/** Any selector token produced by the parser. */
export type Selector =
    | PseudoSelector
    | PseudoElement
    | AttributeSelector
    | TagSelector
    | UniversalSelector
    | Traversal;

/** Discriminants for selector token kinds. */
export enum SelectorType {
    Attribute = "attribute",
    Pseudo = "pseudo",
    PseudoElement = "pseudo-element",
    Tag = "tag",
    Universal = "universal",

    // Traversals
    Adjacent = "adjacent",
    Child = "child",
    Descendant = "descendant",
    Parent = "parent",
    Sibling = "sibling",
    ColumnCombinator = "column-combinator",
}

/**
 * Modes for ignore case.
 *
 * This could be updated to an enum, and the object is
 * the current stand-in that will allow code to be updated
 * without big changes.
 */
export const IgnoreCaseMode = {
    Unknown: null,
    QuirksMode: "quirks",
    IgnoreCase: true,
    CaseSensitive: false,
} as const;

/** `[attr]`-style selector token. */
export interface AttributeSelector {
    type: SelectorType.Attribute;
    name: string;
    action: AttributeAction;
    value: string;
    ignoreCase: "quirks" | boolean | null;
    namespace: string | null;
}

/** Payload used by pseudo selectors. */
export type DataType = Selector[][] | null | string;

/** `:pseudo(...)` selector token. */
export interface PseudoSelector {
    type: SelectorType.Pseudo;
    name: string;
    data: DataType;
}

/** `::pseudo-element` selector token. */
export interface PseudoElement {
    type: SelectorType.PseudoElement;
    name: string;
    data: string | null;
}

/** Tag-name selector token. */
export interface TagSelector {
    type: SelectorType.Tag;
    name: string;
    namespace: string | null;
}

/** Universal selector token (`*`). */
export interface UniversalSelector {
    type: SelectorType.Universal;
    namespace: string | null;
}

/** Combinator/traversal selector token. */
export interface Traversal {
    type: TraversalType;
}

/** Operators available for attribute selectors. */
export enum AttributeAction {
    Any = "any",
    Element = "element",
    End = "end",
    Equals = "equals",
    Exists = "exists",
    Hyphen = "hyphen",
    Not = "not",
    Start = "start",
}

/** Union of traversal/combinator selector types. */
export type TraversalType =
    | SelectorType.Adjacent
    | SelectorType.Child
    | SelectorType.Descendant
    | SelectorType.Parent
    | SelectorType.Sibling
    | SelectorType.ColumnCombinator;