import { describe, it, expect, beforeEach } from 'vitest';
import { Node, Edge } from '@xyflow/react';

/**
 * Phase 4: Graph Visualization & Dual Views - Layout Tests
 *
 * Tests for Dagre-based hierarchical layout algorithm.
 * These tests validate layout generation, node positioning, performance,
 * and edge routing capabilities.
 *
 * SPECIFICATION: docs/specs/003-real-time-dashboard/PLAN.md Phase 4
 * REQUIREMENT: Auto-layout completes <200ms for 10 nodes
 */

// Type definitions for the layout service (to be implemented)
interface LayoutOptions {
  direction?: 'TB' | 'LR' | 'BT' | 'RL';
  nodeSpacing?: number;
  rankSpacing?: number;
}

interface LayoutResult {
  nodes: Node[];
  edges: Edge[];
  width: number;
  height: number;
}

// Mock layout service interface (implementation will be in layout.ts)
interface LayoutService {
  applyHierarchicalLayout(nodes: Node[], edges: Edge[], options?: LayoutOptions): LayoutResult;
}

describe('Layout Service', () => {
  // This will be replaced with actual implementation
  let layoutService: LayoutService;

  beforeEach(() => {
    // Mock implementation for testing
    layoutService = {
      applyHierarchicalLayout: (_nodes, _edges, _options) => {
        // Placeholder that will fail until real implementation
        throw new Error('Layout service not implemented');
      },
    };
  });

  describe('Hierarchical Layout Generation', () => {
    it('should generate hierarchical layout in vertical direction (TB)', () => {
      const nodes: Node[] = [
        { id: 'agent-1', type: 'agent', position: { x: 0, y: 0 }, data: { name: 'Agent 1' } },
        { id: 'agent-2', type: 'agent', position: { x: 0, y: 0 }, data: { name: 'Agent 2' } },
        { id: 'agent-3', type: 'agent', position: { x: 0, y: 0 }, data: { name: 'Agent 3' } },
      ];

      const edges: Edge[] = [
        { id: 'e1-2', source: 'agent-1', target: 'agent-2' },
        { id: 'e2-3', source: 'agent-2', target: 'agent-3' },
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges, { direction: 'TB' });
      }).toThrow('Layout service not implemented');

      // Expected behavior after implementation:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges, { direction: 'TB' });
      //
      // expect(result.nodes).toHaveLength(3);
      //
      // // Verify vertical hierarchy: agent-1 should be above agent-2, agent-2 above agent-3
      // const node1 = result.nodes.find(n => n.id === 'agent-1');
      // const node2 = result.nodes.find(n => n.id === 'agent-2');
      // const node3 = result.nodes.find(n => n.id === 'agent-3');
      //
      // expect(node1!.position.y).toBeLessThan(node2!.position.y);
      // expect(node2!.position.y).toBeLessThan(node3!.position.y);
    });

    it('should generate hierarchical layout in horizontal direction (LR)', () => {
      const nodes: Node[] = [
        { id: 'agent-1', type: 'agent', position: { x: 0, y: 0 }, data: { name: 'Agent 1' } },
        { id: 'agent-2', type: 'agent', position: { x: 0, y: 0 }, data: { name: 'Agent 2' } },
      ];

      const edges: Edge[] = [
        { id: 'e1-2', source: 'agent-1', target: 'agent-2' },
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges, { direction: 'LR' });
      }).toThrow('Layout service not implemented');

      // Expected behavior after implementation:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges, { direction: 'LR' });
      //
      // const node1 = result.nodes.find(n => n.id === 'agent-1');
      // const node2 = result.nodes.find(n => n.id === 'agent-2');
      //
      // // Verify horizontal hierarchy: agent-1 should be left of agent-2
      // expect(node1!.position.x).toBeLessThan(node2!.position.x);
    });

    it('should handle cyclic graphs gracefully', () => {
      const nodes: Node[] = [
        { id: 'agent-1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'agent-2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'agent-3', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];

      const edges: Edge[] = [
        { id: 'e1-2', source: 'agent-1', target: 'agent-2' },
        { id: 'e2-3', source: 'agent-2', target: 'agent-3' },
        { id: 'e3-1', source: 'agent-3', target: 'agent-1' }, // Cycle
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior: Should not throw, should produce valid layout
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      // expect(result.nodes).toHaveLength(3);
      // result.nodes.forEach(node => {
      //   expect(node.position.x).toBeGreaterThanOrEqual(0);
      //   expect(node.position.y).toBeGreaterThanOrEqual(0);
      // });
    });
  });

  describe('Node Positioning', () => {
    it('should assign x, y coordinates to all nodes', () => {
      const nodes: Node[] = [
        { id: 'node-1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'node-2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'node-3', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];

      const edges: Edge[] = [
        { id: 'e1-2', source: 'node-1', target: 'node-2' },
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      //
      // result.nodes.forEach(node => {
      //   expect(node.position).toHaveProperty('x');
      //   expect(node.position).toHaveProperty('y');
      //   expect(typeof node.position.x).toBe('number');
      //   expect(typeof node.position.y).toBe('number');
      //   expect(Number.isFinite(node.position.x)).toBe(true);
      //   expect(Number.isFinite(node.position.y)).toBe(true);
      // });
    });

    it('should prevent node overlap with proper spacing', () => {
      const nodes: Node[] = Array.from({ length: 5 }, (_, i) => ({
        id: `node-${i}`,
        type: 'agent',
        position: { x: 0, y: 0 },
        data: { name: `Agent ${i}` },
      }));

      const edges: Edge[] = Array.from({ length: 4 }, (_, i) => ({
        id: `e${i}-${i + 1}`,
        source: `node-${i}`,
        target: `node-${i + 1}`,
      }));

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges, { nodeSpacing: 50 });
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges, { nodeSpacing: 50 });
      //
      // // Check that no two nodes are too close
      // const minDistance = 50; // Based on nodeSpacing
      // for (let i = 0; i < result.nodes.length; i++) {
      //   for (let j = i + 1; j < result.nodes.length; j++) {
      //     const node1 = result.nodes[i];
      //     const node2 = result.nodes[j];
      //     const distance = Math.sqrt(
      //       Math.pow(node1.position.x - node2.position.x, 2) +
      //       Math.pow(node1.position.y - node2.position.y, 2)
      //     );
      //     expect(distance).toBeGreaterThanOrEqual(minDistance);
      //   }
      // }
    });

    it('should respect custom node spacing', () => {
      const nodes: Node[] = [
        { id: 'node-1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'node-2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];

      const edges: Edge[] = [
        { id: 'e1-2', source: 'node-1', target: 'node-2' },
      ];

      expect(() => {
        const customSpacing = 100;
        layoutService.applyHierarchicalLayout(nodes, edges, { nodeSpacing: customSpacing });
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges, { nodeSpacing: 100 });
      //
      // const node1 = result.nodes.find(n => n.id === 'node-1')!;
      // const node2 = result.nodes.find(n => n.id === 'node-2')!;
      //
      // // Distance should be at least the custom spacing
      // const distance = Math.abs(node2.position.y - node1.position.y);
      // expect(distance).toBeGreaterThanOrEqual(100);
    });
  });

  describe('Layout Performance', () => {
    it('should complete layout in <200ms for 10 nodes (REQUIREMENT)', () => {
      const nodes: Node[] = Array.from({ length: 10 }, (_, i) => ({
        id: `node-${i}`,
        type: 'agent',
        position: { x: 0, y: 0 },
        data: { name: `Agent ${i}` },
      }));

      // Create a connected graph
      const edges: Edge[] = Array.from({ length: 9 }, (_, i) => ({
        id: `e${i}-${i + 1}`,
        source: `node-${i}`,
        target: `node-${i + 1}`,
      }));

      expect(() => {
        const startTime = performance.now();
        layoutService.applyHierarchicalLayout(nodes, edges);
        const endTime = performance.now();
        const duration = endTime - startTime;

        // This will fail until implementation
        expect(duration).toBeLessThan(200);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const startTime = performance.now();
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      // const endTime = performance.now();
      // const duration = endTime - startTime;
      //
      // expect(duration).toBeLessThan(200); // REQUIREMENT: <200ms for 10 nodes
      // expect(result.nodes).toHaveLength(10);
    });

    it('should handle large graphs efficiently (50 nodes)', () => {
      const nodes: Node[] = Array.from({ length: 50 }, (_, i) => ({
        id: `node-${i}`,
        type: 'agent',
        position: { x: 0, y: 0 },
        data: { name: `Agent ${i}` },
      }));

      // Create edges with some complexity (not just linear)
      const edges: Edge[] = [];
      for (let i = 0; i < 49; i++) {
        edges.push({
          id: `e${i}-${i + 1}`,
          source: `node-${i}`,
          target: `node-${i + 1}`,
        });
        // Add some cross-edges for complexity
        if (i % 5 === 0 && i + 2 < 50) {
          edges.push({
            id: `e${i}-${i + 2}`,
            source: `node-${i}`,
            target: `node-${i + 2}`,
          });
        }
      }

      expect(() => {
        const startTime = performance.now();
        layoutService.applyHierarchicalLayout(nodes, edges);
        const endTime = performance.now();
        const duration = endTime - startTime;

        // Should still be reasonably fast (<1s)
        expect(duration).toBeLessThan(1000);
      }).toThrow('Layout service not implemented');
    });
  });

  describe('Edge Routing', () => {
    it('should preserve edge connections after layout', () => {
      const nodes: Node[] = [
        { id: 'a', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'b', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'c', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];

      const edges: Edge[] = [
        { id: 'e-a-b', source: 'a', target: 'b' },
        { id: 'e-b-c', source: 'b', target: 'c' },
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      //
      // // Edges should remain unchanged in structure
      // expect(result.edges).toHaveLength(2);
      // expect(result.edges.find(e => e.id === 'e-a-b')).toBeDefined();
      // expect(result.edges.find(e => e.id === 'e-b-c')).toBeDefined();
      //
      // // Source and target should still match
      // const edgeAB = result.edges.find(e => e.id === 'e-a-b')!;
      // expect(edgeAB.source).toBe('a');
      // expect(edgeAB.target).toBe('b');
    });

    it('should return layout dimensions (width, height)', () => {
      const nodes: Node[] = [
        { id: 'node-1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'node-2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];

      const edges: Edge[] = [
        { id: 'e1-2', source: 'node-1', target: 'node-2' },
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      //
      // expect(result).toHaveProperty('width');
      // expect(result).toHaveProperty('height');
      // expect(typeof result.width).toBe('number');
      // expect(typeof result.height).toBe('number');
      // expect(result.width).toBeGreaterThan(0);
      // expect(result.height).toBeGreaterThan(0);
    });

    it('should handle disconnected components', () => {
      const nodes: Node[] = [
        { id: 'a1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'a2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'b1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'b2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];

      const edges: Edge[] = [
        { id: 'e-a1-a2', source: 'a1', target: 'a2' },
        { id: 'e-b1-b2', source: 'b1', target: 'b2' },
        // No edges between a* and b* - two separate components
      ];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      //
      // // All nodes should still get positions
      // expect(result.nodes).toHaveLength(4);
      // result.nodes.forEach(node => {
      //   expect(Number.isFinite(node.position.x)).toBe(true);
      //   expect(Number.isFinite(node.position.y)).toBe(true);
      // });
    });
  });

  describe('Empty and Edge Cases', () => {
    it('should handle empty node list', () => {
      const nodes: Node[] = [];
      const edges: Edge[] = [];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      // expect(result.nodes).toHaveLength(0);
      // expect(result.edges).toHaveLength(0);
    });

    it('should handle single node with no edges', () => {
      const nodes: Node[] = [
        { id: 'lone-node', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];
      const edges: Edge[] = [];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      // expect(result.nodes).toHaveLength(1);
      // expect(result.nodes[0].position.x).toBeGreaterThanOrEqual(0);
      // expect(result.nodes[0].position.y).toBeGreaterThanOrEqual(0);
    });

    it('should handle nodes with no connecting edges', () => {
      const nodes: Node[] = [
        { id: 'node-1', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'node-2', type: 'agent', position: { x: 0, y: 0 }, data: {} },
        { id: 'node-3', type: 'agent', position: { x: 0, y: 0 }, data: {} },
      ];
      const edges: Edge[] = [];

      expect(() => {
        layoutService.applyHierarchicalLayout(nodes, edges);
      }).toThrow('Layout service not implemented');

      // Expected behavior:
      // const result = layoutService.applyHierarchicalLayout(nodes, edges);
      // expect(result.nodes).toHaveLength(3);
      //
      // // All nodes should get valid positions
      // result.nodes.forEach(node => {
      //   expect(Number.isFinite(node.position.x)).toBe(true);
      //   expect(Number.isFinite(node.position.y)).toBe(true);
      // });
    });
  });
});
