From fdd25200f8038d750c3315e61bbb443f1dcde46a Mon Sep 17 00:00:00 2001
From: Yusuke Tsutsumi <yusuke@tsutsumi.io>
Date: Tue, 14 Jan 2025 10:47:36 -0800
Subject: [PATCH] wip: use cel2db to CEL -> SQL conversion

a proof of concept of cel2db, written in Rust,
being consumed by our example service.

In the future, this pattern will be productionalized
via some simple way to consume the native library
in a native go repository. But for now, this proves
the viability.
---
 .gitignore                  |  2 ++
 BUILD.bazel                 |  0
 DEVELOPMENT.md              | 15 ++++++++++++++-
 example/service/cel.go      | 16 ++++++++++++++++
 example/service/cel_test.go |  5 +++++
 5 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 BUILD.bazel

diff --git a/.gitignore b/.gitignore
index 6a07036..ef96c38 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 main
 terraform-provider-bookstore
+# libcel2db should be compiled and added.
+example/service/libcel2db.a
\ No newline at end of file
diff --git a/BUILD.bazel b/BUILD.bazel
new file mode 100644
index 0000000..e69de29
diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index 923db5e..f3b043a 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -27,4 +27,17 @@ go install github.com/aep-dev/api-linter/cmd/api-linter@latest
 The standard GoLang toolchain is used, with the addition of protobuf for
 compiling the resource definition.
 1. `./scripts/regenerate-all.sh`
-2. `go build main.go`
\ No newline at end of file
+2. `go build main.go`
+
+## Importing cel2db
+
+Today, the CEL <-> SQL translation in the example service requireds [cel2db](https://github.com/aep-dev/cel2db), written in Rust and therefore not compatible with the standard `go get` approach to managing dependencies.
+
+This will be streamlined in the future, but for now, do the following (bazel and rust build tooling is required):
+
+```bash
+git clone git@github.com:aep-dev/cel2db.git
+cd ./cel2db
+bazel build //cel2db:cel2db_static
+cp bazel-bin/cel2db/libcel2db.a ${AEPC_REPO}/example/service/
+```
\ No newline at end of file
diff --git a/example/service/cel.go b/example/service/cel.go
index 14e6a40..8a4977d 100644
--- a/example/service/cel.go
+++ b/example/service/cel.go
@@ -1,11 +1,27 @@
 package service
 
+// required for cel2db.
+
+// extern char *cel_to_sql(const char *cel_expr, const char *sql_dialect);
+// #cgo LDFLAGS: -L ${SRCDIR} -lcel2db
+import "C"
+
 import (
+	"errors"
+
 	"github.com/aep-dev/aepc/pkg/cel2ansisql"
 	"github.com/google/cel-go/cel"
 )
 
 func convertCELToSQL(expr string) (string, error) {
+	condition := C.cel_to_sql(C.CString(expr), C.CString("sqlite"))
+	if condition == nil {
+		return "", errors.New("failed to convert CEL to SQL")
+	}
+	return C.GoString(condition), nil
+}
+
+func convertCELToSQL2(expr string) (string, error) {
 	if expr == "" {
 		return "", nil
 	}
diff --git a/example/service/cel_test.go b/example/service/cel_test.go
index e19f63a..f65eb11 100644
--- a/example/service/cel_test.go
+++ b/example/service/cel_test.go
@@ -15,6 +15,11 @@ func TestCELToSQL(t *testing.T) {
 			input:    "description.startsWith('tomorrow')",
 			expected: "description LIKE CONCAT('tomorrow', '%')",
 		},
+		{
+			name:     "arithemtic",
+			input:    "1 + 2",
+			expected: "1 + 2",
+		},
 		{
 			name:     "empty",
 			input:    "",