fix(CLI): Display for Errors + refactor

* refactored errors into a hierarchy
* implemented `Display` trait for all error types, including some
  'hierarchy-aware' printing.

Fixes #54

src/mako/cli/lib/cli.py

@@ -15,6 +15,7 @@
 OUTPUT_FLAG = 'o'
 VALUE_ARG = 'v'
 SCOPE_FLAG = 'scope'
+CONFIG_DIR_FLAG = 'config-dir'
 
 FILE_ARG = '<file>'
 MIME_ARG = '<mime>'

src/mako/cli/lib/docopt.mako

@@ -2,7 +2,8 @@
 <%!
     from util import (put_and, supports_scopes)
     from cli import (mangle_subcommand, new_method_context, PARAM_FLAG, STRUCT_FLAG, UPLOAD_FLAG, OUTPUT_FLAG, VALUE_ARG,
-                     CONFIG_DIR, SCOPE_FLAG, is_request_value_property, FIELD_SEP, docopt_mode, FILE_ARG, MIME_ARG, OUT_ARG)
+                     CONFIG_DIR, SCOPE_FLAG, is_request_value_property, FIELD_SEP, docopt_mode, FILE_ARG, MIME_ARG, OUT_ARG, 
+                     CONFIG_DIR_FLAG)
 
     v_arg = '<%s>' % VALUE_ARG
 %>\
@@ -63,7 +64,7 @@ Configuration:
             the user to grant this application permission to use it.
             If unset, it defaults to the shortest scope url for a particular method.
 % endif scopes
-  --config-dir <folder>
+  --${CONFIG_DIR_FLAG} <folder>
             A directory into which we will store our persistent data. Defaults to a user-writable
             directory that we will create during the first invocation.
             [default: ${CONFIG_DIR}]

src/mako/cli/lib/engine.mako

@@ -7,7 +7,7 @@
 %>\
 <%def name="new(c)">\
 mod cmn;
-use cmn::{InvalidOptionsError};
+use cmn::InvalidOptionsError;
 
 use oauth2::ApplicationSecret;
 

src/mako/cli/main.rs.mako

@@ -30,7 +30,7 @@ fn main() {
     println!("{:?}", opts);
     match Engine::new(opts) {
         Err(e) => {
-            write!(io::stderr(), "{:?}", e).ok();
+            write!(io::stderr(), "{}", e).ok();
             env::set_exit_status(e.exit_code);
         },
         Ok(mut engine) => {

src/rust/cli/cmn.rs

@@ -4,20 +4,70 @@ use rustc_serialize::json;
 use std::fs;
 use std::env;
 use std::io;
+use std::fmt;
 use std::path::Path;
+use std::cell::RefCell;
 
 use std::io::{Write, Read};
 
 use std::default::Default;
 
 #[derive(Debug)]
-pub enum ArgumentError {
-    ConfigurationDirectoryInaccessible((String, io::Error)),
-    ConfigurationDirectoryUnset,
-    UsernameExpansionFailed(String),
+pub enum ApplicationSecretError {
+    DecoderError((String, json::DecoderError)),
+    FormatError(String),    
+}
+
+impl fmt::Display for ApplicationSecretError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match *self {
+            ApplicationSecretError::DecoderError((ref path, ref err))
+                => writeln!(f, "Could not decode file at '{}' with error: {}"
+                          , path, err),
+            ApplicationSecretError::FormatError(ref path)
+                => writeln!(f, "'installed' field is unset in secret file at '{}'"
+                            , path),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum ConfigurationError {
+    DirectoryCreationFailed((String, io::Error)),
+    DirectoryUnset,
+    HomeExpansionFailed(String),
+    Secret(ApplicationSecretError),
     IOError((String, io::Error)),
-    SecretDecoderError((String, json::DecoderError)),
-    SecretFormatError(String),
+}
+
+impl fmt::Display for ConfigurationError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match *self {
+            ConfigurationError::DirectoryCreationFailed((ref dir, ref err))
+                => writeln!(f, "Directory '{}' could not be created with error: {}", dir, err),
+            ConfigurationError::DirectoryUnset 
+                => writeln!(f, "--config-dir was unset or empty"),
+            ConfigurationError::HomeExpansionFailed(ref dir)
+                => writeln!(f, "Couldn't find HOME directory of current user, failed to expand '{}'", dir),
+            ConfigurationError::Secret(ref err)
+                => writeln!(f, "Secret -> {}", err),
+            ConfigurationError::IOError((ref path, ref err))
+                => writeln!(f, "IO operation failed on path '{}' with error: {}", path, err),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum ArgumentError {
+    Configuration(ConfigurationError),
+}
+
+impl fmt::Display for ArgumentError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match *self {
+            ArgumentError::Configuration(ref err) => writeln!(f, "Configuration -> {}", err)
+        }
+    }
 }
 
 #[derive(Debug)]
@@ -26,6 +76,15 @@ pub struct InvalidOptionsError {
     pub exit_code: i32,
 }
 
+impl fmt::Display for InvalidOptionsError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        for issue in &self.issues {
+            try!(issue.fmt(f));
+        }
+        Ok(())
+    }
+}
+
 impl InvalidOptionsError {
     pub fn single(err: ArgumentError, exit_code: i32) -> InvalidOptionsError {
         InvalidOptionsError {
@@ -38,13 +97,13 @@ impl InvalidOptionsError {
 pub fn assure_config_dir_exists(dir: &str) -> Result<String, ArgumentError> {
     let trdir = dir.trim();
     if trdir.len() == 0 {
-        return Err(ArgumentError::ConfigurationDirectoryUnset)
+        return Err(ArgumentError::Configuration(ConfigurationError::DirectoryUnset))
     }
 
     let expanded_config_dir = 
         if trdir.as_bytes()[0] == b'~' {
             match env::var("HOME").ok().or(env::var("UserProfile").ok()) {
-                None => return Err(ArgumentError::UsernameExpansionFailed(trdir.to_string())),
+                None => return Err(ArgumentError::Configuration(ConfigurationError::HomeExpansionFailed(trdir.to_string()))),
                 Some(mut user) => {
                     user.push_str(&trdir[1..]);
                     user
@@ -56,7 +115,8 @@ pub fn assure_config_dir_exists(dir: &str) -> Result<String, ArgumentError> {
 
     if let Err(err) = fs::create_dir(&expanded_config_dir) {
         if err.kind() != io::ErrorKind::AlreadyExists {
-            return Err(ArgumentError::ConfigurationDirectoryInaccessible((expanded_config_dir, err)))
+            return Err(ArgumentError::Configuration(
+                    ConfigurationError::DirectoryCreationFailed((expanded_config_dir, err))))
         }
     }
 
@@ -67,15 +127,15 @@ pub fn application_secret_from_directory(dir: &str, secret_basename: &str) -> Re
     let secret_path = Path::new(dir).join(secret_basename);
     let secret_str = || secret_path.as_path().to_str().unwrap().to_string();
     let secret_io_error = |io_err: io::Error| {
-            Err(ArgumentError::IOError(
+            Err(ArgumentError::Configuration(ConfigurationError::IOError(
                 (secret_str(), io_err)
-            ))
+            )))
     };
 
     for _ in 0..2 {
         match fs::File::open(&secret_path) {
-            Err(mut e) => {
-                if e.kind() == io::ErrorKind::NotFound {
+            Err(mut err) => {
+                if err.kind() == io::ErrorKind::NotFound {
                     // Write our built-in one - user may adjust the written file at will
                     let secret = ApplicationSecret {
                         client_id: "14070749909-vgip2f1okm7bkvajhi9jugan6126io9v.apps.googleusercontent.com".to_string(),
@@ -94,7 +154,7 @@ pub fn application_secret_from_directory(dir: &str, secret_basename: &str) -> Re
                     };
 
                     let json_enocded_secret = json::encode(&app_secret).unwrap();
-                    e = match fs::OpenOptions::new().create(true).write(true).open(&secret_path) {
+                    err = match fs::OpenOptions::new().create(true).write(true).open(&secret_path) {
                         Err(cfe) => cfe,
                         Ok(mut f) => {
                             match f.write(json_enocded_secret.as_bytes()) {
@@ -105,20 +165,25 @@ pub fn application_secret_from_directory(dir: &str, secret_basename: &str) -> Re
                     };
                     // fall through to IO error handling
                 }
-                return secret_io_error(e)
+                return secret_io_error(err)
             },
             Ok(mut f) => {
                 let mut json_encoded_secret = String::new();
                 if let Err(io_err) = f.read_to_string(&mut json_encoded_secret) {
                     return secret_io_error(io_err)
                 }
                 match json::decode::<ConsoleApplicationSecret>(&json_encoded_secret) {
-                    Err(json_decode_error) => return Err(ArgumentError::SecretDecoderError(
+                    Err(json_decode_error) => return Err(ArgumentError::Configuration(
+                        ConfigurationError::Secret(ApplicationSecretError::DecoderError(
                                                 (secret_str(), json_decode_error)
-                                              )),
+                                              )))),
                     Ok(console_secret) => match console_secret.installed {
                         Some(secret) => return Ok(secret),
-                        None => return Err(ArgumentError::SecretFormatError(secret_str()))
+                        None => return Err(
+                                    ArgumentError::Configuration(
+                                    ConfigurationError::Secret(
+                                    ApplicationSecretError::FormatError(secret_str())
+                                    )))
                     },
                 }
             }