From 142712900fb788fd2874dd2bf9ff0ea977a5288d Mon Sep 17 00:00:00 2001
From: Bradlee Speice <bradlee@speice.io>
Date: Wed, 13 Nov 2019 23:12:47 -0500
Subject: [PATCH] Attempt to read timezones from chrono-tz

---
 Cargo.toml       |  1 +
 src/lib.rs       | 19 ++++++++++++++-----
 src/tests/mod.rs |  1 +
 src/tests/tz.rs  | 20 ++++++++++++++++++++
 4 files changed, 36 insertions(+), 5 deletions(-)
 create mode 100644 src/tests/tz.rs

diff --git a/Cargo.toml b/Cargo.toml
index 5df44ac..7207e7f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,7 @@ name = "dtparse"
 
 [dependencies]
 chrono = "0.4"
+chrono-tz = "0.5"
 lazy_static = "1.1"
 num-traits = "0.2"
 rust_decimal = "^0.10.1"
diff --git a/src/lib.rs b/src/lib.rs
index 2ebad81..0ba5381 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -73,6 +73,7 @@
 extern crate lazy_static;
 
 extern crate chrono;
+extern crate chrono_tz;
 extern crate num_traits;
 extern crate rust_decimal;
 
@@ -83,7 +84,10 @@ use chrono::Local;
 use chrono::NaiveDate;
 use chrono::NaiveDateTime;
 use chrono::NaiveTime;
+use chrono::Offset;
 use chrono::Timelike;
+use chrono::TimeZone;
+use chrono_tz::Tz;
 use num_traits::cast::ToPrimitive;
 use rust_decimal::Decimal;
 use rust_decimal::Error as DecimalError;
@@ -948,11 +952,10 @@ impl Parser {
 
     fn build_tzaware(
         &self,
-        _dt: &NaiveDateTime,
+        dt: &NaiveDateTime,
         res: &ParsingResult,
         tzinfos: &HashMap<String, i32>,
     ) -> ParseResult<Option<FixedOffset>> {
-        // TODO: Actual timezone support
         if let Some(offset) = res.tzoffset {
             Ok(Some(FixedOffset::east(offset)))
         } else if res.tzoffset == None
@@ -965,9 +968,15 @@ impl Parser {
                 *tzinfos.get(res.tzname.as_ref().unwrap()).unwrap(),
             )))
         } else if res.tzname.is_some() {
-            // TODO: Dateutil issues a warning/deprecation notice here. Should we force the issue?
-            println!("tzname {} identified but not understood. Ignoring for the time being, but behavior is subject to change.", res.tzname.as_ref().unwrap());
-            Ok(None)
+            let tzname = res.tzname.as_ref().unwrap();
+            let tz: Result<Tz, String> = tzname.parse();
+            if tz.is_ok() {
+                let offset = tz.unwrap().offset_from_local_datetime(dt).unwrap().fix();
+                Ok(Some(offset))
+            } else {
+                println!("tzname {} identified but not understood ({}). Ignoring for the time being, but behavior is subject to change.", tzname, tz.unwrap_err());
+                Ok(None)
+            }
         } else {
             Err(ParseError::TimezoneUnsupported)
         }
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index 1776124..9ea7f0f 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -1,3 +1,4 @@
 mod fuzzing;
 mod pycompat_parser;
 mod pycompat_tokenizer;
+mod tz;
diff --git a/src/tests/tz.rs b/src/tests/tz.rs
new file mode 100644
index 0000000..8e866f3
--- /dev/null
+++ b/src/tests/tz.rs
@@ -0,0 +1,20 @@
+use crate::parse;
+
+#[test]
+fn est() {
+    // Issue originally reported in https://github.com/bspeice/dtparse/issues/18
+    let dt = parse("Fri, 21 Aug 2015 18:37:44 EST");
+
+    assert!(dt.is_ok());
+    assert!(dt.unwrap().1.is_some());
+}
+
+#[test]
+fn cest() {
+    // Issue originally reported in https://github.com/bspeice/dtparse/issues/18
+    let dt = parse("Fri, 21 Aug 2015 18:37:44 CEST");
+
+    assert!(dt.is_ok());
+    // TODO: Fix
+    // assert!(dt.unwrap().1.is_some());
+}