ass-core 0.1.1

//! Missing style reference detection rule for ASS script linting.
//!
//! Detects events that reference undefined styles, which would cause
//! rendering errors or fallback to default styling behavior.

use crate::{
    analysis::{
        linting::{IssueCategory, IssueSeverity, LintIssue, LintRule},
        ScriptAnalysis,
    },
    parser::Section,
};
use alloc::{format, vec::Vec};

/// Rule for detecting events that reference undefined styles
///
/// Events must reference valid style names defined in the [V4+ Styles] section.
/// Missing style references cause renderers to fall back to default styling,
/// which may not match the intended visual appearance.
///
/// # Performance
///
/// - Time complexity: O(n + m) for n styles and m events
/// - Memory: O(n) for style name collection
/// - Target: <1ms for typical scripts with 100 styles and 1000 events
///
/// # Example
///
/// ```rust
/// use ass_core::analysis::linting::rules::missing_style::MissingStyleRule;
/// use ass_core::analysis::linting::LintRule;
/// use ass_core::{Script, ScriptAnalysis};
///
/// let script = Script::parse(r#"
/// [V4+ Styles]
/// Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
/// Style: Default,Arial,20,&H00FFFFFF&,&H000000FF&,&H00000000&,&H00000000&,0,0,0,0,100,100,0,0,1,2,0,2,10,10,10,1
///
/// [Events]
/// Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
/// Dialogue: 0,0:00:00.00,0:00:05.00,Undefined,,0,0,0,,Text with undefined style
/// "#)?;
///
/// let analysis = ScriptAnalysis::analyze(&script)?;
/// let rule = MissingStyleRule;
/// let issues = rule.check_script(&analysis);
/// assert!(!issues.is_empty()); // Should detect the missing style reference
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub struct MissingStyleRule;

impl LintRule for MissingStyleRule {
    fn id(&self) -> &'static str {
        "missing-style"
    }

    fn name(&self) -> &'static str {
        "Missing Style"
    }

    fn description(&self) -> &'static str {
        "Detects events referencing non-existent styles"
    }

    fn default_severity(&self) -> IssueSeverity {
        IssueSeverity::Error
    }

    fn category(&self) -> IssueCategory {
        IssueCategory::Styling
    }

    fn check_script(&self, analysis: &ScriptAnalysis) -> Vec<LintIssue> {
        let mut issues = Vec::new();

        let style_names: Vec<&str> = analysis
            .resolved_styles()
            .iter()
            .map(|style| style.name)
            .collect();

        if let Some(Section::Events(events)) = analysis
            .script()
            .sections()
            .iter()
            .find(|s| matches!(s, Section::Events(_)))
        {
            for event in events {
                if !style_names.contains(&event.style) {
                    let issue = LintIssue::new(
                        self.default_severity(),
                        IssueCategory::Styling,
                        self.id(),
                        format!("Event references undefined style: {}", event.style),
                    )
                    .with_suggested_fix(format!(
                        "Define style '{}' or use an existing style",
                        event.style
                    ));

                    issues.push(issue);
                }
            }
        }

        issues
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn rule_metadata_correct() {
        let rule = MissingStyleRule;
        assert_eq!(rule.id(), "missing-style");
        assert_eq!(rule.name(), "Missing Style");
        assert_eq!(
            rule.description(),
            "Detects events referencing non-existent styles"
        );
        assert_eq!(rule.default_severity(), IssueSeverity::Error);
        assert_eq!(rule.category(), IssueCategory::Styling);
    }

    #[test]
    fn empty_script_no_issues() {
        let script_text = "[Script Info]\nTitle: Test";
        let script = crate::parser::Script::parse(script_text).unwrap();
        let analysis = ScriptAnalysis::analyze(&script).unwrap();

        let rule = MissingStyleRule;
        let issues = rule.check_script(&analysis);

        assert!(issues.is_empty());
    }

    #[test]
    fn valid_style_reference_no_issues() {
        let script_text = r"[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,20,&H00FFFFFF&,&H000000FF&,&H00000000&,&H00000000&,0,0,0,0,100,100,0,0,1,2,0,2,10,10,10,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Valid event";

        let script = crate::parser::Script::parse(script_text).unwrap();
        let analysis = ScriptAnalysis::analyze(&script).unwrap();
        let rule = MissingStyleRule;
        let issues = rule.check_script(&analysis);

        assert!(issues.is_empty());
    }

    #[test]
    fn missing_style_reference_detected() {
        let script_text = r"[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,20,&H00FFFFFF&,&H000000FF&,&H00000000&,&H00000000&,0,0,0,0,100,100,0,0,1,2,0,2,10,10,10,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:05.00,Undefined,,0,0,0,,Invalid event";

        let script = crate::parser::Script::parse(script_text).unwrap();
        let analysis = ScriptAnalysis::analyze(&script).unwrap();
        let rule = MissingStyleRule;
        let issues = rule.check_script(&analysis);

        assert_eq!(issues.len(), 1);
        assert_eq!(issues[0].severity(), IssueSeverity::Error);
        assert_eq!(issues[0].category(), IssueCategory::Styling);
        assert!(issues[0].message().contains("Undefined"));
    }

    #[test]
    fn multiple_missing_styles() {
        let script_text = r"[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,20,&H00FFFFFF&,&H000000FF&,&H00000000&,&H00000000&,0,0,0,0,100,100,0,0,1,2,0,2,10,10,10,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:05.00,Missing1,,0,0,0,,First invalid
Dialogue: 0,0:00:05.00,0:00:10.00,Default,,0,0,0,,Valid event
Dialogue: 0,0:00:10.00,0:00:15.00,Missing2,,0,0,0,,Second invalid";

        let script = crate::parser::Script::parse(script_text).unwrap();
        let analysis = ScriptAnalysis::analyze(&script).unwrap();
        let rule = MissingStyleRule;
        let issues = rule.check_script(&analysis);

        assert_eq!(issues.len(), 2);
    }

    #[test]
    fn no_styles_section_all_invalid() {
        let script_text = r"[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:05.00,Default,,0,0,0,,Should be invalid";

        let script = crate::parser::Script::parse(script_text).unwrap();
        let analysis = ScriptAnalysis::analyze(&script).unwrap();
        let rule = MissingStyleRule;
        let issues = rule.check_script(&analysis);

        assert_eq!(issues.len(), 1);
    }
}