import { describe, it, expect } 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 on first axis', () => {
            const part1 = createPart('p1', [5, 10]);
            const part2 = createPart('p2', [7, 20]);
            const part3 = createPart('p3', [2, 30]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, align: 'start' }, { name: 'y' }],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // 排序后应该是 part3(2), part1(5), part2(7) -> 对齐到 0, 1, 2 (第一轴)
            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);
            // 第二轴保持不变
            expect(region.children[0].value.position[1]).toBe(30);
            expect(region.children[1].value.position[1]).toBe(10);
            expect(region.children[2].value.position[1]).toBe(20);
        });

        it('should align parts to start with custom min', () => {
            const part1 = createPart('p1', [5, 100]);
            const part2 = createPart('p2', [7, 200]);
            
            const region = createRegion(
                [{ name: 'x', min: 10, align: 'start' }, { name: 'y' }],
                [part1, part2]
            );
            
            applyAlign(region);
            
            expect(region.children[0].value.position[0]).toBe(10);
            expect(region.children[1].value.position[0]).toBe(11);
            // 第二轴保持不变
            expect(region.children[0].value.position[1]).toBe(100);
            expect(region.children[1].value.position[1]).toBe(200);
        });

        it('should align parts to end on first axis', () => {
            const part1 = createPart('p1', [2, 50]);
            const part2 = createPart('p2', [4, 60]);
            const part3 = createPart('p3', [1, 70]);
            
            const region = createRegion(
                [{ name: 'x', max: 10, align: 'end' }, { name: 'y' }],
                [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 on first axis', () => {
            const part1 = createPart('p1', [0, 5]);
            const part2 = createPart('p2', [1, 6]);
            const part3 = createPart('p3', [2, 7]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, max: 10, align: 'center' }, { name: 'y' }],
                [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, 10]);
            const part2 = createPart('p2', [1, 20]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, max: 10, align: 'center' }, { name: 'y' }],
                [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 on current axis', () => {
            const part1 = createPart('p1', [5, 100]);
            const part2 = createPart('p2', [1, 200]);
            const part3 = createPart('p3', [3, 300]);
            
            const region = createRegion(
                [{ name: 'x', min: 0, align: 'start' }, { name: 'y' }],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // children 应该按第一轴位置排序
            expect(region.children[0].value.id).toBe('p2');
            expect(region.children[1].value.id).toBe('p3');
            expect(region.children[2].value.id).toBe('p1');
        });

        it('should align on multiple axes', () => {
            const part1 = createPart('p1', [5, 10]);
            const part2 = createPart('p2', [7, 20]);
            const part3 = createPart('p3', [2, 30]);
            
            const region = createRegion(
                [
                    { name: 'x', min: 0, align: 'start' },
                    { name: 'y', min: 0, align: 'start' }
                ],
                [part1, part2, part3]
            );
            
            applyAlign(region);
            
            // X 轴对齐：
            // 唯一位置值：[2, 5, 7] -> 映射到 [0, 1, 2]
            // part3: 2->0, part1: 5->1, part2: 7->2
            // 结果：part3=[0,30], part1=[1,10], part2=[2,20]
            //
            // Y 轴对齐：
            // 唯一位置值：[10, 20, 30] -> 映射到 [0, 1, 2]
            // part1: 10->0, part2: 20->1, part3: 30->2
            // 最终：part1=[1,0], part2=[2,1], part3=[0,2]
            
            const positions = region.children.map(c => ({
                id: c.value.id,
                position: c.value.position
            }));
            
            // children 按位置排序后的顺序
            expect(positions[0].id).toBe('p3');
            expect(positions[0].position).toEqual([0, 2]);
            
            expect(positions[1].id).toBe('p1');
            expect(positions[1].position).toEqual([1, 0]);
            
            expect(positions[2].id).toBe('p2');
            expect(positions[2].position).toEqual([2, 1]);
        });

        it('should align 4 elements on rectangle corners', () => {
            // 4 个元素放在矩形的四个角：(0,0), (10,0), (10,1), (0,1)
            // 期望：保持矩形布局，只是紧凑到 (0,0), (1,0), (1,1), (0,1)
            const part1 = createPart('p1', [0, 0]);   // 左下角
            const part2 = createPart('p2', [10, 0]);  // 右下角
            const part3 = createPart('p3', [10, 1]);  // 右上角
            const part4 = createPart('p4', [0, 1]);   // 左上角
            
            const region = createRegion(
                [
                    { name: 'x', min: 0, max: 10, align: 'start' },
                    { name: 'y', min: 0, max: 10, align: 'start' }
                ],
                [part1, part2, part3, part4]
            );
            
            applyAlign(region);
            
            // X 轴对齐：
            // 唯一位置值：[0, 10] -> 映射到 [0, 1]
            // part1: 0->0, part4: 0->0, part2: 10->1, part3: 10->1
            // 结果：part1=[0,0], part4=[0,1], part2=[1,0], part3=[1,1]
            //
            // Y 轴对齐：
            // 唯一位置值：[0, 1] -> 映射到 [0, 1] (已经是紧凑的)
            // part1: 0->0, part2: 0->0, part4: 1->1, part3: 1->1
            // 最终：part1=[0,0], part2=[1,0], part4=[0,1], part3=[1,1]
            
            const positions = region.children.map(c => ({
                id: c.value.id,
                position: c.value.position
            }));
            
            // children 按位置排序后的顺序：(0,0), (0,1), (1,0), (1,1)
            expect(positions[0].id).toBe('p1');
            expect(positions[0].position).toEqual([0, 0]);
            
            expect(positions[1].id).toBe('p4');
            expect(positions[1].position).toEqual([0, 1]);
            
            expect(positions[2].id).toBe('p2');
            expect(positions[2].position).toEqual([1, 0]);
            
            expect(positions[3].id).toBe('p3');
            expect(positions[3].position).toEqual([1, 1]);
        });
    });

    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, 0]);
            const region = createRegion([], [part]);
            const rng = createRNG(42);
            shuffle(region, rng);
            expect(region.children[0].value.position).toEqual([0, 0, 0]);
        });

        it('should shuffle positions of multiple parts', () => {
            const part1 = createPart('p1', [0, 100]);
            const part2 = createPart('p2', [1, 200]);
            const part3 = createPart('p3', [2, 300]);
            
            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, 10]);
                const part2 = createPart('p2', [1, 20]);
                const part3 = createPart('p3', [2, 30]);
                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 createRegionForTest = () => {
                const part1 = createPart('p1', [0, 10]);
                const part2 = createPart('p2', [1, 20]);
                const part3 = createPart('p3', [2, 30]);
                const part4 = createPart('p4', [3, 40]);
                const part5 = createPart('p5', [4, 50]);
                return createRegion([], [part1, part2, part3, part4, part5]);
            };

            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 = createRegionForTest();
                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);
        });
    });
});