declaration.ts

import { LogLevel } from "../loggers";

/**
 * An interface describing all TypeDoc specific options. Generated from a
 * map which contains more information about each option for better types when
 * defining said options.
 */
export type TypeDocOptions = {
    [K in keyof TypeDocOptionMap]: TypeDocOptionMap[K] extends Record<
        string,
        infer U
    >
        ? Exclude<U, string> | keyof TypeDocOptionMap[K]
        : TypeDocOptionMap[K];
};

/**
 * Describes all TypeDoc specific options as returned by {@link Options.getValue}, this is
 * slightly more restrictive than the {@link TypeDocOptions} since it does not allow both
 * keys and values for mapped option types.
 */
export type TypeDocOptionValues = {
    [K in keyof TypeDocOptionMap]: TypeDocOptionMap[K] extends Record<
        string,
        infer U
    >
        ? Exclude<U, string>
        : TypeDocOptionMap[K];
};

/**
 * Describes all TypeDoc options. Used internally to provide better types when fetching options.
 * External consumers should likely use [[TypeDocOptions]] instead.
 */
export interface TypeDocOptionMap {
    options: string;
    tsconfig: string;

    entryPoints: string[];
    exclude: string[];
    externalPattern: string[];
    excludeExternals: boolean;
    excludePrivate: boolean;
    excludeProtected: boolean;
    excludeNotDocumented: boolean;
    excludeInternal: boolean;
    disableSources: boolean;
    includes: string;
    media: string;

    emit: boolean;
    watch: boolean;
    preserveWatchOutput: boolean;

    out: string;
    json: string;

    theme: string;
    name: string;
    includeVersion: boolean;
    excludeTags: string[];
    readme: string;
    defaultCategory: string;
    categoryOrder: string[];
    categorizeByGroup: boolean;
    gitRevision: string;
    gitRemote: string;
    gaID: string;
    gaSite: string;
    hideGenerator: boolean;
    toc: string[];
    disableOutputCheck: boolean;

    help: boolean;
    version: boolean;
    showConfig: boolean;
    plugin: string[];
    logger: unknown; // string | Function
    logLevel: typeof LogLevel;
    listInvalidSymbolLinks: boolean;
    markedOptions: unknown;

    highlightTheme: string;
}

/**
 * Converts a given TypeDoc option key to the type of the declaration expected.
 */
export type KeyToDeclaration<
    K extends keyof TypeDocOptionMap
> = TypeDocOptionMap[K] extends boolean
    ? BooleanDeclarationOption
    : TypeDocOptionMap[K] extends string
    ? StringDeclarationOption
    : TypeDocOptionMap[K] extends number
    ? NumberDeclarationOption
    : TypeDocOptionMap[K] extends string[]
    ? ArrayDeclarationOption
    : unknown extends TypeDocOptionMap[K]
    ? MixedDeclarationOption
    : TypeDocOptionMap[K] extends Record<string | number, infer U>
    ? MapDeclarationOption<U>
    : never;

export enum ParameterHint {
    File,
    Directory,
}

export enum ParameterType {
    String,
    Number,
    Boolean,
    Map,
    Mixed,
    Array,
}

export interface DeclarationOptionBase {
    /**
     * The option name.
     */
    name: string;

    /**
     * The help text to be displayed to the user when --help is passed.
     */
    help: string;

    /**
     * The parameter type, used to convert user configuration values into the expected type.
     * If not set, the type will be a string.
     */
    type?: ParameterType;
}

export interface StringDeclarationOption extends DeclarationOptionBase {
    type?: ParameterType.String;

    /**
     * If not specified defaults to the empty string.
     */
    defaultValue?: string;

    /**
     * An optional hint for the type of input expected, will be displayed in the help output.
     */
    hint?: ParameterHint;

    /**
     * An optional validation function that validates a potential value of this option.
     * The function must throw an Error if the validation fails and should do nothing otherwise.
     */
    validate?: (value: string) => void;
}

export interface NumberDeclarationOption extends DeclarationOptionBase {
    type: ParameterType.Number;

    /**
     * Lowest possible value.
     */
    minValue?: number;

    /**
     * Highest possible value.
     */
    maxValue?: number;

    /**
     * If not specified defaults to 0.
     */
    defaultValue?: number;

    /**
     * An optional validation function that validates a potential value of this option.
     * The function must throw an Error if the validation fails and should do nothing otherwise.
     */
    validate?: (value: number) => void;
}

export interface BooleanDeclarationOption extends DeclarationOptionBase {
    type: ParameterType.Boolean;

    /**
     * If not specified defaults to false.
     */
    defaultValue?: boolean;
}

export interface ArrayDeclarationOption extends DeclarationOptionBase {
    type: ParameterType.Array;

    /**
     * If not specified defaults to an empty array.
     */
    defaultValue?: string[];

    /**
     * An optional validation function that validates a potential value of this option.
     * The function must throw an Error if the validation fails and should do nothing otherwise.
     */
    validate?: (value: string[]) => void;
}

export interface MixedDeclarationOption extends DeclarationOptionBase {
    type: ParameterType.Mixed;

    /**
     * If not specified defaults to undefined.
     */
    defaultValue?: unknown;

    /**
     * An optional validation function that validates a potential value of this option.
     * The function must throw an Error if the validation fails and should do nothing otherwise.
     */
    validate?: (value: unknown) => void;
}

export interface MapDeclarationOption<T> extends DeclarationOptionBase {
    type: ParameterType.Map;

    /**
     * Maps a given value to the option type. The map type may be a TypeScript enum.
     * In that case, when generating an error message for a mismatched key, the numeric
     * keys will not be listed.
     */
    map: Map<string, T> | Record<string | number, T>;

    /**
     * Unlike the rest of the option types, there is no sensible generic default for mapped option types.
     * The default value for a mapped type must be specified.
     */
    defaultValue: T;

    /**
     * Optional override for the error reported when an invalid key is provided.
     */
    mapError?: string;
}

export type DeclarationOption =
    | StringDeclarationOption
    | NumberDeclarationOption
    | BooleanDeclarationOption
    | MixedDeclarationOption
    | MapDeclarationOption<unknown>
    | ArrayDeclarationOption;

export type DeclarationOptionToOptionType<
    T extends DeclarationOption
> = T extends StringDeclarationOption
    ? string
    : T extends NumberDeclarationOption
    ? number
    : T extends BooleanDeclarationOption
    ? boolean
    : T extends MixedDeclarationOption
    ? unknown
    : T extends MapDeclarationOption<infer U>
    ? U
    : T extends ArrayDeclarationOption
    ? string[]
    : never;

/**
 * The default conversion function used by the Options container. Readers may
 * re-use this conversion function or implement their own. The arguments reader
 * implements its own since 'false' should not be converted to true for a boolean option.
 * @param value The value to convert.
 * @param option The option for which the value should be converted.
 * @returns The result of the conversion. Might be the value or an error.
 */
export function convert<T extends DeclarationOption>(
    value: unknown,
    option: T
): DeclarationOptionToOptionType<T>;
export function convert<T>(value: unknown, option: MapDeclarationOption<T>): T;
export function convert(value: unknown, option: DeclarationOption): unknown {
    switch (option.type) {
        case undefined:
        case ParameterType.String: {
            const stringValue = value == null ? "" : String(value);
            if (option.validate) {
                option.validate(stringValue);
            }
            return stringValue;
        }
        case ParameterType.Number: {
            const numValue = parseInt(String(value), 10) || 0;
            if (
                !valueIsWithinBounds(numValue, option.minValue, option.maxValue)
            ) {
                throw new Error(
                    getBoundsError(
                        option.name,
                        option.minValue,
                        option.maxValue
                    )
                );
            }
            if (option.validate) {
                option.validate(numValue);
            }
            return numValue;
        }

        case ParameterType.Boolean:
            return Boolean(value);

        case ParameterType.Array: {
            let strArrValue = new Array<string>();
            if (Array.isArray(value)) {
                strArrValue = value.map(String);
            } else if (typeof value === "string") {
                strArrValue = value.split(",");
            }
            if (option.validate) {
                option.validate(strArrValue);
            }
            return strArrValue;
        }
        case ParameterType.Map: {
            const key = String(value).toLowerCase();
            if (option.map instanceof Map) {
                if (option.map.has(key)) {
                    return option.map.get(key);
                } else if ([...option.map.values()].includes(value)) {
                    return value;
                }
            } else if (key in option.map) {
                return option.map[key];
            } else if (Object.values(option.map).includes(value)) {
                return value;
            }
            throw new Error(
                option.mapError ?? getMapError(option.map, option.name)
            );
        }
        case ParameterType.Mixed:
            if (option.validate) {
                option.validate(value);
            }
            return value;
    }
}

/**
 * Returns an error message for a map option, indicating that a given value was not one of the values within the map.
 * @param map The values for the option.
 * @param name The name of the option.
 * @returns The error message.
 */
function getMapError(
    map: MapDeclarationOption<unknown>["map"],
    name: string
): string {
    let keys = map instanceof Map ? [...map.keys()] : Object.keys(map);
    const getString = (key: string) =>
        String(map instanceof Map ? map.get(key) : map[key]);

    // If the map is a TS numeric enum we need to filter out the numeric keys.
    // TS numeric enums have the property that every key maps to a value, which maps back to that key.
    if (
        !(map instanceof Map) &&
        keys.every((key) => getString(getString(key)) === key)
    ) {
        // This works because TS enum keys may not be numeric.
        keys = keys.filter((key) => Number.isNaN(parseInt(key, 10)));
    }

    return `${name} must be one of ${keys.join(", ")}`;
}

/**
 * Returns an error message for a value that is out of bounds of the given min and/or max values.
 * @param name The name of the thing the value represents.
 * @param minValue The lower bound of the range of allowed values.
 * @param maxValue The upper bound of the range of allowed values.
 * @returns The error message.
 */
function getBoundsError(
    name: string,
    minValue?: number,
    maxValue?: number
): string {
    if (isFiniteNumber(minValue) && isFiniteNumber(maxValue)) {
        return `${name} must be between ${minValue} and ${maxValue}`;
    } else if (isFiniteNumber(minValue)) {
        return `${name} must be >= ${minValue}`;
    } else if (isFiniteNumber(maxValue)) {
        return `${name} must be <= ${maxValue}`;
    }
    throw new Error("Unreachable");
}

/**
 * Checks if the given value is a finite number.
 * @param value The value being checked.
 * @returns True, if the value is a finite number, otherwise false.
 */
function isFiniteNumber(value: unknown): value is number {
    return Number.isFinite(value);
}

/**
 * Checks if a value is between the bounds of the given min and/or max values.
 * @param value The value being checked.
 * @param minValue The lower bound of the range of allowed values.
 * @param maxValue The upper bound of the range of allowed values.
 * @returns True, if the value is within the given bounds, otherwise false.
 */
function valueIsWithinBounds(
    value: number,
    minValue?: number,
    maxValue?: number
): boolean {
    if (isFiniteNumber(minValue) && isFiniteNumber(maxValue)) {
        return minValue <= value && value <= maxValue;
    } else if (isFiniteNumber(minValue)) {
        return minValue <= value;
    } else if (isFiniteNumber(maxValue)) {
        return value <= maxValue;
    } else {
        return true;
    }
}