Initial protocol implementation

Empathy needs this patch before it will display the settings:
https://gitlab.gnome.org/GNOME/telepathy-account-widgets/-/merge_requests/1

src/padfoot/protocol.rs

@@ -1 +1,106 @@
+use crate::telepathy;
+use dbus::{arg, tree};
+use std::collections::HashMap;
+
+#[derive(Debug)]
 pub struct Protocol {}
+
+pub type ParamSpec = (
+    String,                                       // Name
+    u32,                                          // Flags (Conn_Mgr_Param_Flags)
+    String,                                       // Signature
+    arg::Variant<Box<dyn arg::RefArg + 'static>>, // Default
+);
+
+pub type Variant = arg::Variant<Box<dyn arg::RefArg + 'static>>;
+
+pub const NAME: &'static str = "delta";
+
+// FIXME: these should come from codegen
+//const FLAG_NONE: u32 = 0;
+const FLAG_REQUIRED: u32 = 1;
+//const FLAG_REGISTER: u32 = 2;
+//const FLAG_HAS_DEFAULT: u32 = 4;
+const FLAG_SECRET: u32 = 8;
+//const FLAG_DBUS_PROP: u32 = 16;
+
+pub fn parameters() -> Vec<ParamSpec> {
+    vec![
+        (
+            "account".to_string(),
+            FLAG_REQUIRED,
+            "s".to_string(),
+            arg::Variant(Box::new("".to_string())),
+        ),
+        (
+            "password".to_string(),
+            FLAG_REQUIRED | FLAG_SECRET,
+            "s".to_string(),
+            arg::Variant(Box::new("".to_string())),
+        ),
+    ]
+}
+
+impl telepathy::Protocol for Protocol {
+    fn identify_account(&self, params: HashMap<&str, Variant>) -> Result<String, tree::MethodErr> {
+        println!("Protocol::identify_account({:?})", params);
+
+        Err(tree::MethodErr::no_arg())
+    }
+
+    fn normalize_contact(&self, contact_id: &str) -> Result<String, tree::MethodErr> {
+        println!("Protocol::normalize_contact({})", contact_id);
+
+        Err(tree::MethodErr::no_arg())
+    }
+
+    fn interfaces(&self) -> Result<Vec<String>, tree::MethodErr> {
+        println!("Protocol::interfaces()");
+
+        Ok(vec![])
+    }
+    fn parameters(&self) -> Result<Vec<ParamSpec>, tree::MethodErr> {
+        println!("Protocol::parameters()");
+
+        Ok(parameters())
+    }
+
+    fn connection_interfaces(&self) -> Result<Vec<String>, tree::MethodErr> {
+        println!("Protocol::connection_interfaces()");
+
+        Ok(vec![])
+    }
+    fn requestable_channel_classes(
+        &self,
+    ) -> Result<
+        Vec<(
+            ::std::collections::HashMap<String, arg::Variant<Box<dyn arg::RefArg + 'static>>>,
+            Vec<String>,
+        )>,
+        tree::MethodErr,
+    > {
+        println!("Protocol::requestable_channel_classes()");
+
+        Ok(vec![])
+    }
+    fn vcard_field(&self) -> Result<String, tree::MethodErr> {
+        println!("Protocol::vcard_field()");
+
+        Ok("email".to_string())
+    }
+    fn english_name(&self) -> Result<String, tree::MethodErr> {
+        println!("Protocol::english_name()");
+
+        Ok("Delta Chat".to_string())
+    }
+    fn icon(&self) -> Result<String, tree::MethodErr> {
+        println!("Protocol::icon()");
+
+        Ok("im-delta".to_string())
+    }
+    fn authentication_types(&self) -> Result<Vec<String>, tree::MethodErr> {
+        println!("Protocol::authentication_types()");
+
+        Ok(vec![])
+    }
+}