Impl select_pronouns and add parse_prefstring to InstanceSettings

Signed-off-by: Ben Aaron Goldberg <ben@benaaron.dev>

doc/User-Preference-String-Spec.txt

@@ -10,7 +10,7 @@ contents         := version-0 | ...
 If user-preferences is not present (i.e. is zero-length), then the default preferences
 should be assumed.  Default preferences will be set by the instance operator
 
-version-1           := variant-0-0
+version-0           := variant-0-0
 
 variant-0-0         := default-enabled default-weight *command
 default-enabled     := 1 bit

src/lib.rs

@@ -46,6 +46,7 @@ use std::fmt;
 
 use serde::{Serialize, Deserialize, self};
 
+use user_preferences::{ParseError, Preference};
 pub use weighted_table::WeightedTable;
 pub use user_preferences::UserPreferences;
 
@@ -73,15 +74,21 @@ impl InstanceSettings {
     /// ```
 	/// # use pronouns_today::InstanceSettings;
     /// # let settings = InstanceSettings::default();
-    /// # let name = String::from("Sashanora");
+    /// # let name = String::from("Sashanoraa");
     /// # let prefstring = String::from("todo");
-    /// let pronouns = settings.parse_prefstring(Some(&prefstring)).select_pronouns(Some(&name));
+    /// let pronouns = InstanceSettings::parse_prefstring(Some(&prefstring))?.select_pronouns(&settings, Some(&name));
     /// # assert_eq!(pronouns, settings.select_pronouns(Some(&name), Some(&prefstring)));
     /// ```
-    pub fn select_pronouns(&self, name: Option<impl AsRef<str>>, pref_string: Option<impl AsRef<str>>) -> &str {
-        todo!()
+    pub fn select_pronouns(&self, name: Option<&str>, pref_string: Option<&str>) -> Result<&Pronoun, ParseError> {
+		Self::parse_prefstring(pref_string)?.select_pronoun(&self, name)
     }
 
+	pub fn parse_prefstring(pref_string: Option<&str>) -> Result<UserPreferences, ParseError> {
+		match pref_string {
+			Some(pref_string) => UserPreferences::from_prefstring(pref_string),
+			None => Ok(UserPreferences::default())
+		}
+	}
 }
 
 impl Default for InstanceSettings {

src/user_preferences/mod.rs

@@ -29,6 +29,12 @@ pub enum UserPreferences {
 	V0(v0::UserPreferencesV0)
 }
 
+impl Default for UserPreferences {
+	fn default() -> Self {
+	    UserPreferences::V0(UserPreferencesV0::default())
+	}
+}
+
 /// Functionality provided by any version of user preferences
 ///
 /// See also: [`UserPreferences`]
@@ -76,6 +82,14 @@ pub trait Preference {
 	fn into_prefstring(&self) -> String {
 		BASE32_NOPAD.encode(&self.into_prefstring_bytes())
 	}
+
+	fn select_pronoun<'a>(&self, settings: &'a InstanceSettings, name: Option<&str>) -> Result<&'a Pronoun, ParseError> {
+		let seed = match name {
+			Some(name) => name.as_bytes(),
+			None => &[],
+		};
+		Ok(self.into_weighted_table(settings)?.select_today(seed))
+	}
 }
 
 impl Preference for UserPreferences {

src/user_preferences/v0.rs

@@ -119,7 +119,27 @@ impl Preference for UserPreferencesV0 {
 	}
 
 	fn into_prefstring_bytes(&self) -> Vec<u8> {
-		todo!()
+		let mut defaults_byte = 0u8;
+		if self.default_enabled {
+			defaults_byte |= 0b10000000;
+		}
+		defaults_byte |= self.default_weight & 0b01111111;
+		vec![defaults_byte]
+			.into_iter()
+			.chain(self.commands.iter().map(|cmd| cmd.into()))
+			.collect()
+	}
+}
+
+/// Default to all pronouns on with equal weight
+/// TODO make this configurable
+impl Default for UserPreferencesV0 {
+	fn default() -> Self {
+	    Self {
+			default_enabled: true,
+			default_weight: 1,
+			commands: vec![],
+		}
 	}
 }
 
@@ -166,6 +186,18 @@ impl From<u8> for Command {
 	}
 }
 
+impl From<&Command> for u8 {
+	fn from(command: &Command) -> Self {
+		match command {
+			// Some these ands shouldn't be needed if the command is valid
+			Command::SetWeight(weight) => weight & 0b01111111,
+			Command::Move { toggle_enabled, distance } => {
+				0b10000000 | ((*toggle_enabled as u8) << 6) | (distance & 0b00111111)
+			}
+		}
+	}
+}
+
 
 #[cfg(test)]
 mod tests {