1 files changed, 133 insertions, 0 deletions
diff --git a/helix-term/src/ui/lsp.rs b/helix-term/src/ui/lsp.rs
new file mode 100644
index 00000000..f2854551
--- /dev/null
+++ b/helix-term/src/ui/lsp.rs
@@ -0,0 +1,133 @@
+use std::sync::Arc;
+
+use helix_core::syntax;
+use helix_view::graphics::{Margin, Rect, Style};
+use tui::buffer::Buffer;
+use tui::widgets::{BorderType, Paragraph, Widget, Wrap};
+
+use crate::compositor::{Component, Compositor, Context};
+
+use crate::ui::Markdown;
+
+use super::Popup;
+
+pub struct SignatureHelp {
+    signature: String,
+    signature_doc: Option<String>,
+    /// Part of signature text
+    active_param_range: Option<(usize, usize)>,
+
+    language: String,
+    config_loader: Arc<syntax::Loader>,
+}
+
+impl SignatureHelp {
+    pub const ID: &'static str = "signature-help";
+
+    pub fn new(signature: String, language: String, config_loader: Arc<syntax::Loader>) -> Self {
+        Self {
+            signature,
+            signature_doc: None,
+            active_param_range: None,
+            language,
+            config_loader,
+        }
+    }
+
+    pub fn set_signature_doc(&mut self, signature_doc: Option<String>) {
+        self.signature_doc = signature_doc;
+    }
+
+    pub fn set_active_param_range(&mut self, offset: Option<(usize, usize)>) {
+        self.active_param_range = offset;
+    }
+
+    pub fn visible_popup(compositor: &mut Compositor) -> Option<&mut Popup<Self>> {
+        compositor.find_id::<Popup<Self>>(Self::ID)
+    }
+}
+
+impl Component for SignatureHelp {
+    fn render(&mut self, area: Rect, surface: &mut Buffer, cx: &mut Context) {
+        let margin = Margin::horizontal(1);
+
+        let active_param_span = self.active_param_range.map(|(start, end)| {
+            vec![(
+                cx.editor.theme.find_scope_index("ui.selection").unwrap(),
+                start..end,
+            )]
+        });
+
+        let sig_text = crate::ui::markdown::highlighted_code_block(
+            self.signature.clone(),
+            &self.language,
+            Some(&cx.editor.theme),
+            Arc::clone(&self.config_loader),
+            active_param_span,
+        );
+
+        let (_, sig_text_height) = crate::ui::text::required_size(&sig_text, area.width);
+        let sig_text_area = area.clip_top(1).with_height(sig_text_height);
+        let sig_text_para = Paragraph::new(sig_text).wrap(Wrap { trim: false });
+        sig_text_para.render(sig_text_area.inner(&margin), surface);
+
+        if self.signature_doc.is_none() {
+            return;
+        }
+
+        let sep_style = Style::default();
+        let borders = BorderType::line_symbols(BorderType::Plain);
+        for x in sig_text_area.left()..sig_text_area.right() {
+            if let Some(cell) = surface.get_mut(x, sig_text_area.bottom()) {
+                cell.set_symbol(borders.horizontal).set_style(sep_style);
+            }
+        }
+
+        let sig_doc = match &self.signature_doc {
+            None => return,
+            Some(doc) => Markdown::new(doc.clone(), Arc::clone(&self.config_loader)),
+        };
+        let sig_doc = sig_doc.parse(Some(&cx.editor.theme));
+        let sig_doc_area = area.clip_top(sig_text_area.height + 2);
+        let sig_doc_para = Paragraph::new(sig_doc)
+            .wrap(Wrap { trim: false })
+            .scroll((cx.scroll.unwrap_or_default() as u16, 0));
+        sig_doc_para.render(sig_doc_area.inner(&margin), surface);
+    }
+
+    fn required_size(&mut self, viewport: (u16, u16)) -> Option<(u16, u16)> {
+        const PADDING: u16 = 2;
+        const SEPARATOR_HEIGHT: u16 = 1;
+
+        if PADDING >= viewport.1 || PADDING >= viewport.0 {
+            return None;
+        }
+        let max_text_width = (viewport.0 - PADDING).min(120);
+
+        let signature_text = crate::ui::markdown::highlighted_code_block(
+            self.signature.clone(),
+            &self.language,
+            None,
+            Arc::clone(&self.config_loader),
+            None,
+        );
+        let (sig_width, sig_height) =
+            crate::ui::text::required_size(&signature_text, max_text_width);
+
+        let (width, height) = match self.signature_doc {
+            Some(ref doc) => {
+                let doc_md = Markdown::new(doc.clone(), Arc::clone(&self.config_loader));
+                let doc_text = doc_md.parse(None);
+                let (doc_width, doc_height) =
+                    crate::ui::text::required_size(&doc_text, max_text_width);
+                (
+                    sig_width.max(doc_width),
+                    sig_height + SEPARATOR_HEIGHT + doc_height,
+                )
+            }
+            None => (sig_width, sig_height),
+        };
+
+        Some((width + PADDING, height + PADDING))
+    }
+}