[PHASE-7] Implement the client

cmd/client/main.go

@@ -0,0 +1,134 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"time"
+
+	"hash-of-wisdom/internal/pow/challenge"
+	"hash-of-wisdom/internal/pow/solver"
+	"hash-of-wisdom/internal/protocol"
+)
+
+func main() {
+	serverAddr := flag.String("addr", "localhost:8080", "server address")
+	flag.Parse()
+
+	fmt.Printf("Connecting to Word of Wisdom server at %s\n", *serverAddr)
+
+	// Step 1: Get challenge
+	challengeResp, err := requestChallenge(*serverAddr)
+	if err != nil {
+		log.Fatalf("Failed to get challenge: %v", err)
+	}
+
+	fmt.Printf("Received challenge with difficulty %d\n", challengeResp.Challenge.Difficulty)
+
+	// Step 2: Solve challenge
+	fmt.Println("Solving challenge...")
+	start := time.Now()
+
+	s := solver.NewSolver()
+	solution, err := s.Solve(context.Background(), challengeResp.Challenge)
+	if err != nil {
+		log.Fatalf("Failed to solve challenge: %v", err)
+	}
+
+	solveTime := time.Since(start)
+	fmt.Printf("Challenge solved in %v with nonce %d\n", solveTime, solution.Nonce)
+
+	// Step 3: Submit solution and get quote
+	err = submitSolution(*serverAddr, challengeResp.Challenge, solution.Nonce)
+	if err != nil {
+		log.Fatalf("Failed to submit solution: %v", err)
+	}
+}
+
+func requestChallenge(serverAddr string) (*protocol.ChallengeResponse, error) {
+	// Connect with timeout
+	conn, err := net.DialTimeout("tcp", serverAddr, 5*time.Second)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect: %w", err)
+	}
+	defer conn.Close()
+
+	// Request challenge
+	fmt.Println("Requesting challenge...")
+	challengeReq := &protocol.ChallengeRequest{}
+	if err := challengeReq.Encode(conn); err != nil {
+		return nil, fmt.Errorf("failed to send challenge request: %w", err)
+	}
+
+	// Receive challenge
+	decoder := protocol.NewMessageDecoder()
+	msg, err := decoder.Decode(conn)
+	if err != nil {
+		return nil, fmt.Errorf("failed to receive challenge: %w", err)
+	}
+
+	if msg.Type != protocol.ChallengeResponseType {
+		return nil, fmt.Errorf("unexpected response type: %v", msg.Type)
+	}
+
+	// Parse challenge
+	challengeResp := &protocol.ChallengeResponse{}
+	if err := challengeResp.Decode(msg.PayloadStream); err != nil {
+		return nil, fmt.Errorf("failed to parse challenge: %w", err)
+	}
+
+	return challengeResp, nil
+}
+
+func submitSolution(serverAddr string, chall *challenge.Challenge, nonce uint64) error {
+	// Connect with timeout
+	conn, err := net.DialTimeout("tcp", serverAddr, 5*time.Second)
+	if err != nil {
+		return fmt.Errorf("failed to connect: %w", err)
+	}
+	defer conn.Close()
+
+	// Submit solution
+	solutionReq := &protocol.SolutionRequest{
+		Challenge: *chall,
+		Nonce:     nonce,
+	}
+
+	fmt.Println("Submitting solution...")
+	if err := solutionReq.Encode(conn); err != nil {
+		return fmt.Errorf("failed to send solution: %w", err)
+	}
+
+	// Receive quote or error
+	decoder := protocol.NewMessageDecoder()
+	msg, err := decoder.Decode(conn)
+	if err != nil {
+		return fmt.Errorf("failed to receive response: %w", err)
+	}
+
+	switch msg.Type {
+	case protocol.QuoteResponseType:
+		solutionResp := &protocol.SolutionResponse{}
+		if err := solutionResp.Decode(msg.PayloadStream); err != nil {
+			return fmt.Errorf("failed to parse quote: %w", err)
+		}
+		fmt.Printf("\nQuote received:\n\"%s\"\n— %s\n", solutionResp.Quote.Text, solutionResp.Quote.Author)
+	case protocol.ErrorResponseType:
+		errorResp := &protocol.ErrorResponse{}
+		if err := errorResp.Decode(msg.PayloadStream); err != nil {
+			fmt.Println("Error: Contact administrator")
+			return nil
+		}
+		if errorResp.Code == protocol.ErrServerError {
+			fmt.Println("Error: Contact administrator")
+		} else {
+			fmt.Printf("Error: %s\n", errorResp.Message)
+		}
+	default:
+		return fmt.Errorf("unexpected response type: %v", msg.Type)
+	}
+
+	return nil
+}