rea/src/domain/providerSelectionError.ts

import type { JsonValue } from "./jsonValue.js";
import {
  AnalysisError,
  type AnalysisCapturedOutput,
} from "./analysisErrorBase.js";

/** Stable failure classes for target-bound deep-provider selection. */
export type ProviderSelectionFailureReason =
  | "unknown_provider"
  | "provider_unavailable"
  | "target_unsupported"
  | "ambiguous"
  | "invalid_options";

/** One actionable candidate rejection retained in caller diagnostics. */
export interface ProviderSelectionRejection {
  readonly providerId: string;
  readonly code: string;
  readonly reason: string;
  readonly diagnostics: Readonly<Record<string, JsonValue>>;
}

/** Complete typed context for one failed deep-provider selection. */
export interface ProviderSelectionErrorOptions {
  readonly capturedOutput?: AnalysisCapturedOutput;
  readonly operation?: string;
  readonly reason: ProviderSelectionFailureReason;
  readonly requestedProviderId: string;
  readonly candidateIds: readonly string[];
  readonly rejections?: readonly ProviderSelectionRejection[];
}

/** No configured provider can satisfy a requested operation or target binding. */
export class ProviderSelectionError extends AnalysisError {
  readonly _tag = "ProviderSelectionError";
  readonly operation: string;
  readonly reason: ProviderSelectionFailureReason;
  readonly requestedProviderId: string;
  readonly candidateIds: readonly string[];
  readonly rejections: readonly ProviderSelectionRejection[];
  override readonly userMessage: string;

  constructor(options: ProviderSelectionErrorOptions) {
    const operation = options.operation ?? "open_binary";
    super(
      providerSelectionDiagnostic(options),
      options.capturedOutput === undefined
        ? undefined
        : { capturedOutput: options.capturedOutput },
    );
    this.operation = operation;
    this.reason = options.reason;
    this.requestedProviderId = options.requestedProviderId;
    this.candidateIds = [...options.candidateIds];
    this.rejections = [...(options.rejections ?? [])].map((rejection) => ({
      ...rejection,
      diagnostics: structuredClone(rejection.diagnostics),
    }));
    this.userMessage = providerSelectionUserMessage(options);
  }
}

const providerSelectionDiagnostic = (
  options: ProviderSelectionErrorOptions,
): string => {
  const candidates =
    options.candidateIds.length === 0
      ? "none"
      : options.candidateIds.join(", ");
  return `Analysis provider selection failed (${options.reason}) for ${options.requestedProviderId}; candidates: ${candidates}`;
};

const providerSelectionUserMessage = (
  options: ProviderSelectionErrorOptions,
): string => {
  switch (options.reason) {
    case "ambiguous":
      return "Multiple analysis providers support this target. Choose one with provider_id, --provider, or REA_ANALYSIS_PROVIDER.";
    case "unknown_provider":
      return `The requested analysis provider is unknown. Choose one of: ${options.candidateIds.join(", ") || "no configured providers"}.`;
    case "provider_unavailable":
      return "The selected analysis provider is unavailable. Review the reported local diagnostics or run `rea doctor`, then retry.";
    case "target_unsupported":
      return "The selected analysis provider does not support this target. Choose another provider or open a supported extracted binary.";
    case "invalid_options":
      return "The analysis provider selection or open options are invalid. Correct them and try again.";
  }
};