1 files changed, 274 insertions, 0 deletions
diff --git a/aero-dav/src/xml.rs b/aero-dav/src/xml.rs
new file mode 100644
index 0000000..98037ac
--- /dev/null
+++ b/aero-dav/src/xml.rs
@@ -0,0 +1,274 @@
+use futures::Future;
+use quick_xml::events::{Event, BytesStart};
+use quick_xml::name::ResolveResult;
+use quick_xml::reader::NsReader;
+use tokio::io::{AsyncWrite, AsyncBufRead};
+
+use super::error::ParsingError;
+
+// Constants
+pub const DAV_URN: &[u8] = b"DAV:";
+pub const CAL_URN: &[u8] = b"urn:ietf:params:xml:ns:caldav";
+pub const CARD_URN: &[u8] = b"urn:ietf:params:xml:ns:carddav";
+
+// Async traits
+pub trait IWrite = AsyncWrite + Unpin;
+pub trait IRead = AsyncBufRead + Unpin;
+
+// Serialization/Deserialization traits
+pub trait QWrite {
+    fn qwrite(&self, xml: &mut Writer<impl IWrite>) -> impl Future<Output = Result<(), quick_xml::Error>>; 
+}
+pub trait QRead<T> {
+    fn qread(xml: &mut Reader<impl IRead>) -> impl Future<Output = Result<T, ParsingError>>;
+}
+
+// The representation of an XML node in Rust
+pub trait Node<T> = QRead<T> + QWrite + std::fmt::Debug + PartialEq;
+
+// ---------------
+
+/// Transform a Rust object into an XML stream of characters
+pub struct Writer<T: IWrite> {
+    pub q: quick_xml::writer::Writer<T>,
+    pub ns_to_apply: Vec<(String, String)>,
+}
+impl<T: IWrite> Writer<T> {
+    pub fn create_dav_element(&mut self, name: &str) -> BytesStart<'static> {
+        self.create_ns_element("D", name)
+    }
+    pub fn create_cal_element(&mut self, name: &str) -> BytesStart<'static> {
+        self.create_ns_element("C", name)
+    }
+
+    fn create_ns_element(&mut self, ns: &str, name: &str) -> BytesStart<'static> {
+        let mut start = BytesStart::new(format!("{}:{}", ns, name));
+        if !self.ns_to_apply.is_empty() {
+            start.extend_attributes(self.ns_to_apply.iter().map(|(k, n)| (k.as_str(), n.as_str())));
+            self.ns_to_apply.clear()
+        }
+        start
+    }
+}
+
+/// Transform an XML stream of characters into a Rust object
+pub struct Reader<T: IRead> {
+    pub rdr: NsReader<T>,
+    cur: Event<'static>,
+    parents: Vec<Event<'static>>,
+    buf: Vec<u8>,
+}
+impl<T: IRead> Reader<T> {
+    pub async fn new(mut rdr: NsReader<T>) -> Result<Self, ParsingError> {
+        let mut buf: Vec<u8> = vec![];
+        let cur = rdr.read_event_into_async(&mut buf).await?.into_owned();
+        let parents = vec![];
+        buf.clear();
+        Ok(Self { cur, parents, rdr, buf })
+    }
+
+    /// read one more tag
+    /// do not expose it publicly
+    async fn next(&mut self) -> Result<Event<'static>, ParsingError> {
+       let evt = self.rdr.read_event_into_async(&mut self.buf).await?.into_owned(); 
+       self.buf.clear();
+       let old_evt = std::mem::replace(&mut self.cur, evt);
+       Ok(old_evt)
+    }
+
+    /// skip a node at current level
+    /// I would like to make this one private but not ready
+    pub async fn skip(&mut self) -> Result<Event<'static>, ParsingError> {
+        //println!("skipping inside node {:?}", self.parents.last());
+        match &self.cur {
+            Event::Start(b) => {
+                let _span = self.rdr.read_to_end_into_async(b.to_end().name(), &mut self.buf).await?;
+                self.next().await
+            },
+            Event::End(_) => Err(ParsingError::WrongToken),
+            Event::Eof => Err(ParsingError::Eof),
+            _ => self.next().await,
+        }
+    }
+
+    /// check if this is the desired tag
+    fn is_tag(&self, ns: &[u8], key: &str) -> bool {
+        let qname = match self.peek() {
+            Event::Start(bs) | Event::Empty(bs) => bs.name(),
+            Event::End(be) => be.name(),
+            _ => return false,
+        };
+    
+        let (extr_ns, local) = self.rdr.resolve_element(qname);
+
+        if local.into_inner() != key.as_bytes() {
+            return false
+        }
+        
+        match extr_ns {
+            ResolveResult::Bound(v) => v.into_inner() == ns,
+            _ => false,
+        }
+    }
+
+    fn parent_has_child(&self) -> bool {
+        matches!(self.parents.last(), Some(Event::Start(_)) | None)
+    }
+
+    fn ensure_parent_has_child(&self) -> Result<(), ParsingError> {
+        match self.parent_has_child() {
+            true => Ok(()),
+            false => Err(ParsingError::Recoverable),
+        }
+    }
+
+    pub fn peek(&self) -> &Event<'static> {
+        &self.cur
+    }
+
+    // NEW API
+    pub async fn tag_string(&mut self) -> Result<String, ParsingError> {
+        self.ensure_parent_has_child()?;
+
+        let mut acc = String::new();
+        loop {
+            match self.peek() {
+                Event::CData(unescaped) => {
+                    acc.push_str(std::str::from_utf8(unescaped.as_ref())?);
+                    self.next().await?
+                },
+                Event::Text(escaped) => {
+                    acc.push_str(escaped.unescape()?.as_ref());
+                    self.next().await?
+                }
+                Event::End(_) | Event::Start(_) | Event::Empty(_) => return Ok(acc),
+                _ => self.next().await?,
+            };
+        }
+    }
+
+    pub async fn maybe_read<N: Node<N>>(&mut self, t: &mut Option<N>, dirty: &mut bool) -> Result<(), ParsingError> {
+        if !self.parent_has_child() {
+            return Ok(())
+        }
+
+        match N::qread(self).await {
+            Ok(v) => { 
+                *t = Some(v); 
+                *dirty = true;
+                Ok(()) 
+            },
+            Err(ParsingError::Recoverable) => Ok(()),
+            Err(e) => Err(e),
+        }
+    }
+
+    pub async fn maybe_push<N: Node<N>>(&mut self, t: &mut Vec<N>, dirty: &mut bool) -> Result<(), ParsingError> {
+        if !self.parent_has_child() {
+            return Ok(())
+        }
+
+        match N::qread(self).await {
+            Ok(v) => { 
+                t.push(v); 
+                *dirty = true;
+                Ok(()) 
+            },
+            Err(ParsingError::Recoverable) => Ok(()),
+            Err(e) => Err(e),
+        }
+    }
+
+    pub async fn find<N: Node<N>>(&mut self) -> Result<N, ParsingError> {
+        self.ensure_parent_has_child()?;
+
+        loop {
+            // Try parse
+            match N::qread(self).await {
+                Err(ParsingError::Recoverable) => (),
+                otherwise => return otherwise,
+            }
+
+            // If recovered, skip the element
+            self.skip().await?;
+        }
+    }
+
+    pub async fn maybe_find<N: Node<N>>(&mut self) -> Result<Option<N>, ParsingError> {
+        self.ensure_parent_has_child()?;
+
+        loop {
+            // Try parse
+            match N::qread(self).await {
+                Err(ParsingError::Recoverable) => (),
+                otherwise => return otherwise.map(Some),
+            }
+
+            match self.peek() {
+                Event::End(_) => return Ok(None),
+                _ => self.skip().await?,
+            };
+        }
+    }
+
+    pub async fn collect<N: Node<N>>(&mut self) -> Result<Vec<N>, ParsingError> {
+        self.ensure_parent_has_child()?;
+        let mut acc = Vec::new();
+
+        loop {
+            match N::qread(self).await {
+                Err(ParsingError::Recoverable) => match self.peek() {
+                    Event::End(_) => return Ok(acc),
+                    _ => {
+                        self.skip().await?;
+                    },
+                },
+                Ok(v) => acc.push(v),
+                Err(e) => return Err(e),
+            }
+        }
+    }
+
+    pub async fn open(&mut self, ns: &[u8], key: &str) -> Result<Event<'static>, ParsingError> {
+        let evt = match self.peek() {
+            Event::Empty(_) if self.is_tag(ns, key) => self.cur.clone(),
+            Event::Start(_) if self.is_tag(ns, key) => self.next().await?,
+            _ => return Err(ParsingError::Recoverable),
+        };
+
+        //println!("open tag {:?}", evt);
+        self.parents.push(evt.clone());
+        Ok(evt)
+    }
+
+    pub async fn maybe_open(&mut self, ns: &[u8], key: &str) -> Result<Option<Event<'static>>, ParsingError> {
+        match self.open(ns, key).await {
+            Ok(v) => Ok(Some(v)),
+            Err(ParsingError::Recoverable) => Ok(None),
+            Err(e) => Err(e),
+        }
+    }
+
+    // find stop tag
+    pub async fn close(&mut self) -> Result<Event<'static>, ParsingError> {
+        //println!("close tag {:?}", self.parents.last());
+
+        // Handle the empty case
+        if !self.parent_has_child() {
+            self.parents.pop();
+            return self.next().await 
+        }
+
+        // Handle the start/end case
+        loop {
+            match self.peek() {
+                Event::End(_) => {
+                    self.parents.pop();
+                    return self.next().await
+                },
+                _ => self.skip().await?,
+            };
+        }
+    }
+}
+