Add from-eml command (#1656)

* from-eml initial ver

* Adding tests for `from-eml`

* Add eml to prepares_and_decorates_filesystem_source_files

* Sort the file order

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

crates/nu-cli/src/cli.rs

@@ -328,6 +328,7 @@ pub fn create_default_context(
             whole_stream_command(ToYAML),
             // File format input
             whole_stream_command(FromCSV),
+            whole_stream_command(FromEML),
             whole_stream_command(FromTSV),
             whole_stream_command(FromSSV),
             whole_stream_command(FromINI),

crates/nu-cli/src/commands.rs

@@ -32,6 +32,7 @@ pub(crate) mod first;
 pub(crate) mod format;
 pub(crate) mod from_bson;
 pub(crate) mod from_csv;
+pub(crate) mod from_eml;
 pub(crate) mod from_ics;
 pub(crate) mod from_ini;
 pub(crate) mod from_json;
@@ -145,6 +146,7 @@ pub(crate) use first::First;
 pub(crate) use format::Format;
 pub(crate) use from_bson::FromBSON;
 pub(crate) use from_csv::FromCSV;
+pub(crate) use from_eml::FromEML;
 pub(crate) use from_ics::FromIcs;
 pub(crate) use from_ini::FromINI;
 pub(crate) use from_json::FromJSON;

crates/nu-cli/src/commands/from_eml.rs

@@ -0,0 +1,122 @@
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use ::eml_parser::eml::*;
+use ::eml_parser::EmlParser;
+use nu_errors::ShellError;
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, TaggedDictBuilder, UntaggedValue};
+use nu_source::Tagged;
+
+pub struct FromEML;
+
+const DEFAULT_BODY_PREVIEW: usize = 50;
+
+#[derive(Deserialize, Clone)]
+pub struct FromEMLArgs {
+    #[serde(rename(deserialize = "preview-body"))]
+    preview_body: Option<Tagged<usize>>,
+}
+
+impl WholeStreamCommand for FromEML {
+    fn name(&self) -> &str {
+        "from-eml"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("from-eml").named(
+            "preview-body",
+            SyntaxShape::Int,
+            "How many bytes of the body to preview",
+            Some('b'),
+        )
+    }
+
+    fn usage(&self) -> &str {
+        "Parse text as .eml and create table."
+    }
+
+    fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        args.process(registry, from_eml)?.run()
+    }
+}
+
+fn emailaddress_to_value(tag: &Tag, email_address: &EmailAddress) -> TaggedDictBuilder {
+    let mut dict = TaggedDictBuilder::with_capacity(tag, 2);
+    let (n, a) = match email_address {
+        EmailAddress::AddressOnly { address } => {
+            (UntaggedValue::nothing(), UntaggedValue::string(address))
+        }
+        EmailAddress::NameAndEmailAddress { name, address } => {
+            (UntaggedValue::string(name), UntaggedValue::string(address))
+        }
+    };
+
+    dict.insert_untagged("Name", n);
+    dict.insert_untagged("Address", a);
+
+    dict
+}
+
+fn headerfieldvalue_to_value(tag: &Tag, value: &HeaderFieldValue) -> UntaggedValue {
+    use HeaderFieldValue::*;
+
+    match value {
+        SingleEmailAddress(address) => emailaddress_to_value(tag, address).into_untagged_value(),
+        MultipleEmailAddresses(addresses) => UntaggedValue::Table(
+            addresses
+                .iter()
+                .map(|a| emailaddress_to_value(tag, a).into_value())
+                .collect(),
+        ),
+        Unstructured(s) => UntaggedValue::string(s),
+        Empty => UntaggedValue::nothing(),
+    }
+}
+
+fn from_eml(
+    eml_args: FromEMLArgs,
+    runnable_context: RunnableContext,
+) -> Result<OutputStream, ShellError> {
+    let input = runnable_context.input;
+    let tag = runnable_context.name;
+
+    let stream = async_stream! {
+        let value = input.collect_string(tag.clone()).await?;
+
+        let body_preview = eml_args.preview_body.map(|b| b.item).unwrap_or(DEFAULT_BODY_PREVIEW);
+
+        let eml = EmlParser::from_string(value.item)
+        .with_body_preview(body_preview)
+        .parse()
+        .map_err(|_| ShellError::labeled_error("Could not parse .eml file", "could not parse .eml file", &tag))?;
+
+        let mut dict = TaggedDictBuilder::new(&tag);
+
+        if let Some(subj) = eml.subject {
+           dict.insert_untagged("Subject", UntaggedValue::string(subj));
+        }
+
+        if let Some(from) = eml.from {
+           dict.insert_untagged("From", headerfieldvalue_to_value(&tag, &from));
+        }
+
+        if let Some(to) = eml.to {
+           dict.insert_untagged("To", headerfieldvalue_to_value(&tag, &to));
+        }
+
+        for HeaderField{ name, value } in eml.headers.iter() {
+           dict.insert_untagged(name, headerfieldvalue_to_value(&tag, &value));
+        }
+
+        if let Some(body) = eml.body {
+           dict.insert_untagged("Body", UntaggedValue::string(body));
+        }
+
+        yield ReturnSuccess::value(dict.into_value());
+    };
+
+    Ok(stream.to_output_stream())
+}

crates/nu-cli/src/utils.rs

@@ -301,6 +301,10 @@ mod tests {
                     loc: fixtures().join("sample.db"),
                     at: 0
                 },
+                Res {
+                    loc: fixtures().join("sample.eml"),
+                    at: 0
+                },
                 Res {
                     loc: fixtures().join("sample.ini"),
                     at: 0