Allow to break long message. (Fix #6)

Fix patch address and offsets

src/utils/str.rs

@@ -18,3 +18,50 @@ pub fn truncate_string(s: &str, length: usize, encoding: Encoding, check: bool)
     }
     return Ok(result);
 }
+
+/// Truncate a string to a specified length, encoding it with the given encoding.
+/// Output size may less than or equal to the specified length.
+/// Returns the encoded bytes and the remaining string.
+pub fn truncate_string2(
+    s: &str,
+    length: usize,
+    encoding: Encoding,
+) -> Result<(Vec<u8>, Option<&str>)> {
+    let vec: Vec<_> = UnicodeSegmentation::graphemes(s, true).collect();
+    let mut result = Vec::new();
+    let mut used = 0;
+    for graphemes in vec {
+        let data = encode_string(encoding, graphemes, false)?;
+        if result.len() + data.len() > length {
+            break;
+        }
+        result.extend(data);
+        used += graphemes.len();
+    }
+    let remaining = if used < s.len() {
+        Some(&s[used..])
+    } else {
+        None
+    };
+    return Ok((result, remaining));
+}
+
+/// Truncate a string to a specified length, encoding it with the given encoding.
+/// Output size may less than or equal to the specified length.
+/// Returns the encoded bytes and the remaining string.
+/// Will try splitting at line breaks first.
+pub fn truncate_string_with_enter(
+    s: &str,
+    length: usize,
+    encoding: Encoding,
+) -> Result<(Vec<u8>, Option<&str>)> {
+    if let Some(pos) = s.find('\n') {
+        let (first, rest) = s.split_at(pos + 1);
+        // Try encoding the first part with line break
+        let data = encode_string(encoding, &first[..pos], false)?;
+        if data.len() <= length {
+            return Ok((data, if rest.is_empty() { None } else { Some(rest) }));
+        }
+    }
+    truncate_string2(s, length, encoding)
+}