internal/puzzle: Add Solver interface and Run solutions func

Author: obalunenko

internal/puzzle/solver.go

@@ -0,0 +1,108 @@
+package puzzle
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"log"
+	"sort"
+	"sync"
+
+	"github.com/pkg/errors"
+)
+
+// Solver represents solutions for puzzles methods.
+type Solver interface {
+	Part1(input io.Reader) (string, error)
+	Part2(input io.Reader) (string, error)
+	Name() string
+}
+
+var (
+	solversMu sync.RWMutex
+	solvers   = make(map[string]Solver)
+)
+
+// Register makes a puzzle solver available by the provided name.
+// If Register is called twice with the same name or if solver is nil,
+// it panics.
+func Register(name string, solver Solver) {
+	solversMu.Lock()
+	defer solversMu.Unlock()
+	if solver == nil {
+		panic("puzzle: Register solver is nil")
+	}
+	if _, dup := solvers[name]; dup {
+		panic("puzzle: Register called twice for solver " + name)
+	}
+	solvers[name] = solver
+}
+
+func unregisterAllSolvers() {
+	solversMu.Lock()
+	defer solversMu.Unlock()
+	// For tests.
+	solvers = make(map[string]Solver)
+}
+
+// Solvers returns a sorted list of the names of the registered puzzle solvers.
+func Solvers() []string {
+	solversMu.RLock()
+	defer solversMu.RUnlock()
+	var list []string
+	for name := range solvers {
+		list = append(list, name)
+	}
+	sort.Strings(list)
+	return list
+}
+
+// GetSolver returns registered solver by passed puzzle name.
+func GetSolver(name string) (Solver, error) {
+	if name == "" {
+		return nil, errors.New("empty puzzle name")
+	}
+
+	solversMu.Lock()
+	defer solversMu.Unlock()
+
+	s, exist := solvers[name]
+
+	if !exist {
+		return nil, errors.Errorf("unknown puzzle name [%s]", name)
+	}
+
+	return s, nil
+}
+
+// Run uses solver of puzzle and path to input.
+func Run(solver Solver, filepath string) error {
+	var (
+		input []byte
+		res   string
+		err   error
+	)
+
+	input, err = ioutil.ReadFile(filepath)
+	if err != nil {
+		return errors.Wrap(err, "failed to open file")
+	}
+
+	log.Printf("run puzzle solver [%s]\n", solver.Name())
+
+	res, err = solver.Part1(bytes.NewBuffer(input))
+	if err != nil {
+		return errors.Wrapf(err, "failed to run Part1 for puzzle [%s]", solver.Name())
+	}
+
+	log.Printf("Part1 answer: %s \n", res)
+
+	res, err = solver.Part2(bytes.NewBuffer(input))
+	if err != nil {
+		return errors.Wrapf(err, "failed to run Part2 for puzzle [%s]", solver.Name())
+	}
+
+	log.Printf("Part2 answer: %s \n", res)
+
+	return nil
+}