1 files changed, 62 insertions, 10 deletions

diff --git a/src/writer.rs b/src/writer.rs
index 21d5fe0..9e770c7 100644
--- a/src/writer.rs
+++ b/src/writer.rs
@@ -1,4 +1,4 @@
-use std::collections::HashSet;
+use std::{collections::HashSet, str::FromStr};
 
 use futures::Sink;
 use tokio::io::AsyncWrite;
@@ -7,6 +7,7 @@ use crate::{
     element::{Element, Name, NamespaceDeclaration},
     error::Error,
     xml::{self, composers::Composer, parsers_complete::Parser, ETag},
+    Result,
 };
 
 // pub struct Writer<W, C = Composer> {
@@ -17,17 +18,68 @@ pub struct Writer<W> {
 }
 
 impl<W: AsyncWrite + Unpin> Writer<W> {
-    pub async fn write(&mut self, element: Element) -> Result<(), Error> {
+    pub async fn write(&mut self, element: Element) -> Result<()> {
         todo!()
     }
 
-    pub async fn write_start(&mut self, element: Element) -> Result<(), Error> {
-        todo!()
+    pub async fn write_start(&mut self, element: Element) -> Result<()> {
+        let mut namespace_declarations_stack: Vec<_> = self
+            .namespace_declarations
+            .iter()
+            .flatten()
+            .chain(&element.namespace_declarations)
+            .collect();
+        let name_namespace_declaration = namespace_declarations_stack
+            .iter()
+            .rfind(|namespace_declaration| {
+                namespace_declaration.namespace == element.name.namespace
+            })
+            .ok_or(Error::UndeclaredNamespace(element.name.namespace.clone()))?;
+        let prefix = &name_namespace_declaration.prefix;
+        let name;
+        if let Some(prefix) = &prefix {
+            name = xml::QName::PrefixedName(xml::PrefixedName {
+                prefix: xml::Prefix::parse_full(prefix)?,
+                local_part: xml::LocalPart::parse_full(&element.name.local_name)?,
+            })
+        } else {
+            name = xml::QName::UnprefixedName(xml::UnprefixedName::parse_full(
+                &element.name.local_name,
+            )?)
+        }
+
+        namespace_declarations_stack.push(name_namespace_declaration);
+
+        let mut attributes = Vec::new();
+
+        for namespace_declaration in &element.namespace_declarations {
+            let ns_name = namespace_declaration
+                .prefix
+                .as_ref()
+                .map(|prefix| -> Result<_> {
+                    Ok(xml::NSAttName::PrefixedAttName(
+                        xml::PrefixedAttName::parse_full(&prefix)?,
+                    ))
+                })
+                .unwrap_or(Ok(xml::NSAttName::DefaultAttName))?;
+            let value = xml::AttValue::from(namespace_declaration.namespace.as_str());
+            let xml_attribute = xml::Attribute::NamespaceDeclaration { ns_name, value };
+            attributes.push(xml_attribute);
+        }
+
+        let s_tag = xml::STag { name, attributes };
+
+        s_tag.write(&mut self.inner).await?;
+
+        self.depth.push(element.name);
+        self.namespace_declarations
+            .push(element.namespace_declarations);
+        Ok(())
     }
 
-    pub async fn write_end(&mut self) -> Result<(), Error> {
-        let e_tag;
+    pub async fn write_end(&mut self) -> Result<()> {
         if let Some(name) = &self.depth.pop() {
+            let e_tag;
             let namespace_declarations_stack: Vec<_> =
                 self.namespace_declarations.iter().flatten().collect();
             let namespace_declaration = namespace_declarations_stack
@@ -65,25 +117,25 @@ impl<W: AsyncWrite, E: Into<Element>> Sink<E> for Writer<W> {
     fn poll_ready(
         self: std::pin::Pin<&mut Self>,
         cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Result<(), Self::Error>> {
+    ) -> std::task::Poll<Result<()>> {
         todo!()
     }
 
-    fn start_send(self: std::pin::Pin<&mut Self>, item: E) -> Result<(), Self::Error> {
+    fn start_send(self: std::pin::Pin<&mut Self>, item: E) -> Result<()> {
         todo!()
     }
 
     fn poll_flush(
         self: std::pin::Pin<&mut Self>,
         cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Result<(), Self::Error>> {
+    ) -> std::task::Poll<Result<()>> {
         todo!()
     }
 
     fn poll_close(
         self: std::pin::Pin<&mut Self>,
         cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Result<(), Self::Error>> {
+    ) -> std::task::Poll<Result<()>> {
         todo!()
     }
 }