Add the history import command (#13450)

# Description

Adds a simple command for importing history between different file
formats. It essentially opens the history of the format opposite of the
one currently selected, and writes new items to the current history. It
also supports piping, because why not.

As more history backends are added, this may need to be extended -
either make the source explicit, or autodetect based on existing files.
For now it should be good though.

This should replace some of the work-arounds mentioned in
https://github.com/nushell/nushell/issues/9403.

I suspect it will have at least one problem:
https://github.com/nushell/nushell/issues/9403 mentions the history file
might be locked on Windows. That being said, I was able to successfully
import plaintext history into sqlite on Linux, so the command should be
functional at least in that environment.

The locking issue could be solved later by plumbing reedline history to
the command (so that it doesn't have to reopen it). But first, I want to
get some general input on the approach.

# User-Facing Changes
New command: `history import`

# Tests + Formatting
There's a unit test, but didn't add a proper integration test yet. Not
entirely sure how - I see there's the `nu!` macro for that, but not sure
how feasible it's to inspect history generated by commands ran that way.
Could use a hint.2

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

@@ -17,6 +17,7 @@ pub fn add_cli_context(mut engine_state: EngineState) -> EngineState {
             CommandlineGetCursor,
             CommandlineSetCursor,
             History,
+            HistoryImport,
             HistorySession,
             Keybindings,
             KeybindingsDefault,

crates/nu-cli/src/commands/history/fields.rs

@@ -0,0 +1,10 @@
+// Each const is named after a HistoryItem field, and the value is the field name to be displayed to
+// the user (or accept during import).
+pub const COMMAND_LINE: &str = "command";
+pub const ID: &str = "item_id";
+pub const START_TIMESTAMP: &str = "start_timestamp";
+pub const HOSTNAME: &str = "hostname";
+pub const CWD: &str = "cwd";
+pub const EXIT_STATUS: &str = "exit_status";
+pub const DURATION: &str = "duration";
+pub const SESSION_ID: &str = "session_id";

crates/nu-cli/src/commands/history/history_.rs

@@ -5,6 +5,8 @@ use reedline::{
     SqliteBackedHistory,
 };
 
+use super::fields;
+
 #[derive(Clone)]
 pub struct History;
 
@@ -83,7 +85,8 @@ impl Command for History {
                     entries.into_iter().enumerate().map(move |(idx, entry)| {
                         Value::record(
                             record! {
-                                "command" => Value::string(entry.command_line, head),
+                                fields::COMMAND_LINE => Value::string(entry.command_line, head),
+                                // TODO: This name is inconsistent with create_history_record.
                                 "index" => Value::int(idx as i64, head),
                             },
                             head,
@@ -175,14 +178,14 @@ fn create_history_record(idx: usize, entry: HistoryItem, long: bool, head: Span)
     if long {
         Value::record(
             record! {
-                "item_id" => item_id_value,
-                "start_timestamp" => start_timestamp_value,
-                "command" => command_value,
-                "session_id" => session_id_value,
-                "hostname" => hostname_value,
-                "cwd" => cwd_value,
-                "duration" => duration_value,
-                "exit_status" => exit_status_value,
+                fields::ID => item_id_value,
+                fields::START_TIMESTAMP => start_timestamp_value,
+                fields::COMMAND_LINE => command_value,
+                fields::SESSION_ID => session_id_value,
+                fields::HOSTNAME => hostname_value,
+                fields::CWD => cwd_value,
+                fields::DURATION => duration_value,
+                fields::EXIT_STATUS => exit_status_value,
                 "idx" => index_value,
             },
             head,
@@ -190,11 +193,11 @@ fn create_history_record(idx: usize, entry: HistoryItem, long: bool, head: Span)
     } else {
         Value::record(
             record! {
-                "start_timestamp" => start_timestamp_value,
-                "command" => command_value,
-                "cwd" => cwd_value,
-                "duration" => duration_value,
-                "exit_status" => exit_status_value,
+                fields::START_TIMESTAMP => start_timestamp_value,
+                fields::COMMAND_LINE => command_value,
+                fields::CWD => cwd_value,
+                fields::DURATION => duration_value,
+                fields::EXIT_STATUS => exit_status_value,
             },
             head,
         )

crates/nu-cli/src/commands/history/history_import.rs

@@ -0,0 +1,332 @@
+use nu_engine::command_prelude::*;
+use nu_protocol::HistoryFileFormat;
+
+use reedline::{
+    FileBackedHistory, History, HistoryItem, HistoryItemId, ReedlineError, SearchQuery,
+    SqliteBackedHistory,
+};
+
+use super::fields;
+
+#[derive(Clone)]
+pub struct HistoryImport;
+
+impl Command for HistoryImport {
+    fn name(&self) -> &str {
+        "history import"
+    }
+
+    fn description(&self) -> &str {
+        "Import command line history"
+    }
+
+    fn extra_description(&self) -> &str {
+        r#"Can import history from input, either successive command lines or more detailed records. If providing records, available fields are:
+    command_line, id, start_timestamp, hostname, cwd, duration, exit_status.
+
+If no input is provided, will import all history items from existing history in the other format: if current history is stored in sqlite, it will store it in plain text and vice versa."#
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("history import")
+            .category(Category::History)
+            .input_output_types(vec![
+                (Type::Nothing, Type::Nothing),
+                (Type::List(Box::new(Type::String)), Type::Nothing),
+                (Type::table(), Type::Nothing),
+            ])
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                example: "history import",
+                description:
+                    "Append all items from history in the other format to the current history",
+                result: None,
+            },
+            Example {
+                example: "echo foo | history import",
+                description: "Append `foo` to the current history",
+                result: None,
+            },
+            Example {
+                example: "[[ command_line cwd ]; [ foo /home ]] | history import",
+                description: "Append `foo` ran from `/home` to the current history",
+                result: None,
+            },
+        ]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        _stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let ok = Ok(Value::nothing(call.head).into_pipeline_data());
+
+        let Some(history) = engine_state.history_config() else {
+            return ok;
+        };
+        let Some(current_history_path) = history.file_path() else {
+            return Err(ShellError::ConfigDirNotFound {
+                span: Some(call.head),
+            });
+        };
+
+        match input {
+            PipelineData::Empty => {
+                let other_format = match history.file_format {
+                    HistoryFileFormat::Sqlite => HistoryFileFormat::Plaintext,
+                    HistoryFileFormat::Plaintext => HistoryFileFormat::Sqlite,
+                };
+                let src = new_backend(other_format, None)?;
+                let mut dst = new_backend(history.file_format, Some(current_history_path))?;
+                let items = src
+                    .search(SearchQuery::everything(
+                        reedline::SearchDirection::Forward,
+                        None,
+                    ))
+                    .map_err(error_from_reedline)?
+                    .into_iter()
+                    .map(Ok);
+                import(dst.as_mut(), items)
+            }
+            _ => {
+                let input = input.into_iter().map(item_from_value);
+                import(
+                    new_backend(history.file_format, Some(current_history_path))?.as_mut(),
+                    input,
+                )
+            }
+        }?;
+
+        ok
+    }
+}
+
+fn new_backend(
+    format: HistoryFileFormat,
+    path: Option<std::path::PathBuf>,
+) -> Result<Box<dyn History>, ShellError> {
+    let path = match path {
+        Some(path) => path,
+        None => {
+            let Some(mut path) = nu_path::nu_config_dir() else {
+                return Err(ShellError::ConfigDirNotFound { span: None });
+            };
+            path.push(format.default_file_name());
+            path.into_std_path_buf()
+        }
+    };
+
+    fn map(
+        result: Result<impl History + 'static, ReedlineError>,
+    ) -> Result<Box<dyn History>, ShellError> {
+        result
+            .map(|x| Box::new(x) as Box<dyn History>)
+            .map_err(error_from_reedline)
+    }
+    match format {
+        // Use a reasonably large value for maximum capacity.
+        HistoryFileFormat::Plaintext => map(FileBackedHistory::with_file(0xfffffff, path)),
+        HistoryFileFormat::Sqlite => map(SqliteBackedHistory::with_file(path, None, None)),
+    }
+}
+
+fn import(
+    dst: &mut dyn History,
+    src: impl Iterator<Item = Result<HistoryItem, ShellError>>,
+) -> Result<(), ShellError> {
+    for item in src {
+        dst.save(item?).map_err(error_from_reedline)?;
+    }
+    Ok(())
+}
+
+fn error_from_reedline(e: ReedlineError) -> ShellError {
+    // TODO: Should we add a new ShellError variant?
+    ShellError::GenericError {
+        error: "Reedline error".to_owned(),
+        msg: format!("{e}"),
+        span: None,
+        help: None,
+        inner: Vec::new(),
+    }
+}
+
+fn item_from_value(v: Value) -> Result<HistoryItem, ShellError> {
+    let span = v.span();
+    match v {
+        Value::Record { val, .. } => item_from_record(val.into_owned(), span),
+        Value::String { val, .. } => Ok(HistoryItem {
+            command_line: val,
+            id: None,
+            start_timestamp: None,
+            session_id: None,
+            hostname: None,
+            cwd: None,
+            duration: None,
+            exit_status: None,
+            more_info: None,
+        }),
+        _ => Err(ShellError::UnsupportedInput {
+            msg: "Only list and record inputs are supported".to_owned(),
+            input: v.get_type().to_string(),
+            msg_span: span,
+            input_span: span,
+        }),
+    }
+}
+
+fn item_from_record(mut rec: Record, span: Span) -> Result<HistoryItem, ShellError> {
+    let cmd = match rec.remove(fields::COMMAND_LINE) {
+        Some(v) => v.as_str()?.to_owned(),
+        None => {
+            return Err(ShellError::TypeMismatch {
+                err_message: format!("missing column: {}", fields::COMMAND_LINE),
+                span,
+            })
+        }
+    };
+
+    fn get<T>(
+        rec: &mut Record,
+        field: &'static str,
+        f: impl FnOnce(Value) -> Result<T, ShellError>,
+    ) -> Result<Option<T>, ShellError> {
+        rec.remove(field).map(f).transpose()
+    }
+
+    let rec = &mut rec;
+    let item = HistoryItem {
+        command_line: cmd,
+        id: get(rec, fields::ID, |v| Ok(HistoryItemId::new(v.as_int()?)))?,
+        start_timestamp: get(rec, fields::START_TIMESTAMP, |v| Ok(v.as_date()?.to_utc()))?,
+        hostname: get(rec, fields::HOSTNAME, |v| Ok(v.as_str()?.to_owned()))?,
+        cwd: get(rec, fields::CWD, |v| Ok(v.as_str()?.to_owned()))?,
+        exit_status: get(rec, fields::EXIT_STATUS, |v| v.as_i64())?,
+        duration: get(rec, fields::DURATION, duration_from_value)?,
+        more_info: None,
+        // TODO: Currently reedline doesn't let you create session IDs.
+        session_id: None,
+    };
+
+    if !rec.is_empty() {
+        let cols = rec.columns().map(|s| s.as_str()).collect::<Vec<_>>();
+        return Err(ShellError::TypeMismatch {
+            err_message: format!("unsupported column names: {}", cols.join(", ")),
+            span,
+        });
+    }
+    Ok(item)
+}
+
+fn duration_from_value(v: Value) -> Result<std::time::Duration, ShellError> {
+    chrono::Duration::nanoseconds(v.as_duration()?)
+        .to_std()
+        .map_err(|_| ShellError::IOError {
+            msg: "negative duration not supported".to_string(),
+        })
+}
+
+#[cfg(test)]
+mod tests {
+    use chrono::DateTime;
+
+    use super::*;
+
+    #[test]
+    fn test_item_from_value_string() -> Result<(), ShellError> {
+        let item = item_from_value(Value::string("foo", Span::unknown()))?;
+        assert_eq!(
+            item,
+            HistoryItem {
+                command_line: "foo".to_string(),
+                id: None,
+                start_timestamp: None,
+                session_id: None,
+                hostname: None,
+                cwd: None,
+                duration: None,
+                exit_status: None,
+                more_info: None
+            }
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn test_item_from_value_record() {
+        let span = Span::unknown();
+        let rec = new_record(&[
+            ("command", Value::string("foo", span)),
+            ("item_id", Value::int(1, span)),
+            (
+                "start_timestamp",
+                Value::date(
+                    DateTime::parse_from_rfc3339("1996-12-19T16:39:57-08:00").unwrap(),
+                    span,
+                ),
+            ),
+            ("hostname", Value::string("localhost", span)),
+            ("cwd", Value::string("/home/test", span)),
+            ("duration", Value::duration(100_000_000, span)),
+            ("exit_status", Value::int(42, span)),
+        ]);
+        let item = item_from_value(rec).unwrap();
+        assert_eq!(
+            item,
+            HistoryItem {
+                command_line: "foo".to_string(),
+                id: Some(HistoryItemId::new(1)),
+                start_timestamp: Some(
+                    DateTime::parse_from_rfc3339("1996-12-19T16:39:57-08:00")
+                        .unwrap()
+                        .to_utc()
+                ),
+                hostname: Some("localhost".to_string()),
+                cwd: Some("/home/test".to_string()),
+                duration: Some(std::time::Duration::from_nanos(100_000_000)),
+                exit_status: Some(42),
+
+                session_id: None,
+                more_info: None
+            }
+        );
+    }
+
+    #[test]
+    fn test_item_from_value_record_extra_field() {
+        let span = Span::unknown();
+        let rec = new_record(&[
+            ("command_line", Value::string("foo", span)),
+            ("id_nonexistent", Value::int(1, span)),
+        ]);
+        assert!(item_from_value(rec).is_err());
+    }
+
+    #[test]
+    fn test_item_from_value_record_bad_type() {
+        let span = Span::unknown();
+        let rec = new_record(&[
+            ("command_line", Value::string("foo", span)),
+            ("id", Value::string("one".to_string(), span)),
+        ]);
+        assert!(item_from_value(rec).is_err());
+    }
+
+    fn new_record(rec: &[(&'static str, Value)]) -> Value {
+        let span = Span::unknown();
+        let rec = Record::from_raw_cols_vals(
+            rec.iter().map(|(col, _)| col.to_string()).collect(),
+            rec.iter().map(|(_, val)| val.clone()).collect(),
+            span,
+            span,
+        )
+        .unwrap();
+        Value::record(rec, span)
+    }
+}

crates/nu-cli/src/commands/history/mod.rs

@@ -1,5 +1,8 @@
+mod fields;
 mod history_;
+mod history_import;
 mod history_session;
 
 pub use history_::History;
+pub use history_import::HistoryImport;
 pub use history_session::HistorySession;

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

@@ -7,7 +7,7 @@ mod keybindings_list;
 mod keybindings_listen;
 
 pub use commandline::{Commandline, CommandlineEdit, CommandlineGetCursor, CommandlineSetCursor};
-pub use history::{History, HistorySession};
+pub use history::{History, HistoryImport, HistorySession};
 pub use keybindings::Keybindings;
 pub use keybindings_default::KeybindingsDefault;
 pub use keybindings_list::KeybindingsList;