package payments

import (
	"go/parser"
	"go/token"
	"io/fs"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
)

// TestPaymentsSchemaImportBoundary enforces that only this package reaches the
// payments jet code. The payments schema is isolated behind this domain; the
// application connects to Postgres as a superuser that bypasses the schema
// grants, so the runtime wall that keeps every other package out of payments.*
// is this import boundary, not the DB privileges. If another package imported
// the generated payments tables it could issue SQL against the schema directly,
// breaking the single-writer guarantee and the domain's extractability.
func TestPaymentsSchemaImportBoundary(t *testing.T) {
	const jetPkg = "scrabble/backend/internal/postgres/jet/payments"

	_, thisFile, _, ok := runtime.Caller(0)
	if !ok {
		t.Fatal("cannot resolve the test file path")
	}
	// thisFile = .../backend/internal/payments/boundary_test.go
	backendRoot := filepath.Clean(filepath.Join(filepath.Dir(thisFile), "..", ".."))
	allowedPrefix := filepath.Join(backendRoot, "internal", "payments") + string(filepath.Separator)

	fset := token.NewFileSet()
	walkErr := filepath.WalkDir(backendRoot, func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() || !strings.HasSuffix(path, ".go") {
			return nil
		}
		file, perr := parser.ParseFile(fset, path, nil, parser.ImportsOnly)
		if perr != nil {
			return perr
		}
		for _, imp := range file.Imports {
			p := strings.Trim(imp.Path.Value, `"`)
			if p != jetPkg && !strings.HasPrefix(p, jetPkg+"/") {
				continue
			}
			if !strings.HasPrefix(path, allowedPrefix) {
				t.Errorf("%s imports %s — only internal/payments may reach the payments jet code", path, p)
			}
		}
		return nil
	})
	if walkErr != nil {
		t.Fatalf("walk backend tree: %v", walkErr)
	}
}