import { describe, it, expect, beforeEach } from 'vitest';
import { applyAlign, shuffle, type Region, type RegionAxis } from '../../src/core/region';
import { createRNG } from '../../src/utils/rng';
import { createEntityCollection } from '../../src/utils/entity';
import { type Part } from '../../src/core/part';

describe('Region', () => {
    function createPart(id: string, position: number[]): Part {
        const collection = createEntityCollection<Part>();
        const part: Part = {
            id,
            sides: 1,
            side: 0,
            region: { id: 'region1', value: {} as Region },
            position: [...position]
        };
        collection.add(part);
        return part;
    }

    function createRegion(axes: RegionAxis[], parts: Part[]): Region {
        const region: Region = {
            id: 'region1',
            axes: [...axes],
            children: parts.map(p => ({ id: p.id, value: p }))
        };
        return region;
    }

    describe('applyAlign', () => {
        it('should do nothing with empty region', () => {
            const region = createRegion([{ name: 'x', min: 0, align: 'start' }], []);
            applyAlign(region);
            expect(region.children).toHaveLength(0);
        });

        it('should align parts to start', () => {
            const part1 = createPart('p1', [5, 0]);
            const part2 = createPart('p2', [7, 0]);
            const part3 = createPart('p3', [2, 0]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, align: 'start' }],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // 排序后应该是 part3(2), part1(5), part2(7) -> 对齐到 0, 1, 2
            expect(region.children[0].value.position[0]).toBe(0);
            expect(region.children[1].value.position[0]).toBe(1);
            expect(region.children[2].value.position[0]).toBe(2);
        });

        it('should align parts to start with custom min', () => {
            const part1 = createPart('p1', [5, 0]);
            const part2 = createPart('p2', [7, 0]);
            
            const region = createRegion(
                [{ name: 'x', min: 10, align: 'start' }],
                [part1, part2]
            );
            
            applyAlign(region);
            
            expect(region.children[0].value.position[0]).toBe(10);
            expect(region.children[1].value.position[0]).toBe(11);
        });

        it('should align parts to end', () => {
            const part1 = createPart('p1', [2, 0]);
            const part2 = createPart('p2', [4, 0]);
            const part3 = createPart('p3', [1, 0]);
            
            const region = createRegion(
                [{ name: 'x', max: 10, align: 'end' }],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // 3 个部分，对齐到 end(max=10)，应该是 8, 9, 10
            expect(region.children[0].value.position[0]).toBe(8);
            expect(region.children[1].value.position[0]).toBe(9);
            expect(region.children[2].value.position[0]).toBe(10);
        });

        it('should align parts to center', () => {
            const part1 = createPart('p1', [0, 0]);
            const part2 = createPart('p2', [1, 0]);
            const part3 = createPart('p3', [2, 0]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, max: 10, align: 'center' }],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // 中心是 5，3 个部分应该是 4, 5, 6
            expect(region.children[0].value.position[0]).toBe(4);
            expect(region.children[1].value.position[0]).toBe(5);
            expect(region.children[2].value.position[0]).toBe(6);
        });

        it('should handle even count center alignment', () => {
            const part1 = createPart('p1', [0, 0]);
            const part2 = createPart('p2', [1, 0]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, max: 10, align: 'center' }],
                [part1, part2]
            );
            
            applyAlign(region);
            
            // 中心是 5，2 个部分应该是 4.5, 5.5
            expect(region.children[0].value.position[0]).toBe(4.5);
            expect(region.children[1].value.position[0]).toBe(5.5);
        });

        it('should sort children by position', () => {
            const part1 = createPart('p1', [5, 0]);
            const part2 = createPart('p2', [1, 0]);
            const part3 = createPart('p3', [3, 0]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, align: 'start' }],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // children 应该按位置排序
            expect(region.children[0].value.id).toBe('p2');
            expect(region.children[1].value.id).toBe('p3');
            expect(region.children[2].value.id).toBe('p1');
        });
    });

    describe('shuffle', () => {
        it('should do nothing with empty region', () => {
            const region = createRegion([], []);
            const rng = createRNG(42);
            shuffle(region, rng);
            expect(region.children).toHaveLength(0);
        });

        it('should do nothing with single part', () => {
            const part = createPart('p1', [0, 0]);
            const region = createRegion([], [part]);
            const rng = createRNG(42);
            shuffle(region, rng);
            expect(region.children[0].value.position).toEqual([0, 0]);
        });

        it('should shuffle positions of multiple parts', () => {
            const part1 = createPart('p1', [0, 0]);
            const part2 = createPart('p2', [1, 0]);
            const part3 = createPart('p3', [2, 0]);
            
            const region = createRegion([], [part1, part2, part3]);
            const rng = createRNG(42);
            
            const originalPositions = region.children.map(c => [...c.value.position]);
            shuffle(region, rng);
            
            // 位置应该被交换
            const newPositions = region.children.map(c => c.value.position);
            
            // 验证所有原始位置仍然存在（只是被交换了）
            originalPositions.forEach(origPos => {
                const found = newPositions.some(newPos => 
                    newPos[0] === origPos[0] && newPos[1] === origPos[1]
                );
                expect(found).toBe(true);
            });
        });

        it('should be deterministic with same seed', () => {
            const createRegionForTest = () => {
                const part1 = createPart('p1', [0, 0]);
                const part2 = createPart('p2', [1, 0]);
                const part3 = createPart('p3', [2, 0]);
                return createRegion([], [part1, part2, part3]);
            };

            const region1 = createRegionForTest();
            const region2 = createRegionForTest();
            
            const rng1 = createRNG(42);
            const rng2 = createRNG(42);
            
            shuffle(region1, rng1);
            shuffle(region2, rng2);
            
            const positions1 = region1.children.map(c => c.value.position);
            const positions2 = region2.children.map(c => c.value.position);
            
            expect(positions1).toEqual(positions2);
        });

        it('should produce different results with different seeds', () => {
            const part1 = createPart('p1', [0, 0]);
            const part2 = createPart('p2', [1, 0]);
            const part3 = createPart('p3', [2, 0]);
            const part4 = createPart('p4', [3, 0]);
            const part5 = createPart('p5', [4, 0]);
            
            const results = new Set<string>();
            
            // 尝试多个种子，确保大多数产生不同结果
            for (let seed = 1; seed <= 10; seed++) {
                const region = createRegion([], [part1, part2, part3, part4, part5]);
                const rng = createRNG(seed);
                shuffle(region, rng);
                
                const positions = JSON.stringify(region.children.map(c => c.value.position));
                results.add(positions);
            }
            
            // 10 个种子中至少应该有 5 个不同的结果
            expect(results.size).toBeGreaterThan(5);
        });
    });
});