Impl from_preferences

With creates a Preference instance from a list of pronoun weights.

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

src/user_preferences/mod.rs

@@ -65,6 +65,13 @@ pub trait Preference {
 	/// [1]: https://fem.mint.lgbt/Emi/PronounsToday/raw/branch/main/doc/User-Preference-String-Spec.txt
 	fn as_prefstring_bytes(&self) -> Vec<u8>;
 
+	/// Create a Preference instance from a list of pronoun preferences
+	///
+	/// This should produce an instance of Preference using the provided preferences.
+	/// `prefs` is a list of pronoun preferences. Each entry is the weight of the pronoun
+	/// at that index in the pronoun list in the settings.
+	fn from_preferences(prefs: &[u8]) -> Self where Self: Sized;
+
 	/// Parse a base64 prefstring
 	///
 	/// This is the primary method of creating a `Preference` object from a prefstring.  The
@@ -128,4 +135,8 @@ impl Preference for UserPreferences {
 			UserPreferences::V0(pref) => pref,
 		}.as_prefstring_bytes()
 	}
+
+	fn from_preferences(prefs: &[u8]) -> Self where Self: Sized {
+	    UserPreferences::V0(UserPreferencesV0::from_preferences(prefs))
+	}
 }

src/user_preferences/v0.rs

@@ -17,6 +17,7 @@ use std::{
 /// See the [prefstring specification][1] for more information about how this is interpretted.
 ///
 /// [1]: https://fem.mint.lgbt/Emi/PronounsToday/raw/branch/main/doc/User-Preference-String-Spec.txt
+#[derive(Debug, PartialEq, Eq)]
 pub struct UserPreferencesV0 {
 	pub default_weight: u8,
 	pub default_enabled: bool,
@@ -129,6 +130,91 @@ impl Preference for UserPreferencesV0 {
 			.chain(self.commands.iter().map(|cmd| cmd.into()))
 			.collect()
 	}
+
+	fn from_preferences(prefs: &[u8]) -> Self where Self: Sized {
+		if prefs.is_empty() {
+			return Self::default();
+		}
+		let mut weight_counts = vec![0u8; *prefs.iter().max().unwrap() as usize + 1];
+		let mut num_zeros = 0;
+		for w in prefs {
+			if *w == 0 {
+				num_zeros += 1;
+			} else {
+				weight_counts[*w as usize] += 1;
+			}
+		}
+		let default_weight = weight_counts
+			.iter()
+			.enumerate()
+			.max_by(|(_, v1), (_, v2)| v1.cmp(v2))
+			.map(|(w, _)| w as u8)
+			.unwrap();
+		let default_enabled = num_zeros < prefs.len() / 2;
+		let mut commands = Vec::new();
+		if default_enabled {
+			let mut last_default = -1;
+			for (i, w) in prefs.iter().enumerate() {
+				let i = i as isize;
+				if *w == default_weight {
+					continue;
+				} else {
+					if i - last_default > 1 {
+						let toggle_enabled = *w == 0;
+						let distance = if toggle_enabled {
+							(i - last_default) as u8 - 1
+						} else {
+							(i - last_default) as u8 - 2
+						};
+						eprintln!("{} {} {} {}", toggle_enabled, distance, i, last_default);
+						commands.push(Command::Move {
+							toggle_enabled,
+							distance
+						});
+						if !toggle_enabled {
+							commands.push(Command::SetWeight(*w));
+						}
+					} else {
+						commands.push(Command::SetWeight(*w));
+					}
+					last_default = i;
+				}
+			}
+		} else {
+			let mut last_enabled = -1;
+			for (i, w) in prefs.iter().enumerate() {
+				let i = i as isize;
+				if *w == 0 {
+					continue;
+				} else {
+					if i - last_enabled > 1 {
+						let toggle_enabled = *w == default_weight;
+						let distance = if toggle_enabled {
+							(i - last_enabled) as u8 - 1
+						} else {
+							(i - last_enabled) as u8 - 2
+						};
+						eprintln!("{} {} {} {}", toggle_enabled, distance, i, last_enabled);
+						commands.push(Command::Move {
+							toggle_enabled,
+							distance
+						});
+						if !toggle_enabled {
+							commands.push(Command::SetWeight(*w));
+						}
+					} else {
+						commands.push(Command::SetWeight(*w));
+					}
+					last_enabled = i;
+				}
+			}
+		}
+	    Self {
+			default_weight,
+			default_enabled,
+			commands,
+		}
+	}
 }
 
 /// Default to all pronouns on with equal weight
@@ -392,4 +478,132 @@ mod tests {
 
 		check_table(table, expected_table);
 	}
+
+	#[test]
+	fn test_from_prefs_most_disabled1() {
+		let pref_vals = vec![0,1,2,0,0];
+		let expected_prefs = UserPreferencesV0 {
+			default_enabled: false,
+			default_weight: 2,
+			commands: vec![
+				Command::Move {
+					toggle_enabled: false,
+					distance: 0,
+				},
+				Command::SetWeight(1),
+				Command::SetWeight(2),
+			],
+		};
+		let prefs = UserPreferencesV0::from_preferences(&pref_vals);
+		assert_eq!(prefs, expected_prefs);
+	}
+
+	#[test]
+	fn test_from_prefs_most_disabled2() {
+		let pref_vals = vec![0,1,1,0,0,0,2];
+		let expected_prefs = UserPreferencesV0 {
+			default_enabled: false,
+			default_weight: 1,
+			commands: vec![
+				Command::Move {
+					toggle_enabled: true,
+					distance: 1,
+				},
+				Command::SetWeight(1),
+				Command::Move {
+					toggle_enabled: false,
+					distance: 2,
+				},
+				Command::SetWeight(2),
+			],
+		};
+		let prefs = UserPreferencesV0::from_preferences(&pref_vals);
+		assert_eq!(prefs, expected_prefs);
+	}
+
+	#[test]
+	fn test_from_prefs_most_disabled3() {
+		let pref_vals = vec![0,0,0,0,1,0,0,0,2];
+		let expected_prefs = UserPreferencesV0 {
+			default_enabled: false,
+			default_weight: 2,
+			commands: vec![
+				Command::Move {
+					toggle_enabled: false,
+					distance: 3,
+				},
+				Command::SetWeight(1),
+				Command::Move {
+					toggle_enabled: true,
+					distance: 3,
+				},
+			],
+		};
+		let prefs = UserPreferencesV0::from_preferences(&pref_vals);
+		assert_eq!(prefs, expected_prefs);
+	}
+
+	#[test]
+	fn test_from_prefs_most_enabled1() {
+		let pref_vals = vec![0,1,2,1,1];
+		let expected_prefs = UserPreferencesV0 {
+			default_enabled: true,
+			default_weight: 1,
+			commands: vec![
+				Command::SetWeight(0),
+				Command::Move {
+					toggle_enabled: false,
+					distance: 0,
+				},
+				Command::SetWeight(2),
+			],
+		};
+		let prefs = UserPreferencesV0::from_preferences(&pref_vals);
+		assert_eq!(prefs, expected_prefs);
+	}
+
+	#[test]
+	fn test_from_prefs_most_enabled2() {
+		let pref_vals = vec![1,0,0,1,1,1,2];
+		let expected_prefs = UserPreferencesV0 {
+			default_enabled: true,
+			default_weight: 1,
+			commands: vec![
+				Command::Move {
+					toggle_enabled: true,
+					distance: 1,
+				},
+				Command::SetWeight(0),
+				Command::Move {
+					toggle_enabled: false,
+					distance: 2,
+				},
+				Command::SetWeight(2),
+			],
+		};
+		let prefs = UserPreferencesV0::from_preferences(&pref_vals);
+		assert_eq!(prefs, expected_prefs);
+	}
+
+	#[test]
+	fn test_from_prefs_most_enabled3() {
+		let pref_vals = vec![1,1,1,1,0,1,1,1,2];
+		let expected_prefs = UserPreferencesV0 {
+			default_enabled: true,
+			default_weight: 1,
+			commands: vec![
+				Command::Move {
+					toggle_enabled: true,
+					distance: 4,
+				},
+				Command::Move {
+					toggle_enabled: false,
+					distance: 2,
+				},
+				Command::SetWeight(2),
+			],
+		};
+		let prefs = UserPreferencesV0::from_preferences(&pref_vals);
+		assert_eq!(prefs, expected_prefs);
+	}
 }