load default variables from the plugin metadata #669

pkg/plugins/plugin.go

@@ -3,7 +3,6 @@ package plugins
 import (
 	"bytes"
 	"context"
-	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -181,7 +180,7 @@ func NewPlugin(command string) *Plugin {
 // Use the context for cancelation.
 func (p *Plugin) Run(ctx context.Context) {
 	var err error
-	p.Variables, err = p.loadVariablesFromJSONFile()
+	p.Variables, err = p.loadVariablesAsEnvVars()
 	if err != nil {
 		p.Debugf("ERR: %s", err)
 		p.OnErr(err)
@@ -316,34 +315,6 @@ func (p *Plugin) refresh(ctx context.Context) error {
 	return nil
 }
 
-func (p *Plugin) loadVariablesFromJSONFile() ([]string, error) {
-	variablesJSONFilename := p.Command + variableJSONFileExt
-	f, err := os.Open(variablesJSONFilename)
-	if err != nil && os.IsNotExist(err) {
-		// no .vars.json file - no probs
-		p.Debugf("(skipping) no variable file: %s", variablesJSONFilename)
-		return nil, nil
-	} else if err != nil {
-		p.Debugf("ERR: %s", variablesJSONFilename, err)
-		p.OnErr(err)
-	}
-	defer f.Close()
-	b, err := io.ReadAll(io.LimitReader(f, 1_000_000))
-	if err != nil {
-		return nil, err
-	}
-	p.Debugf("%s: %s", variablesJSONFilename, string(b))
-	var varmap map[string]interface{}
-	if err := json.Unmarshal(b, &varmap); err != nil {
-		return nil, errors.Wrap(err, "json.Unmarshal")
-	}
-	var vars []string
-	for k, v := range varmap {
-		vars = append(vars, fmt.Sprintf("%s=%v", k, v))
-	}
-	return vars, nil
-}
-
 // OnErr is called when something has gone wrong at some point.
 func (p *Plugin) OnErr(err error) {
 	p.Items.CycleItems = []*Item{

pkg/plugins/testdata/vars-test/plugin.sh

@@ -1,3 +1,9 @@
 #!/bin/bash
+
+# <xbar.var>string(XBAR_TEST_EXPLICIT_VAR): An explicit variable</xbar.var>
+# <xbar.var>string(XBAR_TEST_DEFAULT_VAR="default-value"): A default variable (from metadata)</xbar.var>
+# <xbar.var>string(XBAR_TEST_SET_IN_VARS_JSON): A variable set in the JSON</xbar.var>
+
 echo "XBAR_TEST_EXPLICIT_VAR=${XBAR_TEST_EXPLICIT_VAR}"
 echo "XBAR_TEST_SET_IN_VARS_JSON=${XBAR_TEST_SET_IN_VARS_JSON}"
+echo "XBAR_TEST_DEFAULT_VAR=${XBAR_TEST_DEFAULT_VAR}"

pkg/plugins/variables.go

@@ -2,11 +2,14 @@ package plugins
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sync"
 
+	"github.com/matryer/xbar/pkg/metadata"
 	"github.com/pkg/errors"
 )
 
@@ -50,3 +53,93 @@ func LoadVariableValues(pluginDir, installedPluginPath string) (map[string]inter
 	}
 	return values, nil
 }
+
+func (p *Plugin) loadVariablesAsEnvVars() ([]string, error) {
+	vars, err := p.loadVariables()
+	if err != nil {
+		return nil, errors.Wrap(err, "loadVariables")
+	}
+	envvars := make([]string, 0, len(vars))
+	for k, v := range vars {
+		envvars = append(envvars, fmt.Sprintf("%s=%v", k, v))
+	}
+	return envvars, nil
+}
+
+func (p *Plugin) loadVariables() (map[string]interface{}, error) {
+	var wg sync.WaitGroup
+	var defaultVars, jsonFileVars map[string]interface{}
+	var defaultVarsErr, jsonFileVarsErr error
+	wg.Add(1)
+	go func() {
+		defaultVars, defaultVarsErr = p.loadVariablesFromPluginMetadata()
+		wg.Done()
+	}()
+	wg.Add(1)
+	go func() {
+		jsonFileVars, jsonFileVarsErr = p.loadVariablesFromJSONFile()
+		wg.Done()
+	}()
+	wg.Wait()
+	if defaultVarsErr != nil {
+		return nil, errors.Wrap(defaultVarsErr, "load default vars")
+	}
+	if jsonFileVarsErr != nil {
+		return nil, errors.Wrap(jsonFileVarsErr, "load json file vars")
+	}
+	// add the json file vars to the defaults,
+	// and return them.
+	for k, v := range jsonFileVars {
+		defaultVars[k] = v
+	}
+	return defaultVars, nil
+}
+
+// loadVariablesFromJSONFile gets a list of environment variable friendly
+// key=value pairs.
+func (p *Plugin) loadVariablesFromJSONFile() (map[string]interface{}, error) {
+	variablesJSONFilename := p.Command + variableJSONFileExt
+	f, err := os.Open(variablesJSONFilename)
+	if err != nil && os.IsNotExist(err) {
+		// no .vars.json file - no probs
+		return nil, nil
+	} else if err != nil {
+		return nil, errors.Wrap(err, "open vars json file")
+	}
+	defer f.Close()
+	b, err := io.ReadAll(io.LimitReader(f, 1_000_000))
+	if err != nil {
+		return nil, err
+	}
+	var vars map[string]interface{}
+	if err := json.Unmarshal(b, &vars); err != nil {
+		return nil, errors.Wrap(err, "json.Unmarshal")
+	}
+	return vars, nil
+}
+
+func (p *Plugin) loadVariablesFromPluginMetadata() (map[string]interface{}, error) {
+	// read the plugin metadata for default values
+	pluginFile, err := os.Open(p.Command)
+	if err != nil {
+		return nil, errors.Wrap(err, "open plugin source")
+	}
+	defer pluginFile.Close()
+	pluginFileB, err := io.ReadAll(io.LimitReader(pluginFile, 1_000_000))
+	if err != nil {
+		return nil, errors.Wrap(err, "read plugin source")
+	}
+	pluginMetadata, err := metadata.Parse(metadata.DebugFunc(p.Debugf), p.CleanFilename(), string(pluginFileB))
+	if err != nil {
+		return nil, errors.Wrap(err, "metadata.Parse")
+	}
+	vars := make(map[string]interface{})
+	for _, pluginVar := range pluginMetadata.Vars {
+		if pluginVar.Default == "" {
+			// skip values with no default
+			continue
+		}
+		vars[pluginVar.Name] = pluginVar.DefaultValue()
+	}
+	return vars, nil
+}

pkg/plugins/variables_test.go

@@ -34,9 +34,10 @@ func TestEnvironmentVariables(t *testing.T) {
 	}
 	p.Run(ctx)
 
-	is.Equal(len(p.Items.CycleItems), 2)
-	is.Equal(p.Items.CycleItems[0].Text, `XBAR_TEST_EXPLICIT_VAR=explicit`) // inherited
-	is.Equal(p.Items.CycleItems[1].Text, `XBAR_TEST_SET_IN_VARS_JSON=json`) // in vars.json file
+	is.Equal(len(p.Items.CycleItems), 3)
+	is.Equal(p.Items.CycleItems[0].Text, `XBAR_TEST_EXPLICIT_VAR=explicit`)     // inherited
+	is.Equal(p.Items.CycleItems[1].Text, `XBAR_TEST_SET_IN_VARS_JSON=json`)     // in vars.json file
+	is.Equal(p.Items.CycleItems[2].Text, `XBAR_TEST_DEFAULT_VAR=default-value`) // from plugin metadata
 
 }