/**
 * Defines the {@link IPipelineStep} interface which specifies all data available for a single step.
 * @module
 */
import type { MergeableRecord } from '../../util/objects';
import type { InternalStepPrinter, IPipelineStepPrinter, StepOutputFormat } from '../print/print';
import type { FlowrConfig } from '../../config';
/**
 * This represents the format of a step processor which retrieves two things:
 *
 * 1) the input configuration as passed to the {@link PipelineExecutor}.
 * 2) the output produced by the previous steps.
 *
 * Please be aware, that if the respective information is available is not ensured by the type system but rather
 * ensured at runtime by your dependencies. If you want to make sure, that the information is present,
 * list all steps that you require as your {@link IPipelineStepOrder#dependencies|dependencies}, even if they would be
 * already covered transitively.
 */
export type StepProcessingFunction = (results: Record<string, unknown>, input: Record<string, unknown>, config: FlowrConfig) => unknown;
/**
 * This represents the required execution frequency of a step.
 */
export declare const enum PipelineStepStage {
    /** This step has to be executed once per file */
    OncePerFile = 0,
    /** This step has to be executed once per request (e.g., slice for a given variable) */
    OncePerRequest = 1
}
/** Name of a single {@link IPipelineStep|step} in a pipeline (branded to avoid type-mishaps). */
export type PipelineStepName = string & {
    __brand?: 'StepName';
};
/**
 * Contains the data to specify the order of {@link IPipelineStep|steps} in a pipeline.
 */
export interface IPipelineStepOrder<Name extends PipelineStepName = PipelineStepName> {
    /**
     * Name of the respective step, it does not have to be unique in general but only unique per-pipeline.
     * In other words, you can have multiple steps with a name like `parse` as long as you use only one of them in a given pipeline.
     * This is, because these names are required in the {@link IPipelineStep#dependencies} field to refer to other steps this one relies on.
     */
    readonly name: Name;
    /**
     * Give the names of other steps this one requires to be completed as a prerequisite (e.g., to gain access to their input).
     * Does not have to be transitive, this will be checked by the scheduler of the pipeline.
     */
    readonly dependencies: readonly PipelineStepName[];
    readonly executed: PipelineStepStage;
    /**
     * This is similar to {@link dependencies}, but is used to say that a given step _decorates_ another one.
     * This imbues two requirements:
     * The step must take the output of the decorated step as input, and produce the same output as the decorated step.
     *
     * If so, it is ensured that _this_ step is executed _after_ the step it decorates, but before any step that depends on it.
     */
    readonly decorates?: PipelineStepName;
}
/**
 * Defines what is to be known of a single step in a pipeline.
 * It wraps around a single {@link IPipelineStep#processor|processor} function, providing additional information.
 * Steps will be executed synchronously, in-sequence, based on their {@link IPipelineStep#dependencies|dependencies}.
 */
export interface IPipelineStep<Name extends PipelineStepName = PipelineStepName, Fn extends StepProcessingFunction = (...args: any[]) => any> extends MergeableRecord, IPipelineStepOrder<Name> {
    /** Human-readable name of this step */
    readonly humanReadableName: string;
    /** Human-readable description of this step */
    readonly description: string;
    /** The main processor that essentially performs the logic of this step */
    readonly processor: (...input: Parameters<Fn>) => ReturnType<Fn>;
    /** How to visualize the results of the respective step to the user? */
    readonly printer: {
        [K in StepOutputFormat]?: IPipelineStepPrinter<Fn, K, never[]>;
    } & {
        [StepOutputFormat.Internal]: InternalStepPrinter<Fn>;
    };
    /**
     * Input configuration required to perform the respective steps.
     * Required inputs of dependencies do not have to, but can be repeated.
     * <p>
     * Use the pattern `undefined as unknown as T` to indicate that the value is required but not provided.
     */
    readonly requiredInput: object;
}