/** @packageDocumentation Abstract Tag base class shared by all format-specific tag implementations. */
import { PropertyMap } from "./toolkit/propertyMap.js";
import type { VariantMap } from "./toolkit/variant.js";
/**
 * Abstract base class for all tag implementations. Subclasses provide
 * format-specific reading/writing of metadata fields.
 */
export declare abstract class Tag {
    /** Track title. An empty string indicates the field is not set. */
    abstract get title(): string;
    /** @param value The title to store, or an empty string to clear it. */
    abstract set title(value: string);
    /** Primary artist or performer. An empty string indicates the field is not set. */
    abstract get artist(): string;
    /** @param value The artist to store, or an empty string to clear it. */
    abstract set artist(value: string);
    /** Album name. An empty string indicates the field is not set. */
    abstract get album(): string;
    /** @param value The album name to store, or an empty string to clear it. */
    abstract set album(value: string);
    /** Free-form comment. An empty string indicates the field is not set. */
    abstract get comment(): string;
    /** @param value The comment to store, or an empty string to clear it. */
    abstract set comment(value: string);
    /** Genre string (may be an ID3v1 genre name or a custom string). An empty string indicates the field is not set. */
    abstract get genre(): string;
    /** @param value The genre to store, or an empty string to clear it. */
    abstract set genre(value: string);
    /** Release year. Returns `0` if not set. */
    abstract get year(): number;
    /** @param value The year to store, or `0` to clear it. */
    abstract set year(value: number);
    /** Track number within the album. Returns `0` if not set. */
    abstract get track(): number;
    /** @param value The track number to store, or `0` to clear it. */
    abstract set track(value: number);
    /** True when every field is empty / zero. */
    get isEmpty(): boolean;
    /**
     * Export the tag as a PropertyMap.
     *
     * @returns A {@link PropertyMap} populated with all non-empty tag fields.
     */
    properties(): PropertyMap;
    /**
     * Apply a PropertyMap to the tag, returning unhandled properties.
     *
     * @param properties The property map to apply.
     * @returns A {@link PropertyMap} containing any keys that this tag does not
     *          support.
     */
    setProperties(properties: PropertyMap): PropertyMap;
    /**
     * Remove properties that are not supported by this tag format.
     * The default implementation is a no-op; subclasses may override.
     *
     * @param _properties Keys of the properties to remove.
     */
    removeUnsupportedProperties(_properties: string[]): void;
    /**
     * Return the keys of all complex (non-string) properties stored in this tag.
     * Complex properties include embedded pictures and similar structured data.
     *
     * @returns An array of property key strings, or an empty array if none.
     */
    complexPropertyKeys(): string[];
    /**
     * Return all complex property values for the given key.
     *
     * @param _key The property key (e.g. `"PICTURE"`).
     * @returns An array of {@link VariantMap} objects, or an empty array if the
     *          key is not present.
     */
    complexProperties(_key: string): VariantMap[];
    /**
     * Set complex property values for the given key, replacing any existing values.
     *
     * @param _key   The property key (e.g. `"PICTURE"`).
     * @param _value The new values to store.
     * @returns `true` if the property was stored, `false` if the format does not
     *          support complex properties.
     */
    setComplexProperties(_key: string, _value: VariantMap[]): boolean;
    /**
     * Copy tag fields from `source` to `target`. When `overwrite` is false,
     * only empty fields in the target are filled in.
     *
     * @param source    The tag to copy values from.
     * @param target    The tag to copy values into.
     * @param overwrite When `true`, all fields in `target` are overwritten;
     *                  when `false`, only unset fields are populated.
     */
    static duplicate(source: Tag, target: Tag, overwrite: boolean): void;
    /**
     * Join an array of tag values with " / ".
     *
     * @param values The string values to join.
     * @returns A single string with values separated by `" / "`.
     */
    static joinTagValues(values: string[]): string;
}
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