refactor: Move vcard code to their own file (#6776)

So that we can directly link to the tests from the new Autocrypt
specification.

deltachat-contact-tools/src/vcard.rs

@@ -0,0 +1,232 @@
+use std::sync::LazyLock;
+
+use anyhow::Context as _;
+use anyhow::Result;
+use chrono::DateTime;
+use chrono::NaiveDateTime;
+use regex::Regex;
+
+use crate::sanitize_name_and_addr;
+
+#[derive(Debug)]
+/// A Contact, as represented in a VCard.
+pub struct VcardContact {
+    /// The email address, vcard property `email`
+    pub addr: String,
+    /// This must be the name authorized by the contact itself, not a locally given name. Vcard
+    /// property `fn`. Can be empty, one should use `display_name()` to obtain the display name.
+    pub authname: String,
+    /// The contact's public PGP key in Base64, vcard property `key`
+    pub key: Option<String>,
+    /// The contact's profile image (=avatar) in Base64, vcard property `photo`
+    pub profile_image: Option<String>,
+    /// The timestamp when the vcard was created / last updated, vcard property `rev`
+    pub timestamp: Result<i64>,
+}
+
+impl VcardContact {
+    /// Returns the contact's display name.
+    pub fn display_name(&self) -> &str {
+        match self.authname.is_empty() {
+            false => &self.authname,
+            true => &self.addr,
+        }
+    }
+}
+
+/// Returns a vCard containing given contacts.
+///
+/// Calling [`parse_vcard()`] on the returned result is a reverse operation.
+pub fn make_vcard(contacts: &[VcardContact]) -> String {
+    fn format_timestamp(c: &VcardContact) -> Option<String> {
+        let timestamp = *c.timestamp.as_ref().ok()?;
+        let datetime = DateTime::from_timestamp(timestamp, 0)?;
+        Some(datetime.format("%Y%m%dT%H%M%SZ").to_string())
+    }
+
+    let mut res = "".to_string();
+    for c in contacts {
+        let addr = &c.addr;
+        let display_name = c.display_name();
+        res += &format!(
+            "BEGIN:VCARD\r\n\
+             VERSION:4.0\r\n\
+             EMAIL:{addr}\r\n\
+             FN:{display_name}\r\n"
+        );
+        if let Some(key) = &c.key {
+            res += &format!("KEY:data:application/pgp-keys;base64,{key}\r\n");
+        }
+        if let Some(profile_image) = &c.profile_image {
+            res += &format!("PHOTO:data:image/jpeg;base64,{profile_image}\r\n");
+        }
+        if let Some(timestamp) = format_timestamp(c) {
+            res += &format!("REV:{timestamp}\r\n");
+        }
+        res += "END:VCARD\r\n";
+    }
+    res
+}
+
+/// Parses `VcardContact`s from a given `&str`.
+pub fn parse_vcard(vcard: &str) -> Vec<VcardContact> {
+    fn remove_prefix<'a>(s: &'a str, prefix: &str) -> Option<&'a str> {
+        let start_of_s = s.get(..prefix.len())?;
+
+        if start_of_s.eq_ignore_ascii_case(prefix) {
+            s.get(prefix.len()..)
+        } else {
+            None
+        }
+    }
+    /// Returns (parameters, value) tuple.
+    fn vcard_property<'a>(line: &'a str, property: &str) -> Option<(&'a str, &'a str)> {
+        let remainder = remove_prefix(line, property)?;
+        // If `s` is `EMAIL;TYPE=work:alice@example.com` and `property` is `EMAIL`,
+        // then `remainder` is now `;TYPE=work:alice@example.com`
+
+        // Note: This doesn't handle the case where there are quotes around a colon,
+        // like `NAME;Foo="Some quoted text: that contains a colon":value`.
+        // This could be improved in the future, but for now, the parsing is good enough.
+        let (mut params, value) = remainder.split_once(':')?;
+        // In the example from above, `params` is now `;TYPE=work`
+        // and `value` is now `alice@example.com`
+
+        if params
+            .chars()
+            .next()
+            .filter(|c| !c.is_ascii_punctuation() || *c == '_')
+            .is_some()
+        {
+            // `s` started with `property`, but the next character after it was not punctuation,
+            // so this line's property is actually something else
+            return None;
+        }
+        if let Some(p) = remove_prefix(params, ";") {
+            params = p;
+        }
+        if let Some(p) = remove_prefix(params, "PREF=1") {
+            params = p;
+        }
+        Some((params, value))
+    }
+    fn base64_key(line: &str) -> Option<&str> {
+        let (params, value) = vcard_property(line, "key")?;
+        if params.eq_ignore_ascii_case("PGP;ENCODING=BASE64")
+            || params.eq_ignore_ascii_case("TYPE=PGP;ENCODING=b")
+        {
+            return Some(value);
+        }
+        if let Some(value) = remove_prefix(value, "data:application/pgp-keys;base64,")
+            .or_else(|| remove_prefix(value, r"data:application/pgp-keys;base64\,"))
+        {
+            return Some(value);
+        }
+
+        None
+    }
+    fn base64_photo(line: &str) -> Option<&str> {
+        let (params, value) = vcard_property(line, "photo")?;
+        if params.eq_ignore_ascii_case("JPEG;ENCODING=BASE64")
+            || params.eq_ignore_ascii_case("ENCODING=BASE64;JPEG")
+            || params.eq_ignore_ascii_case("TYPE=JPEG;ENCODING=b")
+            || params.eq_ignore_ascii_case("ENCODING=b;TYPE=JPEG")
+            || params.eq_ignore_ascii_case("ENCODING=BASE64;TYPE=JPEG")
+            || params.eq_ignore_ascii_case("TYPE=JPEG;ENCODING=BASE64")
+        {
+            return Some(value);
+        }
+        if let Some(value) = remove_prefix(value, "data:image/jpeg;base64,")
+            .or_else(|| remove_prefix(value, r"data:image/jpeg;base64\,"))
+        {
+            return Some(value);
+        }
+
+        None
+    }
+    fn parse_datetime(datetime: &str) -> Result<i64> {
+        // According to https://www.rfc-editor.org/rfc/rfc6350#section-4.3.5, the timestamp
+        // is in ISO.8601.2004 format. DateTime::parse_from_rfc3339() apparently parses
+        // ISO.8601, but fails to parse any of the examples given.
+        // So, instead just parse using a format string.
+
+        // Parses 19961022T140000Z, 19961022T140000-05, or 19961022T140000-0500.
+        let timestamp = match DateTime::parse_from_str(datetime, "%Y%m%dT%H%M%S%#z") {
+            Ok(datetime) => datetime.timestamp(),
+            // Parses 19961022T140000.
+            Err(e) => match NaiveDateTime::parse_from_str(datetime, "%Y%m%dT%H%M%S") {
+                Ok(datetime) => datetime
+                    .and_local_timezone(chrono::offset::Local)
+                    .single()
+                    .context("Could not apply local timezone to parsed date and time")?
+                    .timestamp(),
+                Err(_) => return Err(e.into()),
+            },
+        };
+        Ok(timestamp)
+    }
+
+    // Remove line folding, see https://datatracker.ietf.org/doc/html/rfc6350#section-3.2
+    static NEWLINE_AND_SPACE_OR_TAB: LazyLock<Regex> =
+        LazyLock::new(|| Regex::new("\r?\n[\t ]").unwrap());
+    let unfolded_lines = NEWLINE_AND_SPACE_OR_TAB.replace_all(vcard, "");
+
+    let mut lines = unfolded_lines.lines().peekable();
+    let mut contacts = Vec::new();
+
+    while lines.peek().is_some() {
+        // Skip to the start of the vcard:
+        for line in lines.by_ref() {
+            if line.eq_ignore_ascii_case("BEGIN:VCARD") {
+                break;
+            }
+        }
+
+        let mut display_name = None;
+        let mut addr = None;
+        let mut key = None;
+        let mut photo = None;
+        let mut datetime = None;
+
+        for mut line in lines.by_ref() {
+            if let Some(remainder) = remove_prefix(line, "item1.") {
+                // Remove the group name, if the group is called "item1".
+                // If necessary, we can improve this to also remove groups that are called something different that "item1".
+                //
+                // Search "group name" at https://datatracker.ietf.org/doc/html/rfc6350 for more infos.
+                line = remainder;
+            }
+
+            if let Some((_params, email)) = vcard_property(line, "email") {
+                addr.get_or_insert(email);
+            } else if let Some((_params, name)) = vcard_property(line, "fn") {
+                display_name.get_or_insert(name);
+            } else if let Some(k) = base64_key(line) {
+                key.get_or_insert(k);
+            } else if let Some(p) = base64_photo(line) {
+                photo.get_or_insert(p);
+            } else if let Some((_params, rev)) = vcard_property(line, "rev") {
+                datetime.get_or_insert(rev);
+            } else if line.eq_ignore_ascii_case("END:VCARD") {
+                let (authname, addr) =
+                    sanitize_name_and_addr(display_name.unwrap_or(""), addr.unwrap_or(""));
+
+                contacts.push(VcardContact {
+                    authname,
+                    addr,
+                    key: key.map(|s| s.to_string()),
+                    profile_image: photo.map(|s| s.to_string()),
+                    timestamp: datetime
+                        .context("No timestamp in vcard")
+                        .and_then(parse_datetime),
+                });
+                break;
+            }
+        }
+    }
+
+    contacts
+}
+
+#[cfg(test)]
+mod vcard_tests;