/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import { ReadFileTool, ReadFileToolParams } from './read-file.js';
import path from 'path';
import os from 'os';
import fs from 'fs';
import fsp from 'fs/promises';
import { Config } from '../config/config.js';
import { FileDiscoveryService } from '../services/fileDiscoveryService.js';
import { createMockWorkspaceContext } from '../test-utils/mockWorkspaceContext.js';
import { ToolInvocation, ToolResult } from './tools.js';

describe('ReadFileTool', () => {
  let tempRootDir: string;
  let tool: ReadFileTool;
  const abortSignal = new AbortController().signal;

  beforeEach(async () => {
    // Create a unique temporary root directory for each test run
    tempRootDir = await fsp.mkdtemp(
      path.join(os.tmpdir(), 'read-file-tool-root-'),
    );

    const mockConfigInstance = {
      getFileService: () => new FileDiscoveryService(tempRootDir),
      getTargetDir: () => tempRootDir,
      getWorkspaceContext: () => createMockWorkspaceContext(tempRootDir),
    } as unknown as Config;
    tool = new ReadFileTool(mockConfigInstance);
  });

  afterEach(async () => {
    // Clean up the temporary root directory
    if (fs.existsSync(tempRootDir)) {
      await fsp.rm(tempRootDir, { recursive: true, force: true });
    }
  });

  describe('build', () => {
    it('should return an invocation for valid params (absolute path within root)', () => {
      const params: ReadFileToolParams = {
        absolute_path: path.join(tempRootDir, 'test.txt'),
      };
      const result = tool.build(params);
      expect(result).not.toBeTypeOf('string');
      expect(typeof result).toBe('object');
      expect(
        (result as ToolInvocation<ReadFileToolParams, ToolResult>).params,
      ).toEqual(params);
    });

    it('should return an invocation for valid params with offset and limit', () => {
      const params: ReadFileToolParams = {
        absolute_path: path.join(tempRootDir, 'test.txt'),
        offset: 0,
        limit: 10,
      };
      const result = tool.build(params);
      expect(result).not.toBeTypeOf('string');
    });

    it('should throw error for relative path', () => {
      const params: ReadFileToolParams = { absolute_path: 'test.txt' };
      expect(() => tool.build(params)).toThrow(
        `File path must be absolute, but was relative: test.txt. You must provide an absolute path.`,
      );
    });

    it('should throw error for path outside root', () => {
      const outsidePath = path.resolve(os.tmpdir(), 'outside-root.txt');
      const params: ReadFileToolParams = { absolute_path: outsidePath };
      expect(() => tool.build(params)).toThrow(
        'File path must be within one of the workspace directories',
      );
    });

    it('should throw error for negative offset', () => {
      const params: ReadFileToolParams = {
        absolute_path: path.join(tempRootDir, 'test.txt'),
        offset: -1,
        limit: 10,
      };
      expect(() => tool.build(params)).toThrow(
        'Offset must be a non-negative number',
      );
    });

    it('should throw error for non-positive limit', () => {
      const paramsZero: ReadFileToolParams = {
        absolute_path: path.join(tempRootDir, 'test.txt'),
        offset: 0,
        limit: 0,
      };
      expect(() => tool.build(paramsZero)).toThrow(
        'Limit must be a positive number',
      );
      const paramsNegative: ReadFileToolParams = {
        absolute_path: path.join(tempRootDir, 'test.txt'),
        offset: 0,
        limit: -5,
      };
      expect(() => tool.build(paramsNegative)).toThrow(
        'Limit must be a positive number',
      );
    });

    it('should throw error for schema validation failure (e.g. missing path)', () => {
      const params = { offset: 0 } as unknown as ReadFileToolParams;
      expect(() => tool.build(params)).toThrow(
        `params must have required property 'absolute_path'`,
      );
    });
  });

  describe('ToolInvocation', () => {
    describe('getDescription', () => {
      it('should return a shortened, relative path', () => {
        const filePath = path.join(tempRootDir, 'sub', 'dir', 'file.txt');
        const params: ReadFileToolParams = { absolute_path: filePath };
        const invocation = tool.build(params);
        expect(typeof invocation).not.toBe('string');
        expect(
          (
            invocation as ToolInvocation<ReadFileToolParams, ToolResult>
          ).getDescription(),
        ).toBe(path.join('sub', 'dir', 'file.txt'));
      });

      it('should return . if path is the root directory', () => {
        const params: ReadFileToolParams = { absolute_path: tempRootDir };
        const invocation = tool.build(params);
        expect(typeof invocation).not.toBe('string');
        expect(
          (
            invocation as ToolInvocation<ReadFileToolParams, ToolResult>
          ).getDescription(),
        ).toBe('.');
      });
    });

    describe('execute', () => {
      it('should return error if file does not exist', async () => {
        const filePath = path.join(tempRootDir, 'nonexistent.txt');
        const params: ReadFileToolParams = { absolute_path: filePath };
        const invocation = tool.build(params) as ToolInvocation<
          ReadFileToolParams,
          ToolResult
        >;

        expect(await invocation.execute(abortSignal)).toEqual({
          llmContent: `File not found: ${filePath}`,
          returnDisplay: 'File not found.',
        });
      });

      it('should return success result for a text file', async () => {
        const filePath = path.join(tempRootDir, 'textfile.txt');
        const fileContent = 'This is a test file.';
        await fsp.writeFile(filePath, fileContent, 'utf-8');
        const params: ReadFileToolParams = { absolute_path: filePath };
        const invocation = tool.build(params) as ToolInvocation<
          ReadFileToolParams,
          ToolResult
        >;

        expect(await invocation.execute(abortSignal)).toEqual({
          llmContent: fileContent,
          returnDisplay: '',
        });
      });

      it('should return success result for an image file', async () => {
        // A minimal 1x1 transparent PNG file.
        const pngContent = Buffer.from([
          137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0,
          1, 0, 0, 0, 1, 8, 6, 0, 0, 0, 31, 21, 196, 137, 0, 0, 0, 10, 73, 68,
          65, 84, 120, 156, 99, 0, 1, 0, 0, 5, 0, 1, 13, 10, 45, 180, 0, 0, 0,
          0, 73, 69, 78, 68, 174, 66, 96, 130,
        ]);
        const filePath = path.join(tempRootDir, 'image.png');
        await fsp.writeFile(filePath, pngContent);
        const params: ReadFileToolParams = { absolute_path: filePath };
        const invocation = tool.build(params) as ToolInvocation<
          ReadFileToolParams,
          ToolResult
        >;

        expect(await invocation.execute(abortSignal)).toEqual({
          llmContent: {
            inlineData: {
              mimeType: 'image/png',
              data: pngContent.toString('base64'),
            },
          },
          returnDisplay: `Read image file: image.png`,
        });
      });

      it('should treat a non-image file with image extension as an image', async () => {
        const filePath = path.join(tempRootDir, 'fake-image.png');
        const fileContent = 'This is not a real png.';
        await fsp.writeFile(filePath, fileContent, 'utf-8');
        const params: ReadFileToolParams = { absolute_path: filePath };
        const invocation = tool.build(params) as ToolInvocation<
          ReadFileToolParams,
          ToolResult
        >;

        expect(await invocation.execute(abortSignal)).toEqual({
          llmContent: {
            inlineData: {
              mimeType: 'image/png',
              data: Buffer.from(fileContent).toString('base64'),
            },
          },
          returnDisplay: `Read image file: fake-image.png`,
        });
      });

      it('should pass offset and limit to read a slice of a text file', async () => {
        const filePath = path.join(tempRootDir, 'paginated.txt');
        const fileContent = Array.from(
          { length: 20 },
          (_, i) => `Line ${i + 1}`,
        ).join('\n');
        await fsp.writeFile(filePath, fileContent, 'utf-8');

        const params: ReadFileToolParams = {
          absolute_path: filePath,
          offset: 5, // Start from line 6
          limit: 3,
        };
        const invocation = tool.build(params) as ToolInvocation<
          ReadFileToolParams,
          ToolResult
        >;

        expect(await invocation.execute(abortSignal)).toEqual({
          llmContent: [
            '[File content truncated: showing lines 6-8 of 20 total lines. Use offset/limit parameters to view more.]',
            'Line 6',
            'Line 7',
            'Line 8',
          ].join('\n'),
          returnDisplay: 'Read lines 6-8 of 20 from paginated.txt',
        });
      });

      describe('with .geminiignore', () => {
        beforeEach(async () => {
          await fsp.writeFile(
            path.join(tempRootDir, '.geminiignore'),
            ['foo.*', 'ignored/'].join('\n'),
          );
        });

        it('should throw error if path is ignored by a .geminiignore pattern', async () => {
          const ignoredFilePath = path.join(tempRootDir, 'foo.bar');
          await fsp.writeFile(ignoredFilePath, 'content', 'utf-8');
          const params: ReadFileToolParams = {
            absolute_path: ignoredFilePath,
          };
          const expectedError = `File path '${ignoredFilePath}' is ignored by .geminiignore pattern(s).`;
          expect(() => tool.build(params)).toThrow(expectedError);
        });

        it('should throw error if path is in an ignored directory', async () => {
          const ignoredDirPath = path.join(tempRootDir, 'ignored');
          await fsp.mkdir(ignoredDirPath);
          const filePath = path.join(ignoredDirPath, 'somefile.txt');
          await fsp.writeFile(filePath, 'content', 'utf-8');

          const params: ReadFileToolParams = {
            absolute_path: filePath,
          };
          const expectedError = `File path '${filePath}' is ignored by .geminiignore pattern(s).`;
          expect(() => tool.build(params)).toThrow(expectedError);
        });
      });
    });
  });

  describe('workspace boundary validation', () => {
    it('should validate paths are within workspace root', () => {
      const params: ReadFileToolParams = {
        absolute_path: path.join(tempRootDir, 'file.txt'),
      };
      expect(() => tool.build(params)).not.toThrow();
    });

    it('should reject paths outside workspace root', () => {
      const params: ReadFileToolParams = {
        absolute_path: '/etc/passwd',
      };
      expect(() => tool.build(params)).toThrow(
        'File path must be within one of the workspace directories',
      );
    });

    it('should provide clear error message with workspace directories', () => {
      const outsidePath = path.join(os.tmpdir(), 'outside-workspace.txt');
      const params: ReadFileToolParams = {
        absolute_path: outsidePath,
      };
      expect(() => tool.build(params)).toThrow(
        'File path must be within one of the workspace directories',
      );
    });
  });
});