Move repl loop and command/script execution to nu_cli (#4846)

* Refactor usage of is_perf_true to be a parameter passed around

* Move repl loop and command/script execution to nu_cli

* Move config setup out of nu_cli

* Update config_files.rs

* Update main.rs

Co-authored-by: JT <547158+jntrnr@users.noreply.github.com>

crates/nu-cli/src/config_files.rs

@@ -0,0 +1,84 @@
+use crate::util::{eval_source, report_error};
+#[cfg(feature = "plugin")]
+use log::info;
+use nu_protocol::engine::{EngineState, Stack, StateDelta, StateWorkingSet};
+use nu_protocol::{PipelineData, Span};
+use std::path::PathBuf;
+
+#[cfg(feature = "plugin")]
+const PLUGIN_FILE: &str = "plugin.nu";
+
+#[cfg(feature = "plugin")]
+pub fn read_plugin_file(
+    engine_state: &mut EngineState,
+    stack: &mut Stack,
+    storage_path: &str,
+    is_perf_true: bool,
+) {
+    // Reading signatures from signature file
+    // The plugin.nu file stores the parsed signature collected from each registered plugin
+    add_plugin_file(engine_state, storage_path);
+
+    let plugin_path = engine_state.plugin_signatures.clone();
+    if let Some(plugin_path) = plugin_path {
+        let plugin_filename = plugin_path.to_string_lossy().to_owned();
+
+        if let Ok(contents) = std::fs::read(&plugin_path) {
+            eval_source(
+                engine_state,
+                stack,
+                &contents,
+                &plugin_filename,
+                PipelineData::new(Span::new(0, 0)),
+            );
+        }
+    }
+
+    if is_perf_true {
+        info!("read_plugin_file {}:{}:{}", file!(), line!(), column!());
+    }
+}
+
+#[cfg(feature = "plugin")]
+pub fn add_plugin_file(engine_state: &mut EngineState, storage_path: &str) {
+    if let Some(mut plugin_path) = nu_path::config_dir() {
+        // Path to store plugins signatures
+        plugin_path.push(storage_path);
+        plugin_path.push(PLUGIN_FILE);
+        engine_state.plugin_signatures = Some(plugin_path.clone());
+    }
+}
+
+pub fn eval_config_contents(
+    config_path: PathBuf,
+    engine_state: &mut EngineState,
+    stack: &mut Stack,
+) {
+    if config_path.exists() & config_path.is_file() {
+        let config_filename = config_path.to_string_lossy().to_owned();
+
+        if let Ok(contents) = std::fs::read(&config_path) {
+            eval_source(
+                engine_state,
+                stack,
+                &contents,
+                &config_filename,
+                PipelineData::new(Span::new(0, 0)),
+            );
+
+            // Merge the delta in case env vars changed in the config
+            match nu_engine::env::current_dir(engine_state, stack) {
+                Ok(cwd) => {
+                    if let Err(e) = engine_state.merge_delta(StateDelta::new(), Some(stack), cwd) {
+                        let working_set = StateWorkingSet::new(engine_state);
+                        report_error(&working_set, &e);
+                    }
+                }
+                Err(e) => {
+                    let working_set = StateWorkingSet::new(engine_state);
+                    report_error(&working_set, &e);
+                }
+            }
+        }
+    }
+}