Add plugin tasks (#651)

pkg/plugin/common/msg.go

@@ -0,0 +1,99 @@
+package common
+
+import "net/http"
+
+// StashServerConnection represents the connection details needed for a
+// plugin instance to connect to its parent stash server.
+type StashServerConnection struct {
+	// http or https
+	Scheme string
+
+	Port int
+
+	// Cookie for authentication purposes
+	SessionCookie *http.Cookie
+
+	// Dir specifies the directory containing the stash server's configuration
+	// file.
+	Dir string
+
+	// PluginDir specifies the directory containing the plugin configuration
+	// file.
+	PluginDir string
+}
+
+// PluginArgValue represents a single value parameter for plugin operations.
+type PluginArgValue interface{}
+
+// ArgsMap is a map of argument key to value.
+type ArgsMap map[string]PluginArgValue
+
+// String returns the string field or an empty string if the string field is
+// nil
+func (m ArgsMap) String(key string) string {
+	v, found := m[key]
+	var ret string
+	if !found {
+		return ret
+	}
+	ret, _ = v.(string)
+	return ret
+}
+
+// Int returns the int field or 0 if the int field is nil
+func (m ArgsMap) Int(key string) int {
+	v, found := m[key]
+	var ret int
+	if !found {
+		return ret
+	}
+	ret, _ = v.(int)
+	return ret
+}
+
+// Bool returns the boolean field or false if the boolean field is nil
+func (m ArgsMap) Bool(key string) bool {
+	v, found := m[key]
+	var ret bool
+	if !found {
+		return ret
+	}
+	ret, _ = v.(bool)
+	return ret
+}
+
+// Float returns the float field or 0 if the float field is nil
+func (m ArgsMap) Float(key string) float64 {
+	v, found := m[key]
+	var ret float64
+	if !found {
+		return ret
+	}
+	ret, _ = v.(float64)
+	return ret
+}
+
+// PluginInput is the data structure that is sent to plugin instances when they
+// are spawned.
+type PluginInput struct {
+	// Server details to connect to the stash server.
+	ServerConnection StashServerConnection `json:"server_connection"`
+
+	// Arguments to the plugin operation.
+	Args ArgsMap `json:"args"`
+}
+
+// PluginOutput is the data structure that is expected to be output by plugin
+// processes when execution has concluded. It is expected that this data will
+// be encoded as JSON.
+type PluginOutput struct {
+	Error  *string     `json:"error"`
+	Output interface{} `json:"output"`
+}
+
+// SetError is a convenience method that sets the Error field based on the
+// provided error.
+func (o *PluginOutput) SetError(err error) {
+	errStr := err.Error()
+	o.Error = &errStr
+}