Refactor Sudoku field and solver implementation

sudoku/sudoku.go

@@ -14,36 +14,43 @@ type Game struct {
 	solver logic.Solver
 }
 
-func New(parser parser.Parser, solver logic.Solver, data []byte) (*Game, error) {
-	err := parser.Parse(data)
-	if err != nil {
-		return &Game{}, fmt.Errorf("can not create game: %w", err)
+func New(input parser.Parser, solver logic.Solver, data []byte, fieldIndex int) (*Game, error) {
+	if input == nil {
+		return nil, errors.New("cannot create game: nil parser")
 	}
-	return &Game{solver: solver, field: parser.GetField(2)}, nil
+	if err := input.Parse(data); err != nil {
+		return nil, fmt.Errorf("cannot create game: %w", err)
+	}
+	parsedField, err := input.GetField(fieldIndex)
+	if err != nil {
+		return nil, fmt.Errorf("cannot create game: %w", err)
+	}
+	if parsedField == nil || !parsedField.IsValid() {
+		return nil, fmt.Errorf("cannot create game: %w", field.ErrInvalidField)
+	}
+	return &Game{solver: solver, field: parsedField}, nil
 }
 
 func (g *Game) Solve() error {
-	g.solver.InitStragies(g.field)
-	for !g.isFinished() {
-		if !g.nextSolveStep() {
-			return errors.New("no strategy can solve the puzzle")
-		}
+	if g == nil || g.field == nil {
+		return field.ErrInvalidField
+	}
+	if err := g.solver.InitStrategies(g.field); err != nil {
+		return err
+	}
+	solved, err := g.solver.Run(0)
+	if err != nil {
+		return err
+	}
+	if !solved {
+		return logic.ErrNoProgress
 	}
 	return nil
 }
 
-func (g *Game) nextSolveStep() bool {
-	return g.solver.Run(0)
-}
-
-func (g *Game) prevSolveStep() {
-	// far far in the future
-}
-
-func (g *Game) isFinished() bool {
-	return g.field.IsSolved()
-}
-
-func (g *Game) GetField() field.Field {
-	return *g.field
+func (g *Game) GetField() *field.Field {
+	if g == nil {
+		return nil
+	}
+	return g.field
 }