WIP on config

generate/config.go

@@ -0,0 +1,76 @@
+package generate
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+
+	"gopkg.in/yaml.v2"
+)
+
+var defaultConfig = &Config{
+	Schema:    "schema.graphql",
+	Queries:   "queries.graphql",
+	Generated: "generated.go",
+}
+
+type Config struct {
+	// The package name for the output code; defaults to the directory name of
+	// Generated
+	Package string `yaml:"package"`
+	// The filename with the GraphQL schema (in SDL format); defaults to
+	// schema.graphql
+	// TODO: allow other formats
+	// TODO: allow URLs
+	Schema string `yaml:"schema"`
+	// The filename with the queries; defaults to queries.graphql
+	Queries string `yaml:"queries"`
+	// The filename to which to write the generated code; defaults to
+	// generated.go
+	Generated string `yaml:"generated"`
+}
+
+func (c *Config) ValidateAndFillDefaults() error {
+	if c.Schema == "" {
+		c.Schema = defaultConfig.Schema
+	}
+	if c.Queries == "" {
+		c.Queries = defaultConfig.Queries
+	}
+	if c.Generated == "" {
+		c.Generated = defaultConfig.Generated
+	}
+
+	if c.Package == "" {
+		abs, err := filepath.Abs(c.Generated)
+		if err != nil {
+			return fmt.Errorf("unable to guess package-name: %v", err)
+		}
+
+		base := filepath.Base(abs)
+		// TODO: remove/replace bad chars, make sure there's something left?
+		c.Package = base
+	}
+
+	return nil
+}
+
+func ReadAndValidateConfig(filename string) (*Config, error) {
+	text, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, fmt.Errorf("unreadable config file %v: %v", filename, err)
+	}
+
+	var config Config
+	err = yaml.Unmarshal(text, config)
+	if err != nil {
+		return nil, fmt.Errorf("invalid config file %v: %v", filename, err)
+	}
+
+	err = config.ValidateAndFillDefaults()
+	if err != nil {
+		return nil, fmt.Errorf("invalid config file %v: %v", filename, err)
+	}
+
+	return &config, nil
+}

generate/generate.go

@@ -90,7 +90,6 @@ func fromASTOperation(op *ast.OperationDefinition, schema *ast.Schema) operation
 }
 
 func Generate(schema *ast.Schema, document *ast.QueryDocument) ([]byte, error) {
-	// TODO: this should probably get factored out
 	operations := make([]operation, len(document.Operations))
 	for i, op := range document.Operations {
 		operations[i] = fromASTOperation(op, schema)

generate/main.go

@@ -2,30 +2,27 @@ package generate
 
 import (
 	"fmt"
-	"io"
 	"os"
 )
 
-func outputWriter(filename string) (io.Writer, error) {
-	if filename == "-" {
-		return os.Stdout, nil
-	}
-
-	f, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
-	if err != nil {
-		return nil, fmt.Errorf("could not open generated file %v: %v",
-			filename, err)
-	}
-	return f, nil
-}
-
-func ParseGenerateAndWrite(specFilename, schemaFilename string, out io.Writer) error {
-	schema, err := getSchema(schemaFilename)
+func parseGenerateAndWrite(configFilename string) error {
+	config, err := ReadAndValidateConfig(configFilename)
 	if err != nil {
 		return err
 	}
 
-	document, err := getAndValidateQueries(specFilename, schema)
+	out, err := os.OpenFile(config.Generated, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return fmt.Errorf("could not open generated file %v: %v",
+			config.Generated, err)
+	}
+
+	schema, err := getSchema(config.Schema)
+	if err != nil {
+		return err
+	}
+
+	document, err := getAndValidateQueries(config.Queries, schema)
 	if err != nil {
 		return err
 	}
@@ -48,16 +45,10 @@ func Main() {
 		}
 	}()
 
-	if len(os.Args) != 4 {
-		err = fmt.Errorf("usage: %s queries.graphql schema.graphql generated.go",
-			os.Args[0])
+	if len(os.Args) != 2 {
+		err = fmt.Errorf("usage: %s genql.yaml", os.Args[0])
 		return
 	}
 
-	out, err := outputWriter(os.Args[3])
-	if err != nil {
-		return
-	}
-
-	err = ParseGenerateAndWrite(os.Args[1], os.Args[2], out)
+	err = parseGenerateAndWrite(os.Args[1])
 }

go.mod

@@ -7,4 +7,5 @@ require (
 	github.com/shurcooL/graphql v0.0.0-20181231061246-d48a9a75455f // indirect
 	github.com/vektah/gqlparser v1.2.0
 	golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553 // indirect
+	gopkg.in/yaml.v2 v2.2.2
 )

graphql/client.go

@@ -30,6 +30,7 @@ type payload struct {
 }
 
 func (client *Client) MakeRequest(ctx context.Context, query string, retval interface{}, variables map[string]interface{}) error {
+	// TODO: streaming reads and writes
 	body, err := json.Marshal(payload{
 		Query:     query,
 		Variables: variables,