
 
 func TestGetDelegation(t *testing.T) {
@@ -25,8 +26,7 @@ func TestGetDelegation(t *testing.T) {
 		t.Parallel()
 
 		tkn, err := delegationtest.GetDelegation(cid.Undef)
-		require.ErrorIs(t, err, invocation.ErrMissingDelegation)
-		require.ErrorContains(t, err, "CID b")
+		require.ErrorIs(t, err, delegation.ErrDelegationNotFound)
 		assert.Nil(t, tkn)
 	})
 }
diff --git a/token/delegation/loader.go b/token/delegation/loader.go
new file mode 100644
index 0000000..13dd81d
--- /dev/null
+++ b/token/delegation/loader.go
@@ -0,0 +1,17 @@
+package delegation
+
+import (
+	"fmt"
+
+	"github.com/ipfs/go-cid"
+)
+
+// ErrDelegationNotFound is returned if a delegation token is not found
+var ErrDelegationNotFound = fmt.Errorf("delegation not found")
+
+// Loader is a delegation token loader.
+type Loader interface {
+	// GetDelegation returns the delegation.Token matching the given CID.
+	// If not found, ErrDelegationNotFound is returned.
+	GetDelegation(cid cid.Cid) (*Token, error)
+}
diff --git a/token/internal/nonce/nonce.go b/token/internal/nonce/nonce.go
index 3bda21b..f4928a8 100644
--- a/token/internal/nonce/nonce.go
+++ b/token/internal/nonce/nonce.go
@@ -2,8 +2,25 @@ package nonce
 
 import "crypto/rand"
 
-// Generate creates a 12-byte random nonce.
 // TODO: some crypto scheme require more, is that our case?
+//
+// The spec mention:
+// The REQUIRED nonce parameter nonce MAY be any value.
+// A randomly generated string is RECOMMENDED to provide a unique UCAN, though it MAY
+// also be a monotonically increasing count of the number of links in the hash chain.
+// This field helps prevent replay attacks and ensures a unique CID per delegation.
+// The iss, aud, and exp fields together will often ensure that UCANs are unique,
+// but adding the nonce ensures uniqueness.
+//
+// The recommended size of the nonce differs by key type. In many cases, a random
+// 12-byte nonce is sufficient. If uncertain, check the nonce in your DID's crypto suite.
+//
+// 12 bytes is 10^28, 16 bytes is 10^38. Both sounds like a lot of random to achieve
+// those goals, but maybe the crypto voodoo require more.
+//
+// The rust implementation use 16 bytes nonce.
+
+// Generate creates a 12-byte random nonce.
 func Generate() ([]byte, error) {
 	res := make([]byte, 12)
 	_, err := rand.Read(res)
diff --git a/token/invocation/invocation.go b/token/invocation/invocation.go
index 3faa0d3..12f0a08 100644
--- a/token/invocation/invocation.go
+++ b/token/invocation/invocation.go
@@ -102,34 +102,38 @@ func New(iss, sub did.DID, cmd command.Command, prf []cid.Cid, opts ...Option) (
 	return &tkn, nil
 }
 
-func (t *Token) ExecutionAllowed(loader DelegationLoader) (bool, error) {
+func (t *Token) ExecutionAllowed(loader delegation.Loader) error {
 	return t.executionAllowed(loader, t.arguments)
 }
 
-func (t *Token) ExecutionAllowedWithArgsHook(loader DelegationLoader, hook func(*args.Args) *args.Args) (bool, error) {
-	return t.executionAllowed(loader, hook(t.arguments))
+func (t *Token) ExecutionAllowedWithArgsHook(loader delegation.Loader, hook func(args args.ReadOnly) (*args.Args, error)) error {
+	newArgs, err := hook(t.arguments.ReadOnly())
+	if err != nil {
+		return err
+	}
+	return t.executionAllowed(loader, newArgs)
 }
 
-func (t *Token) executionAllowed(loader DelegationLoader, arguments *args.Args) (bool, error) {
+func (t *Token) executionAllowed(loader delegation.Loader, arguments *args.Args) error {
 	delegations, err := t.loadProofs(loader)
 	if err != nil {
 		// All referenced delegations must be available - 4b
-		return false, err
+		return err
 	}
 
 	if err := t.verifyProofs(delegations); err != nil {
-		return false, err
+		return err
 	}
 
 	if err := t.verifyTimeBound(delegations); err != nil {
-		return false, err
+		return err
 	}
 
 	if err := t.verifyArgs(delegations, arguments); err != nil {
-		return false, err
+		return err
 	}
 
-	return true, nil
+	return nil
 }
 
 // Issuer returns the did.DID representing the Token's issuer.
@@ -154,8 +158,8 @@ func (t *Token) Command() command.Command {
 
 // Arguments returns the arguments to be used when the command is
 // invoked.
-func (t *Token) Arguments() *args.Args {
-	return t.arguments
+func (t *Token) Arguments() args.ReadOnly {
+	return t.arguments.ReadOnly()
 }
 
 // Proof() returns the ordered list of cid.Cid which reference the
@@ -225,7 +229,7 @@ func (t *Token) validate() error {
 	return errs
 }
 
-func (t *Token) loadProofs(loader DelegationLoader) (res []*delegation.Token, err error) {
+func (t *Token) loadProofs(loader delegation.Loader) (res []*delegation.Token, err error) {
 	res = make([]*delegation.Token, len(t.proof))
 	for i, c := range t.proof {
 		res[i], err = loader.GetDelegation(c)
diff --git a/token/invocation/invocation_test.go b/token/invocation/invocation_test.go
index 6482606..ea0ba2a 100644
--- a/token/invocation/invocation_test.go
+++ b/token/invocation/invocation_test.go
@@ -5,13 +5,12 @@ import (
 
 	"github.com/ipfs/go-cid"
 	"github.com/stretchr/testify/require"
+
 	"github.com/ucan-wg/go-ucan/did/didtest"
 	"github.com/ucan-wg/go-ucan/pkg/args"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/token/delegation/delegationtest"
 	"github.com/ucan-wg/go-ucan/token/invocation"
-
-	"github.com/stretchr/testify/assert"
 )
 
 const (
@@ -118,7 +117,7 @@ func TestToken_ExecutionAllowed(t *testing.T) {
 	})
 }
 
-func test(t *testing.T, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) (bool, error) {
+func test(t *testing.T, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) error {
 	t.Helper()
 
 	tkn, err := invocation.New(persona.DID(t), didtest.PersonaAlice.DID(t), cmd, prf, opts...)
@@ -131,13 +130,11 @@ func test(t *testing.T, persona didtest.Persona, cmd command.Command, args *args
 }
 
 func testFails(t *testing.T, expErr error, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) {
-	ok, err := test(t, persona, cmd, args, prf, opts...)
+	err := test(t, persona, cmd, args, prf, opts...)
 	require.ErrorIs(t, err, expErr)
-	assert.False(t, ok)
 }
 
 func testPasses(t *testing.T, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) {
-	ok, err := test(t, persona, cmd, args, prf, opts...)
+	err := test(t, persona, cmd, args, prf, opts...)
 	require.NoError(t, err)
-	assert.True(t, ok)
 }
diff --git a/token/invocation/proof.go b/token/invocation/proof.go
index a644c17..a61e022 100644
--- a/token/invocation/proof.go
+++ b/token/invocation/proof.go
@@ -4,8 +4,6 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/ipfs/go-cid"
-
 	"github.com/ucan-wg/go-ucan/pkg/args"
 	"github.com/ucan-wg/go-ucan/pkg/policy"
 	"github.com/ucan-wg/go-ucan/token/delegation"
@@ -49,10 +47,6 @@ import (
 //     a. The policy must "match" the arguments. (verifyArgs below)
 //     b. The nonce (if present) is not reused. (out of scope for go-ucan)
 
-type DelegationLoader interface {
-	GetDelegation(cid cid.Cid) (*delegation.Token, error)
-}
-
 // verifyProofs controls that the proof chain allows the invocation:
 // - principal alignment
 // - command alignment