Add user sessions and login

This isn't quite perfect, but gets much of the hard work done.

auth.go

@@ -0,0 +1,157 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strconv"
+
+	"github.com/aarondl/opt/omit"
+	"github.com/aarondl/opt/omitnull"
+	"github.com/Gleipnir-Technology/nidus-sync/enums"
+	"github.com/Gleipnir-Technology/nidus-sync/models"
+	"github.com/Gleipnir-Technology/nidus-sync/sql"
+	"golang.org/x/crypto/bcrypt"
+)
+
+type NoCredentialsError struct{}
+func (e NoCredentialsError) Error() string { return "No credentials were present in the request" }
+
+type InvalidCredentials struct{}
+func (e InvalidCredentials) Error() string { return "No username with that password exists" }
+
+type InvalidUsername struct{}
+func (e InvalidUsername) Error() string { return "That username doesn't exist" }
+
+func addUserSession(r *http.Request, user *models.User) {
+	id := strconv.Itoa(int(user.ID))
+	sessionManager.Put(r.Context(), "user_id", id)
+	sessionManager.Put(r.Context(), "username", user.Username)
+	slog.Info("Created new user session",
+		slog.String("username", user.Username),
+		slog.String("user_id", id))
+}
+
+func getAuthenticatedUser(r *http.Request) (*models.User, error) {
+	//user_id := sessionManager.GetInt(r.Context(), "user_id")
+	user_id_str := sessionManager.GetString(r.Context(), "user_id")
+	user_id, err := strconv.Atoi(user_id_str)
+	if err != nil {
+		return nil, fmt.Errorf("Failed to convert user_id to int: %v", err)
+	}
+	username := sessionManager.GetString(r.Context(), "username")
+	slog.Info("Current session info",
+		slog.Int("user_id", user_id),
+		slog.String("username", username))
+	if user_id > 0 && username != "" {
+		return models.FindUser(r.Context(), PGInstance.BobDB, int32(user_id))
+	}
+	// If we can't get the user from the session try to get from auth headers
+	username, password, ok := r.BasicAuth()
+	if !ok {
+		return nil, &NoCredentialsError{}
+	}
+	user, err := validateUser(r.Context(), username, password)
+	if err != nil {
+		return nil, err
+	}
+	addUserSession(r, user)
+	return user, nil
+}
+
+func hashPassword(password string) (string, error) {
+	bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
+	return string(bytes), err
+}
+
+func signinUser(r *http.Request, username string, password string) (*models.User, error) {
+	user, err := validateUser(r.Context(), username, password)
+	if err != nil {
+		return nil, err
+	}
+	if user == nil {
+		return nil, errors.New("No matching user")
+	}
+	addUserSession(r, user)
+	return user, nil
+}
+
+func signupUser(username string, name string, password string) (*models.User, error) {
+	passwordHash, err := hashPassword(password)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot signup user: %v", err)
+	}
+	setter := models.UserSetter{
+		DisplayName: omitnull.From(name),
+		PasswordHash: omitnull.From(passwordHash),
+		PasswordHashType: omitnull.From(enums.HashtypeBcrypt14),
+		Username: omit.From(username),
+	}
+	u, err := models.Users.Insert(&setter).One(context.TODO(), PGInstance.BobDB)
+	if err != nil {
+		return nil, fmt.Errorf("Failed to create user: %v", err)
+	}
+	slog.Info("Created user",
+		slog.Int("ID", int(u.ID)),
+		slog.String("username", u.Username))
+
+	return u, nil
+}
+
+func validatePassword(password, hash string) bool {
+	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+	return err == nil
+}
+
+func validateUser(ctx context.Context, username string, password string) (*models.User, error) {
+	passwordHash, err := hashPassword(password)
+	if err != nil {
+		return nil, fmt.Errorf("Failed to hash password: %v", err)
+	}
+	slog.Info("Validating user",
+		slog.String("username", username),
+		slog.String("password", password),
+		slog.String("hash", passwordHash))
+	result, err := sql.UserByUsername(username).All(ctx, PGInstance.BobDB)
+	if err != nil {
+		return nil, fmt.Errorf("Failed to query for user: %v", err)
+	}
+	switch len(result) {
+		case 0:
+		return nil, InvalidUsername{}
+	case 1:
+		row := result[0]
+		hash, err := row.PasswordHash.Value()
+		if err != nil {
+			return nil, err
+		}
+		if hash == nil {
+			return nil, errors.New("Hash is nil")
+		}
+		 hashStr, ok := hash.(string);
+		if !ok {
+			return nil, errors.New("Hash isn't a string")
+		}
+		if !validatePassword(password, hashStr) {
+			return nil, InvalidCredentials{}
+		}
+		user := models.User{
+			ID: row.ID,
+			ArcgisAccessToken: row.ArcgisAccessToken,
+			ArcgisLicense: row.ArcgisLicense,
+			ArcgisRefreshToken: row.ArcgisRefreshToken,
+			ArcgisRefreshTokenExpires: row.ArcgisRefreshTokenExpires,
+			ArcgisRole: row.ArcgisRole,
+			DisplayName: row.DisplayName,
+			Email: row.Email,
+			OrganizationID: row.OrganizationID,
+			Username: row.Username,
+		}
+		return &user, nil
+	default:
+		return nil, errors.New("More than one matching row, this should be impossible.")
+
+	}
+}