1 files changed, 103 insertions, 0 deletions
diff --git a/libgitmail/src/patch/mod.rs b/libgitmail/src/patch/mod.rs
new file mode 100644
index 0000000..b4b09a4
--- /dev/null
+++ b/libgitmail/src/patch/mod.rs
@@ -0,0 +1,103 @@
+use crate::{Error, Result};
+use std::collections::HashMap;
+
+mod parsers;
+use parsers::get_header;
+pub use parsers::{Segment, Subject};
+
+#[doc(hidden)]
+pub type HeaderMap = HashMap<String, String>;
+
+/// Message ID of an email in a thread
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Id(pub String);
+
+impl Id {
+  pub fn from(headers: &HeaderMap, key: &str) -> Result<Self> {
+    get_header(&headers, key).and_then(|h| match h {
+      Header::Single(h) => Ok(Self(h)),
+      _ => Err(Error::FailedParsing),
+    })
+  }
+}
+
+/// A semi typed header value for mail
+pub(crate) enum Header {
+  /// A single header value
+  Single(String),
+  /// A set of values that was separated by `,`
+  Multi(Vec<String>),
+}
+
+impl Header {
+  fn single(self) -> Result<String> {
+    match self {
+      Self::Single(s) => Ok(s),
+      Self::Multi(_) => Err(Error::FailedParsing),
+    }
+  }
+}
+
+/// A single patch, metadata and email body
+///
+/// This type is constructed from a single email in a thread, and can
+/// then be combined into a [PatchSet](struct.PatchSet.html) via the
+/// [PatchTree](struct.PatchTree.html) builder.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Patch<'mail> {
+  pub id: Id,
+  pub reply_to: Option<Id>,
+  pub subject: Subject,
+  pub headers: HeaderMap,
+  pub raw: &'mail str,
+}
+
+impl<'mail> Patch<'mail> {
+  #[doc(hidden)]
+  pub fn preprocess(raw: &'mail str) -> HeaderMap {
+    let mail = mailparse::parse_mail(raw.as_bytes())
+      .map_err(|_| Error::FailedParsing)
+      .unwrap();
+    mail
+      .headers
+      .into_iter()
+      .fold(HashMap::new(), |mut acc, header| {
+        let key = header.get_key().unwrap();
+        let val = header.get_value().unwrap();
+        acc.insert(key, val);
+        acc
+      })
+  }
+
+  pub fn new(raw: &'mail str) -> Result<Self> {
+    let mail = mailparse::parse_mail(raw.as_bytes())
+      .map_err(|_| Error::FailedParsing)?;
+    let headers =
+      mail
+        .headers
+        .into_iter()
+        .fold(HashMap::new(), |mut acc, header| {
+          let key = header.get_key().unwrap();
+          let val = header.get_value().unwrap();
+          acc.insert(key, val);
+          acc
+        });
+
+    get_header(&headers, "X-Mailer").and_then(|h| match h {
+      Header::Single(s) if s.contains("git-send-email") => Ok(()),
+      _ => Err(Error::NotAGitMail),
+    })?;
+
+    Ok(Self {
+      id: Id::from(&headers, "Message-Id")?,
+      reply_to: Id::from(&headers, "In-Reply-To")
+        .map(|id| Some(id))
+        .unwrap_or(None),
+      subject: get_header(&headers, "Subject")
+        .and_then(|h| h.single())
+        .and_then(|s| Subject::from(s))?,
+      headers,
+      raw,
+    })
+  }
+}