// test-fusion.js
const { RETRIEVAL } = require('./packages/shared/src/config/constants');

function fuseEpisodeResults(semanticEps, keywordEps, { semanticWeight, keywordWeight, limit }) {
    const k = RETRIEVAL.RRF_K;
    const scores = new Map();
    semanticEps.forEach((ep, i) => {
        scores.set(ep.id, { episode: ep, score: semanticWeight / (k + i + 1) });
    });
    keywordEps.forEach((ep, i) => {
        const contrib = keywordWeight / (k + i + 1);
        if (scores.has(ep.id)) {
            scores.get(ep.id).score += contrib;
        } else if (contrib > 0) {
            scores.set(ep.id, { episode: ep, score: contrib });
        }
    });
    return [...scores.values()]
        .sort((a, b) => b.score - a.score)
        .slice(0, limit)
        .map(({ episode }) => episode);
}

// --- Test 1: episodes in both lists rank highest ---
const semantic = [
    { id: 1, user_message: 'ep1 — semantic only, rank 1' },
    { id: 2, user_message: 'ep2 — in both lists, rank 2 semantic' },
    { id: 3, user_message: 'ep3 — in both lists, rank 3 semantic' },
];
const keyword = [
    { id: 3, user_message: 'ep3 — rank 1 FTS' },
    { id: 2, user_message: 'ep2 — rank 2 FTS' },
    { id: 4, user_message: 'ep4 — FTS only, rank 3' },
];

const result = fuseEpisodeResults(semantic, keyword, { semanticWeight: 1, keywordWeight: 1, limit: 5 });
console.log('Test 1 — equal weights, episodes in both lists should rank highest:');
result.forEach((ep, i) => console.log(`  ${i + 1}. id=${ep.id} "${ep.user_message}"`));
console.assert(result[0].id === 2 || result[0].id === 3, 'FAIL: ep2 or ep3 should be rank 1');
console.assert(!result.find(e => e.id === 1) || result.indexOf(result.find(e => e.id === 1)) > result.indexOf(result.find(e => e.id === 2)), 'FAIL: ep1 (semantic only) should rank below ep2');
console.log('  PASS\n');

// --- Test 2: keywordWeight:0 → pure semantic passthrough ---
const result2 = fuseEpisodeResults(semantic, keyword, { semanticWeight: 1, keywordWeight: 0, limit: 5 });
console.log('Test 2 — keywordWeight:0 should return only semantic results in original order:');
result2.forEach((ep, i) => console.log(`  ${i + 1}. id=${ep.id}`));
console.assert(result2.length === 3, `FAIL: expected 3, got ${result2.length}`);
console.assert(result2[0].id === 1, 'FAIL: ep1 should be rank 1');
console.assert(result2[1].id === 2, 'FAIL: ep2 should be rank 2');
console.log('  PASS\n');

// --- Test 3: limit is respected ---
const result3 = fuseEpisodeResults(semantic, keyword, { semanticWeight: 1, keywordWeight: 1, limit: 2 });
console.log('Test 3 — limit:2 should return exactly 2 results:');
console.assert(result3.length === 2, `FAIL: expected 2, got ${result3.length}`);
console.log('  PASS\n');

// --- Test 4: no overlap → all unique episodes, ordered by individual contribution ---
const semOnly = [{ id: 10, user_message: 'sem' }];
const ftsOnly = [{ id: 20, user_message: 'fts' }];
const result4 = fuseEpisodeResults(semOnly, ftsOnly, { semanticWeight: 1, keywordWeight: 1, limit: 5 });
console.log('Test 4 — no overlap, both should appear:');
console.assert(result4.length === 2, `FAIL: expected 2, got ${result4.length}`);
console.assert(result4[0].id === 10, 'FAIL: semantic rank-1 should beat fts rank-1 (same weight, both rank 1, but semantic inserted first — tie goes to semantic)');
console.log('  PASS\n');

console.log('All tests passed.');