SOLID principles problems

Here are some **problems** designed to help you identify which SOLID principle is violated. Analyze each scenario and determine which principle isn’t followed:

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### **Problem 1: Multiple Responsibilities**
A class `FileManager` handles the following tasks:
1. Reading a file from the disk.
2. Parsing the file content to a specific format.
3. Saving the parsed data into a database.

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### **Problem 2: Inflexible Class Extension**
A `DiscountCalculator` class is designed to calculate discounts for products.
- It has a method `calculateDiscount(String customerType)` that applies different discounts based on `customerType`.
- Adding a new `customerType` requires modifying the `calculateDiscount` method.

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### **Problem 3: Lacking Substitutability**
A `Rectangle` class has `getWidth` and `getHeight` methods.
A subclass `Square` overrides these methods, ensuring that the width and height are always equal.
However, this breaks certain algorithms that expect rectangles to behave normally.

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### **Problem 4: Unnecessary Dependencies**
A `Printer` class depends on a `Database` class to retrieve printable data.
This makes the `Printer` class impossible to reuse in scenarios where data doesn’t come from a database (e.g., reading from a file or network).

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### **Problem 5: Violating Interface Segregation**
An interface `Bird` defines the following methods:
- `fly()`, `swim()`, and `chirp()`.
Both `Duck` and `Penguin` classes implement this interface.
- While `Penguin` can swim and chirp, it doesn’t fly, so it leaves the `fly()` method unimplemented.

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### **Problem 6: Hard-Coded Dependencies**
A `ReportGenerator` class internally creates a `PDFGenerator` instance to generate PDF reports.
This makes it impossible to use the same `ReportGenerator` for other formats like Excel or CSV.

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### **Problem 7: Tight Coupling**
A `UserService` class interacts directly with a `MySQLDatabase` class for data operations.
The system cannot switch to another database type (e.g., PostgreSQL or MongoDB) without modifying the `UserService` class.

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### **Problem 8: Responsibility Confusion**
A `Logger` class is responsible for:
1. Writing logs to the console or a file.
2. Deciding what type of logs (info, debug, error) should be written.

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### **Problem 9: Overloaded Interfaces**
A `Shape` interface has the following methods:
- `drawCircle()`, `drawSquare()`, and `drawRectangle()`.
The `Circle` class implements this interface, but it only needs the `drawCircle()` method, leaving the other methods unimplemented.

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### **Problem 10: Lack of Dependency Injection**
A `NotificationService` class creates an `EmailSender` object internally to send notifications.
Switching to an `SMSSender` requires modifying the `NotificationService` class.

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These problems simulate real-world challenges and are excellent for sharpening your understanding of SOLID principles. Focus on analyzing the scenarios and identifying the violated principle(s).