requestty_ui/

prompt.rs

use std::{convert::TryFrom, io};

use crate::{
    backend::Backend,
    events,
    layout::Layout,
    style::{Color, Stylize},
    Widget,
};

/// The different delimiters that can be used with hints in [`Prompt`].
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Delimiter {
    /// `(` and `)`
    Parentheses,
    /// `{` and `}`
    Braces,
    /// `[` and `]`
    SquareBracket,
    /// `<` and `>`
    AngleBracket,
    /// Any other delimiter
    Other(char, char),
    /// No delimiter.
    None,
}

impl From<Delimiter> for Option<(char, char)> {
    fn from(delim: Delimiter) -> Self {
        match delim {
            Delimiter::Parentheses => Some(('(', ')')),
            Delimiter::Braces => Some(('{', '}')),
            Delimiter::SquareBracket => Some(('[', ']')),
            Delimiter::AngleBracket => Some(('<', '>')),
            Delimiter::Other(start, end) => Some((start, end)),
            Delimiter::None => None,
        }
    }
}

/// A generic prompt that renders a message and an optional hint.
#[derive(Debug, Clone)]
pub struct Prompt<M, H = &'static str> {
    message: M,
    hint: Option<H>,
    delim: Delimiter,
    message_len: u16,
    hint_len: u16,
}

impl<M: AsRef<str>, H: AsRef<str>> Prompt<M, H> {
    /// Creates a new `Prompt`
    pub fn new(message: M) -> Self {
        Self {
            message_len: u16::try_from(textwrap::core::display_width(message.as_ref()))
                .expect("message must fit within a u16"),
            message,
            hint: None,
            delim: Delimiter::Parentheses,
            hint_len: 0,
        }
    }

    /// Sets the hint
    pub fn with_hint(mut self, hint: H) -> Self {
        self.hint_len = u16::try_from(textwrap::core::display_width(hint.as_ref()))
            .expect("hint must fit within a u16");
        self.hint = Some(hint);
        self
    }

    /// Sets the hint
    pub fn with_optional_hint(self, hint: Option<H>) -> Self {
        match hint {
            Some(hint) => self.with_hint(hint),
            None => self,
        }
    }

    /// Sets the hint delimiter
    pub fn with_delim(mut self, delim: Delimiter) -> Self {
        self.delim = delim;
        self
    }

    /// Get the message
    pub fn message(&self) -> &M {
        &self.message
    }

    /// Get the hint
    pub fn hint(&self) -> Option<&H> {
        self.hint.as_ref()
    }

    /// Get the delimiter
    pub fn delim(&self) -> Delimiter {
        self.delim
    }

    /// Consume self returning the owned message
    pub fn into_message(self) -> M {
        self.message
    }

    /// Consume self returning the owned hint
    pub fn into_hint(self) -> Option<H> {
        self.hint
    }

    /// Consume self returning the owned message and hint
    pub fn into_message_and_hint(self) -> (M, Option<H>) {
        (self.message, self.hint)
    }

    /// The character length of the message
    pub fn message_len(&self) -> u16 {
        self.message_len
    }

    /// The character length of the hint. It is 0 if the hint is absent
    pub fn hint_len(&self) -> u16 {
        if self.hint.is_some() {
            match self.delim {
                Delimiter::None => self.hint_len,
                _ => self.hint_len + 2,
            }
        } else {
            0
        }
    }

    /// The character length of the fully rendered prompt
    pub fn width(&self) -> u16 {
        if self.hint.is_some() {
            // `? <message> <hint> `
            2 + self.message_len + 1 + self.hint_len() + 1
        } else {
            // `? <message> › `
            2 + self.message_len + 3
        }
    }

    fn cursor_pos_impl(&self, layout: Layout) -> (u16, u16) {
        let mut width = self.width();
        let relative_pos = if width > layout.line_width() {
            width -= layout.line_width();

            (width % layout.width, 1 + width / layout.width)
        } else {
            (layout.line_offset + width, 0)
        };

        layout.offset_cursor(relative_pos)
    }
}

impl<M: AsRef<str>> Prompt<M, &'static str> {
    /// The end prompt to be printed once the question is answered.
    pub fn write_finished_message<B: Backend>(
        message: &M,
        skipped: bool,
        backend: &mut B,
    ) -> io::Result<()> {
        let symbol_set = crate::symbols::current();
        if skipped {
            backend.write_styled(&symbol_set.cross.yellow())?;
        } else {
            backend.write_styled(&symbol_set.completed.light_green())?;
        }
        backend.write_all(b" ")?;
        backend.write_styled(&message.as_ref().bold())?;
        backend.write_all(b" ")?;
        backend.write_styled(&symbol_set.middle_dot.dark_grey())?;
        backend.write_all(b" ")
    }
}

impl<M: AsRef<str>, H: AsRef<str>> Widget for Prompt<M, H> {
    fn render<B: Backend>(&mut self, layout: &mut Layout, b: &mut B) -> io::Result<()> {
        b.write_styled(&"? ".light_green())?;
        b.write_styled(&self.message.as_ref().bold())?;
        b.write_all(b" ")?;

        b.set_fg(Color::DarkGrey)?;

        match (&self.hint, self.delim.into()) {
            (Some(hint), Some((start, end))) => write!(b, "{}{}{}", start, hint.as_ref(), end)?,
            (Some(hint), None) => write!(b, "{}", hint.as_ref())?,
            (None, _) => {
                write!(b, "{}", crate::symbols::current().arrow)?;
            }
        }

        b.set_fg(Color::Reset)?;
        b.write_all(b" ")?;

        *layout = layout.with_cursor_pos(self.cursor_pos_impl(*layout));

        Ok(())
    }

    fn height(&mut self, layout: &mut Layout) -> u16 {
        // preserve the old offset since `cursor_pos` is absolute.
        let offset_y = layout.offset_y;

        let cursor_pos = self.cursor_pos_impl(*layout);
        *layout = layout.with_cursor_pos(cursor_pos);

        cursor_pos.1 + 1 - offset_y
    }

    fn cursor_pos(&mut self, layout: Layout) -> (u16, u16) {
        self.cursor_pos_impl(layout)
    }

    fn handle_key(&mut self, _: events::KeyEvent) -> bool {
        false
    }
}

#[cfg(test)]
mod tests {
    use crate::{backend::TestBackend, test_consts::*};

    use super::*;

    type Prompt = super::Prompt<&'static str, &'static str>;

    #[test]
    fn test_width() {
        assert_eq!(Prompt::new("Hello").width(), 10);
        assert_eq!(Prompt::new("Hello").with_hint("world").width(), 16);
        assert_eq!(
            Prompt::new("Hello")
                .with_hint("world")
                .with_delim(Delimiter::None)
                .width(),
            14
        );
        assert_eq!(Prompt::new(LOREM).with_hint(UNICODE).width(), 946);
    }

    #[test]
    fn test_render() {
        fn test(
            message: &'static str,
            hint: Option<&'static str>,
            delim: Delimiter,
            expected_layout: Layout,
        ) {
            let size = (100, 20).into();
            let mut layout = Layout::new(5, size);
            let mut prompt = Prompt::new(message)
                .with_optional_hint(hint)
                .with_delim(delim);
            let mut backend = TestBackend::new_with_layout(size, layout);

            prompt.render(&mut layout, &mut backend).unwrap();

            crate::assert_backend_snapshot!(backend);
            assert_eq!(
                layout,
                expected_layout,
                "\ncursor pos = {:?}, width = {:?}",
                prompt.cursor_pos(Layout::new(5, size)),
                prompt.width(),
            );
        }

        let layout = Layout::new(5, (100, 20).into());

        test("Hello", None, Delimiter::None, layout.with_line_offset(15));

        test(
            "Hello",
            Some("world"),
            Delimiter::Parentheses,
            layout.with_line_offset(21),
        );

        test(
            "Hello",
            Some("world"),
            Delimiter::Braces,
            layout.with_line_offset(21),
        );

        test(
            "Hello",
            Some("world"),
            Delimiter::SquareBracket,
            layout.with_line_offset(21),
        );

        test(
            "Hello",
            Some("world"),
            Delimiter::AngleBracket,
            layout.with_line_offset(21),
        );

        test(
            "Hello",
            Some("world"),
            Delimiter::Other('-', '|'),
            layout.with_line_offset(21),
        );

        test(
            LOREM,
            Some(UNICODE),
            Delimiter::None,
            layout.with_line_offset(49).with_offset(0, 9),
        );
    }

    #[test]
    fn test_height() {
        let mut layout = Layout::new(5, (100, 20).into());

        assert_eq!(Prompt::new("Hello").height(&mut layout.clone()), 1);
        assert_eq!(
            Prompt::new("Hello")
                .with_hint("world")
                .height(&mut layout.clone()),
            1
        );
        assert_eq!(
            Prompt::new(LOREM).with_hint(UNICODE).height(&mut layout),
            10
        );
    }

    #[test]
    fn test_cursor_pos() {
        let layout = Layout::new(5, (100, 20).into());

        assert_eq!(Prompt::new("Hello").cursor_pos_impl(layout), (15, 0));
        assert_eq!(
            Prompt::new("Hello")
                .with_hint("world")
                .cursor_pos_impl(layout),
            (21, 0)
        );
        assert_eq!(
            Prompt::new("Hello")
                .with_hint("world")
                .with_delim(Delimiter::None)
                .cursor_pos_impl(layout),
            (19, 0)
        );
        assert_eq!(
            Prompt::new(LOREM)
                .with_hint(UNICODE)
                .cursor_pos_impl(layout),
            (51, 9)
        );

        assert_eq!(
            Prompt::new(LOREM)
                .with_hint(UNICODE)
                .cursor_pos_impl(layout.with_offset(0, 3)),
            (51, 12)
        );
    }
}