nu-cli refactor moving commands into their own crate nu-command (#2910)

* move commands, futures.rs, script.rs, utils

* move over maybe_print_errors

* add nu_command crate references to nu_cli

* in commands.rs open up to pub mod from pub(crate)

* nu-cli, nu-command, and nu tests are now passing

* cargo fmt

* clean up nu-cli/src/prelude.rs

* code cleanup

* for some reason lex.rs was not formatted, may be causing my error

* remove mod completion from lib.rs which was not being used along with quickcheck macros

* add in allow unused imports

* comment out one failing external test; comment out one failing internal test

* revert commenting out failing tests; something else might be going on; someone with a windows machine should check and see what is going on with these failing windows tests

* Update Cargo.toml

Extend the optional features to nu-command

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

crates/nu-command/src/commands/math/avg.rs

@@ -0,0 +1,195 @@
+use crate::prelude::*;
+
+use crate::commands::math::reducers::{reducer_for, Reduce};
+use crate::commands::math::utils::run_with_function;
+use nu_engine::WholeStreamCommand;
+
+use nu_errors::ShellError;
+use nu_protocol::{
+    hir::{convert_number_to_u64, Number, Operator},
+    Primitive, Signature, UntaggedValue, Value,
+};
+
+use bigdecimal::FromPrimitive;
+
+pub struct SubCommand;
+
+#[async_trait]
+impl WholeStreamCommand for SubCommand {
+    fn name(&self) -> &str {
+        "math avg"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("math avg")
+    }
+
+    fn usage(&self) -> &str {
+        "Finds the average of a list of numbers or tables"
+    }
+
+    async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        run_with_function(
+            RunnableContext {
+                input: args.input,
+                scope: args.scope.clone(),
+                shell_manager: args.shell_manager,
+                host: args.host,
+                ctrl_c: args.ctrl_c,
+                current_errors: args.current_errors,
+                name: args.call_info.name_tag,
+            },
+            average,
+        )
+        .await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Get the average of a list of numbers",
+            example: "echo [-50 100.0 25] | math avg",
+            result: Some(vec![UntaggedValue::decimal_from_float(
+                25.0,
+                Span::unknown(),
+            )
+            .into()]),
+        }]
+    }
+}
+
+fn to_byte(value: &Value) -> Option<Value> {
+    match &value.value {
+        UntaggedValue::Primitive(Primitive::Int(num)) => Some(
+            UntaggedValue::Primitive(Primitive::Filesize(convert_number_to_u64(&Number::Int(
+                num.clone(),
+            ))))
+            .into_untagged_value(),
+        ),
+        _ => None,
+    }
+}
+
+pub fn average(values: &[Value], name: &Tag) -> Result<Value, ShellError> {
+    let sum = reducer_for(Reduce::Summation);
+
+    let number = BigDecimal::from_usize(values.len()).ok_or_else(|| {
+        ShellError::labeled_error("nothing to average", "nothing to average", &name.span)
+    })?;
+
+    let total_rows = UntaggedValue::decimal(number);
+
+    let are_bytes = values
+        .get(0)
+        .ok_or_else(|| {
+            ShellError::unexpected("Cannot perform aggregate math operation on empty data")
+        })?
+        .is_filesize();
+
+    let total = if are_bytes {
+        to_byte(&sum(
+            UntaggedValue::int(0).into_untagged_value(),
+            values
+                .to_vec()
+                .iter()
+                .map(|v| match v {
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Filesize(num)),
+                        ..
+                    } => UntaggedValue::int(*num as usize).into_untagged_value(),
+                    other => other.clone(),
+                })
+                .collect::<Vec<_>>(),
+        )?)
+        .ok_or_else(|| {
+            ShellError::labeled_error(
+                "could not convert to big decimal",
+                "could not convert to big decimal",
+                &name.span,
+            )
+        })
+    } else {
+        sum(UntaggedValue::int(0).into_untagged_value(), values.to_vec())
+    }?;
+
+    match total {
+        Value {
+            value: UntaggedValue::Primitive(Primitive::Filesize(num)),
+            ..
+        } => {
+            let left = UntaggedValue::from(Primitive::Int(num.into()));
+            let result = nu_data::value::compute_values(Operator::Divide, &left, &total_rows);
+
+            match result {
+                Ok(UntaggedValue::Primitive(Primitive::Decimal(result))) => {
+                    let number = Number::Decimal(result);
+                    let number = convert_number_to_u64(&number);
+                    Ok(UntaggedValue::filesize(number).into_value(name))
+                }
+                Ok(_) => Err(ShellError::labeled_error(
+                    "could not calculate average of non-integer or unrelated types",
+                    "source",
+                    name,
+                )),
+                Err((left_type, right_type)) => Err(ShellError::coerce_error(
+                    left_type.spanned(name.span),
+                    right_type.spanned(name.span),
+                )),
+            }
+        }
+        Value {
+            value: UntaggedValue::Primitive(Primitive::Duration(duration)),
+            ..
+        } => {
+            let left = UntaggedValue::from(Primitive::Duration(duration));
+            let result = nu_data::value::compute_values(Operator::Divide, &left, &total_rows);
+
+            match result {
+                Ok(UntaggedValue::Primitive(Primitive::Duration(result))) => {
+                    Ok(UntaggedValue::duration(result).into_value(name))
+                }
+                Ok(_) => Err(ShellError::labeled_error(
+                    "could not calculate average of non-integer or unrelated types",
+                    "source",
+                    name,
+                )),
+                Err((left_type, right_type)) => Err(ShellError::coerce_error(
+                    left_type.spanned(name.span),
+                    right_type.spanned(name.span),
+                )),
+            }
+        }
+        Value {
+            value: UntaggedValue::Primitive(other),
+            ..
+        } => {
+            let left = UntaggedValue::from(other);
+            let result = nu_data::value::compute_values(Operator::Divide, &left, &total_rows);
+
+            match result {
+                Ok(value) => Ok(value.into_value(name)),
+                Err((left_type, right_type)) => Err(ShellError::coerce_error(
+                    left_type.spanned(name.span),
+                    right_type.spanned(name.span),
+                )),
+            }
+        }
+        _ => Err(ShellError::labeled_error(
+            "could not calculate average of non-integer or unrelated types",
+            "source",
+            name,
+        )),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::ShellError;
+    use super::SubCommand;
+
+    #[test]
+    fn examples_work_as_expected() -> Result<(), ShellError> {
+        use crate::examples::test as test_examples;
+
+        Ok(test_examples(SubCommand {})?)
+    }
+}