import { InternalSearchResult } from './types.js';
export interface RerankOptions {
originalQuery?: string;
}
function resultSignature(result: InternalSearchResult): string {
const lines = result.lines ?? '';
const contentSnippet = result.content.slice(0, 120).replace(/\s+/g, ' ').trim();
return `${result.path}::${lines}::${contentSnippet}`;
}
function parseStartLine(lines?: string): number {
if (!lines) {
return Number.MAX_SAFE_INTEGER;
}
const match = lines.match(/(\d+)/);
if (!match) {
return Number.MAX_SAFE_INTEGER;
}
const value = Number(match[1]);
return Number.isNaN(value) ? Number.MAX_SAFE_INTEGER : value;
}
export function rerankResults(
results: InternalSearchResult[],
options: RerankOptions = {}
): InternalSearchResult[] {
const stats = new Map<string, { count: number; hasOriginal: boolean }>();
for (const result of results) {
const key = resultSignature(result);
const entry = stats.get(key) ?? { count: 0, hasOriginal: false };
entry.count += 1;
if (result.variantIndex === 0) {
entry.hasOriginal = true;
}
stats.set(key, entry);
}
const ranked = results.map((result, index) => {
const baseScore = result.relevanceScore ?? result.score ?? 0;
const entry = stats.get(resultSignature(result)) ?? { count: 1, hasOriginal: false };
const frequencyBonus = Math.log2(1 + entry.count) * 0.08;
const originalBonus = entry.hasOriginal ? 0.05 : 0;
const variantWeightBonus = (result.variantWeight - 0.5) * 0.05;
const combinedScore = baseScore + frequencyBonus + originalBonus + variantWeightBonus;
return {
result: {
...result,
combinedScore,
},
combinedScore,
baseScore,
index,
};
});
ranked.sort((a, b) => {
if (b.combinedScore !== a.combinedScore) {
return b.combinedScore - a.combinedScore;
}
if (b.baseScore !== a.baseScore) {
return b.baseScore - a.baseScore;
}
if (a.result.path !== b.result.path) {
return a.result.path.localeCompare(b.result.path);
}
const lineA = parseStartLine(a.result.lines);
const lineB = parseStartLine(b.result.lines);
if (lineA !== lineB) {
return lineA - lineB;
}
return a.index - b.index;
});
return ranked.map(entry => entry.result);
}
