Add solution for Challenge 30 by kiramux (#726)

* Add solution for Challenge 30

* Update challenge-30/submissions/kiramux/solution-template.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

---------

Co-authored-by: go-interview-practice-bot[bot] <230190823+go-interview-practice-bot[bot]@users.noreply.github.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: 3 people

challenge-30/submissions/kiramux/solution-template.go

@@ -0,0 +1,160 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+)
+
+// ContextManager defines a simplified interface for basic context operations
+type ContextManager interface {
+	// Create a cancellable context from a parent context
+	CreateCancellableContext(parent context.Context) (context.Context, context.CancelFunc)
+
+	// Create a context with timeout
+	CreateTimeoutContext(parent context.Context, timeout time.Duration) (context.Context, context.CancelFunc)
+
+	// Add a value to context
+	AddValue(parent context.Context, key, value interface{}) context.Context
+
+	// Get a value from context
+	GetValue(ctx context.Context, key interface{}) (interface{}, bool)
+
+	// Execute a task with context cancellation support
+	ExecuteWithContext(ctx context.Context, task func() error) error
+
+	// Wait for context cancellation or completion
+	WaitForCompletion(ctx context.Context, duration time.Duration) error
+}
+
+// Simple context manager implementation
+type simpleContextManager struct{}
+
+// NewContextManager creates a new context manager
+func NewContextManager() ContextManager {
+	return &simpleContextManager{}
+}
+
+// CreateCancellableContext creates a cancellable context
+func (cm *simpleContextManager) CreateCancellableContext(parent context.Context) (context.Context, context.CancelFunc) {
+	// DONE: Implement cancellable context creation
+	// Hint: Use context.WithCancel(parent)
+	ctx, cancel := context.WithCancel(parent)
+	return ctx, cancel
+}
+
+// CreateTimeoutContext creates a context with timeout
+func (cm *simpleContextManager) CreateTimeoutContext(parent context.Context, timeout time.Duration) (context.Context, context.CancelFunc) {
+	// DONE: Implement timeout context creation
+	// Hint: Use context.WithTimeout(parent, timeout)
+	ctx, cancel := context.WithTimeout(parent, timeout)
+	return ctx, cancel
+}
+
+// AddValue adds a key-value pair to the context
+func (cm *simpleContextManager) AddValue(parent context.Context, key, value interface{}) context.Context {
+	// DONE: Implement value context creation
+	// Hint: Use context.WithValue(parent, key, value)
+	ctx := context.WithValue(parent, key, value)
+	return ctx
+}
+
+// GetValue retrieves a value from the context
+func (cm *simpleContextManager) GetValue(ctx context.Context, key interface{}) (interface{}, bool) {
+	// DONE: Implement value retrieval from context
+	// Hint: Use ctx.Value(key) and check if it's nil
+	value := ctx.Value(key)
+	// Return the value and a boolean indicating if it was found
+	if value != nil {
+		return value, true
+	} else {
+		return nil, false
+	}
+}
+
+// ExecuteWithContext executes a task that can be cancelled via context
+func (cm *simpleContextManager) ExecuteWithContext(ctx context.Context, task func() error) error {
+	// DONE: Implement task execution with context cancellation
+	// Hint: Run the task in a goroutine and use select with ctx.Done()
+	done := make(chan error, 1)
+
+	go func() {
+		done <- task()
+	}()
+
+	// Return context error if cancelled, task error if task fails
+	select {
+	case err := <-done:
+		return err // Task completed first
+	case <-ctx.Done():
+		return ctx.Err() // Context cancelled/timeout first
+	}
+}
+
+// WaitForCompletion waits for a duration or until context is cancelled
+func (cm *simpleContextManager) WaitForCompletion(ctx context.Context, duration time.Duration) error {
+	// DONE: Implement waiting with context awareness
+	// Hint: Use select with ctx.Done() and time.After(duration)
+	// Return context error if cancelled, nil if duration completes
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-time.After(duration):
+		return nil
+	}
+}
+
+// Helper function - simulate work that can be cancelled
+func SimulateWork(ctx context.Context, workDuration time.Duration, description string) error {
+	// DONE: Implement cancellable work simulation
+	// Hint: Use select with ctx.Done() and time.After(workDuration)
+	// Print progress messages and respect cancellation
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-time.After(workDuration):
+		fmt.Println(description)
+		return nil
+	}
+}
+
+// Helper function - process multiple items with context
+func ProcessItems(ctx context.Context, items []string) ([]string, error) {
+	// DONE: Implement batch processing with context awareness
+	// Process each item but check for cancellation between items
+	// Return partial results if cancelled
+	result := make([]string, 0, len(items))
+	for _, s := range items {
+		select {
+		case <-ctx.Done():
+			return result, ctx.Err()
+		default:
+		    // The test file's cancellation wait time is too short; a wait time needs to be set.
+			time.Sleep(30 * time.Millisecond)
+			processedStr := "processed_" + s
+			result = append(result, processedStr)
+		}
+	}
+	return result, nil
+
+}
+
+// Example usage
+func main() {
+	fmt.Println("Context Management Challenge")
+	fmt.Println("Implement the context manager methods!")
+
+	// Example of how the context manager should work:
+	cm := NewContextManager()
+
+	// Create a cancellable context
+	ctx, cancel := cm.CreateCancellableContext(context.Background())
+	defer cancel()
+
+	// Add some values
+	ctx = cm.AddValue(ctx, "user", "alice")
+	ctx = cm.AddValue(ctx, "requestID", "12345")
+
+	// Use the context
+	fmt.Println("Context created with values!")
+}