import { describe, it, expect } from 'vitest';
import { applyAlign, shuffle, moveToRegion, moveToRegionAll, removeFromRegion, type Region, type RegionAxis } from '@/core/region';
import { createRNG } from '@/utils/rng';
import { entity, Entity } from '@/utils/entity';
import { type Part } from '@/core/part';

describe('Region', () => {
    function createTestRegion(axes: RegionAxis[], parts: Part[]): Entity<Region> {
        const partEntities = parts.map(p => entity(p.id, p));
        return entity('region1', {
            id: 'region1',
            axes: [...axes],
            children: partEntities,
        });
    }

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

        it('should align parts to start on first axis', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [5, 10] };
            const part2: Part = { id: 'p2', region: null as any, position: [7, 20] };
            const part3: Part = { id: 'p3', region: null as any, position: [2, 30] };

            const region = createTestRegion(
                [{ name: 'x', min: 0, align: 'start' }, { name: 'y' }],
                [part1, part2, part3]
            );

            applyAlign(region);

            expect(region.value.children[0].value.position[0]).toBe(0);
            expect(region.value.children[1].value.position[0]).toBe(1);
            expect(region.value.children[2].value.position[0]).toBe(2);
            expect(region.value.children[0].value.position[1]).toBe(30);
            expect(region.value.children[1].value.position[1]).toBe(10);
            expect(region.value.children[2].value.position[1]).toBe(20);
        });

        it('should align parts to start with custom min', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [5, 100] };
            const part2: Part = { id: 'p2', region: null as any, position: [7, 200] };

            const region = createTestRegion(
                [{ name: 'x', min: 10, align: 'start' }, { name: 'y' }],
                [part1, part2]
            );

            applyAlign(region);

            expect(region.value.children[0].value.position[0]).toBe(10);
            expect(region.value.children[1].value.position[0]).toBe(11);
            expect(region.value.children[0].value.position[1]).toBe(100);
            expect(region.value.children[1].value.position[1]).toBe(200);
        });

        it('should align parts to end on first axis', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [2, 50] };
            const part2: Part = { id: 'p2', region: null as any, position: [4, 60] };
            const part3: Part = { id: 'p3', region: null as any, position: [1, 70] };

            const region = createTestRegion(
                [{ name: 'x', max: 10, align: 'end' }, { name: 'y' }],
                [part1, part2, part3]
            );

            applyAlign(region);

            expect(region.value.children[0].value.position[0]).toBe(8);
            expect(region.value.children[1].value.position[0]).toBe(9);
            expect(region.value.children[2].value.position[0]).toBe(10);
        });

        it('should align parts to center on first axis', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [0, 5] };
            const part2: Part = { id: 'p2', region: null as any, position: [1, 6] };
            const part3: Part = { id: 'p3', region: null as any, position: [2, 7] };

            const region = createTestRegion(
                [{ name: 'x', min: 0, max: 10, align: 'center' }, { name: 'y' }],
                [part1, part2, part3]
            );

            applyAlign(region);

            expect(region.value.children[0].value.position[0]).toBe(4);
            expect(region.value.children[1].value.position[0]).toBe(5);
            expect(region.value.children[2].value.position[0]).toBe(6);
        });

        it('should handle even count center alignment', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [0, 10] };
            const part2: Part = { id: 'p2', region: null as any, position: [1, 20] };

            const region = createTestRegion(
                [{ name: 'x', min: 0, max: 10, align: 'center' }, { name: 'y' }],
                [part1, part2]
            );

            applyAlign(region);

            expect(region.value.children[0].value.position[0]).toBe(4.5);
            expect(region.value.children[1].value.position[0]).toBe(5.5);
        });

        it('should sort children by position on current axis', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [5, 100] };
            const part2: Part = { id: 'p2', region: null as any, position: [1, 200] };
            const part3: Part = { id: 'p3', region: null as any, position: [3, 300] };

            const region = createTestRegion(
                [{ name: 'x', min: 0, align: 'start' }, { name: 'y' }],
                [part1, part2, part3]
            );

            applyAlign(region);

            expect(region.value.children[0].value.id).toBe('p2');
            expect(region.value.children[1].value.id).toBe('p3');
            expect(region.value.children[2].value.id).toBe('p1');
        });

        it('should align on multiple axes', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [5, 10] };
            const part2: Part = { id: 'p2', region: null as any, position: [7, 20] };
            const part3: Part = { id: 'p3', region: null as any, position: [2, 30] };

            const region = createTestRegion(
                [
                    { name: 'x', min: 0, align: 'start' },
                    { name: 'y', min: 0, align: 'start' }
                ],
                [part1, part2, part3]
            );

            applyAlign(region);

            const positions = region.value.children.map(c => ({
                id: c.value.id,
                position: c.value.position
            }));

            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', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [0, 0] };
            const part2: Part = { id: 'p2', region: null as any, position: [10, 0] };
            const part3: Part = { id: 'p3', region: null as any, position: [10, 1] };
            const part4: Part = { id: 'p4', region: null as any, position: [0, 1] };

            const region = createTestRegion(
                [
                    { name: 'x', min: 0, max: 10, align: 'start' },
                    { name: 'y', min: 0, max: 10, align: 'start' }
                ],
                [part1, part2, part3, part4]
            );

            applyAlign(region);

            const positions = region.value.children.map(c => ({
                id: c.value.id,
                position: c.value.position
            }));

            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 = createTestRegion([], []);
            const rng = createRNG(42);
            shuffle(region, rng);
            expect(region.value.children).toHaveLength(0);
        });

        it('should do nothing with single part', () => {
            const part: Part = { id: 'p1', region: null as any, position: [0, 0, 0] };
            const region = createTestRegion([], [part]);
            const rng = createRNG(42);
            shuffle(region, rng);
            expect(region.value.children[0].value.position).toEqual([0, 0, 0]);
        });

        it('should shuffle positions of multiple parts', () => {
            const part1: Part = { id: 'p1', region: null as any, position: [0, 100] };
            const part2: Part = { id: 'p2', region: null as any, position: [1, 200] };
            const part3: Part = { id: 'p3', region: null as any, position: [2, 300] };

            const region = createTestRegion([], [part1, part2, part3]);
            const rng = createRNG(42);

            const originalPositions = region.value.children.map(c => [...c.value.position]);
            shuffle(region, rng);

            const newPositions = region.value.children.map(c => c.value.position);

            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: Part = { id: 'p1', region: null as any, position: [0, 10] };
                const part2: Part = { id: 'p2', region: null as any, position: [1, 20] };
                const part3: Part = { id: 'p3', region: null as any, position: [2, 30] };
                return createTestRegion([], [part1, part2, part3]);
            };

            const setup1 = createRegionForTest();
            const setup2 = createRegionForTest();

            const rng1 = createRNG(42);
            const rng2 = createRNG(42);

            shuffle(setup1, rng1);
            shuffle(setup2, rng2);

            const positions1 = setup1.value.children.map(c => c.value.position);
            const positions2 = setup2.value.children.map(c => c.value.position);

            expect(positions1).toEqual(positions2);
        });

        it('should produce different results with different seeds', () => {
            const createRegionForTest = () => {
                const part1: Part = { id: 'p1', region: null as any, position: [0, 10] };
                const part2: Part = { id: 'p2', region: null as any, position: [1, 20] };
                const part3: Part = { id: 'p3', region: null as any, position: [2, 30] };
                const part4: Part = { id: 'p4', region: null as any, position: [3, 40] };
                const part5: Part = { id: 'p5', region: null as any, position: [4, 50] };
                return createTestRegion([], [part1, part2, part3, part4, part5]);
            };

            const results = new Set<string>();

            for (let seed = 1; seed <= 10; seed++) {
                const setup = createRegionForTest();
                const rng = createRNG(seed);
                shuffle(setup, rng);

                const positions = JSON.stringify(setup.value.children.map(c => c.value.position));
                results.add(positions);
            }

            expect(results.size).toBeGreaterThan(5);
        });
    });

    describe('moveToRegion', () => {
        it('should move a part from one region to another', () => {
            const sourceAxes: RegionAxis[] = [{ name: 'x', min: 0, max: 5 }];
            const targetAxes: RegionAxis[] = [{ name: 'x', min: 0, max: 5 }];
            const sourceRegion = createTestRegion(sourceAxes, []);
            const targetRegion = createTestRegion(targetAxes, []);

            const part: Part = { id: 'p1', region: sourceRegion, position: [2] };
            const partEntity = entity(part.id, part);
            sourceRegion.value.children.push(partEntity);

            expect(sourceRegion.value.children).toHaveLength(1);
            expect(targetRegion.value.children).toHaveLength(0);
            expect(partEntity.value.region.value.id).toBe('region1');

            moveToRegion(partEntity, targetRegion, [0]);

            expect(sourceRegion.value.children).toHaveLength(0);
            expect(targetRegion.value.children).toHaveLength(1);
            expect(partEntity.value.region.value.id).toBe('region1');
            expect(partEntity.value.position).toEqual([0]);
        });

        it('should keep existing position if no position provided', () => {
            const sourceRegion = createTestRegion([{ name: 'x' }], []);
            const targetRegion = createTestRegion([{ name: 'x' }], []);

            const part: Part = { id: 'p1', region: sourceRegion, position: [3] };
            const partEntity = entity(part.id, part);
            sourceRegion.value.children.push(partEntity);

            moveToRegion(partEntity, targetRegion);

            expect(partEntity.value.position).toEqual([3]);
        });
    });

    describe('moveToRegionAll', () => {
        it('should move multiple parts to a target region', () => {
            const sourceRegion = createTestRegion([{ name: 'x' }], []);
            const targetRegion = createTestRegion([{ name: 'x' }], []);

            const parts = [
                entity('p1', { id: 'p1', region: sourceRegion, position: [0] } as Part),
                entity('p2', { id: 'p2', region: sourceRegion, position: [1] } as Part),
                entity('p3', { id: 'p3', region: sourceRegion, position: [2] } as Part),
            ];
            sourceRegion.value.children.push(...parts);

            moveToRegionAll(parts, targetRegion, [[0], [1], [2]]);

            expect(sourceRegion.value.children).toHaveLength(0);
            expect(targetRegion.value.children).toHaveLength(3);
            expect(parts[0].value.position).toEqual([0]);
            expect(parts[1].value.position).toEqual([1]);
            expect(parts[2].value.position).toEqual([2]);
        });

        it('should keep existing positions if no positions provided', () => {
            const sourceRegion = createTestRegion([{ name: 'x' }], []);
            const targetRegion = createTestRegion([{ name: 'x' }], []);

            const parts = [
                entity('p1', { id: 'p1', region: sourceRegion, position: [5] } as Part),
                entity('p2', { id: 'p2', region: sourceRegion, position: [8] } as Part),
            ];
            sourceRegion.value.children.push(...parts);

            moveToRegionAll(parts, targetRegion);

            expect(parts[0].value.position).toEqual([5]);
            expect(parts[1].value.position).toEqual([8]);
        });
    });

    describe('removeFromRegion', () => {
        it('should remove a part from its region', () => {
            const region = createTestRegion([{ name: 'x' }], []);

            const part: Part = { id: 'p1', region: region, position: [2] };
            const partEntity = entity(part.id, part);
            region.value.children.push(partEntity);

            expect(region.value.children).toHaveLength(1);

            removeFromRegion(partEntity);

            expect(region.value.children).toHaveLength(0);
        });

        it('should leave other parts unaffected', () => {
            const region = createTestRegion([{ name: 'x' }], []);

            const p1 = entity('p1', { id: 'p1', region: region, position: [0] } as Part);
            const p2 = entity('p2', { id: 'p2', region: region, position: [1] } as Part);
            const p3 = entity('p3', { id: 'p3', region: region, position: [2] } as Part);
            region.value.children.push(p1, p2, p3);

            removeFromRegion(p2);

            expect(region.value.children).toHaveLength(2);
            expect(region.value.children.map(c => c.value.id)).toEqual(['p1', 'p3']);
        });
    });
});