import { describe, it, expect, beforeEach, vi } from 'vitest';
import { TextDirectiveHandler } from './TextDirectiveHandler.js';
import { createMockStateService, createMockValidationService, createMockResolutionService } from '@tests/utils/testFactories.js';
import { DirectiveError } from '@services/pipeline/DirectiveService/errors/DirectiveError.js';
import type { DirectiveNode } from 'meld-spec';
import type { IStateService } from '@services/state/StateService/IStateService.js';
import { StringLiteralHandler } from '@services/resolution/ResolutionService/resolvers/StringLiteralHandler.js';
import { StringConcatenationHandler } from '@services/resolution/ResolutionService/resolvers/StringConcatenationHandler.js';
// Import the centralized syntax examples and helpers
import { textDirectiveExamples } from '@core/syntax/index.js';
import { ErrorSeverity } from '@core/errors';

/**
 * Helper function to create real AST nodes using meld-ast
 */
const createNodeFromExample = async (code: string): Promise<DirectiveNode> => {
  try {
    const { parse } = await import('meld-ast');
    
    const result = await parse(code, {
      trackLocations: true,
      validateNodes: true,
      structuredPaths: true
    });
    
    return result.ast[0] as DirectiveNode;
  } catch (error) {
    console.error('Error parsing with meld-ast:', error);
    throw error;
  }
};

describe('TextDirectiveHandler', () => {
  let handler: TextDirectiveHandler;
  let stateService: ReturnType<typeof createMockStateService>;
  let validationService: ReturnType<typeof createMockValidationService>;
  let resolutionService: ReturnType<typeof createMockResolutionService>;
  let clonedState: IStateService;
  // Create real instances of the literal and concatenation handlers for testing
  let realStringLiteralHandler: StringLiteralHandler;
  let realStringConcatenationHandler: StringConcatenationHandler;

  beforeEach(() => {
    clonedState = {
      setTextVar: vi.fn(),
      getTextVar: vi.fn(),
      getDataVar: vi.fn(),
      clone: vi.fn(),
    } as unknown as IStateService;

    stateService = {
      setTextVar: vi.fn(),
      getTextVar: vi.fn(),
      getDataVar: vi.fn(),
      clone: vi.fn().mockReturnValue(clonedState)
    } as unknown as IStateService;

    validationService = createMockValidationService();
    resolutionService = createMockResolutionService();
    
    // Create real handlers to match actual implementation
    realStringLiteralHandler = new StringLiteralHandler();
    realStringConcatenationHandler = new StringConcatenationHandler(resolutionService);
    
    // Set up better mocking for variable resolution
    resolutionService.resolveInContext.mockImplementation(async (value: string, context: any) => {
      // Use real string literal handler for string literals
      if (realStringLiteralHandler.isStringLiteral(value)) {
        return realStringLiteralHandler.parseLiteral(value);
      }
      
      // Handle common test case values - this simulates what the real ResolutionService would do
      if (value.includes('{{name}}')) {
        return value.replace(/\{\{name\}\}/g, 'World');
      }
      if (value.includes('{{user.name}}')) {
        return value.replace(/\{\{user\.name\}\}/g, 'Alice');
      }
      if (value.includes('{{ENV_HOME}}')) {
        return value.replace(/\{\{ENV_HOME\}\}/g, '/home/user');
      }
      if (value.includes('{{missing}}')) {
        throw new Error('Variable not found: missing');
      }
      
      // Special case for pass-through directives test
      if (value === '"@run echo \\"test\\""') {
        return '@run echo "test"';
      }
      
      // For string concatenation tests
      if (value === '"Hello" ++ " " ++ "World"') {
        return 'Hello World';
      }
      if (value === '"Hello " ++ "{{name}}"') {
        return 'Hello World';
      }
      if (value === '"Prefix: " ++ "Header" ++ "Footer"') {
        return 'Prefix: HeaderFooter';
      }
      if (value === '"double" ++ \'single\' ++ `backtick`') {
        return 'doublesinglebacktick';
      }
      
      return value;
    });
    
    // Mock validation service to fail for invalid nodes
    validationService.validate.mockImplementation((node: any) => {
      if (node.directive?.value === "'unclosed string") {
        throw new Error('Invalid string literal: unclosed string');
      }
      if (node.directive?.value === '"no"++"spaces"') {
        throw new Error('Invalid concatenation syntax');
      }
      return Promise.resolve();
    });
    
    handler = new TextDirectiveHandler(validationService, stateService, resolutionService);
  });

  describe('execute', () => {
    it('should handle a simple text assignment with string literal', async () => {
      // Arrange
      const example = textDirectiveExamples.atomic.simpleString;
      const node = await createNodeFromExample(example.code);

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      // The example uses 'greeting' as the identifier and "Hello" as the value
      expect(clonedState.setTextVar).toHaveBeenCalledWith('greeting', 'Hello');
    });

    it('should handle text assignment with escaped characters', async () => {
      // Arrange
      const example = textDirectiveExamples.atomic.escapedCharacters;
      const node = await createNodeFromExample(example.code);
      
      // Special case - direct mock to handle expected behavior
      resolutionService.resolveInContext.mockImplementation(async () => {
        return 'Line 1\nLine 2\t"Quoted"';
      });

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      expect(clonedState.setTextVar).toHaveBeenCalledWith('escaped', 'Line 1\nLine 2\t"Quoted"');
    });

    it('should handle a template literal in text directive', async () => {
      // Arrange
      const example = textDirectiveExamples.atomic.templateLiteral;
      const node = await createNodeFromExample(example.code);

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      expect(clonedState.setTextVar).toHaveBeenCalledWith('message', 'Template content');
    });

    it('should handle object property interpolation in text value', async () => {
      // Arrange
      const example = textDirectiveExamples.combinations.objectInterpolation;
      
      // For this test, we need a custom implementation
      const mockResolveInContext = resolutionService.resolveInContext;
      resolutionService.resolveInContext = vi.fn().mockImplementation(() => {
        return 'Hello, Alice! Your ID is 123.';
      });
      
      const node = await createNodeFromExample(example.code.split('\n')[1]); // Get the second line with greeting directive

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      expect(clonedState.setTextVar).toHaveBeenCalledWith('greeting', 'Hello, Alice! Your ID is 123.');
      
      // Restore the original mock
      resolutionService.resolveInContext = mockResolveInContext;
    });

    it('should handle path referencing in text values', async () => {
      // Arrange
      const example = textDirectiveExamples.combinations.pathReferencing;
      
      // For this test, we need a custom implementation
      const mockResolveInContext = resolutionService.resolveInContext;
      resolutionService.resolveInContext = vi.fn().mockImplementation(() => {
        return 'Docs are at $PROJECTPATH/docs';
      });
      
      const node = await createNodeFromExample(example.code.split('\n')[5]); // Get the docsText line

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      expect(clonedState.setTextVar).toHaveBeenCalledWith('configText', 'Docs are at $PROJECTPATH/docs');
      
      // Restore the original mock
      resolutionService.resolveInContext = mockResolveInContext;
    });

    it('should return error if text interpolation contains undefined variables', async () => {
      // Arrange
      const example = textDirectiveExamples.invalid.undefinedVariable;
      
      // For error testing, we need to create a custom implementation
      // that throws an error for this specific test
      const mockResolveInContext = resolutionService.resolveInContext;
      resolutionService.resolveInContext = vi.fn().mockImplementation(() => {
        throw new Error('Variable not found: undefined_var');
      });

      const node = await createNodeFromExample(example.code);

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      await expect(handler.execute(node, context))
        .rejects
        .toThrow(DirectiveError);
        
      // Restore the original mock
      resolutionService.resolveInContext = mockResolveInContext;
    });

    it('should handle basic variable interpolation', async () => {
      // Arrange
      const example = textDirectiveExamples.combinations.basicInterpolation;
      
      // For this test, we need a custom implementation
      const mockResolveInContext = resolutionService.resolveInContext;
      resolutionService.resolveInContext = vi.fn().mockImplementation(() => {
        return 'Hello, World!';
      });
      
      const node = await createNodeFromExample(example.code.split('\n')[2]); // Get the third line with the message directive

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      expect(clonedState.setTextVar).toHaveBeenCalledWith('message', 'Hello, World!');
      
      // Restore the original mock
      resolutionService.resolveInContext = mockResolveInContext;
    });

    it('should register the node as a text directive in the registry', async () => {
      // Arrange
      const example = textDirectiveExamples.atomic.simpleString;
      const node = await createNodeFromExample(example.code);

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      const result = await handler.execute(node, context);
      // The example uses 'greeting' as the identifier and "Hello" as the value
      expect(clonedState.setTextVar).toHaveBeenCalledWith('greeting', 'Hello');
    });

    it('should report error for unclosed string', async () => {
      // For invalid test cases, we'll need to manually create nodes
      // since meld-ast would throw on these during parsing
      const invalidExample = textDirectiveExamples.invalid.unclosedString;
      
      // Create a mock node directly instead of parsing invalid syntax
      const node = {
        type: 'Directive',
        directive: {
          kind: 'text',
          identifier: 'greeting',
          value: '"unclosed string'
        },
        location: {
          start: { line: 1, column: 1 },
          end: { line: 1, column: 30 }
        }
      };

      // Ensure our mock validation service rejects this
      validationService.validate.mockRejectedValueOnce(new Error('Invalid string literal: unclosed string'));

      await expect(handler.execute(node, {
        state: stateService,
        currentFilePath: 'test.meld'
      }))
        .rejects
        .toThrow(DirectiveError);
    });
  });

  /**
   * This section demonstrates how to use the centralized syntax system
   * once the import issues are fixed.
   * 
   * NOTE: This section is commented out until the centralized system imports
   * are working properly.
   */
  /*
  describe('centralized syntax examples (future implementation)', () => {
    it('should handle atomic examples correctly', async () => {
      // Using the centralized atomic examples
      const example = getExample('text', 'atomic', 'simpleString');
      const node = await createNodeFromExample(example.code);

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      await handler.execute(node, context);
      expect(clonedState.setTextVar).toHaveBeenCalledWith('greeting', 'Hello');
    });

    it('should reject invalid examples', async () => {
      // Using the centralized invalid examples
      // Note: For invalid syntax, we need to manually create nodes since parsing would fail
      const invalidExample = getInvalidExample('text', 'unclosedString');
      
      // Create a node that represents what the parser would have created
      // if it didn't throw on invalid syntax
      const node: DirectiveNode = {
        type: 'Directive',
        directive: {
          kind: 'text',
          identifier: 'invalid',
          value: invalidExample.code.split('=')[1]?.trim() || ''
        },
        location: {
          start: { line: 1, column: 1 },
          end: { line: 1, column: invalidExample.code.length }
        }
      };

      const context = {
        state: stateService,
        currentFilePath: 'test.meld'
      };

      // Make the validation service reject this as expected by the invalid example
      validationService.validate.mockRejectedValueOnce(
        new Error(invalidExample.expectedError.message)
      );

      await expect(handler.execute(node, context))
        .rejects
        .toThrow(DirectiveError);
    });

    it('should test multiple examples in bulk', async () => {
      // This is a demonstration of using testParserWithValidExamples
      // to test multiple examples at once
      testParserWithValidExamples(handler, 'text', 'atomic');
    });
  });
  */
});