weavatrix-clone 0.1.4

use crate::canonical::suppress_contained;
use crate::cluster::{families_for_pairs, pair_id};
use crate::config::CloneConfig;
use crate::error::{CloneError, Result};
use crate::fingerprint::winnow;
use crate::index::candidates;
use crate::model::{
    CloneLocation, ClonePair, CloneReport, CloneStatistics, DetectionMode, SourceFragment,
};
use crate::token::{Interner, Tokenized, tokenize};
use crate::verify::{Verifier, evidence};
use std::collections::HashSet;

#[derive(Debug, Clone, Copy, Default)]
pub struct CloneDetector {
    config: CloneConfig,
}

impl CloneDetector {
    /// Creates a detector after validating all safety bounds.
    ///
    /// # Errors
    ///
    /// Returns an error for inconsistent thresholds or zero limits.
    pub fn new(config: CloneConfig) -> Result<Self> {
        Ok(Self {
            config: config.validate()?,
        })
    }

    #[must_use]
    pub const fn config(&self) -> CloneConfig {
        self.config
    }

    /// Detects deterministic Type-1, Type-2, and bounded near-miss Type-3
    /// clones over caller-provided fragments.
    ///
    /// # Errors
    ///
    /// Rejects malformed or duplicate fragments and configured capacity
    /// limits without returning partial output.
    pub fn detect(&self, fragments: &[SourceFragment]) -> Result<CloneReport> {
        if fragments.len() > self.config.max_fragments {
            return Err(CloneError::CapacityExceeded {
                resource: "input fragments",
                limit: self.config.max_fragments,
            });
        }
        validate_fragments(fragments)?;
        let (prepared, mut statistics) = prepare_fragments(self.config, fragments)?;
        let fingerprint_sets = prepared
            .iter()
            .map(|item| item.fingerprints.clone())
            .collect::<Vec<_>>();
        let index = candidates(&fingerprint_sets, self.config)?;
        statistics.candidate_pairs = index.candidates.len();
        statistics.suppressed_buckets = index.suppressed_buckets;
        let locations = prepared
            .iter()
            .map(|item| CloneLocation::from_fragment(&fragments[item.source_index]))
            .collect::<Vec<_>>();
        let pairs = verify_pairs(
            self.config,
            fragments,
            &prepared,
            &locations,
            index.candidates,
        );
        let pairs = suppress_contained(pairs);
        statistics.verified_pairs = pairs.len();
        Ok(CloneReport {
            families: families_for_pairs(&pairs),
            pairs,
            statistics,
        })
    }
}

fn prepare_fragments(
    config: CloneConfig,
    fragments: &[SourceFragment],
) -> Result<(Vec<Prepared>, CloneStatistics)> {
    let mut order = (0..fragments.len()).collect::<Vec<_>>();
    order.sort_unstable_by(|left, right| {
        let left = &fragments[*left];
        let right = &fragments[*right];
        (&left.path, left.span, &left.id).cmp(&(&right.path, right.span, &right.id))
    });
    let mut interner = Interner::default();
    let mut prepared = Vec::with_capacity(fragments.len());
    let mut statistics = CloneStatistics {
        input_fragments: fragments.len(),
        ..CloneStatistics::default()
    };
    for index in order {
        let fragment = &fragments[index];
        let tokens = tokenize(&fragment.text, fragment.language, config, &mut interner)?;
        if tokens.strict.len() < config.min_tokens {
            statistics.skipped_small_fragments += 1;
            continue;
        }
        statistics.tokens = statistics.tokens.saturating_add(tokens.strict.len());
        let fingerprint_tokens = if config.mode == DetectionMode::Exact {
            &tokens.strict
        } else {
            &tokens.renamed
        };
        let fingerprints = winnow(fingerprint_tokens, config.k_gram, config.winnowing_window);
        statistics.fingerprints = statistics.fingerprints.saturating_add(fingerprints.len());
        prepared.push(Prepared {
            source_index: index,
            tokens,
            fingerprints,
        });
    }
    statistics.analyzed_fragments = prepared.len();
    Ok((prepared, statistics))
}

fn verify_pairs(
    config: CloneConfig,
    fragments: &[SourceFragment],
    prepared: &[Prepared],
    locations: &[CloneLocation],
    candidates: Vec<crate::index::Candidate>,
) -> Vec<ClonePair> {
    let mut pairs = Vec::new();
    let mut verifier = Verifier::default();
    for candidate in candidates {
        let left = &prepared[candidate.left];
        let right = &prepared[candidate.right];
        let left_fragment = &fragments[left.source_index];
        let right_fragment = &fragments[right.source_index];
        if !config.compare_overlapping_fragments
            && left_fragment.path == right_fragment.path
            && left_fragment.span.overlaps(right_fragment.span)
        {
            continue;
        }
        let Some(match_result) = verifier.verify(
            &left.tokens.strict,
            &right.tokens.strict,
            &left.tokens.renamed,
            &right.tokens.renamed,
            config,
        ) else {
            continue;
        };
        let left_location = &locations[candidate.left];
        let right_location = &locations[candidate.right];
        let id = pair_id(left_location, right_location);
        pairs.push(ClonePair {
            id,
            left: left_location.clone(),
            right: right_location.clone(),
            kind: match_result.kind,
            similarity: match_result.similarity,
            evidence: evidence(
                &match_result,
                candidate.shared,
                candidate.jaccard,
                candidate.containment,
                left.tokens.renamed.len().max(right.tokens.renamed.len()),
            ),
        });
    }
    pairs
}

struct Prepared {
    source_index: usize,
    tokens: Tokenized,
    fingerprints: Vec<u64>,
}

fn validate_fragments(fragments: &[SourceFragment]) -> Result<()> {
    let mut ids = HashSet::<&str>::with_capacity(fragments.len());
    for fragment in fragments {
        fragment.validate()?;
        if !ids.insert(&fragment.id) {
            return Err(CloneError::DuplicateFragment(fragment.id.clone()));
        }
    }
    Ok(())
}