Refactor and move logic of reading Taskfiles to its own package

Idea to making things easier to start implementing #98

internal/taskfile/read/taskfile.go

@@ -0,0 +1,48 @@
+package read
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/go-task/task/internal/taskfile"
+
+	"github.com/imdario/mergo"
+	"gopkg.in/yaml.v2"
+)
+
+// Taskfile reads a Taskfile for a given directory
+func Taskfile(dir string) (*taskfile.Taskfile, error) {
+	path := filepath.Join(dir, "Taskfile.yml")
+	t, err := readTaskfile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	path = filepath.Join(dir, fmt.Sprintf("Taskfile_%s.yml", runtime.GOOS))
+	if _, err = os.Stat(path); err == nil {
+		osTaskfile, err := readTaskfile(path)
+		if err != nil {
+			return nil, err
+		}
+		if err = mergo.MapWithOverwrite(&t.Tasks, osTaskfile.Tasks); err != nil {
+			return nil, err
+		}
+	}
+
+	for name, task := range t.Tasks {
+		task.Task = name
+	}
+
+	return t, nil
+}
+
+func readTaskfile(file string) (*taskfile.Taskfile, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	var t taskfile.Taskfile
+	return &t, yaml.NewDecoder(f).Decode(&t)
+}

internal/taskfile/read/taskvars.go

@@ -0,0 +1,52 @@
+package read
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/go-task/task/internal/taskfile"
+
+	"gopkg.in/yaml.v2"
+)
+
+// Taskvars reads a Taskvars for a given directory
+func Taskvars(dir string) (taskfile.Vars, error) {
+	vars := make(taskfile.Vars)
+
+	path := filepath.Join(dir, "Taskvars.yml")
+	if _, err := os.Stat(path); err == nil {
+		vars, err = readTaskvars(path)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	path = filepath.Join(dir, fmt.Sprintf("Taskvars_%s.yml", runtime.GOOS))
+	if _, err := os.Stat(path); err == nil {
+		osVars, err := readTaskvars(path)
+		if err != nil {
+			return nil, err
+		}
+
+		if vars == nil {
+			vars = osVars
+		} else {
+			for k, v := range osVars {
+				vars[k] = v
+			}
+		}
+	}
+
+	return vars, nil
+}
+
+func readTaskvars(file string) (taskfile.Vars, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	var vars taskfile.Vars
+	return vars, yaml.NewDecoder(f).Decode(&vars)
+}