add a new welcome banner to nushell (#6163)

* add a new welcome banner to nushell

* remove top line

* tweaked colors and wording

* changed to dimmed white

* removed a comment

* make config nu stand out a little

* fix type-o

Cargo.lock

@@ -2537,6 +2537,7 @@ dependencies = [
  "reedline",
  "regex",
  "rstest",
+ "strip-ansi-escapes",
  "sysinfo",
  "thiserror",
 ]

crates/nu-cli/Cargo.toml

@@ -30,6 +30,7 @@ is_executable = "1.0.1"
 lazy_static = "1.4.0"
 log = "0.4"
 regex = "1.5.4"
+strip-ansi-escapes = "0.1.1"
 sysinfo = "0.24.1"
 
 [features]

crates/nu-cli/src/repl.rs

@@ -14,12 +14,14 @@ use nu_parser::{lex, parse};
 use nu_protocol::{
     ast::PathMember,
     engine::{EngineState, Stack, StateWorkingSet},
-    BlockId, HistoryFileFormat, PipelineData, PositionalArg, ShellError, Span, Type, Value, VarId,
+    format_duration, BlockId, HistoryFileFormat, PipelineData, PositionalArg, ShellError, Span,
+    Type, Value, VarId,
 };
 use reedline::{DefaultHinter, Emacs, SqliteBackedHistory, Vi};
 use regex::Regex;
 use std::io::{self, Write};
 use std::{sync::atomic::Ordering, time::Instant};
+use strip_ansi_escapes::strip;
 use sysinfo::SystemExt;
 
 // According to Daniel Imms @Tyriar, we need to do these this way:
@@ -119,6 +121,25 @@ pub fn evaluate_repl(
 
     let sys = sysinfo::System::new();
 
+    let show_banner = config.show_banner;
+    let use_ansi = config.use_ansi_coloring;
+    if show_banner {
+        let banner = get_banner(engine_state, stack);
+        if use_ansi {
+            println!("{}", banner);
+        } else {
+            let stripped_string = {
+                if let Ok(bytes) = strip(&banner) {
+                    String::from_utf8_lossy(&bytes).to_string()
+                } else {
+                    banner
+                }
+            };
+
+            println!("{}", stripped_string);
+        }
+    }
+
     loop {
         if is_perf_true {
             info!(
@@ -460,6 +481,121 @@ pub fn evaluate_repl(
     Ok(())
 }
 
+fn get_banner(engine_state: &mut EngineState, stack: &mut Stack) -> String {
+    let age = match eval_string_with_input(
+        engine_state,
+        stack,
+        None,
+        "(date now) - ('05/10/2019' | into datetime)",
+    ) {
+        Ok(Value::Duration { val, .. }) => format_duration(val),
+        _ => "".to_string(),
+    };
+
+    let banner = format!(
+        r#"{}     __  ,
+{} .--()°'.' {}Welcome to {}Nushell{}, 
+{}'|, . ,'   {}based on the {}nu{} language,
+{} !_-(_\    {}where all data is structured!
+
+Please join our {}Discord{} community at {}https://discord.gg/NtAbbGn{}
+Our {}GitHub{} repository is at {}https://github.com/nushell/nushell{}
+Our {}Documentation{} is located at {}http://nushell.sh{}
+{}Tweet{} us at {}@nu_shell{}
+
+{}Nushell{} has been around for:
+{}
+
+{}You can disable this banner using the {}config nu{}{} command
+to modify the config.nu file and setting show_banner to false.
+
+let-env config {{
+    show_banner: false
+    ...
+}}{}
+"#,
+        "\x1b[32m",   //start line 1 green
+        "\x1b[32m",   //start line 2
+        "\x1b[0m",    //before welcome
+        "\x1b[32m",   //before nushell
+        "\x1b[0m",    //after nushell
+        "\x1b[32m",   //start line 3
+        "\x1b[0m",    //before based
+        "\x1b[32m",   //before nu
+        "\x1b[0m",    //after nu
+        "\x1b[32m",   //start line 4
+        "\x1b[0m",    //before where
+        "\x1b[35m",   //before Discord purple
+        "\x1b[0m",    //after Discord
+        "\x1b[35m",   //before Discord URL
+        "\x1b[0m",    //after Discord URL
+        "\x1b[1;32m", //before GitHub green_bold
+        "\x1b[0m",    //after GitHub
+        "\x1b[1;32m", //before GitHub URL
+        "\x1b[0m",    //after GitHub URL
+        "\x1b[32m",   //before Documentation
+        "\x1b[0m",    //after Documentation
+        "\x1b[32m",   //before Documentation URL
+        "\x1b[0m",    //after Documentation URL
+        "\x1b[36m",   //before Tweet blue
+        "\x1b[0m",    //after Tweet
+        "\x1b[1;36m", //before @nu_shell cyan_bold
+        "\x1b[0m",    //after @nu_shell
+        "\x1b[32m",   //before Nushell
+        "\x1b[0m",    //after Nushell
+        age,
+        "\x1b[2;37m", //before banner disable dim white
+        "\x1b[2;36m", //before config nu dim cyan
+        "\x1b[0m",    //after config nu
+        "\x1b[2;37m", //after config nu dim white
+        "\x1b[0m",    //after banner disable
+    );
+
+    banner
+}
+
+// Taken from Nana's simple_eval
+/// Evaluate a block of Nu code, optionally with input.
+/// For example, source="$in * 2" will multiply the value in input by 2.
+pub fn eval_string_with_input(
+    engine_state: &mut EngineState,
+    stack: &mut Stack,
+    input: Option<Value>,
+    source: &str,
+) -> Result<Value, ShellError> {
+    let (block, delta) = {
+        let mut working_set = StateWorkingSet::new(engine_state);
+        let (output, _) = parse(
+            &mut working_set,
+            Some("nana"),
+            source.as_bytes(),
+            false,
+            &[],
+        );
+
+        (output, working_set.render())
+    };
+
+    if let Err(err) = engine_state.merge_delta(delta) {
+        return Err(err);
+    }
+
+    let input_as_pipeline_data = match input {
+        Some(input) => PipelineData::Value(input, None),
+        None => PipelineData::new(Span::test_data()),
+    };
+
+    eval_block(
+        engine_state,
+        stack,
+        &block,
+        input_as_pipeline_data,
+        false,
+        true,
+    )
+    .map(|x| x.into_value(Span::test_data()))
+}
+
 pub fn get_command_finished_marker(stack: &Stack, engine_state: &EngineState) -> String {
     let exit_code = stack
         .get_env_var(engine_state, "LAST_EXIT_CODE")

crates/nu-protocol/src/config.rs

@@ -81,6 +81,7 @@ pub struct Config {
     pub case_sensitive_completions: bool,
     pub enable_external_completion: bool,
     pub trim_strategy: TrimStrategy,
+    pub show_banner: bool,
 }
 
 impl Default for Config {
@@ -115,6 +116,7 @@ impl Default for Config {
             case_sensitive_completions: false,
             enable_external_completion: true,
             trim_strategy: TRIM_STRATEGY_DEFAULT,
+            show_banner: true,
         }
     }
 }
@@ -388,6 +390,13 @@ impl Value {
                         }
                     }
                     "table_trim" => config.trim_strategy = try_parse_trim_strategy(value, &config)?,
+                    "show_banner" => {
+                        if let Ok(b) = value.as_bool() {
+                            config.show_banner = b;
+                        } else {
+                            eprintln!("$config.show_banner is not a bool")
+                        }
+                    }
                     x => {
                         eprintln!("$config.{} is an unknown config setting", x)
                     }

docs/sample_config/default_config.nu

@@ -257,7 +257,6 @@ let-env config = {
   case_sensitive_completions: false # set to true to enable case-sensitive completions
   enable_external_completion: true # set to false to prevent nushell looking into $env.PATH to find more suggestions, `false` recommended for WSL users as this look up my be very slow
   max_external_completion_results: 100 # setting it lower can improve completion performance at the cost of omitting some options
-
   # A strategy of managing table view in case of limited space.
   table_trim: {
     methodology: wrapping, # truncating
@@ -266,6 +265,7 @@ let-env config = {
     # A suffix which will be used with 'truncating' methodology
     # truncating_suffix: "..."
   }
+  show_banner: true # true or false to enable or disable the banner
 
   hooks: {
     pre_prompt: [{