rbt_weave

//! Structural staleness analysis for OSINT case files (ADR-021 Layer 1).
//!
//! Analyzes parsed case data offline (no network) to detect cases whose
//! `status` field may no longer reflect reality based on heuristics like
//! event age and status-event mismatches.

use crate::entity::{Entity, FieldValue, Label};
use crate::parser::ParsedCase;

/// Severity of a staleness finding.
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub enum Severity {
    Error,
    Warning,
    Info,
}

impl std::fmt::Display for Severity {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Error => write!(f, "error"),
            Self::Warning => write!(f, "warning"),
            Self::Info => write!(f, "info"),
        }
    }
}

/// A single staleness finding for a case file.
#[derive(Debug)]
pub struct Finding {
    pub severity: Severity,
    pub message: String,
}

/// Configurable thresholds for staleness detection.
#[derive(Debug, Clone)]
pub struct Thresholds {
    pub investigation_months: u32,
    pub trial_months: u32,
    pub appeal_months: u32,
}

impl Default for Thresholds {
    fn default() -> Self {
        Self {
            investigation_months: 6,
            trial_months: 12,
            appeal_months: 12,
        }
    }
}

/// Check a single case for staleness issues.
///
/// `today` is passed explicitly for testability.
pub fn check_case(
    case: &ParsedCase,
    entities: &[Entity],
    thresholds: &Thresholds,
    today: (i32, u32, u32),
) -> Vec<Finding> {
    let mut findings = Vec::new();

    let Some(status) = case.status.as_deref() else {
        return findings;
    };

    let events: Vec<&Entity> = entities
        .iter()
        .filter(|e| e.label == Label::Event)
        .collect();

    // Rule: No events
    if events.is_empty() {
        findings.push(Finding {
            severity: Severity::Error,
            message: format!("status is '{status}' but case has no events"),
        });
        return findings;
    }

    let event_types = collect_event_types(&events);
    let latest_date = find_latest_date(&events);

    check_age_rules(status, latest_date, thresholds, today, &mut findings);
    check_mismatch_rules(status, &event_types, &mut findings);

    findings
}

/// Check age-based staleness rules.
fn check_age_rules(
    status: &str,
    latest_date: Option<(i32, u32, u32)>,
    thresholds: &Thresholds,
    today: (i32, u32, u32),
    findings: &mut Vec<Finding>,
) {
    let Some((y, m, d)) = latest_date else {
        return;
    };
    let months_ago = months_between((y, m, d), today);

    let (threshold, applies) = match status {
        "under_investigation" => (thresholds.investigation_months, true),
        "trial" | "open" => (thresholds.trial_months, true),
        "appeal" => (thresholds.appeal_months, true),
        _ => (0, false),
    };

    if applies && months_ago > threshold {
        findings.push(Finding {
            severity: Severity::Warning,
            message: format!(
                "status is '{status}' and latest event is {months_ago} months ago \
                 (threshold: {threshold} months)"
            ),
        });
    }
}

/// Check status-event mismatch rules.
fn check_mismatch_rules(
    status: &str,
    event_types: &std::collections::HashSet<String>,
    findings: &mut Vec<Finding>,
) {
    // Missing verdict (trial without verdict/sentencing)
    if status == "trial" && !has_any(event_types, VERDICT_TYPES) {
        findings.push(Finding {
            severity: Severity::Info,
            message: "status is 'trial' but no verdict/sentencing/conviction/acquittal event found"
                .to_string(),
        });
    }

    if status == "convicted" && !has_any(event_types, &["verdict", "sentencing", "conviction"]) {
        findings.push(Finding {
            severity: Severity::Warning,
            message: "status is 'convicted' but no verdict/sentencing/conviction event found"
                .to_string(),
        });
    }

    if status == "acquitted" && !has_any(event_types, &["verdict", "acquittal"]) {
        findings.push(Finding {
            severity: Severity::Warning,
            message: "status is 'acquitted' but no verdict/acquittal event found".to_string(),
        });
    }

    if status == "pardoned"
        && !has_any(
            event_types,
            &["verdict", "sentencing", "conviction", "pardon"],
        )
    {
        findings.push(Finding {
            severity: Severity::Warning,
            message: "status is 'pardoned' but no verdict/sentencing/conviction/pardon event found"
                .to_string(),
        });
    }
}

/// Event types that indicate a verdict or resolution.
const VERDICT_TYPES: &[&str] = &["verdict", "sentencing", "conviction", "acquittal"];

/// Check if the set contains any of the given values.
fn has_any(set: &std::collections::HashSet<String>, values: &[&str]) -> bool {
    values.iter().any(|v| set.contains(*v))
}

/// Collect all `event_type` values from events.
fn collect_event_types(events: &[&Entity]) -> std::collections::HashSet<String> {
    let mut types = std::collections::HashSet::new();
    for e in events {
        if let Some((_, FieldValue::Single(val))) = e.fields.iter().find(|(k, _)| k == "event_type")
        {
            // Normalize: strip "custom:" prefix if present
            let normalized = val
                .strip_prefix("custom:")
                .unwrap_or(val)
                .to_lowercase()
                .replace(' ', "_");
            types.insert(normalized);
        }
    }
    types
}

/// Find the latest `occurred_at` date among events.
/// Returns `(year, month, day)`. Partial dates use end-of-period defaults.
fn find_latest_date(events: &[&Entity]) -> Option<(i32, u32, u32)> {
    let mut latest: Option<(i32, u32, u32)> = None;

    for e in events {
        if let Some((_, FieldValue::Single(val))) =
            e.fields.iter().find(|(k, _)| k == "occurred_at")
            && let Some(parsed) = parse_date(val)
        {
            latest = Some(match latest {
                None => parsed,
                Some(prev) => {
                    if date_cmp(parsed, prev) == std::cmp::Ordering::Greater {
                        parsed
                    } else {
                        prev
                    }
                }
            });
        }
    }

    latest
}

/// Parse a date string in YYYY, YYYY-MM, or YYYY-MM-DD format.
fn parse_date(s: &str) -> Option<(i32, u32, u32)> {
    let parts: Vec<&str> = s.split('-').collect();
    match parts.len() {
        1 => {
            let y = parts[0].parse::<i32>().ok()?;
            Some((y, 12, 31)) // year-only: assume end of year for staleness
        }
        2 => {
            let y = parts[0].parse::<i32>().ok()?;
            let m = parts[1].parse::<u32>().ok()?;
            if !(1..=12).contains(&m) {
                return None;
            }
            Some((y, m, 28)) // month-only: assume end of month (conservative)
        }
        3 => {
            let y = parts[0].parse::<i32>().ok()?;
            let m = parts[1].parse::<u32>().ok()?;
            let d = parts[2].parse::<u32>().ok()?;
            if !(1..=12).contains(&m) || !(1..=31).contains(&d) {
                return None;
            }
            Some((y, m, d))
        }
        _ => None,
    }
}

/// Compare two date tuples.
fn date_cmp(a: (i32, u32, u32), b: (i32, u32, u32)) -> std::cmp::Ordering {
    a.0.cmp(&b.0).then(a.1.cmp(&b.1)).then(a.2.cmp(&b.2))
}

/// Calculate approximate months between two dates.
fn months_between(from: (i32, u32, u32), to: (i32, u32, u32)) -> u32 {
    let year_diff = to.0 - from.0;
    let month_diff = i64::from(to.1) - i64::from(from.1);
    let total = i64::from(year_diff) * 12 + month_diff;
    #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
    if total < 0 { 0 } else { total as u32 }
}

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

    fn make_event(name: &str, event_type: &str, occurred_at: &str) -> Entity {
        Entity {
            name: name.to_string(),
            label: Label::Event,
            fields: vec![
                (
                    "event_type".to_string(),
                    FieldValue::Single(event_type.to_string()),
                ),
                (
                    "occurred_at".to_string(),
                    FieldValue::Single(occurred_at.to_string()),
                ),
            ],
            id: Some("01TEST00000000000000000000".to_string()),
            line: 1,
            tags: Vec::new(),
            slug: None,
        }
    }

    fn make_case(status: &str) -> ParsedCase {
        ParsedCase {
            id: Some("01TEST00000000000000000000".to_string()),
            sources: Vec::new(),
            title: "Test Case".to_string(),
            summary: "Test summary.".to_string(),
            sections: Vec::new(),
            case_type: Some("corruption".to_string()),
            status: Some(status.to_string()),
            amounts: None,
            tags: Vec::new(),
            tagline: None,
            related_cases: Vec::new(),
            involved: Vec::new(),
        }
    }

    fn today() -> (i32, u32, u32) {
        (2026, 4, 21)
    }

    #[test]
    fn no_events_is_error() {
        let case = make_case("convicted");
        let findings = check_case(&case, &[], &Thresholds::default(), today());
        assert_eq!(findings.len(), 1);
        assert_eq!(findings[0].severity, Severity::Error);
        assert!(findings[0].message.contains("no events"));
    }

    #[test]
    fn investigation_stale() {
        let case = make_case("under_investigation");
        let events = vec![make_event("Raid", "raid", "2025-06-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert_eq!(findings.len(), 1);
        assert_eq!(findings[0].severity, Severity::Warning);
        assert!(findings[0].message.contains("under_investigation"));
        assert!(findings[0].message.contains("10 months ago"));
    }

    #[test]
    fn investigation_fresh() {
        let case = make_case("under_investigation");
        let events = vec![make_event("Raid", "raid", "2026-02-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert!(findings.is_empty());
    }

    #[test]
    fn trial_stale() {
        let case = make_case("trial");
        let events = vec![make_event("Indictment", "indictment", "2024-12-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        // Should have warning (stale) + info (missing verdict)
        assert!(findings.iter().any(|f| f.severity == Severity::Warning));
        assert!(findings.iter().any(|f| f.severity == Severity::Info));
    }

    #[test]
    fn trial_with_verdict_not_missing() {
        let case = make_case("trial");
        let events = vec![
            make_event("Indictment", "indictment", "2026-03-01"),
            make_event("Verdict", "conviction", "2026-04-01"),
        ];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert!(findings.is_empty());
    }

    #[test]
    fn convicted_without_verdict() {
        let case = make_case("convicted");
        let events = vec![make_event("Arrest", "arrest", "2026-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert_eq!(findings.len(), 1);
        assert_eq!(findings[0].severity, Severity::Warning);
        assert!(findings[0].message.contains("convicted"));
    }

    #[test]
    fn convicted_with_sentencing() {
        let case = make_case("convicted");
        let events = vec![make_event("Sentencing", "sentencing", "2026-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert!(findings.is_empty());
    }

    #[test]
    fn acquitted_without_verdict() {
        let case = make_case("acquitted");
        let events = vec![make_event("Trial", "trial", "2026-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert_eq!(findings.len(), 1);
        assert!(findings[0].message.contains("acquitted"));
    }

    #[test]
    fn pardoned_without_conviction() {
        let case = make_case("pardoned");
        let events = vec![make_event("Arrest", "arrest", "2026-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert_eq!(findings.len(), 1);
        assert!(findings[0].message.contains("pardoned"));
    }

    #[test]
    fn pardoned_with_pardon_event() {
        let case = make_case("pardoned");
        let events = vec![make_event("Pardon", "pardon", "2026-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert!(findings.is_empty());
    }

    #[test]
    fn custom_thresholds() {
        let case = make_case("under_investigation");
        let events = vec![make_event("Raid", "raid", "2026-01-01")];
        let thresholds = Thresholds {
            investigation_months: 2,
            ..Thresholds::default()
        };
        let findings = check_case(&case, &events, &thresholds, today());
        assert_eq!(findings.len(), 1);
        assert!(findings[0].message.contains("3 months ago"));
    }

    #[test]
    fn no_status_no_findings() {
        let mut case = make_case("convicted");
        case.status = None;
        let events = vec![make_event("Arrest", "arrest", "2020-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert!(findings.is_empty());
    }

    #[test]
    fn partial_date_year_only() {
        let case = make_case("under_investigation");
        let events = vec![make_event("Raid", "raid", "2025")];
        // 2025 -> (2025, 12, 31), which is ~4 months ago from 2026-04-21
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert!(findings.is_empty()); // 4 months < 6 month threshold
    }

    #[test]
    fn open_case_stale() {
        let case = make_case("open");
        let events = vec![make_event("Filing", "investigation_opened", "2024-01-01")];
        let findings = check_case(&case, &events, &Thresholds::default(), today());
        assert_eq!(findings.len(), 1);
        assert!(findings[0].message.contains("open"));
    }

    #[test]
    fn months_between_same_date() {
        assert_eq!(months_between((2026, 4, 21), (2026, 4, 21)), 0);
    }

    #[test]
    fn months_between_year_diff() {
        assert_eq!(months_between((2024, 4, 1), (2026, 4, 21)), 24);
    }

    #[test]
    fn parse_date_formats() {
        assert_eq!(parse_date("2025"), Some((2025, 12, 31)));
        assert_eq!(parse_date("2025-06"), Some((2025, 6, 28)));
        assert_eq!(parse_date("2025-06-15"), Some((2025, 6, 15)));
        assert_eq!(parse_date("invalid"), None);
        assert_eq!(parse_date("2025-13"), None);
    }
}