From 03ae71497046f915125806ce4fb9dd687c3836ac Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Wed, 21 Sep 2016 18:14:11 +0200
Subject: [PATCH] Add MailHasher

---
 libimagmail/src/error.rs  |  1 +
 libimagmail/src/hasher.rs | 64 +++++++++++++++++++++++++++++++++++++++
 libimagmail/src/lib.rs    |  3 +-
 3 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 libimagmail/src/hasher.rs

diff --git a/libimagmail/src/error.rs b/libimagmail/src/error.rs
index cac14af1..59664b66 100644
--- a/libimagmail/src/error.rs
+++ b/libimagmail/src/error.rs
@@ -1,6 +1,7 @@
 generate_error_module!(
     generate_error_types!(MailError, MailErrorKind,
         RefCreationError => "Error creating a reference to a file/directory",
+        MailParsingError => "Error while parsing mail",
         IOError => "IO Error"
     );
 );
diff --git a/libimagmail/src/hasher.rs b/libimagmail/src/hasher.rs
new file mode 100644
index 00000000..f0ced139
--- /dev/null
+++ b/libimagmail/src/hasher.rs
@@ -0,0 +1,64 @@
+use std::io::Read;
+use std::path::PathBuf;
+
+use mailparse::{MailHeader, parse_mail};
+
+use libimagref::hasher::Hasher;
+use libimagref::hasher::DefaultHasher;
+use libimagref::error::RefErrorKind as REK;
+use libimagref::error::MapErrInto;
+use libimagref::result::Result as RResult;
+use libimagerror::into::IntoError;
+
+use error::MailErrorKind as MEK;
+
+pub struct MailHasher {
+    defaulthasher: DefaultHasher,
+}
+
+impl MailHasher {
+
+    pub fn new() -> MailHasher {
+        MailHasher { defaulthasher: DefaultHasher::new() }
+    }
+
+}
+
+impl Hasher for MailHasher {
+
+    fn hash_name(&self) -> &'static str {
+        "default_mail_hasher"
+    }
+
+    fn create_hash<R: Read>(&mut self, pb: &PathBuf, c: &mut R) -> RResult<String> {
+        use filters::filter::Filter;
+
+        let mut s = String::new();
+        try!(c.read_to_string(&mut s).map_err_into(REK::UTF8Error).map_err_into(REK::IOError));
+
+        parse_mail(&s.as_bytes())
+            .map_err(Box::new)
+            .map_err(|e| MEK::MailParsingError.into_error_with_cause(e))
+            .map_err_into(REK::RefHashingError)
+            .and_then(|mail| {
+                let has_key = |hdr: &MailHeader, exp: &str|
+                    hdr.get_key().map(|s| s == exp).unwrap_or(false);
+
+                let subject_filter = |hdr: &MailHeader| has_key(hdr, "Subject");
+                let from_filter    = |hdr: &MailHeader| has_key(hdr, "From");
+                let to_filter      = |hdr: &MailHeader| has_key(hdr, "To");
+
+                let filter = subject_filter.or(from_filter).or(to_filter);
+
+                let s : String = mail.headers
+                    .iter()
+                    .filter(|item| filter.filter(item))
+                    .filter_map(|hdr| hdr.get_value().ok()) // TODO: Do not hide error here
+                    .collect::<Vec<String>>()
+                    .join("");
+
+                self.defaulthasher.create_hash(pb, &mut s.as_bytes())
+            })
+    }
+
+}
diff --git a/libimagmail/src/lib.rs b/libimagmail/src/lib.rs
index d21252eb..14105f3c 100644
--- a/libimagmail/src/lib.rs
+++ b/libimagmail/src/lib.rs
@@ -7,7 +7,8 @@ extern crate filters;
 #[macro_use] extern crate libimagerror;
 extern crate libimagstore;
 
-pub mod mail;
 pub mod error;
+pub mod hasher;
+pub mod mail;
 pub mod result;