import type { ApplicationNode } from "./javascriptApplicationGraphSchemas.js";
import type { JavaScriptApplicationGraph } from "./javascriptApplicationGraph.js";
import {
  projectedExportReturnShapesSchema,
  type JavaScriptExportShapeComparisonResult,
  type ProjectedExportReturnShapes,
} from "./javascriptExportShapeComparisonSchemas.js";
import { compareUnicodeCodePoints } from "../unicodeCodePointOrder.js";

type Shape = ProjectedExportReturnShapes["static_return_shapes"][number];
type SelectorResult = JavaScriptExportShapeComparisonResult["left"];
type SelectorBase = Omit<SelectorResult, "status" | "selected_node_id">;
type ReturnShapeSelection =
  | {
      readonly projection: ProjectedExportReturnShapes;
      readonly observationComplete: boolean;
    }
  | {
      readonly projection: null;
      readonly observationComplete: false;
      readonly reason: string;
    };

/** One authenticated graph and exact export selector. */
export interface JavaScriptExportShapeSideInput {
  readonly evidenceId: string;
  readonly graph: JavaScriptApplicationGraph;
  readonly modulePath: string;
  readonly exportName: string;
}

interface ExportCandidate {
  readonly node: ApplicationNode;
  readonly modulePath: string;
  readonly exportName: string;
  readonly trusted: boolean;
}

/** Exact selector result plus any admitted static return-shape projection. */
export type SelectedJavaScriptExport =
  | {
      readonly selection: Extract<SelectorResult, { status: "selected" }>;
      readonly projection: ProjectedExportReturnShapes;
      readonly observationComplete: boolean;
      readonly limitations: readonly [];
    }
  | {
      readonly selection: Exclude<SelectorResult, { status: "selected" }>;
      readonly projection: null;
      readonly observationComplete: false;
      readonly limitations: readonly string[];
    };

/** Complete return-shape inventory retained from an authenticated projection. */
export interface RetainedJavaScriptExportShapes {
  readonly shapes: readonly Shape[];
  readonly omitted: number;
}

/** Select one exact trusted export and its exact static return-shape observation. */
export const selectJavaScriptExport = (
  side: JavaScriptExportShapeSideInput,
): SelectedJavaScriptExport => {
  const candidates = exportCandidates(side.graph);
  const exact = candidates.filter(
    ({ modulePath, exportName }) =>
      modulePath === side.modulePath && exportName === side.exportName,
  );
  const matchingOneSelector = candidates.filter(
    ({ modulePath, exportName }) =>
      modulePath === side.modulePath || exportName === side.exportName,
  );
  const diagnosticPool =
    exact.length > 0
      ? exact
      : matchingOneSelector.length > 0
        ? matchingOneSelector
        : candidates;
  const base = selectorBase(side, diagnosticPool);
  if (exact.length === 0)
    return unresolvedSelection(
      base,
      { status: "missing", selected_node_id: null },
      [
        `No exact export binding matched ${side.modulePath}:${side.exportName}.`,
      ],
    );
  if (exact.length > 1)
    return unresolvedSelection(
      base,
      { status: "ambiguous", selected_node_id: null },
      [
        `Multiple exact export bindings matched ${side.modulePath}:${side.exportName}; none was selected.`,
      ],
    );
  const selected = exact[0];
  if (selected === undefined || !selected.trusted)
    return unresolvedSelection(
      base,
      {
        status: "unavailable",
        selected_node_id: selected?.node.node_id ?? null,
      },
      [
        "The exact export binding lacks the expected static-analysis authority.",
      ],
    );
  const returnShape = returnShapeFor(selected.node, side);
  if (returnShape.projection === null)
    return unresolvedSelection(
      base,
      { status: "unavailable", selected_node_id: selected.node.node_id },
      [returnShape.reason],
    );
  return {
    selection: {
      ...base,
      status: "selected",
      selected_node_id: selected.node.node_id,
    },
    projection: returnShape.projection,
    observationComplete: returnShape.observationComplete,
    limitations: [],
  };
};

/** Retain every authenticated variant with its explicit slot presence. */
export const retainJavaScriptExportShapes = (
  selection: SelectedJavaScriptExport,
): RetainedJavaScriptExportShapes => ({
  shapes: selection.projection?.static_return_shapes ?? [],
  omitted: 0,
});

const selectorBase = (
  side: JavaScriptExportShapeSideInput,
  candidates: readonly ExportCandidate[],
): SelectorBase => ({
  evidence_id: side.evidenceId,
  graph_id: side.graph.graph_id,
  requested_module_path: side.modulePath,
  requested_export_name: side.exportName,
  candidates: candidates.map((candidate) => ({
    node_id: candidate.node.node_id,
    module_path: candidate.modulePath,
    export_name: candidate.exportName,
    matches_requested_module: candidate.modulePath === side.modulePath,
    matches_requested_export: candidate.exportName === side.exportName,
  })),
  omitted_candidates: 0,
});

const unresolvedSelection = (
  base: SelectorBase,
  resolution:
    | {
        readonly status: "missing" | "ambiguous";
        readonly selected_node_id: null;
      }
    | {
        readonly status: "unavailable";
        readonly selected_node_id: string | null;
      },
  limitations: readonly string[],
): SelectedJavaScriptExport => ({
  selection: { ...base, ...resolution },
  projection: null,
  observationComplete: false,
  limitations,
});

const exportCandidates = (
  graph: JavaScriptApplicationGraph,
): ExportCandidate[] => {
  const candidates = new Map<string, ExportCandidate>();
  for (const node of graph.nodes) {
    for (const observation of node.observations) {
      const properties = observation.properties;
      if (properties.semantic_role !== "export-binding") continue;
      const modulePath = properties.module_path;
      const exportName = properties.exported_name;
      if (typeof modulePath !== "string" || typeof exportName !== "string")
        continue;
      const key = `${node.node_id}\0${modulePath}\0${exportName}`;
      const trusted =
        observation.evidence.authority === "ast-static-analysis" &&
        observation.evidence.state === "observed" &&
        observation.evidence.extractor.operation === "recover-module-export";
      const existing = candidates.get(key);
      candidates.set(key, {
        node,
        modulePath,
        exportName,
        trusted: trusted || existing?.trusted === true,
      });
    }
  }
  return [...candidates.values()].sort((left, right) =>
    compareUnicodeCodePoints(candidateKey(left), candidateKey(right)),
  );
};

const candidateKey = (candidate: ExportCandidate): string =>
  `${candidate.modulePath}\0${candidate.exportName}\0${candidate.node.node_id}`;

const returnShapeFor = (
  node: ApplicationNode,
  side: JavaScriptExportShapeSideInput,
): ReturnShapeSelection => {
  const roleObservations = node.observations.filter(
    ({ properties }) => properties.semantic_role === "export-return-shapes",
  );
  const parsed = roleObservations.map((observation) => ({
    observation,
    result: projectedExportReturnShapesSchema.safeParse(observation.properties),
  }));
  if (parsed.some(({ result }) => !result.success))
    return unavailableReturnShape(
      "The export return-shape observation is malformed.",
    );
  const matching = parsed.filter(
    ({ result }) =>
      result.success &&
      result.data.module_path === side.modulePath &&
      result.data.exported_name === side.exportName,
  );
  if (matching.length !== 1)
    return unavailableReturnShape(
      matching.length === 0
        ? "No exact static return-shape observation is available for the selected export."
        : "Multiple static return-shape observations matched the selected export.",
    );
  const selected = matching[0];
  if (selected === undefined || !selected.result.success)
    return unavailableReturnShape(
      "The selected return-shape observation could not be parsed.",
    );
  const { observation } = selected;
  const trusted =
    observation.evidence.authority === "static-relationship-inference" &&
    observation.evidence.state === "inferred" &&
    observation.evidence.extractor.operation === "recover-export-return-shapes";
  if (!trusted)
    return unavailableReturnShape(
      "The return-shape observation lacks the expected static-inference authority.",
    );
  return {
    projection: selected.result.data,
    observationComplete:
      observation.evidence.coverage.status === "complete" &&
      !observation.evidence.coverage.truncated,
  };
};

const unavailableReturnShape = (
  reason: string,
): Extract<ReturnShapeSelection, { readonly projection: null }> => ({
  projection: null,
  observationComplete: false,
  reason,
});