feat: surface errors to users

Makefile

@@ -2,5 +2,17 @@
 build-wasm: build/preview.wasm
 	mkdir -p public/build
 
+# TODO: remove vendoring workaround
 build/preview.wasm: $(GO_SRC_FILES)
-	GOOS=js GOARCH=wasm go build -C ./preview -o ../public/build/preview.wasm .
+	cd preview && go mod vendor
+	(find preview/vendor -name "*.go" -type f -exec sed -i 's/os\.Getwd()/"", nil/g' {} +)
+	GOOS=js GOARCH=wasm go build -C ./preview -o ../public/build/preview.wasm
+	rm -rf preview/vendor
+
+.PHONY: gen-types
+gen-types: src/gen/types.ts
+
+src/gen/types.ts: preview/scripts/types/main.go preview/apitypes/apitypes.go
+	mkdir -p src/gen
+	go run -C ./preview/scripts/types main.go > $@
+	touch "$@"

preview/apitypes/apitypes.go

@@ -0,0 +1,30 @@
+package apitypes
+
+import (
+	"time"
+
+	"github.com/coder/preview"
+	"github.com/coder/preview/types"
+)
+
+type PreviewOutput struct {
+	Output *preview.Output   `json:"output"`
+	Diags  types.Diagnostics `json:"diags"`
+	// ParserLogs are trivy logs that occur during parsing the
+	// Terraform files. This is useful for debugging issues with the
+	// invalid terraform syntax.
+	ParserLogs []ParserLog `json:"parser_logs,omitempty"`
+}
+
+type ParserLog struct {
+	Time    time.Time `json:"time"`
+	Level   string    `json:"level"`
+	Message string    `json:"msg"`
+	Prefix  string    `json:"prefix"`
+	Module  string    `json:"root"`
+	Err     string    `json:"err"`
+}
+
+type NullHCLString = types.NullHCLString
+
+type FriendlyDiagnostic = types.FriendlyDiagnostic

preview/go.mod

@@ -1,9 +1,11 @@
-module github.com/brettkolodny/parameters-playground/preview
+module github.com/coder/parameters-playground/preview
 
 go 1.24.3
 
 require (
+	github.com/coder/guts v1.5.0
 	github.com/coder/preview v0.0.2-0.20250528204104-320b553c3e2c
+	github.com/hashicorp/hcl/v2 v2.23.0
 	github.com/spf13/afero v1.14.0
 )
 
@@ -30,15 +32,20 @@ require (
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cncf/xds/go v0.0.0-20250121191232-2f005788dc42 // indirect
 	github.com/coder/terraform-provider-coder/v2 v2.4.2 // indirect
+	github.com/dlclark/regexp2 v1.11.4 // indirect
+	github.com/dop251/goja v0.0.0-20241024094426-79f3a7efcdbd // indirect
 	github.com/envoyproxy/go-control-plane/envoy v1.32.4 // indirect
 	github.com/envoyproxy/protoc-gen-validate v1.2.1 // indirect
 	github.com/fatih/color v1.18.0 // indirect
+	github.com/fatih/structtag v1.2.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/go-jose/go-jose/v4 v4.0.5 // indirect
 	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-sourcemap/sourcemap v2.1.3+incompatible // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/google/pprof v0.0.0-20240227163752-401108e1b7e7 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
@@ -52,7 +59,6 @@ require (
 	github.com/hashicorp/go-safetemp v1.0.0 // indirect
 	github.com/hashicorp/go-uuid v1.0.3 // indirect
 	github.com/hashicorp/go-version v1.7.0 // indirect
-	github.com/hashicorp/hcl/v2 v2.23.0 // indirect
 	github.com/hashicorp/logutils v1.0.0 // indirect
 	github.com/hashicorp/terraform-json v0.24.0 // indirect
 	github.com/hashicorp/terraform-plugin-go v0.26.0 // indirect

preview/go.sum

@@ -632,6 +632,9 @@ github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/cloudmock v0
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.49.0 h1:GYUJLfvd++4DMuMhCFLgLXvFwofIxh/qOwoGuS/LTew=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.49.0/go.mod h1:wRbFgBQUVm1YXrvWKofAEmq9HNJTDphbAaJSSX01KUI=
 github.com/JohnCGriffin/overflow v0.0.0-20211019200055-46fa312c352c/go.mod h1:X0CRv0ky0k6m906ixxpzmDRLvX58TFUKS2eePweuyxk=
+github.com/Masterminds/semver v1.5.0 h1:H65muMkzWKEuNDnfl9d70GUjFniHKHRbFPGBuZ3QEww=
+github.com/Masterminds/semver/v3 v3.3.0 h1:B8LGeaivUe71a5qox1ICM/JLl0NqZSW5CHyL+hmvYS0=
+github.com/Masterminds/semver/v3 v3.3.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
 github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
 github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
@@ -702,12 +705,10 @@ github.com/cncf/xds/go v0.0.0-20230105202645-06c439db220b/go.mod h1:eXthEFrGJvWH
 github.com/cncf/xds/go v0.0.0-20230607035331-e9ce68804cb4/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20250121191232-2f005788dc42 h1:Om6kYQYDUk5wWbT0t0q6pvyM49i9XZAv9dDrkDA7gjk=
 github.com/cncf/xds/go v0.0.0-20250121191232-2f005788dc42/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
-github.com/coder/preview v0.0.1 h1:2X5McKdMOZJILTIDf7qRplXKupT+91qTJBN67XUh5cA=
-github.com/coder/preview v0.0.1/go.mod h1:eInDmOdSDF8cxCvapIvYkGRzmzvcvGAFL1HYqcA4g+E=
+github.com/coder/guts v1.5.0 h1:a94apf7xMf5jDdg1bIHzncbRiTn3+BvBZgrFSDbUnyI=
+github.com/coder/guts v1.5.0/go.mod h1:0Sbv5Kp83u1Nl7MIQiV2zmacJ3o02I341bkWkjWXSUQ=
 github.com/coder/preview v0.0.2-0.20250528204104-320b553c3e2c h1:ShixosbLEdK6/RfFI1MTAKsYOTyhUOk7jwcJ70Yp0Wg=
 github.com/coder/preview v0.0.2-0.20250528204104-320b553c3e2c/go.mod h1:Ltd83BrbNN7Nj+hToa6My7xTTj8FVa2xNk5589b1DJc=
-github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250417100258-c86bb5c3ddcd h1:FsIG6Fd0YOEK7D0Hl/CJywRA+Y6Gd5RQbSIa2L+/BmE=
-github.com/coder/terraform-provider-coder/v2 v2.4.0-pre1.0.20250417100258-c86bb5c3ddcd/go.mod h1:56/KdGYaA+VbwXJbTI8CA57XPfnuTxN8rjxbR34PbZw=
 github.com/coder/terraform-provider-coder/v2 v2.4.2 h1:41SJkgwgiA555kwQzGIQcNS3bCm12sVMUmBSa5zGr+A=
 github.com/coder/terraform-provider-coder/v2 v2.4.2/go.mod h1:2kaBpn5k9ZWtgKq5k4JbkVZG9DzEqR4mJSmpdshcO+s=
 github.com/coder/trivy v0.0.0-20250527170238-9416a59d7019 h1:MHkv/W7l9eRAN9gOG0qZ1TLRGWIIfNi92273vPAQ8Fs=
@@ -736,6 +737,8 @@ github.com/docker/go-connections v0.5.0/go.mod h1:ov60Kzw0kKElRwhNs9UlUHAE/F9Fe6
 github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
 github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
 github.com/docopt/docopt-go v0.0.0-20180111231733-ee0de3bc6815/go.mod h1:WwZ+bS3ebgob9U8Nd0kOddGdZWjyMGR8Wziv+TBNwSE=
+github.com/dop251/goja v0.0.0-20241024094426-79f3a7efcdbd h1:QMSNEh9uQkDjyPwu/J541GgSH+4hw+0skJDIj9HJ3mE=
+github.com/dop251/goja v0.0.0-20241024094426-79f3a7efcdbd/go.mod h1:MxLav0peU43GgvwVgNbLAj1s/bSGboKkhuULvq/7hx4=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/ebitengine/purego v0.8.2 h1:jPPGWs2sZ1UgOSgD2bClL0MJIqu58nOmIcBuXr62z1I=
 github.com/ebitengine/purego v0.8.2/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
@@ -768,6 +771,8 @@ github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5Kwzbycv
 github.com/fatih/color v1.13.0/go.mod h1:kLAiJbzzSOZDVNGyDpeOxJ47H46qBXwg5ILebYFFOfk=
 github.com/fatih/color v1.18.0 h1:S8gINlzdQ840/4pfAwic/ZE0djQEH3wM94VfqLTZcOM=
 github.com/fatih/color v1.18.0/go.mod h1:4FelSpRwEGDpQ12mAdzqdOukCy4u8WUtOY6lkT/6HfU=
+github.com/fatih/structtag v1.2.0 h1:/OdNE99OxoI/PqaW/SuSK9uxxT3f/tcSZgon/ssNSx4=
+github.com/fatih/structtag v1.2.0/go.mod h1:mBJUNpUnHmRKrKlQQlmCrh5PuhftFbNv8Ys4/aAZl94=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/fogleman/gg v1.2.1-0.20190220221249-0403632d5b90/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
@@ -800,6 +805,8 @@ github.com/go-ole/go-ole v1.3.0 h1:Dt6ye7+vXGIKZ7Xtk4s6/xVdGDQynvom7xCFEdWr6uE=
 github.com/go-ole/go-ole v1.3.0/go.mod h1:5LS6F96DhAwUc7C+1HLexzMXY1xGRSryjyPPKW6zv78=
 github.com/go-pdf/fpdf v0.5.0/go.mod h1:HzcnA+A23uwogo0tp9yU+l3V+KXhiESpt1PMayhOh5M=
 github.com/go-pdf/fpdf v0.6.0/go.mod h1:HzcnA+A23uwogo0tp9yU+l3V+KXhiESpt1PMayhOh5M=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible h1:W1iEw64niKVGogNgBN3ePyLFfuisuzeidWPMPWmECqU=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
 github.com/go-test/deep v1.0.3 h1:ZrJSEWsXzPOxaZnFteGEfooLba+ju3FYIbOrS+rQd68=
 github.com/go-test/deep v1.0.3/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
 github.com/goccy/go-json v0.9.11/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
@@ -893,6 +900,8 @@ github.com/google/pprof v0.0.0-20210226084205-cbba55b83ad5/go.mod h1:kpwsk12EmLe
 github.com/google/pprof v0.0.0-20210601050228-01bbb1931b22/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20210609004039-a478d1d731e9/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20210720184732-4bb14d4b1be1/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
+github.com/google/pprof v0.0.0-20240227163752-401108e1b7e7 h1:y3N7Bm7Y9/CtpiVkw/ZWj6lSlDF3F74SfKwfTCer72Q=
+github.com/google/pprof v0.0.0-20240227163752-401108e1b7e7/go.mod h1:czg5+yv1E0ZGTi6S6vVK1mke0fV+FaUhNGcd6VRS9Ik=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/s2a-go v0.1.9 h1:LGD7gtMgezd8a/Xak7mEWL0PjoTQFvpRudN895yqKW0=
 github.com/google/s2a-go v0.1.9/go.mod h1:YA0Ei2ZQL3acow2O62kdp9UlnvMmU7kA6Eutn0dXayM=
@@ -1592,8 +1601,6 @@ golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/tools v0.7.0/go.mod h1:4pg6aUX35JBAogB10C9AtvVL+qowtN4pT3CGSQex14s=
 golang.org/x/tools v0.13.0/go.mod h1:HvlwmtVNQAhOuCjW7xxvovg8wbNq7LwfXh/k7wXUl58=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=
-golang.org/x/tools v0.32.0 h1:Q7N1vhpkQv7ybVzLFtTjvQya2ewbwNDZzUgfXGqtMWU=
-golang.org/x/tools v0.32.0/go.mod h1:ZxrU41P/wAbZD8EDa6dDCa6XfpkhJ7HFMjHJXfBDu8s=
 golang.org/x/tools v0.33.0 h1:4qz2S3zmRxbGIhDIAgjxvFutSvH5EfnsYrRBj0UI0bc=
 golang.org/x/tools v0.33.0/go.mod h1:CIJMaWEY88juyUfo7UbgPqbC8rU2OqfAV1h2Qp0oMYI=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

preview/main.go

@@ -3,20 +3,23 @@
 package main
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
 	"io/fs"
 	"log/slog"
 	"path/filepath"
+	"sync"
 	"syscall/js"
+	"time"
 
 	"github.com/hashicorp/hcl/v2"
 	"github.com/spf13/afero"
 
 	"github.com/coder/preview"
 	"github.com/coder/preview/types"
+
+	"github.com/coder/parameters-playground/preview/apitypes"
 )
 
 func main() {
@@ -31,23 +34,14 @@ func main() {
 	<-done
 }
 
-type previewOutput struct {
-	Output *preview.Output   `json:"output"`
-	Diags  types.Diagnostics `json:"diags"`
-	// ParserLogs are trivy logs that occur during parsing the
-	// Terraform files. This is useful for debugging issues with the
-	// invalid terraform syntax.
-	ParserLogs string `json:"parser_logs,omitempty"`
-}
-
 func tfpreview(this js.Value, p []js.Value) (output any) {
-	var buf bytes.Buffer
+	l := NewLogger()
 	defer func() {
 		// Return a panic as a diagnostic if one occurs.
 		if r := recover(); r != nil {
-			data, _ := json.Marshal(previewOutput{
+			data, _ := json.Marshal(apitypes.PreviewOutput{
 				Output:     nil,
-				ParserLogs: buf.String(),
+				ParserLogs: l.entries,
 				Diags: types.Diagnostics{
 					{
 						Severity: hcl.DiagError,
@@ -67,10 +61,8 @@ func tfpreview(this js.Value, p []js.Value) (output any) {
 		return err
 	}
 
-	logger := slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{
-		AddSource: false,
-		Level:     slog.LevelDebug,
-	}))
+	handler := slog.NewJSONHandler(l, nil)
+	logger := slog.New(handler)
 	pOutput, diags := preview.Preview(context.Background(), preview.Input{
 		PlanJSONPath:    "",
 		PlanJSON:        nil,
@@ -79,10 +71,10 @@ func tfpreview(this js.Value, p []js.Value) (output any) {
 		Logger:          logger,
 	}, tf)
 
-	data, _ := json.Marshal(previewOutput{
+	data, _ := json.Marshal(apitypes.PreviewOutput{
 		Output:     pOutput,
 		Diags:      types.Diagnostics(diags),
-		ParserLogs: buf.String(),
+		ParserLogs: l.entries,
 	})
 
 	return js.ValueOf(string(data))
@@ -125,3 +117,31 @@ func loadTree(mem afero.Fs, fileTree map[string]any, path ...string) {
 		}
 	}
 }
+
+type Logger struct {
+	mu      sync.Mutex
+	entries []apitypes.ParserLog
+}
+
+func NewLogger() *Logger {
+	return &Logger{
+		entries: make([]apitypes.ParserLog, 0),
+	}
+}
+
+func (l *Logger) Write(p []byte) (n int, err error) {
+	var entry apitypes.ParserLog
+	if err := json.Unmarshal(p, &entry); err != nil {
+		entry = apitypes.ParserLog{
+			Time:    time.Now(),
+			Level:   "unknown",
+			Message: string(p),
+		}
+	}
+
+	l.mu.Lock()
+	l.entries = append(l.entries, entry)
+	l.mu.Unlock()
+
+	return len(p), nil
+}