feat: add local schema diff

If no remote URI is specified for schema diff it will attempt to diff the local project

closes #2174

cmd/ftl/cmd_schema_diff.go

@@ -2,39 +2,65 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/url"
 	"os"
+	"path/filepath"
 
 	"connectrpc.com/connect"
 	"github.com/alecthomas/chroma/v2/quick"
 	"github.com/hexops/gotextdiff"
 	"github.com/hexops/gotextdiff/myers"
 	"github.com/hexops/gotextdiff/span"
 	"github.com/mattn/go-isatty"
+	"google.golang.org/protobuf/proto"
 
 	ftlv1 "github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1"
 	"github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/ftlv1connect"
 	schemapb "github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/schema"
 	"github.com/TBD54566975/ftl/backend/schema"
+	"github.com/TBD54566975/ftl/common/projectconfig"
 	"github.com/TBD54566975/ftl/internal/log"
 	"github.com/TBD54566975/ftl/internal/rpc"
 )
 
 type schemaDiffCmd struct {
-	OtherEndpoint url.URL `arg:"" help:"Other endpoint URL to compare against."`
+	OtherEndpoint url.URL `arg:"" help:"Other endpoint URL to compare against. If this is not specified then ftl will perform a diff against the local schema." optional:""`
 	Color         bool    `help:"Enable colored output regardless of TTY."`
 }
 
-func (d *schemaDiffCmd) Run(ctx context.Context, currentURL *url.URL) error {
-	other, err := schemaForURL(ctx, d.OtherEndpoint)
+func (d *schemaDiffCmd) Run(ctx context.Context, currentURL *url.URL, projConfig projectconfig.Config) error {
+	var other *schema.Schema
+	var err error
+	sameModulesOnly := false
+	if d.OtherEndpoint.String() == "" {
+		sameModulesOnly = true
+		other, err = localSchema(projConfig)
+	} else {
+		other, err = schemaForURL(ctx, d.OtherEndpoint)
+	}
+
 	if err != nil {
 		return fmt.Errorf("failed to get other schema: %w", err)
 	}
 	current, err := schemaForURL(ctx, *currentURL)
 	if err != nil {
 		return fmt.Errorf("failed to get current schema: %w", err)
 	}
+	if sameModulesOnly {
+		tempModules := current.Modules
+		current.Modules = []*schema.Module{}
+		moduleMap := map[string]*schema.Module{}
+		for _, i := range tempModules {
+			moduleMap[i.Name] = i
+		}
+		for _, i := range other.Modules {
+			if mod, ok := moduleMap[i.Name]; ok {
+				current.Modules = append(current.Modules, mod)
+			}
+		}
+	}
 
 	edits := myers.ComputeEdits(span.URIFromPath(""), other.String(), current.String())
 	diff := fmt.Sprint(gotextdiff.ToUnified(d.OtherEndpoint.String(), currentURL.String(), other.String(), edits))
@@ -57,6 +83,60 @@ func (d *schemaDiffCmd) Run(ctx context.Context, currentURL *url.URL) error {
 	return nil
 }
 
+func localSchema(moduleDirs projectconfig.Config) (*schema.Schema, error) {
+	pb := &schemapb.Schema{}
+	found := false
+	tried := ""
+	moduleFound := false
+	moduleTried := ""
+	for _, modulePaths := range moduleDirs.AbsModuleDirs() {
+		entries, err := os.ReadDir(modulePaths)
+		if err != nil {
+			return nil, fmt.Errorf("failed to list directory %w", err)
+		}
+		for _, module := range entries {
+			if !module.IsDir() {
+				continue
+			}
+			path := filepath.Join(modulePaths, module.Name(), ".ftl", "schema.pb")
+			mod, err := loadProtoSchema(path)
+			if err != nil {
+				moduleTried += fmt.Sprintf("failed to read schema file %s; did you run ftl build?", path)
+			} else {
+				moduleFound = true
+				found = true
+				pb.Modules = append(pb.Modules, mod)
+			}
+		}
+	}
+	if !moduleFound {
+		tried += moduleTried
+	}
+
+	if !found {
+		return nil, errors.New(tried)
+	}
+
+	s, err := schema.FromProto(pb)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse local schema: %w", err)
+	}
+	return s, nil
+}
+
+func loadProtoSchema(file string) (*schemapb.Module, error) {
+	content, err := os.ReadFile(file)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read schema file %w", err)
+	}
+	module := &schemapb.Module{}
+	err = proto.Unmarshal(content, module)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal schema %w", err)
+	}
+	return module, nil
+}
+
 func schemaForURL(ctx context.Context, url url.URL) (*schema.Schema, error) {
 	client := rpc.Dial(ftlv1connect.NewControllerServiceClient, url.String(), log.Error)
 	resp, err := client.PullSchema(ctx, connect.NewRequest(&ftlv1.PullSchemaRequest{}))