HTML USSD

Appearance

Validator and Transformer ​

This module is responsible for validating and transforming the parsed TagElements from the TagAdapter.

It checks the structure of your page and converts it into a strongly typed HtmlUssdTree that the UssdController use.

Validation Rules ​

  • Must have one <html> tag
  • <html> must contain exactly one <head> and one <body>
  • <head> must have one <title> with text
  • <body> must contain only:
    • <p> or text before any <form> or <a>
    • Either multiple <a> tags or a single <form>
  • <form> must:
    • Have one <input>
    • Use method="get" or method="post"
    • Point to a server URL in the action attribute
    • Include name and placeholder in <input>
  • <a> must:
    • Have an href attribute (either file or server URL)
    • Contain link text

Cache and History ​

Two optional attributes can be added to the <html> tag:

  • cache="false" → disables caching only for that screen.
  • history-enabled="false" → disables navigation history.

If not specified, both are enabled by default.

Transformation ​

Once validated, the content is transformed into a HtmlUssdTree

Code
rust
pub struct HtmlUssdTree {
    pub source: Html,
}

pub struct Html {
    pub attributes: HashMap<String, String>,
    pub head: Head,
    pub body: Body,
    pub history_enabled: bool,
    pub cache: bool
}

pub struct Head {
    pub attributes: HashMap<String, String>,
    pub title: Title,
}

pub struct Title {
    pub attributes: HashMap<String, String>,
    pub text: String,
}

pub struct Body {
    pub attributes: HashMap<String, String>,
    pub paragraphs: Vec<Paragraph>,
    pub content: BodyContent,
}

pub enum BodyContent {
    Form(Form),
    Links(Vec<Link>),
    Empty,
}

pub struct Form {
    pub attributes: HashMap<String, String>,
    pub input: Input,
    pub method: FormMethod,
    pub action: String,
}

pub enum FormMethod {
    Get,
    Post,
}

pub struct Input {
    pub attributes: HashMap<String, String>,
    pub input_type: InputType,
    pub name: String,
    pub placeholder: String,
}

pub enum InputType {
    Text,
    Number,
}

pub struct Paragraph {
    pub attributes: HashMap<String, String>,
    pub text: String,
}

pub struct Link {
    pub attributes: HashMap<String, String>,
    pub text: String,
    pub href: Href,
}

pub struct Href {
    pub url: String,
    pub href_type: HrefType,
}

pub enum HrefType {
    File,
    Server,
}

Errors ​

The validator can raise several detailed errors

Code
rust
pub enum ValidatorAndTransformerError {
    TagNotFound(Tag),
    FormAndLinkTogether,
    UnexpectedTag(Tag),
    TextExpected(Tag),
    UnexpectedChilds(TagElement, Vec<TagElement>),
    FormMustHaveOneInput,
    InvalidInputType(String),
    InvalidFormMethod(String),
    MissingFormAction,
    FormActionMustBeServerUrl,
    MissingFormMethod,
    EmptyBody,
    MissingInputType,
    MissingInputPlaceholder,
    MissingInputName,
    MutlipleForm,
    MissingHref,
    MissingTextInLink,
    MissingTextInTitle,
    InvalidHref(String),
    TextMustBeBeforeLinkOrForm,
}