Add solver

internal/pow/solver/solver.go

@@ -0,0 +1,94 @@
+package solver
+
+import (
+	"context"
+	"runtime"
+	"sync/atomic"
+
+	"hash-of-wisdom/internal/pow/challenge"
+)
+
+// Solver handles parallel PoW solving with configurable parallelism
+type Solver struct {
+	workers int
+}
+
+// SolverOption represents functional options for solver configuration
+type solverOption func(*Solver)
+
+// WithWorkers sets the number of parallel workers
+func WithWorkers(workers int) solverOption {
+	return func(s *Solver) {
+		s.workers = workers
+	}
+}
+
+// NewSolver creates a new parallel PoW solver
+func NewSolver(options ...solverOption) *Solver {
+	solver := &Solver{
+		workers: runtime.NumCPU(), // Default to CPU count
+	}
+
+	for _, option := range options {
+		option(solver)
+	}
+
+	return solver
+}
+
+// Solve attempts to find a valid nonce for the given challenge
+func (s *Solver) Solve(ctx context.Context, ch *challenge.Challenge) (*challenge.Solution, error) {
+	// Create cancellable context for workers
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	// Channel to receive solution from any worker
+	solutionCh := make(chan *challenge.Solution, 1)
+
+	// Shared nonce counter for work distribution
+	var nonceCounter atomic.Uint64
+
+	// Start parallel workers
+	for i := range s.workers {
+		go func(workerID int) {
+			s.worker(ctx, ch, &nonceCounter, solutionCh)
+		}(i)
+	}
+
+	// Wait for either solution or context cancellation
+	select {
+	case solution := <-solutionCh:
+		return solution, nil
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
+// worker performs PoW computation in parallel
+func (s *Solver) worker(ctx context.Context, ch *challenge.Challenge, nonceCounter *atomic.Uint64, solutionCh chan<- *challenge.Solution) {
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			// Get next nonce to try
+			nonce := nonceCounter.Add(1) - 1
+
+			// Try this nonce
+			if ch.VerifySolution(nonce) {
+				// Found solution! Send it back
+				solution := &challenge.Solution{
+					Challenge: *ch,
+					Nonce:     nonce,
+				}
+
+				select {
+				case solutionCh <- solution:
+				case <-ctx.Done():
+				}
+				return
+			}
+		}
+	}
+}