rea/src/domain/javascript/javascriptExportShapeComparison.ts

import { uniqueSorted } from "../canonicalOrdering.js";
import { compareUnicodeCodePoints } from "../unicodeCodePointOrder.js";
import {
  canonicalExportShapeValue,
  digestExportShapeValue,
} from "./javascriptExportShapeComparisonIdentity.js";
import {
  javaScriptExportShapeComparisonResultSchema,
  type JavaScriptExportShapeComparisonChange,
  type JavaScriptExportShapeComparisonResult,
} from "./javascriptExportShapeComparisonSchemas.js";
import {
  retainJavaScriptExportShapes,
  selectJavaScriptExport,
  type JavaScriptExportShapeSideInput,
  type RetainedJavaScriptExportShapes,
  type SelectedJavaScriptExport,
} from "./javascriptExportShapeSelection.js";
import {
  buildJavaScriptExportShapeChanges,
  buildJavaScriptExportShapeInventories,
  hasPartialJavaScriptExportPropertyCoverage,
  pairJavaScriptExportShapeVariants,
  type JavaScriptExportShapePairing,
} from "./javascriptExportShapeVariants.js";

/** Pure comparison input after application-layer Evidence authentication. */
export interface JavaScriptExportShapeComparisonProjectionInput {
  readonly left: JavaScriptExportShapeSideInput;
  readonly right: JavaScriptExportShapeSideInput;
}

/** Compare exact selected export return shapes without executing JavaScript. */
export const compareJavaScriptExportShapes = (
  input: JavaScriptExportShapeComparisonProjectionInput,
): JavaScriptExportShapeComparisonResult => {
  const left = selectJavaScriptExport(input.left);
  const right = selectJavaScriptExport(input.right);
  const leftRetained = retainJavaScriptExportShapes(left);
  const rightRetained = retainJavaScriptExportShapes(right);
  const pairing = pairJavaScriptExportShapeVariants(
    leftRetained.shapes,
    rightRetained.shapes,
  );
  const evidenceLinks = evidencePair(
    input.left.evidenceId,
    input.right.evidenceId,
  );
  const allChanges = sortChanges(
    buildJavaScriptExportShapeChanges({
      leftSelection: left,
      rightSelection: right,
      pairing,
      leftShapes: leftRetained.shapes,
      rightShapes: rightRetained.shapes,
      evidenceLinks,
    }),
  );
  const changes = allChanges;
  const omittedChanges = 0;
  const propertyInventories = buildJavaScriptExportShapeInventories({
    pairing,
    leftShapes: leftRetained.shapes,
    rightShapes: rightRetained.shapes,
  });
  const coverage = comparisonCoverage({
    input,
    left,
    right,
    leftRetained,
    rightRetained,
    pairing,
    allChanges,
    omittedChanges,
  });
  const limitations = comparisonLimitations(left, right, coverage.status);
  const semantic = {
    left: left.selection,
    right: right.selection,
    property_inventories: propertyInventories,
    summary: summarize(allChanges),
    changes,
    coverage,
    evidence_links: evidenceLinks,
    limitations,
  };
  return javaScriptExportShapeComparisonResultSchema.parse({
    ...semantic,
    comparison_id: `jesc_${digestExportShapeValue(semantic)}`,
  });
};

const sortChanges = (
  changes: readonly JavaScriptExportShapeComparisonChange[],
): JavaScriptExportShapeComparisonChange[] =>
  changes
    .map((change, index) => ({
      change,
      index,
      sortKey: canonicalExportShapeValue({
        discriminant: change.discriminant,
        path: change.path,
        status: change.status,
        left_source_range: change.left_source_range,
        right_source_range: change.right_source_range,
        change_id: change.change_id,
      }),
    }))
    .sort(
      (left, right) =>
        compareUnicodeCodePoints(left.sortKey, right.sortKey) ||
        left.index - right.index,
    )
    .map(({ change }) => change);

interface CoverageInput {
  readonly input: JavaScriptExportShapeComparisonProjectionInput;
  readonly left: SelectedJavaScriptExport;
  readonly right: SelectedJavaScriptExport;
  readonly leftRetained: RetainedJavaScriptExportShapes;
  readonly rightRetained: RetainedJavaScriptExportShapes;
  readonly pairing: JavaScriptExportShapePairing;
  readonly allChanges: readonly JavaScriptExportShapeComparisonChange[];
  readonly omittedChanges: number;
}

const comparisonCoverage = (context: CoverageInput) => {
  const leftSource = context.left.projection?.return_shape_coverage;
  const rightSource = context.right.projection?.return_shape_coverage;
  const omittedCandidates =
    context.left.selection.omitted_candidates +
    context.right.selection.omitted_candidates;
  const truncated = comparisonTruncated(context, omittedCandidates);
  const partial = comparisonPartial(context);
  return {
    status: truncated
      ? ("truncated" as const)
      : partial
        ? ("partial" as const)
        : ("complete-within-inputs" as const),
    left_graph_status: context.input.left.graph.coverage.status,
    right_graph_status: context.input.right.graph.coverage.status,
    paired_variants: context.pairing.pairs.length,
    unpaired_left_variants: context.pairing.unpairedLeft.length,
    unpaired_right_variants: context.pairing.unpairedRight.length,
    omitted_left_variants: context.leftRetained.omitted,
    omitted_right_variants: context.rightRetained.omitted,
    left_source_omitted_variants: leftSource?.omitted_return_sites ?? null,
    right_source_omitted_variants: rightSource?.omitted_return_sites ?? null,
    left_omitted_fields: leftSource?.omitted_fields ?? 0,
    right_omitted_fields: rightSource?.omitted_fields ?? 0,
    left_omitted_property_coverage: leftSource?.omitted_property_coverage ?? 0,
    right_omitted_property_coverage:
      rightSource?.omitted_property_coverage ?? 0,
    omitted_candidates: omittedCandidates,
    omitted_changes: context.omittedChanges,
  };
};

const comparisonTruncated = (
  context: CoverageInput,
  omittedCandidates: number,
): boolean =>
  context.leftRetained.omitted > 0 ||
  context.rightRetained.omitted > 0 ||
  omittedCandidates > 0 ||
  context.omittedChanges > 0 ||
  sourceProjectionTruncated(context.left) ||
  sourceProjectionTruncated(context.right);

const sourceProjectionTruncated = (
  selection: SelectedJavaScriptExport,
): boolean => {
  const coverage = selection.projection?.return_shape_coverage;
  if (coverage === undefined) return false;
  return (
    coverage.status === "truncated" ||
    coverage.omitted_fields > 0 ||
    coverage.omitted_property_coverage > 0 ||
    coverage.projection_complete === false
  );
};

const comparisonPartial = (context: CoverageInput): boolean =>
  selectionPartial(context.left) ||
  selectionPartial(context.right) ||
  context.input.left.graph.coverage.status !== "complete" ||
  context.input.right.graph.coverage.status !== "complete" ||
  hasPartialJavaScriptExportPropertyCoverage(context.leftRetained.shapes) ||
  hasPartialJavaScriptExportPropertyCoverage(context.rightRetained.shapes) ||
  context.pairing.unpairedLeft.length > 0 ||
  context.pairing.unpairedRight.length > 0 ||
  context.allChanges.some(({ status }) => status === "unknown");

const selectionPartial = (selection: SelectedJavaScriptExport): boolean => {
  const coverage = selection.projection?.return_shape_coverage;
  return (
    selection.selection.status !== "selected" ||
    !selection.observationComplete ||
    coverage?.status !== "complete" ||
    coverage.projection_complete !== true
  );
};

const comparisonLimitations = (
  left: SelectedJavaScriptExport,
  right: SelectedJavaScriptExport,
  status: "complete-within-inputs" | "partial" | "truncated",
): string[] =>
  uniqueSorted([
    "Return shapes are inferred from inert syntax and do not prove runtime behavior.",
    "Return variants are paired only by unique exact literal discriminants, never by source order.",
    "Dynamic values, incomplete object coverage, and ambiguous variants remain unknown.",
    "This static comparison cannot establish runtime semantics; run behavioral probes directly against the relevant application versions when that evidence is required.",
    ...left.limitations,
    ...right.limitations,
    ...(status === "truncated"
      ? [
          "Comparison output or source return-shape recovery reached an explicit limit.",
        ]
      : []),
    ...(status === "partial"
      ? [
          "At least one selector, graph, return shape, or property boundary is incomplete.",
        ]
      : []),
  ]);

const summarize = (
  changes: readonly JavaScriptExportShapeComparisonChange[],
): JavaScriptExportShapeComparisonResult["summary"] => ({
  added: countStatus(changes, "added"),
  removed: countStatus(changes, "removed"),
  changed: countStatus(changes, "changed"),
  unknown: countStatus(changes, "unknown"),
});

const countStatus = (
  changes: readonly JavaScriptExportShapeComparisonChange[],
  status: JavaScriptExportShapeComparisonChange["status"],
): number => changes.filter((change) => change.status === status).length;

const evidencePair = (left: string, right: string): [string, string] => [
  left,
  right,
];