import { CachedAccess } from '../dataHelper.js';
import GridData from '../grid.js';
import { Instruction } from '../../index.js';
/**
 * Base class that all solvers must extend.
 */
export default abstract class Solver {
    /**
     * The unique identifier of the solver.
     *
     * This is also displayed to the user when selecting a solver.
     */
    abstract get id(): string;
    /**
     * The author(s) of the solver.
     */
    abstract get author(): string;
    /**
     * A short paragraph describing when the user should use this solver.
     */
    abstract get description(): string;
    /**
     * Whether the solver supports cancellation. If `true`, the solver must respond to the abort signal if it is provided.
     */
    abstract get supportsCancellation(): boolean;
    /**
     * Solve the given grid. The implementation should delegate long-running tasks to a worker thread and yield solutions
     * asynchronously.
     *
     * The solver must yield at least once, otherwise the UI will not update.
     *
     * If the solver finds no solution other than those already yielded, it should yield `null`. Yielding `null` on the
     * first iteration indicates that the grid is unsolvable. Yielding `null` on the second iteration indicates that the
     * solution is unique.
     *
     * If the solve finds the trivial solution of not filling any tiles, such as in the case of an underclued grid with
     * too many alternate solutions, it must yield the solution instead of yielding `null`.
     *
     * In the current UI implementation, the solver will be terminated after yielding `null`, or after 2 iterations if
     * `null` is never yielded. The solver should perform any necessary cleanup in the `finally` block of the generator.
     *
     * @param grid The grid to solve. The provided grid is guaranteed to be supported by the solver. Some tiles in the
     * grid may already be filled by the user. It is up to the solver to decide whether to respect these tiles or not.
     * @param abortSignal An optional signal that the solver should subscribe to in order to cancel the operation. If the
     * solver does not support cancellation, it should ignore this parameter.
     */
    abstract solve(grid: GridData, abortSignal?: AbortSignal): AsyncGenerator<GridData | null>;
    /**
     * Check if the solver supports the current browser environment. This method is called once when the user first clicks
     * the "Solve" button, and the result is cached for the duration of the editor session.
     *
     * The `solve` method will not be called if this method returns `false`, and a message will be displayed to the user
     * indicating that the solver is not supported.
     *
     * @returns A promise that resolves to `true` if the environment is supported, or `false` otherwise.
     */
    protected isEnvironmentSupported(): Promise<boolean>;
    readonly environmentCheck: CachedAccess<Promise<boolean>>;
    /**
     * Check if the solver supports the given instruction. This is used to render a small indication in the UI for each
     * instruction in the editor.
     *
     * @param instructionId The unique identifier of the instruction.
     */
    isInstructionSupported(_grid: GridData, instruction: Instruction): boolean;
    /**
     * Check if the solver supports the given grid. This methid is frequently called when the user changes the grid, and
     * the result is used to enable or disable the "Solve" button.
     *
     * The `solve` method will not be called if this method returns `false`, and a message will be displayed to the user
     * indicating that the grid is not supported by this solver.
     *
     * @param grid The grid to check.
     * @returns `true` if the grid is supported, or `false` otherwise.
     */
    isGridSupported(grid: GridData): boolean;
}