api: Add go files

I know this is a huge commit, but I can't be bothered to check
this in part by part.

api/owner_reset_password.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"golang.org/x/crypto/bcrypt"
+	"net/http"
+)
+
+func ownerResetPassword(resetHex string, password string) error {
+	if resetHex == "" || password == "" {
+		return errorMissingField
+	}
+
+	passwordHash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		logger.Errorf("cannot generate hash from password: %v\n", err)
+		return errorInternal
+	}
+
+	statement := `
+		UPDATE owners SET passwordHash=$1
+		WHERE email IN (
+			SELECT email FROM ownerResetHexes
+			WHERE resetHex=$2
+		);
+	`
+	res, err := db.Exec(statement, string(passwordHash), resetHex)
+	if err != nil {
+		logger.Errorf("cannot change user's password: %v\n", err)
+		return errorInternal
+	}
+
+	count, err := res.RowsAffected()
+	if err != nil {
+		logger.Errorf("cannot count rows affected: %v\n", err)
+		return errorInternal
+	}
+
+	if count == 0 {
+		return errorNoSuchResetToken
+	}
+
+	statement = `
+		DELETE FROM ownerResetHexes
+    WHERE resetHex=$1;
+	`
+	_, err = db.Exec(statement, resetHex)
+	if err != nil {
+		logger.Warningf("cannot remove reset token: %v\n", err)
+	}
+
+	return nil
+}
+
+func ownerResetPasswordHandler(w http.ResponseWriter, r *http.Request) {
+	type request struct {
+		ResetHex *string `json:"resetHex"`
+		Password *string `json:"password"`
+	}
+
+	var x request
+	if err := unmarshalBody(r, &x); err != nil {
+		writeBody(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	if err := ownerResetPassword(*x.ResetHex, *x.Password); err != nil {
+		writeBody(w, response{"success": false, "message": err.Error()})
+		return
+	}
+
+	writeBody(w, response{"success": true})
+}