fix(jsonrpc): Use Core's logic for computing VcardContact.color (#7294)

Before, the color was computed from the address, but as we've switched to fingerprint-based contact
colors, this logic became stale. Now `deltachat::contact::get_color()` is used. A test would be nice
to have, but as now all the logic is in Core, this isn't critical as there are Core tests at least.

deltachat-jsonrpc/src/api/types/contact.rs

@@ -1,6 +1,6 @@
 use anyhow::Result;
-use deltachat::color;
 use deltachat::context::Context;
+use deltachat::key::{DcKey, SignedPublicKey};
 use serde::Serialize;
 use typescript_type_def::TypeDef;
 
@@ -130,7 +130,13 @@ pub struct VcardContact {
 impl From<deltachat_contact_tools::VcardContact> for VcardContact {
     fn from(vc: deltachat_contact_tools::VcardContact) -> Self {
         let display_name = vc.display_name().to_string();
-        let color = color::str_to_color(&vc.addr.to_lowercase());
+        let is_self = false;
+        let fpr = vc.key.as_deref().and_then(|k| {
+            SignedPublicKey::from_base64(k)
+                .ok()
+                .map(|k| k.dc_fingerprint())
+        });
+        let color = deltachat::contact::get_color(is_self, &vc.addr, &fpr);
         Self {
             addr: vc.addr,
             display_name,

src/contact.rs

@@ -36,7 +36,7 @@ use crate::message::MessageState;
 use crate::mimeparser::AvatarAction;
 use crate::param::{Param, Params};
 use crate::sync::{self, Sync::*};
-use crate::tools::{SystemTime, duration_to_str, get_abs_path, time};
+use crate::tools::{SystemTime, duration_to_str, get_abs_path, time, to_lowercase};
 use crate::{chat, chatlist_events, ensure_and_debug_assert_ne, stock_str};
 
 /// Time during which a contact is considered as seen recently.
@@ -1574,19 +1574,10 @@ impl Contact {
         Ok(None)
     }
 
-    /// Get a color for the contact.
-    /// The color is calculated from the contact's fingerprint (for key-contacts)
-    /// or email address (for address-contacts) and can be used
-    /// for an fallback avatar with white initials
-    /// as well as for headlines in bubbles of group chats.
+    /// Returns a color for the contact.
+    /// See [`self::get_color`].
     pub fn get_color(&self) -> u32 {
-        if let Some(fingerprint) = self.fingerprint() {
-            str_to_color(&fingerprint.hex())
-        } else if self.id == ContactId::SELF {
-            0x808080
-        } else {
-            str_to_color(&self.addr.to_lowercase())
-        }
+        get_color(self.id == ContactId::SELF, &self.addr, &self.fingerprint())
     }
 
     /// Gets the contact's status.
@@ -1682,6 +1673,21 @@ impl Contact {
     }
 }
 
+/// Returns a color for a contact having given attributes.
+///
+/// The color is calculated from contact's fingerprint (for key-contacts) or email address (for
+/// address-contacts; should be lowercased to avoid allocation) and can be used for an fallback
+/// avatar with white initials as well as for headlines in bubbles of group chats.
+pub fn get_color(is_self: bool, addr: &str, fingerprint: &Option<Fingerprint>) -> u32 {
+    if let Some(fingerprint) = fingerprint {
+        str_to_color(&fingerprint.hex())
+    } else if is_self {
+        0x808080
+    } else {
+        str_to_color(&to_lowercase(addr))
+    }
+}
+
 // Updates the names of the chats which use the contact name.
 //
 // This is one of the few duplicated data, however, getting the chat list is easier this way.

src/key.rs

@@ -25,7 +25,7 @@ use crate::tools::{self, time_elapsed};
 /// This trait is implemented for rPGP's [SignedPublicKey] and
 /// [SignedSecretKey] types and makes working with them a little
 /// easier in the deltachat world.
-pub(crate) trait DcKey: Serialize + Deserializable + Clone {
+pub trait DcKey: Serialize + Deserializable + Clone {
     /// Create a key from some bytes.
     fn from_slice(bytes: &[u8]) -> Result<Self> {
         let res = <Self as Deserializable>::from_bytes(Cursor::new(bytes));
@@ -112,7 +112,10 @@ pub(crate) trait DcKey: Serialize + Deserializable + Clone {
     /// The fingerprint for the key.
     fn dc_fingerprint(&self) -> Fingerprint;
 
+    /// Whether the key is private (or public).
     fn is_private() -> bool;
+
+    /// Returns the OpenPGP Key ID.
     fn key_id(&self) -> KeyId;
 }
 

src/tools.rs

@@ -753,6 +753,14 @@ pub(crate) fn buf_decompress(buf: &[u8]) -> Result<Vec<u8>> {
     Ok(mem::take(decompressor.get_mut()))
 }
 
+/// Returns the given `&str` if already lowercased to avoid allocation, otherwise lowercases it.
+pub(crate) fn to_lowercase(s: &str) -> Cow<'_, str> {
+    match s.chars().all(char::is_lowercase) {
+        true => Cow::Borrowed(s),
+        false => Cow::Owned(s.to_lowercase()),
+    }
+}
+
 /// Increments `*t` and checks that it equals to `expected` after that.
 pub(crate) fn inc_and_check<T: PrimInt + AddAssign + std::fmt::Debug>(
     t: &mut T,