import type { Candidate } from "../../shared/value-objects/candidate.js";
import type { Pattern } from "../../shared/value-objects/pattern.js";

interface ScoringWeights {
	frequency?: number;
	breadth?: number;
	recency?: number;
	consistency?: number;
}

interface RankOptions {
	totalProjects: number;
	totalSessions: number;
	now: string;
	threshold?: number;
	weights?: ScoringWeights;
}

export const rankCandidates = (patterns: Pattern[], options: RankOptions): Candidate[] => {
	const threshold = options.threshold ?? 0;
	const nowMs = new Date(options.now).getTime();

	const scored = patterns.map((p) => {
		const frequency = Math.min(Math.log2(p.count + 1) / 10, 1.0);
		const breadth = options.totalProjects > 0 ? p.projects / options.totalProjects : 0;
		const ageDays = (nowMs - new Date(p.lastSeen).getTime()) / (24 * 60 * 60 * 1000);
		const recency = Math.exp((-ageDays * Math.LN2) / 14);
		const consistency = options.totalSessions > 0 ? p.sessions / options.totalSessions : 0;

		const wF = options.weights?.frequency ?? 0.25;
		const wB = options.weights?.breadth ?? 0.3;
		const wR = options.weights?.recency ?? 0.25;
		const wC = options.weights?.consistency ?? 0.2;

		const score = frequency * wF + breadth * wB + recency * wR + consistency * wC;

		return {
			pattern: p.sequence,
			score: Math.round(score * 100) / 100,
			evidence: { count: p.count, sessions: p.sessions, projects: p.projects },
		};
	});

	return scored.filter((c) => c.score >= threshold).sort((a, b) => b.score - a.score);
};