import { describe, it, expect } from 'vitest';
import { parseShapeString } from '@/samples/slay-the-spire-like/utils/parse-shape';
import { IDENTITY_TRANSFORM } from '@/samples/slay-the-spire-like/utils/shape-collision';
import {
    createGridInventory,
    placeItem,
    removeItem,
    moveItem,
    rotateItem,
    flipItem,
    getOccupiedCellSet,
    getItemAtCell,
    getAdjacentItems,
    validatePlacement,
    type GridInventory,
    type InventoryItem,
} from '@/samples/slay-the-spire-like/grid-inventory';

/**
 * Helper: create a test inventory item.
 */
function createTestItem(id: string, shapeStr: string, transform = IDENTITY_TRANSFORM): InventoryItem {
    const shape = parseShapeString(shapeStr);
    return {
        id,
        shape,
        transform: { ...transform },
    };
}

describe('grid-inventory', () => {
    describe('createGridInventory', () => {
        it('should create an empty inventory with correct dimensions', () => {
            const inv = createGridInventory(6, 4);
            expect(inv.width).toBe(6);
            expect(inv.height).toBe(4);
            expect(inv.items.size).toBe(0);
            expect(inv.occupiedCells.size).toBe(0);
        });
    });

    describe('placeItem', () => {
        it('should place a single-cell item', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('sword', 'o');
            placeItem(inv, item);

            expect(inv.items.size).toBe(1);
            expect(inv.items.has('sword')).toBe(true);
            expect(inv.occupiedCells.has('0,0')).toBe(true);
        });

        it('should place a multi-cell item', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('axe', 'oee');
            placeItem(inv, item);

            expect(inv.items.size).toBe(1);
            expect(inv.occupiedCells.size).toBe(3);
            expect(inv.occupiedCells.has('0,0')).toBe(true);
            expect(inv.occupiedCells.has('1,0')).toBe(true);
            expect(inv.occupiedCells.has('2,0')).toBe(true);
        });

        it('should place multiple items', () => {
            const inv = createGridInventory(6, 4);
            const itemA = createTestItem('a', 'o');
            const itemB = createTestItem('b', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 3, y: 0 } });
            placeItem(inv, itemA);
            placeItem(inv, itemB);

            expect(inv.items.size).toBe(2);
            expect(inv.occupiedCells.size).toBe(2);
            expect(inv.occupiedCells.has('0,0')).toBe(true);
            expect(inv.occupiedCells.has('3,0')).toBe(true);
        });
    });

    describe('removeItem', () => {
        it('should remove an item and free its cells', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('sword', 'oee');
            placeItem(inv, item);

            removeItem(inv, 'sword');

            expect(inv.items.size).toBe(0);
            expect(inv.occupiedCells.size).toBe(0);
        });

        it('should only free the removed item\'s cells', () => {
            const inv = createGridInventory(6, 4);
            const itemA = createTestItem('a', 'o');
            const itemB = createTestItem('b', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 2, y: 0 } });
            placeItem(inv, itemA);
            placeItem(inv, itemB);

            removeItem(inv, 'a');

            expect(inv.items.size).toBe(1);
            expect(inv.occupiedCells.size).toBe(1);
            expect(inv.occupiedCells.has('0,0')).toBe(false);
            expect(inv.occupiedCells.has('2,0')).toBe(true);
        });

        it('should do nothing for non-existent item', () => {
            const inv = createGridInventory(6, 4);
            removeItem(inv, 'nonexistent');
            expect(inv.items.size).toBe(0);
        });
    });

    describe('validatePlacement', () => {
        it('should return valid for empty board', () => {
            const inv = createGridInventory(6, 4);
            const shape = parseShapeString('o');
            const result = validatePlacement(inv, shape, IDENTITY_TRANSFORM);
            expect(result).toEqual({ valid: true });
        });

        it('should return invalid for out of bounds', () => {
            const inv = createGridInventory(6, 4);
            const shape = parseShapeString('o');
            const result = validatePlacement(inv, shape, {
                ...IDENTITY_TRANSFORM,
                offset: { x: 6, y: 0 },
            });
            expect(result).toEqual({ valid: false, reason: '超出边界' });
        });

        it('should return invalid for collision with existing item', () => {
            const inv = createGridInventory(6, 4);
            const existing = createTestItem('a', 'oee');
            placeItem(inv, existing);

            const shape = parseShapeString('o');
            const result = validatePlacement(inv, shape, IDENTITY_TRANSFORM);
            expect(result).toEqual({ valid: false, reason: '与已有物品重叠' });
        });

        it('should return valid when there is room nearby', () => {
            const inv = createGridInventory(6, 4);
            const existing = createTestItem('a', 'o');
            placeItem(inv, existing);

            const shape = parseShapeString('o');
            const result = validatePlacement(inv, shape, {
                ...IDENTITY_TRANSFORM,
                offset: { x: 1, y: 0 },
            });
            expect(result).toEqual({ valid: true });
        });
    });

    describe('moveItem', () => {
        it('should move item to a new position', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('sword', 'o');
            placeItem(inv, item);

            const result = moveItem(inv, 'sword', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 5, y: 3 },
            });

            expect(result).toEqual({ success: true });
            expect(inv.occupiedCells.has('0,0')).toBe(false);
            expect(inv.occupiedCells.has('5,3')).toBe(true);
            expect(item.transform.offset).toEqual({ x: 5, y: 3 });
        });

        it('should reject move that goes out of bounds', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('sword', 'o');
            placeItem(inv, item);

            const result = moveItem(inv, 'sword', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 6, y: 0 },
            });

            expect(result).toEqual({ success: false, reason: '超出边界' });
            expect(inv.occupiedCells.has('0,0')).toBe(true);
            expect(item.transform.offset).toEqual({ x: 0, y: 0 });
        });

        it('should reject move that collides with another item', () => {
            const inv = createGridInventory(6, 4);
            const itemA = createTestItem('a', 'o');
            const itemB = createTestItem('b', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 2, y: 0 } });
            placeItem(inv, itemA);
            placeItem(inv, itemB);

            const result = moveItem(inv, 'b', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 0, y: 0 },
            });

            expect(result).toEqual({ success: false, reason: '与已有物品重叠' });
            expect(inv.occupiedCells.has('2,0')).toBe(true);
        });

        it('should return error for non-existent item', () => {
            const inv = createGridInventory(6, 4);
            const result = moveItem(inv, 'ghost', IDENTITY_TRANSFORM);
            expect(result).toEqual({ success: false, reason: '物品不存在' });
        });

        it('should move multi-cell item correctly', () => {
            const inv = createGridInventory(6, 4);
            // oes: cells at (0,0), (1,0), (1,1)
            const item = createTestItem('axe', 'oes');
            placeItem(inv, item);

            const newTransform = { ...IDENTITY_TRANSFORM, offset: { x: 3, y: 1 } };
            moveItem(inv, 'axe', newTransform);

            // Old cells should be freed
            expect(inv.occupiedCells.has('0,0')).toBe(false);
            expect(inv.occupiedCells.has('1,0')).toBe(false);
            expect(inv.occupiedCells.has('1,1')).toBe(false);
            // New cells: (0,0)+offset(3,1)=(3,1), (1,0)+(3,1)=(4,1), (1,1)+(3,1)=(4,2)
            expect(inv.occupiedCells.has('3,1')).toBe(true);
            expect(inv.occupiedCells.has('4,1')).toBe(true);
            expect(inv.occupiedCells.has('4,2')).toBe(true);
        });
    });

    describe('rotateItem', () => {
        it('should rotate item by 90 degrees', () => {
            const inv = createGridInventory(6, 4);
            // Horizontal line: (0,0), (1,0)
            const item = createTestItem('bar', 'oe', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 0, y: 1 }, // Place away from edge so rotation stays in bounds
            });
            placeItem(inv, item);

            const result = rotateItem(inv, 'bar', 90);

            expect(result).toEqual({ success: true });
            expect(item.transform.rotation).toBe(90);
        });

        it('should reject rotation that goes out of bounds', () => {
            const inv = createGridInventory(3, 3);
            // Item at the edge: place a 2-wide item at x=1
            const item = createTestItem('bar', 'oe', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 1, y: 0 },
            });
            placeItem(inv, item);

            // Rotating 90° would make it vertical starting at (1,0), going to (1,-1) -> out of bounds
            const result = rotateItem(inv, 'bar', 90);

            expect(result).toEqual({ success: false, reason: '超出边界' });
        });

        it('should reject rotation that collides', () => {
            const inv = createGridInventory(4, 4);
            const itemA = createTestItem('a', 'o');
            const itemB = createTestItem('b', 'oe', { ...IDENTITY_TRANSFORM, offset: { x: 2, y: 0 } });
            placeItem(inv, itemA);
            placeItem(inv, itemB);

            // Rotating b 90° would place cells at (2,0) and (2,-1) -> (2,-1) is out of bounds
            // Let's try a different scenario: rotate b 270° -> (2,0) and (2,1) which is fine
            // But rotating to collide with a at (0,0)... need item close to a
            const itemC = createTestItem('c', 'os', { ...IDENTITY_TRANSFORM, offset: { x: 1, y: 0 } });
            placeItem(inv, itemC);

            // Rotating c 90° would give cells at (1,0) and (0,0) -> collision with a
            const result = rotateItem(inv, 'c', 90);
            expect(result).toEqual({ success: false, reason: '与已有物品重叠' });
        });

        it('should return error for non-existent item', () => {
            const inv = createGridInventory(6, 4);
            const result = rotateItem(inv, 'ghost', 90);
            expect(result).toEqual({ success: false, reason: '物品不存在' });
        });
    });

    describe('flipItem', () => {
        it('should flip item horizontally', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('bar', 'oe');
            placeItem(inv, item);

            const result = flipItem(inv, 'bar', 'x');

            expect(result).toEqual({ success: true });
            expect(item.transform.flipX).toBe(true);
        });

        it('should flip item vertically', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('bar', 'os');
            placeItem(inv, item);

            const result = flipItem(inv, 'bar', 'y');

            expect(result).toEqual({ success: true });
            expect(item.transform.flipY).toBe(true);
        });

        it('should reject flip that causes collision', () => {
            // oes local cells: (0,0),(1,0),(1,1). flipY: (0,1),(1,1),(1,0).
            // Place flipper at offset (0,2): world cells (0,2),(1,2),(1,3).
            // flipY gives local (0,1),(1,1),(1,0) + offset(0,2) = (0,3),(1,3),(1,2) — same cells rearranged.
            // Need asymmetric shape where flip changes world position.
            // Use oes at offset (0,0): cells (0,0),(1,0),(1,1). flipY: (0,1),(1,1),(1,0).
            // Place blocker at (0,1) — which is NOT occupied by oes initially.
            const inv = createGridInventory(4, 4);
            const blocker = createTestItem('blocker', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 0, y: 1 } });
            // oes at (0,1): cells (0,1),(1,1),(1,2). This overlaps blocker at (0,1)! 
            // Let me try: blocker at (1,0), flipper at offset (0,2).
            // flipper oes at (0,2): (0,2),(1,2),(1,3). blocker at (1,0) — no overlap.
            // flipY: local (0,1),(1,1),(1,0) + offset(0,2) = (0,3),(1,3),(1,2). No collision with (1,0).
            // 
            // Simpler: oe shape (width=2, height=1). flipY with height=1 is identity. Use os (width=1, height=2).
            // os: (0,0),(0,1). flipY: (0,1),(0,0) — same cells.
            // Need width>1 and height>1 asymmetric shape: oes
            // 
            // Place flipper at (0,0): cells (0,0),(1,0),(1,1). Place blocker at (0,1) — but (0,1) is not occupied.
            // flipY: (0,1),(1,1),(1,0). (0,1) hits blocker!
            const inv2 = createGridInventory(4, 4);
            const blocker2 = createTestItem('blocker', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 0, y: 1 } });
            const flipper2 = createTestItem('flipper', 'oes'); // at (0,0): (0,0),(1,0),(1,1)
            placeItem(inv2, blocker2);
            placeItem(inv2, flipper2);

            const result = flipItem(inv2, 'flipper', 'y');
            expect(result).toEqual({ success: false, reason: '与已有物品重叠' });
        });

        it('should return error for non-existent item', () => {
            const inv = createGridInventory(6, 4);
            const result = flipItem(inv, 'ghost', 'x');
            expect(result).toEqual({ success: false, reason: '物品不存在' });
        });
    });

    describe('getOccupiedCellSet', () => {
        it('should return a copy of occupied cells', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('a', 'oe');
            placeItem(inv, item);

            const cells = getOccupiedCellSet(inv);
            expect(cells).toEqual(new Set(['0,0', '1,0']));

            // Mutating the copy should not affect the original
            cells.clear();
            expect(inv.occupiedCells.size).toBe(2);
        });
    });

    describe('getItemAtCell', () => {
        it('should return item at occupied cell', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('sword', 'oee');
            placeItem(inv, item);

            const found = getItemAtCell(inv, 1, 0);
            expect(found).toBeDefined();
            expect(found!.id).toBe('sword');
        });

        it('should return undefined for empty cell', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('sword', 'o');
            placeItem(inv, item);

            const found = getItemAtCell(inv, 5, 5);
            expect(found).toBeUndefined();
        });

        it('should return correct item when multiple items exist', () => {
            const inv = createGridInventory(6, 4);
            const itemA = createTestItem('a', 'o');
            const itemB = createTestItem('b', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 3, y: 2 } });
            placeItem(inv, itemA);
            placeItem(inv, itemB);

            expect(getItemAtCell(inv, 0, 0)!.id).toBe('a');
            expect(getItemAtCell(inv, 3, 2)!.id).toBe('b');
        });
    });

    describe('getAdjacentItems', () => {
        it('should return orthogonally adjacent items', () => {
            const inv = createGridInventory(6, 4);
            const center = createTestItem('center', 'o', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 2, y: 2 },
            });
            const top = createTestItem('top', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 2, y: 1 } });
            const left = createTestItem('left', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 1, y: 2 } });
            const right = createTestItem('right', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 3, y: 2 } });
            const bottom = createTestItem('bottom', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 2, y: 3 } });
            const diagonal = createTestItem('diagonal', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 1, y: 1 } });

            placeItem(inv, center);
            placeItem(inv, top);
            placeItem(inv, left);
            placeItem(inv, right);
            placeItem(inv, bottom);
            placeItem(inv, diagonal);

            const adj = getAdjacentItems(inv, 'center');
            expect(adj.size).toBe(4);
            expect(adj.has('top')).toBe(true);
            expect(adj.has('left')).toBe(true);
            expect(adj.has('right')).toBe(true);
            expect(adj.has('bottom')).toBe(true);
            expect(adj.has('diagonal')).toBe(false);
        });

        it('should return empty for item with no neighbors', () => {
            const inv = createGridInventory(6, 4);
            const item = createTestItem('alone', 'o');
            placeItem(inv, item);

            const adj = getAdjacentItems(inv, 'alone');
            expect(adj.size).toBe(0);
        });

        it('should return empty for non-existent item', () => {
            const inv = createGridInventory(6, 4);
            const adj = getAdjacentItems(inv, 'ghost');
            expect(adj.size).toBe(0);
        });

        it('should handle multi-cell items with multiple adjacencies', () => {
            const inv = createGridInventory(6, 4);
            // Horizontal bar at (0,0)-(1,0)
            const bar = createTestItem('bar', 'oe');
            // Item above left cell
            const topA = createTestItem('topA', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 0, y: -1 } });
            // Item above right cell
            const topB = createTestItem('topB', 'o', { ...IDENTITY_TRANSFORM, offset: { x: 1, y: -1 } });

            placeItem(inv, bar);
            placeItem(inv, topA);
            placeItem(inv, topB);

            const adj = getAdjacentItems(inv, 'bar');
            expect(adj.size).toBe(2);
            expect(adj.has('topA')).toBe(true);
            expect(adj.has('topB')).toBe(true);
        });
    });

    describe('integration: fill a 4x6 backpack', () => {
        it('should place items fitting a slay-the-spire-like backpack', () => {
            const inv = createGridInventory(4, 6);

            // Sword: 1x3 horizontal at (0,0)
            const sword = createTestItem('sword', 'oee');
            // Shield: 2x2 at (0,1)
            const shield = createTestItem('shield', 'oes', {
                ...IDENTITY_TRANSFORM,
                offset: { x: 0, y: 1 },
            });

            expect(validatePlacement(inv, sword.shape, sword.transform)).toEqual({ valid: true });
            placeItem(inv, sword);

            expect(validatePlacement(inv, shield.shape, shield.transform)).toEqual({ valid: true });
            placeItem(inv, shield);

            expect(inv.items.size).toBe(2);
            expect(inv.occupiedCells.size).toBe(6); // sword(3) + shield(3)

            // Adjacent items should detect each other
            const adjSword = getAdjacentItems(inv, 'sword');
            expect(adjSword.has('shield')).toBe(true);

            const adjShield = getAdjacentItems(inv, 'shield');
            expect(adjShield.has('sword')).toBe(true);
        });
    });
});