commit d95ef7f28fb6180b6eee049c2fb8603563ee0cba
Author: Jeremy Tregunna <jeremy@tregunna.ca>
Date:   Thu Dec 26 00:43:25 2024 -0600

    feat: Initial implementation of an attribute based authentication system

diff --git a/attribute.go b/attribute.go
new file mode 100644
index 0000000..45d6a14
--- /dev/null
+++ b/attribute.go
@@ -0,0 +1,6 @@
+package abac
+
+type Attribute struct {
+	Key   string `json:"key"`
+	Value string `json:"value"`
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..412c336
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,8 @@
+module git.canoozie.net/venturelab02/uncomplicated/abac
+
+go 1.23.3
+
+require (
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-sqlite3 v1.14.24 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..22c220f
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,4 @@
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/mattn/go-sqlite3 v1.14.24 h1:tpSp2G2KyMnnQu99ngJ47EIkWVmliIizyZBfPrBWDRM=
+github.com/mattn/go-sqlite3 v1.14.24/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
diff --git a/policy_engine.go b/policy_engine.go
new file mode 100644
index 0000000..0c12e05
--- /dev/null
+++ b/policy_engine.go
@@ -0,0 +1,17 @@
+package abac
+
+import (
+	"context"
+)
+
+// Result of evaluating an ABAC policy
+type PolicyDecision bool
+
+type PolicyEngine interface {
+	EvaluatePolicy(ctx context.Context, userAttributes []Attribute, resourceAttributes []Attribute, action string) PolicyDecision
+}
+
+const (
+    Allow PolicyDecision = true
+    Deny  PolicyDecision = false
+)
diff --git a/service.go b/service.go
new file mode 100644
index 0000000..37b8a5d
--- /dev/null
+++ b/service.go
@@ -0,0 +1,32 @@
+package abac
+
+import "context"
+
+type Service struct {
+	store        Store
+	policyEngine PolicyEngine
+}
+
+func NewService(store Store, policyEngine PolicyEngine) *Service {
+    return &Service{
+        store:        store,
+        policyEngine: policyEngine,
+    }
+}
+
+func (service *Service) HasAccess(userID, resourceID string, action string) (bool, error) {
+    userAttributes, err := service.store.GetUserAttributes(userID)
+    if err != nil {
+        return false, err
+    }
+
+    resourceAttributes, err := service.store.GetResourceAttributes(resourceID)
+    if err != nil {
+        return false, err
+    }
+
+    ctx := context.Background()
+    decision := service.policyEngine.EvaluatePolicy(ctx, userAttributes, resourceAttributes, action)
+
+    return bool(decision), nil
+}
diff --git a/simple_policy_engine.go b/simple_policy_engine.go
new file mode 100644
index 0000000..1702810
--- /dev/null
+++ b/simple_policy_engine.go
@@ -0,0 +1,40 @@
+package abac
+
+type SimplePolicyEngine struct {
+	rules []Rule
+}
+
+type Rule struct {
+	Effect    string    `json:"effect"`
+	Action    string    `json:"action"`
+	Condition Condition `json:"condition"`
+}
+
+type Condition struct {
+	AttributeKey   string `json:"attribute_key"`
+	AttributeValue string `json:"attribute_value"`
+}
+
+func (engine *SimplePolicyEngine) EvaluatePolicy(userAttributes, resourceAttributes []Attribute, action string) PolicyDecision {
+    for _, rule := range engine.rules {
+        if rule.Action == action {
+            if rule.Condition.AttributeKey != "" && rule.Condition.AttributeValue != "" {
+                attributeFound := false
+                for _, attribute := range userAttributes {
+                    if attribute.Key == rule.Condition.AttributeKey && attribute.Value == rule.Condition.AttributeValue {
+                        attributeFound = true
+                        break
+                    }
+                }
+
+                if !attributeFound {
+                    continue
+                }
+            }
+
+            return PolicyDecision(rule.Effect == "Allow")
+        }
+    }
+
+    return Deny
+}
diff --git a/sql_policy_engine.go b/sql_policy_engine.go
new file mode 100644
index 0000000..13b69e0
--- /dev/null
+++ b/sql_policy_engine.go
@@ -0,0 +1,73 @@
+package abac
+
+type SQLPolicyEngine struct {
+    store *SQLiteStore
+}
+
+func NewSQLPolicyEngine(store *SQLiteStore) *SQLPolicyEngine {
+    return &SQLPolicyEngine{store: store}
+}
+
+func (e *SQLPolicyEngine) EvaluatePolicy(userID, resourceID, action string) (PolicyDecision, error) {
+    userAttributes, err := e.store.GetUserAttributes(userID)
+    if err != nil {
+        return Deny, err
+    }
+
+    resourceAttributes, err := e.store.GetResourceAttributes(resourceID)
+    if err != nil {
+        return Deny, err
+    }
+
+    rows, err := e.store.db.Query(`
+        SELECT effect, condition_attribute_key, condition_attribute_value, condition_attribute_type
+        FROM policies
+        WHERE action = ?;
+    `, action)
+    if err != nil {
+        return Deny, err
+    }
+    defer rows.Close()
+
+    var allowPolicyFound bool = false
+    for rows.Next() {
+        var effect string
+        var conditionAttributeKey string
+        var conditionAttributeValue string
+        var conditionAttributeType string
+
+        err = rows.Scan(&effect, &conditionAttributeKey, &conditionAttributeValue)
+        if err != nil {
+            return Deny, err
+        }
+
+        var hasAttribute bool = false
+        if conditionAttributeType == "user" {
+            hasAttribute = checkAttributes(userAttributes, conditionAttributeKey, conditionAttributeValue)
+        } else if conditionAttributeType == "resource" {
+            hasAttribute = checkAttributes(resourceAttributes, conditionAttributeKey, conditionAttributeValue)
+        }
+
+        if effect == "Deny" && hasAttribute {
+            return Deny, nil
+        } else if effect == "Allow" && hasAttribute {
+            allowPolicyFound = true
+        }
+    }
+
+    if allowPolicyFound {
+        return Allow, nil
+    }
+
+    return Deny, nil
+}
+
+func checkAttributes(attributes []Attribute, key, value string) bool {
+    for _, attribute := range attributes {
+        if attribute.Key == key && attribute.Value == value {
+            return true
+        }
+    }
+
+    return false
+}
diff --git a/sqlite_store.go b/sqlite_store.go
new file mode 100644
index 0000000..bc806f9
--- /dev/null
+++ b/sqlite_store.go
@@ -0,0 +1,145 @@
+package abac
+
+import (
+	"database/sql"
+
+	"github.com/google/uuid"
+	_ "github.com/mattn/go-sqlite3"
+)
+
+type SQLiteStore struct {
+	db *sql.DB
+}
+
+func NewSQLiteStore(dbPath string) (*SQLiteStore, error) {
+	db, err := sql.Open("sqlite3", dbPath)
+	if err != nil {
+		return nil, err
+	}
+
+	store := &SQLiteStore{db: db}
+	err = store.createTables(db)
+	if err != nil {
+		return nil, err
+	}
+
+	return store, nil
+}
+
+func (s *SQLiteStore) Close() error {
+	return s.db.Close()
+}
+
+func (s *SQLiteStore) GetUserAttributes(userID string) ([]Attribute, error) {
+	rows, err := s.db.Query(`
+		SELECT a.key, a.value
+		FROM attributes a
+		JOIN user_attributes ua ON a.id = ua.attribute_id
+		WHERE ua.user_id = ?;
+	`, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var attributes []Attribute
+
+	for rows.Next() {
+		var attribute Attribute
+		err := rows.Scan(&attribute.Key, &attribute.Value)
+		if err != nil {
+			return nil, err
+		}
+
+		attributes = append(attributes, attribute)
+	}
+
+	return attributes, nil
+}
+
+func (s *SQLiteStore) GetResourceAttributes(resourceID string) ([]Attribute, error) {
+	rows, err := s.db.Query(`
+		SELECT a.key, a.value
+		FROM attributes a
+		JOIN resource_attributes ra ON a.id = ra.attribute_id
+		WHERE ra.resource_id = ?;
+	`, resourceID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var attributes []Attribute
+
+	for rows.Next() {
+		var attribute Attribute
+		err := rows.Scan(&attribute.Key, &attribute.Value)
+		if err != nil {
+			return nil, err
+		}
+
+		attributes = append(attributes, attribute)
+	}
+
+	return attributes, nil
+}
+
+func newID() string {
+	uuid, err := uuid.NewV7()
+	if err != nil {
+		panic(err)
+	}
+
+	return uuid.String()
+}
+
+func (s *SQLiteStore) CreatePolicy(effect, action, conditionAttributeKey, conditionAttributeValue string) error {
+	_, err := s.db.Exec(`
+		INSERT INTO policies (id, effect, action, condition_attribute_key, condition_attribute_value)
+		VALUES (?, ?, ?, ?, ?);
+	`, newID(), effect, action, conditionAttributeKey, conditionAttributeValue)
+	return err
+}
+
+func (s *SQLiteStore) createTables(db *sql.DB) error {
+	_, err := db.Exec(`
+		CREATE TABLE IF NOT EXISTS users (
+			id TEXT PRIMARY KEY,
+			username TEXT NOT NULL
+		);
+
+		CREATE TABLE IF NOT EXISTS resources (
+			id TEXT PRIMARY KEY,
+			name TEXT NOT NULL
+		);
+
+		CREATE TABLE IF NOT EXISTS attributes (
+			id TEXT PRIMARY KEY,
+			key TEXT NOT NULL,
+			value TEXT NOT NULL
+		);
+
+		CREATE TABLE IF NOT EXISTS user_attributes (
+			user_id TEXT NOT NULL,
+			attribute_id INTEGER NOT NULL,
+			FOREIGN KEY (user_id) REFERENCES users(id),
+			FOREIGN KEY (attribute_id) REFERENCES attributes(id)
+		);
+
+		CREATE TABLE IF NOT EXISTS resource_attributes (
+			resource_id TEXT NOT NULL,
+			attribute_id TEXT NOT NULL,
+			FOREIGN KEY (resource_id) REFERENCES resources(id),
+			FOREIGN KEY (attribute_id) REFERENCES attributes(id)
+		);
+
+		CREATE TABLE IF NOT EXISTS policies (
+			id TEXT PRIMARY KEY,
+			effect TEXT NOT NULL CHECK(effect IN ('Allow', 'Deny')),
+			action TEXT NOT NULL,
+			condition_attribute_key TEXT,
+			condition_attribute_value TEXT
+		);
+	`)
+	return err
+}
diff --git a/sqlite_store_test.go b/sqlite_store_test.go
new file mode 100644
index 0000000..d4a5301
--- /dev/null
+++ b/sqlite_store_test.go
@@ -0,0 +1,154 @@
+package abac
+
+import (
+	"testing"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func TestNewSQLiteStore(t *testing.T) {
+	dbPath := ":memory:"
+	store, err := NewSQLiteStore(dbPath)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	defer store.Close()
+
+	if store.db == nil {
+		t.Errorf("expected db to be not nil")
+	}
+}
+
+func TestClose(t *testing.T) {
+	dbPath := ":memory:"
+	store, err := NewSQLiteStore(dbPath)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	err = store.Close()
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+}
+
+func TestGetUserAttributes(t *testing.T) {
+    store, err := NewSQLiteStore(":memory:")
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	defer store.Close()
+
+	userID := "user-id"
+	attributeKey := "key"
+	attributeValue := "value"
+
+	_, err = store.db.Exec(`
+    INSERT INTO users (id, username) VALUES (?, ?);
+    `, userID, "username")
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+    attributeId := newID()
+	_, err = store.db.Exec(`
+    INSERT INTO attributes (id, key, value) VALUES (?, ?, ?);
+    `, attributeId, attributeKey, attributeValue)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+	_, err = store.db.Exec(`
+    INSERT INTO user_attributes (user_id, attribute_id) VALUES (?, ?);
+    `, userID, attributeId)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+	attributes, err := store.GetUserAttributes(userID)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+    t.Logf("attributes: %v", attributes)
+	if len(attributes) == 0 {
+		t.Errorf("expected at least one attribute")
+	}
+	if attributes[0].Key != attributeKey || attributes[0].Value != attributeValue {
+		t.Errorf("expected key=%s and value=%s but got key=%s and value=%s",
+			attributeKey, attributeValue, attributes[0].Key, attributes[0].Value)
+	}
+}
+
+func TestGetResourceAttributes(t *testing.T) {
+	dbPath := ":memory:"
+	store, err := NewSQLiteStore(dbPath)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	defer store.Close()
+
+	resourceID := "resource-id"
+	attributeKey := "key"
+	attributeValue := "value"
+
+	_, err = store.db.Exec(`
+    INSERT INTO resources (id, name) VALUES (?, ?);
+    `, resourceID, "name")
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+    attributeId := newID()
+	_, err = store.db.Exec(`
+    INSERT INTO attributes (id, key, value) VALUES (?, ?, ?);
+    `, attributeId, attributeKey, attributeValue)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+	_, err = store.db.Exec(`
+    INSERT INTO resource_attributes (resource_id, attribute_id) VALUES (?, ?);
+    `, resourceID, attributeId)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+	attributes, err := store.GetResourceAttributes(resourceID)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	if len(attributes) == 0 {
+		t.Errorf("expected at least one attribute")
+	}
+	if attributes[0].Key != attributeKey || attributes[0].Value != attributeValue {
+		t.Errorf("expected key=%s and value=%s but got key=%s and value=%s",
+			attributeKey, attributeValue, attributes[0].Key, attributes[0].Value)
+	}
+}
+
+func TestCreatePolicy(t *testing.T) {
+	dbPath := ":memory:"
+	store, err := NewSQLiteStore(dbPath)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	defer store.Close()
+
+	effect := "Allow"
+	action := "action"
+	conditionAttributeKey := "key"
+	conditionAttributeValue := "value"
+
+	err = store.CreatePolicy(effect, action, conditionAttributeKey, conditionAttributeValue)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+
+	var id string
+	err = store.db.QueryRow(`SELECT id FROM policies;`).Scan(&id)
+	if err != nil {
+		t.Errorf("expected no error but got %v", err)
+	}
+	if id == "" {
+		t.Errorf("expected policy id to be not empty")
+	}
+}
diff --git a/store.go b/store.go
new file mode 100644
index 0000000..2fe886b
--- /dev/null
+++ b/store.go
@@ -0,0 +1,8 @@
+package abac
+
+type Store interface {
+    GetUserAttributes(userID string) ([]Attribute, error)
+    GetRoleAttributes(roleID string) ([]Attribute, error)
+    GetResourceAttributes(resourceID string) ([]Attribute, error)
+    HasAccess(userID, resourceID, action string) (bool, error)
+}