Added basic config module

1 files changed, 56 insertions, 0 deletions

diff --git a/config/config.go b/config/config.go
new file mode 100644
index 0000000..653aeb6
--- /dev/null
+++ b/config/config.go
@@ -0,0 +1,56 @@
+package config
+
+import (
+	"net"
+	"os"
+	"regexp"
+
+	"github.com/pkg/errors"
+	"gopkg.in/yaml.v3"
+)
+
+var validToken = regexp.MustCompile(`^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$`)
+
+type Config struct {
+	// Address is the hostname or ip the web server will listen to
+	Address string `yaml:"address",default:"127.0.0.1"`
+	Port    string `yaml:"port",default:"8080"`
+	// Token is the sncf api token
+	Token string `yaml:"token"`
+}
+
+func (c *Config) validate() error {
+	// address
+	if ip := net.ParseIP(c.Address); ip == nil {
+		if _, err := net.LookupIP(c.Address); err != nil {
+			return errors.New("Invalid address " + c.Address + ", it must be a valid ipv4 address, ipv6 address, or resolvable name.")
+		}
+	}
+	// port
+	if _, err := net.LookupPort("tcp", c.Port); err != nil {
+		return errors.New("Invalid port " + c.Port + ", it must be a valid port number or tcp service name. Got error : " + err.Error())
+	}
+	// token
+	if ok := validToken.MatchString(c.Token); !ok {
+		return errors.New("Invalid token, must be an hexadecimal string that lookslike 12345678-9abc-def0-1234-56789abcdef0, got " + c.Token + " instead.")
+	}
+	return nil
+}
+
+// LoadFile loads the c from a given file
+func LoadFile(path string) (*Config, error) {
+	var c *Config
+	f, errOpen := os.Open(path)
+	if errOpen != nil {
+		return nil, errors.Wrapf(errOpen, "Failed to open configuration file %s", path)
+	}
+	defer f.Close()
+	decoder := yaml.NewDecoder(f)
+	if err := decoder.Decode(&c); err != nil {
+		return nil, errors.Wrap(err, "Failed to decode configuration file")
+	}
+	if err := c.validate(); err != nil {
+		return nil, errors.Wrap(err, "Failed to validate configuration")
+	}
+	return c, nil
+}