import { test } from 'node:test'
import assert from 'node:assert/strict'
import {
	assignScorers,
	buildStats,
	clampSkill,
	enumerateMatchings,
	pairKey,
	pairRound,
	pairSkillSum,
	rankByRest,
	roundsRested,
} from '../src/pairing.js'

// 固定亂數（mulberry32），讓測試可重現
function seeded(seed) {
	let a = seed >>> 0
	return () => {
		a = (a + 0x6d2b79f5) >>> 0
		let t = a
		t = Math.imul(t ^ (t >>> 15), t | 1)
		t ^= t + Math.imul(t ^ (t >>> 7), t | 61)
		return ((t ^ (t >>> 14)) >>> 0) / 4294967296
	}
}

const game = (a, b) => ({ teams: [a, b] })
const NAMES = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L']
const activeOf = (result) => result.games.flatMap((g) => [...g.teamA, ...g.teamB])
const pairsOf = (result) => result.games.flatMap((g) => [pairKey(...g.teamA), pairKey(...g.teamB)])

test('buildStats：從今日戰績統計場數、搭檔、對手與最後一場', () => {
	const stats = buildStats([game(['A', 'B'], ['C', 'D']), game(['A', 'E'], ['F', 'G']), game(['H'], ['A'])])
	assert.equal(stats.total, 3)
	assert.equal(stats.playCount.get('A'), 3)
	assert.equal(stats.playCount.get('B'), 1)
	assert.equal(stats.pairUse.get(pairKey('A', 'B')), 1)
	assert.equal(stats.pairUse.get(pairKey('B', 'A')), 1, 'pairKey 不分順序')
	assert.equal(stats.pairUse.get(pairKey('H', 'A')), undefined, '單打不算搭檔')
	assert.equal(stats.opponentUse.get(pairKey('A', 'C')), 1)
	assert.equal(stats.opponentUse.get(pairKey('A', 'H')), 1, '單打算對手')
	assert.equal(stats.lastGame.get('A'), 2)
	assert.equal(stats.lastGame.get('B'), 0)
	assert.equal(stats.lastGame.get('Z'), undefined)
	assert.equal(clampSkill('12'), 10)
	assert.equal(clampSkill(null), 1)
	assert.equal(pairSkillSum(['A', 'B'], { A: 3 }), 4, '查不到的人當 1')
})

test('休息輪數：沒打過 = Infinity、剛打完這輪 = 0，一輪 = 場地數', () => {
	// 兩個場地：第 1 輪 A~H，第 2 輪 I~L + A~D
	const stats = buildStats([
		game(['A', 'B'], ['C', 'D']),
		game(['E', 'F'], ['G', 'H']),
		game(['I', 'J'], ['K', 'L']),
		game(['A', 'C'], ['B', 'D']),
	])
	assert.equal(roundsRested('Z', stats, 2), Infinity)
	assert.equal(roundsRested('A', stats, 2), 0)
	assert.equal(roundsRested('I', stats, 2), 0)
	assert.equal(roundsRested('E', stats, 2), 1, '第 1 輪打完、第 2 輪休息')
	assert.equal(roundsRested('E', stats, 1), 2, '單場地時一輪 = 1 場')
})

test('rankByRest：休息最久優先 → 場數少優先 → 隨機', () => {
	const stats = buildStats([
		game(['A', 'B'], ['C', 'D']),
		game(['E', 'F'], ['G', 'H']),
		game(['I', 'J'], ['K', 'L']),
		game(['A', 'B'], ['C', 'D']),
	])
	const ranked = rankByRest([...NAMES, 'M'], stats, 2, seeded(3))
	assert.equal(ranked[0], 'M', '沒打過的最前面')
	assert.deepEqual(ranked.slice(1, 5).sort(), ['E', 'F', 'G', 'H'], '休息一輪的其次')
	assert.deepEqual(ranked.slice(5, 9).sort(), ['I', 'J', 'K', 'L'], '剛打完但只打 1 場')
	assert.deepEqual(ranked.slice(9).sort(), ['A', 'B', 'C', 'D'], '剛打完又打了 2 場的最後')
})

test('pairRound：剛打完的先休息、沒打過的一定上場；8 人以上排 2、3 號場地', () => {
	const stats = buildStats([game(['A', 'B'], ['C', 'D']), game(['E', 'F'], ['G', 'H'])])
	for (let seed = 1; seed <= 20; seed += 1) {
		const result = pairRound(NAMES, {}, stats, { random: seeded(seed) })
		assert.equal(result.courtCount, 2)
		assert.deepEqual(result.games.map((g) => g.court), [2, 3])
		const active = activeOf(result)
		assert.equal(active.length, 8)
		assert.equal(new Set(active).size, 8, '沒有人同時在兩個場地')
		for (const name of ['I', 'J', 'K', 'L']) assert.ok(active.includes(name), `${name} 沒打過必須上場`)
		assert.equal(result.resting.length, 4)
		assert.ok(result.resting.every((n) => 'ABCDEFGH'.includes(n)), '休息的都是剛打完的人')
	}
})

test('pairRound：搭檔今天沒搭過的優先、對手也錯開；實力互補與兩隊平衡', () => {
	// 8 人全部剛休息完，之前搭過 AB CD EF GH，且 AB 對過 CD、EF 對過 GH
	const stats = buildStats([game(['A', 'B'], ['C', 'D']), game(['E', 'F'], ['G', 'H']), game(['I', 'J'], ['K', 'L']), game(['I', 'K'], ['J', 'L'])])
	const eight = NAMES.slice(0, 8)
	const used = new Set([pairKey('A', 'B'), pairKey('C', 'D'), pairKey('E', 'F'), pairKey('G', 'H')])
	for (let seed = 1; seed <= 20; seed += 1) {
		const result = pairRound(eight, {}, stats, { random: seeded(seed) })
		assert.deepEqual(activeOf(result).sort(), eight, '8 人全上')
		for (const key of pairsOf(result)) assert.ok(!used.has(key), `搭檔 ${key} 今天已搭過，不該再配`)
	}

	// 實力：4 強 4 弱 → 每組一強一弱（合計 10），兩隊實力差 0
	const skills = { A: 9, B: 9, C: 9, D: 9, E: 1, F: 1, G: 1, H: 1 }
	for (let seed = 1; seed <= 20; seed += 1) {
		const result = pairRound(eight, skills, buildStats([]), { random: seeded(seed) })
		for (const g of result.games) {
			assert.equal(pairSkillSum(g.teamA, skills), 10)
			assert.equal(pairSkillSum(g.teamB, skills), 10)
		}
	}
})

test('pairRound：4~7 人只排 2 號場地；不足 4 人回錯誤；名字去重去空白', () => {
	const six = pairRound(['A', 'B', 'C', 'D', 'E', 'F'], {}, buildStats([]), { random: seeded(1) })
	assert.equal(six.courtCount, 1)
	assert.equal(six.games.length, 1)
	assert.equal(six.games[0].court, 2)
	assert.equal(six.resting.length, 2)

	const four = pairRound([' A ', 'B', 'B', 'C', 'D', ''], {}, buildStats([]), { random: seeded(1) })
	assert.equal(four.games.length, 1)
	assert.deepEqual(activeOf(four).sort(), ['A', 'B', 'C', 'D'])
	assert.deepEqual(four.resting, [])

	assert.ok(pairRound(['A', 'B', 'C'], {}, buildStats([]), { random: seeded(1) }).error)
	assert.equal(enumerateMatchings(['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H']).length, 105)
})

test('pairRound：實力不平均時搭檔強弱互補、兩隊總和最接近', () => {
	const skills = { A: 10, B: 8, C: 2, D: 1 }
	for (let seed = 1; seed <= 10; seed += 1) {
		const [g] = pairRound(['A', 'B', 'C', 'D'], skills, buildStats([]), { random: seeded(seed) }).games
		const sums = [pairSkillSum(g.teamA, skills), pairSkillSum(g.teamB, skills)].sort()
		assert.deepEqual(sums, [10, 11], 'A+D=11 對 B+C=10 最平衡')
	}
})

test('assignScorers：從休息的人抽計分人、排除名單不抽、不夠補 null', () => {
	for (let seed = 1; seed <= 10; seed += 1) {
		const s = assignScorers(['A', 'B', 'C'], 2, { exclude: new Set(['B']), random: seeded(seed) })
		assert.equal(s.length, 2)
		assert.ok(s.every((n) => n === 'A' || n === 'C'), '只從沒被排除的休息者抽')
		assert.notEqual(s[0], s[1], '一人只負責一個場地')
	}
	assert.deepEqual(assignScorers(['A'], 2, { exclude: new Set(['A']), random: seeded(1) }), [null, null])
	assert.deepEqual(assignScorers(['A'], 2, { random: seeded(1) }), ['A', null])
	assert.deepEqual(assignScorers([], 1, { random: seeded(1) }), [null])
})