refactor: Diagnostics handling

crates/plotnik-cli/src/commands/debug/mod.rs

@@ -4,7 +4,6 @@ use std::fs;
 use std::io::{self, Read};
 
 use plotnik_lib::Query;
-use plotnik_lib::RenderOptions;
 
 use source::{dump_source, load_source, parse_tree, resolve_lang};
 
@@ -97,12 +96,7 @@ pub fn run(args: DebugArgs) {
     if let Some(ref q) = query
         && !q.is_valid()
     {
-        let options = if args.color {
-            RenderOptions::colored()
-        } else {
-            RenderOptions::plain()
-        };
-        eprint!("{}", q.render_diagnostics(options));
+        eprint!("{}", q.render_diagnostics_colored(args.color));
     }
 }
 

crates/plotnik-lib/src/diagnostics/message.rs

@@ -0,0 +1,118 @@
+//! Diagnostic message types and related structures.
+
+use rowan::TextRange;
+
+/// Severity level of a diagnostic.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum Severity {
+    #[default]
+    Error,
+    Warning,
+}
+
+impl std::fmt::Display for Severity {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Severity::Error => write!(f, "error"),
+            Severity::Warning => write!(f, "warning"),
+        }
+    }
+}
+
+/// A suggested fix for a diagnostic.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Fix {
+    pub(crate) replacement: String,
+    pub(crate) description: String,
+}
+
+impl Fix {
+    pub fn new(replacement: impl Into<String>, description: impl Into<String>) -> Self {
+        Self {
+            replacement: replacement.into(),
+            description: description.into(),
+        }
+    }
+}
+
+/// Related location information for a diagnostic.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RelatedInfo {
+    pub(crate) range: TextRange,
+    pub(crate) message: String,
+}
+
+impl RelatedInfo {
+    pub fn new(range: TextRange, message: impl Into<String>) -> Self {
+        Self {
+            range,
+            message: message.into(),
+        }
+    }
+}
+
+/// A diagnostic message with location, message, severity, and optional fix.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) struct DiagnosticMessage {
+    pub(crate) severity: Severity,
+    pub(crate) range: TextRange,
+    pub(crate) message: String,
+    pub(crate) fix: Option<Fix>,
+    pub(crate) related: Vec<RelatedInfo>,
+}
+
+impl DiagnosticMessage {
+    pub(crate) fn error(range: TextRange, message: impl Into<String>) -> Self {
+        Self {
+            severity: Severity::Error,
+            range,
+            message: message.into(),
+            fix: None,
+            related: Vec::new(),
+        }
+    }
+
+    pub(crate) fn warning(range: TextRange, message: impl Into<String>) -> Self {
+        Self {
+            severity: Severity::Warning,
+            range,
+            message: message.into(),
+            fix: None,
+            related: Vec::new(),
+        }
+    }
+
+    pub(crate) fn is_error(&self) -> bool {
+        self.severity == Severity::Error
+    }
+
+    pub(crate) fn is_warning(&self) -> bool {
+        self.severity == Severity::Warning
+    }
+}
+
+impl std::fmt::Display for DiagnosticMessage {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{} at {}..{}: {}",
+            self.severity,
+            u32::from(self.range.start()),
+            u32::from(self.range.end()),
+            self.message
+        )?;
+        if let Some(fix) = &self.fix {
+            write!(f, " (fix: {})", fix.description)?;
+        }
+        for related in &self.related {
+            write!(
+                f,
+                " (related: {} at {}..{})",
+                related.message,
+                u32::from(related.range.start()),
+                u32::from(related.range.end())
+            )?;
+        }
+        Ok(())
+    }
+}

crates/plotnik-lib/src/diagnostics/mod.rs

@@ -0,0 +1,99 @@
+//! Compiler diagnostics infrastructure.
+//!
+//! This module provides types for collecting and rendering diagnostic messages.
+
+mod message;
+mod printer;
+
+#[cfg(test)]
+mod tests;
+
+use rowan::TextRange;
+
+pub use message::Severity;
+pub use printer::DiagnosticsPrinter;
+
+use message::{DiagnosticMessage, Fix, RelatedInfo};
+
+/// Collection of diagnostic messages from parsing and analysis.
+#[derive(Debug, Clone, Default)]
+pub struct Diagnostics {
+    messages: Vec<DiagnosticMessage>,
+}
+
+/// Builder for constructing a diagnostic message.
+#[must_use = "diagnostic not emitted, call .emit()"]
+pub struct DiagnosticBuilder<'a> {
+    diagnostics: &'a mut Diagnostics,
+    message: DiagnosticMessage,
+}
+
+impl Diagnostics {
+    pub fn new() -> Self {
+        Self {
+            messages: Vec::new(),
+        }
+    }
+
+    pub fn error(&mut self, msg: impl Into<String>, range: TextRange) -> DiagnosticBuilder<'_> {
+        DiagnosticBuilder {
+            diagnostics: self,
+            message: DiagnosticMessage::error(range, msg),
+        }
+    }
+
+    pub fn warning(&mut self, msg: impl Into<String>, range: TextRange) -> DiagnosticBuilder<'_> {
+        DiagnosticBuilder {
+            diagnostics: self,
+            message: DiagnosticMessage::warning(range, msg),
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.messages.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.messages.len()
+    }
+
+    pub fn has_errors(&self) -> bool {
+        self.messages.iter().any(|d| d.is_error())
+    }
+
+    pub fn has_warnings(&self) -> bool {
+        self.messages.iter().any(|d| d.is_warning())
+    }
+
+    pub fn error_count(&self) -> usize {
+        self.messages.iter().filter(|d| d.is_error()).count()
+    }
+
+    pub fn warning_count(&self) -> usize {
+        self.messages.iter().filter(|d| d.is_warning()).count()
+    }
+
+    pub fn printer<'a>(&'a self, source: &'a str) -> DiagnosticsPrinter<'a> {
+        DiagnosticsPrinter::new(&self.messages, source)
+    }
+
+    pub fn extend(&mut self, other: Diagnostics) {
+        self.messages.extend(other.messages);
+    }
+}
+
+impl<'a> DiagnosticBuilder<'a> {
+    pub fn related_to(mut self, msg: impl Into<String>, range: TextRange) -> Self {
+        self.message.related.push(RelatedInfo::new(range, msg));
+        self
+    }
+
+    pub fn fix(mut self, description: impl Into<String>, replacement: impl Into<String>) -> Self {
+        self.message.fix = Some(Fix::new(replacement, description));
+        self
+    }
+
+    pub fn emit(self) {
+        self.diagnostics.messages.push(self.message);
+    }
+}

crates/plotnik-lib/src/diagnostics/printer.rs

@@ -0,0 +1,112 @@
+//! Builder-pattern printer for rendering diagnostics.
+
+use std::fmt::Write;
+
+use annotate_snippets::{AnnotationKind, Group, Level, Patch, Renderer, Snippet};
+use rowan::TextRange;
+
+use super::message::{DiagnosticMessage, Severity};
+
+pub struct DiagnosticsPrinter<'a> {
+    diagnostics: &'a [DiagnosticMessage],
+    source: &'a str,
+    path: Option<&'a str>,
+    colored: bool,
+}
+
+impl<'a> DiagnosticsPrinter<'a> {
+    pub(crate) fn new(diagnostics: &'a [DiagnosticMessage], source: &'a str) -> Self {
+        Self {
+            diagnostics,
+            source,
+            path: None,
+            colored: false,
+        }
+    }
+
+    pub fn path(mut self, path: &'a str) -> Self {
+        self.path = Some(path);
+        self
+    }
+
+    pub fn colored(mut self, value: bool) -> Self {
+        self.colored = value;
+        self
+    }
+
+    pub fn render(&self) -> String {
+        let mut out = String::new();
+        self.format(&mut out).expect("String write never fails");
+        out
+    }
+
+    pub fn format(&self, w: &mut impl Write) -> std::fmt::Result {
+        let renderer = if self.colored {
+            Renderer::styled()
+        } else {
+            Renderer::plain()
+        };
+
+        for (i, diag) in self.diagnostics.iter().enumerate() {
+            let range = adjust_range(diag.range, self.source.len());
+
+            let mut snippet = Snippet::source(self.source).line_start(1).annotation(
+                AnnotationKind::Primary
+                    .span(range.clone())
+                    .label(&diag.message),
+            );
+
+            if let Some(p) = self.path {
+                snippet = snippet.path(p);
+            }
+
+            for related in &diag.related {
+                snippet = snippet.annotation(
+                    AnnotationKind::Context
+                        .span(adjust_range(related.range, self.source.len()))
+                        .label(&related.message),
+                );
+            }
+
+            let level = severity_to_level(diag.severity);
+            let title_group = level.primary_title(&diag.message).element(snippet);
+
+            let mut report: Vec<Group> = vec![title_group];
+
+            if let Some(fix) = &diag.fix {
+                report.push(
+                    Level::HELP.secondary_title(&fix.description).element(
+                        Snippet::source(self.source)
+                            .line_start(1)
+                            .patch(Patch::new(range, &fix.replacement)),
+                    ),
+                );
+            }
+
+            if i > 0 {
+                w.write_char('\n')?;
+            }
+            write!(w, "{}", renderer.render(&report))?;
+        }
+
+        Ok(())
+    }
+}
+
+fn severity_to_level(severity: Severity) -> Level<'static> {
+    match severity {
+        Severity::Error => Level::ERROR,
+        Severity::Warning => Level::WARNING,
+    }
+}
+
+fn adjust_range(range: TextRange, limit: usize) -> std::ops::Range<usize> {
+    let start: usize = range.start().into();
+    let end: usize = range.end().into();
+
+    if start == end {
+        return start..(start + 1).min(limit);
+    }
+
+    start..end
+}