Requirements

Imagine you're building a powerful search utility similar to `grep` in Unix-like systems. This utility needs to efficiently search for files within a specified directory (and its subdirectories) that match a given pattern. The pattern could be a simple string, a wildcard expression, or, for more advanced users, a regular expression. The search should be highly configurable, allowing users to specify whether the search is case-sensitive, whether to follow symbolic links, and whether to search only within file names, file content, or both. The design should be easily extensible to support new search algorithms, pattern types, and output formats. This isn't just about finding files; it's about designing a robust, modular, and easily maintainable search engine that can be adapted to various use cases. # Requirements ## Functional Requirements 1. **Basic Search:** * The application must accept a root directory path and a search pattern as input. * It should recursively traverse the directory structure starting from the given root. * It must identify files that match the search pattern based on user-specified criteria. 2. **Pattern Matching:** * Support for exact string matching. * Support for wildcard matching (e.g., `*.txt`, `file?.*`). * Support for regular expression matching using the `java.util.regex` package. * Allow users to specify the pattern type (string, wildcard, regex). 3. **Search Scope:** * Allow users to specify whether to search only in file names, file content, or both. * If searching in file content, the application should be able to handle large files efficiently (consider using buffering). 4. **Search Options:** * Case-sensitive and case-insensitive search options. * Option to follow symbolic links or not. * Option to limit the depth of the search (i.e., maximum subdirectory levels to traverse). 5. **Output:** * Display the path of each matching file. * Option to display the line number(s) within the file where the pattern was found (if searching file content). * Option to display a snippet of the matching line(s) in the file. * Support different output formats (e.g., plain text, JSON). 6. **Error Handling:** * Gracefully handle file access errors (e.g., permission denied). * Provide informative error messages to the user. 7. **Cancellation:** * Provide a mechanism for the user to cancel the search operation. ## Non-Functional Requirements 1. **Modularity:** * The design should be highly modular, allowing for easy addition of new pattern matching algorithms, search scopes, and output formats without modifying existing code. Aim for a plugin-based architecture. 2. **Extensibility:** * The system should be extensible to support new file types, new search criteria (e.g., file size, modification date), and new output destinations (e.g., writing results to a database). 3. **Thread Safety:** * The search operation should be thread-safe to allow for concurrent searching of different parts of the directory structure, significantly improving performance on multi-core systems. Properly synchronize shared resources. 4. **Testability:** * The code should be highly testable, with well-defined interfaces and dependencies. * Provide unit tests for core components. 5. **Performance:** * Optimize the search algorithm for performance, especially when searching large directories or files. * Consider using multi-threading to improve search speed. 6. **Resource Management:** * Properly manage file handles and memory resources to prevent leaks, especially when dealing with a large number of files or large files. Ensure file streams are closed properly. 7. **SOLID Principles:** * Adhere to SOLID principles: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion. ## Core Entities 1. **`SearchRequest`**: Represents a single search request, encapsulating the root directory, search pattern, pattern type, search scope, search options, and output format. 2. **`Searcher`**: Interface for the core search functionality. Implementations will handle the actual file searching logic. 3. **`FileVisitor`**: Responsible for traversing the directory structure and invoking the appropriate search logic for each file. 4. **`PatternMatcher`**: Interface for matching patterns against file names or content. Implementations will handle different pattern types (string, wildcard, regex). This screams for a Strategy pattern. 5. **`SearchResult`**: Represents a single search result, containing the file path, line number (if applicable), and matching line snippet (if applicable). 6. **`OutputFormatter`**: Interface for formatting the search results. Implementations will handle different output formats (plain text, JSON). 7. **`SearchOption`**: Enum to represent different search options (case-sensitive, follow symlinks, limit search depth) 8. **`SearchScope`**: Enum to represent search scope options (filename, filecontent, both). 9. **`SearchCancellation`**: Allows external cancellation of the search operation

Unix File Search Engine

Requirements

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Functional Requirements

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Non-Functional Requirements

Core Entity Identification

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