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use crate::{
    hinter::get_first_token,
    history::SearchQuery,
    result::{ReedlineError, ReedlineErrorVariants::HistoryFeatureUnsupported},
    Hinter, History,
};
use nu_ansi_term::{Color, Style};

/// A hinter that uses the completions or the history to show a hint to the user
///
/// Similar to `fish` autosuggestions
pub struct CwdAwareHinter {
    style: Style,
    current_hint: String,
    min_chars: usize,
}

impl Hinter for CwdAwareHinter {
    fn handle(
        &mut self,
        line: &str,
        #[allow(unused_variables)] pos: usize,
        history: &dyn History,
        use_ansi_coloring: bool,
    ) -> String {
        self.current_hint = if line.chars().count() >= self.min_chars {
            let with_cwd = history
                .search(SearchQuery::last_with_prefix_and_cwd(
                    line.to_string(),
                    history.session(),
                ))
                .or_else(|err| {
                    if let ReedlineError(HistoryFeatureUnsupported { .. }) = err {
                        history.search(SearchQuery::last_with_prefix(
                            line.to_string(),
                            history.session(),
                        ))
                    } else {
                        Err(err)
                    }
                })
                .unwrap_or_default();
            if !with_cwd.is_empty() {
                with_cwd[0]
                    .command_line
                    .get(line.len()..)
                    .unwrap_or_default()
                    .to_string()
            } else {
                history
                    .search(SearchQuery::last_with_prefix(
                        line.to_string(),
                        history.session(),
                    ))
                    .unwrap_or_default()
                    .first()
                    .map_or_else(String::new, |entry| {
                        entry
                            .command_line
                            .get(line.len()..)
                            .unwrap_or_default()
                            .to_string()
                    })
            }
        } else {
            String::new()
        };

        if use_ansi_coloring && !self.current_hint.is_empty() {
            self.style.paint(&self.current_hint).to_string()
        } else {
            self.current_hint.clone()
        }
    }

    fn complete_hint(&self) -> String {
        self.current_hint.clone()
    }

    fn next_hint_token(&self) -> String {
        get_first_token(&self.current_hint)
    }
}

impl Default for CwdAwareHinter {
    fn default() -> Self {
        CwdAwareHinter {
            style: Style::new().fg(Color::LightGray),
            current_hint: String::new(),
            min_chars: 1,
        }
    }
}

impl CwdAwareHinter {
    /// A builder that sets the style applied to the hint as part of the buffer
    #[must_use]
    pub fn with_style(mut self, style: Style) -> Self {
        self.style = style;
        self
    }

    /// A builder that sets the number of characters that have to be present to enable history hints
    #[must_use]
    pub fn with_min_chars(mut self, min_chars: usize) -> Self {
        self.min_chars = min_chars;
        self
    }
}