import { z } from "zod";
import {
  nativeFunctionMatchingSchema,
  nativeFunctionMatchingContextSchema,
  nativeFunctionMatchSchema,
  nativeFunctionMatchMemberSchema,
  nativeMatchStateSchema,
  type NativeFunctionMatching,
} from "../native/functionMatching.js";
import { isImmutableJsonSnapshot } from "../immutableJson.js";
import { parseAnalysisViewResult } from "./analysisViewParent.js";
import { analysisViewInputError } from "./analysisViewErrors.js";
import {
  boundedViewMessages,
  completeWithinViewCoverage,
  pageViewCoverage,
} from "./analysisViewCoverage.js";
import { err, ok, type Result } from "../result.js";
import type { AnalysisError } from "../analysisErrorBase.js";
import type {
  AnalysisViewParent,
  AnalysisViewRequest,
  UnsignedAnalysisView,
} from "./analysisView.js";
import type { JsonValue } from "../jsonValue.js";

const matchRow = nativeFunctionMatchSchema.extend({
  left_count: z.number().int().nonnegative(),
  right_count: z.number().int().nonnegative(),
});
const functionRow = nativeFunctionMatchMemberSchema.extend({
  match_id: nativeFunctionMatchSchema.shape.match_id,
  state: nativeMatchStateSchema,
  side: z.enum(["left", "right"]),
});
const page = {
  kind: z.literal("function-matches"),
  states: z.array(nativeMatchStateSchema).optional(),
  match_ids: z.array(z.string()).optional(),
  function_ids: z.array(z.string()).optional(),
  offset: z.number().int().nonnegative().default(0),
  limit: z.number().int().positive().default(64),
};
export const nativeFunctionMatchingViewRequestSchema = z.discriminatedUnion(
  "collection",
  [
    z.strictObject({
      ...page,
      collection: z.literal("matches"),
      fields: z.array(matchRow.keyof()).optional(),
    }),
    z.strictObject({
      ...page,
      collection: z.literal("functions"),
      sides: z.array(z.enum(["left", "right"])).optional(),
      names: z.array(z.string()).optional(),
      fields: z.array(functionRow.keyof()).optional(),
    }),
  ],
);
export const nativeFunctionMatchingViewItemsSchema = z.union([
  z.array(
    matchRow.partial().required({
      match_id: true,
      state: true,
      left_count: true,
      right_count: true,
    }),
  ),
  z.array(
    functionRow.partial().required({
      function_id: true,
      match_id: true,
      state: true,
      side: true,
      inventory_evidence_id: true,
      source_index: true,
      address: true,
      evidence_links: true,
    }),
  ),
]);
export const nativeFunctionMatchingViewContextSchema =
  nativeFunctionMatchingContextSchema;
interface FunctionRow {
  readonly member: NativeFunctionMatching["matches"][number]["left"][number];
  readonly match_id: string;
  readonly state: NativeFunctionMatching["matches"][number]["state"];
  readonly side: "left" | "right";
}
interface Checked {
  readonly report: NativeFunctionMatching;
  functions?: readonly FunctionRow[];
  recent?: { readonly key: string; readonly rows: readonly number[] };
}
const checked = new WeakMap<object, Checked>();

type Request = z.output<typeof nativeFunctionMatchingViewRequestSchema>;
const checkedReport = (
  parent: AnalysisViewParent,
): Result<Checked, AnalysisError> => {
  const source = parent.normalizedResult;
  const reusable =
    typeof source === "object" &&
    source !== null &&
    parent.sealedResult === true &&
    isImmutableJsonSnapshot(source);
  const cached = reusable ? checked.get(source) : undefined;
  if (cached !== undefined) return ok(cached);
  const parsed = parseAnalysisViewResult(nativeFunctionMatchingSchema, parent);
  if (!parsed.ok) return parsed;
  const entry: Checked = {
    report: reusable ? (source as NativeFunctionMatching) : parsed.value,
  };
  if (reusable) checked.set(source, entry);
  return ok(entry);
};
const functionRows = (entry: Checked): readonly FunctionRow[] => {
  if (entry.functions !== undefined) return entry.functions;
  const functions: FunctionRow[] = [];
  for (const match of entry.report.matches)
    for (const side of ["left", "right"] as const)
      for (const member of match[side])
        functions.push({
          member,
          match_id: match.match_id,
          state: match.state,
          side,
        });
  entry.functions = functions;
  return functions;
};
const sharedContext = (
  parent: AnalysisViewParent,
  report: NativeFunctionMatching,
) => ({
  parent_evidence_id: parent.evidenceId,
  parent_operation: "match_native_functions" as const,
  parent_digest: parent.evidenceId.slice(3),
  artifact: null,
  limitations: boundedViewMessages(
    [...parent.limitations, ...report.limitations],
    parent.evidenceId,
    "limitations",
  ),
  unknowns: [
    "Unpaired observations and page exhaustion do not establish binary-wide function absence or behavioral equivalence.",
  ],
});
const selected = (values: readonly string[] | undefined) =>
  values === undefined ? undefined : new Set(values);
const filterRows = (entry: Checked, view: Request): readonly number[] => {
  const key = JSON.stringify([
    view.collection,
    view.states,
    view.match_ids,
    view.function_ids,
    view.collection === "functions" ? view.sides : null,
    view.collection === "functions" ? view.names : null,
  ]);
  if (entry.recent?.key === key) return entry.recent.rows;
  const states = selected(view.states),
    ids = selected(view.match_ids),
    functions = selected(view.function_ids),
    sides = selected(view.collection === "functions" ? view.sides : undefined),
    names = selected(view.collection === "functions" ? view.names : undefined);
  const matchesIdentity = (row: { state: string; match_id: string }): boolean =>
    (states === undefined || states.has(row.state)) &&
    (ids === undefined || ids.has(row.match_id));
  const rows: number[] = [];
  if (view.collection === "matches")
    entry.report.matches.forEach((row, index) => {
      if (
        matchesIdentity(row) &&
        (functions === undefined ||
          [...row.left, ...row.right].some((member) =>
            functions.has(member.function_id),
          ))
      )
        rows.push(index);
    });
  else
    functionRows(entry).forEach((row, index) => {
      if (
        matchesIdentity(row) &&
        (functions === undefined || functions.has(row.member.function_id)) &&
        (sides === undefined || sides.has(row.side)) &&
        (names === undefined || names.has(row.member.name))
      )
        rows.push(index);
    });
  // One recent selector and at most one row index per source occurrence.
  const count = entry.report.left.functions + entry.report.right.functions;
  if (key.length <= Math.max(256, count * 8)) entry.recent = { key, rows };
  return rows;
};
const selectedItems = (
  entry: Checked,
  view: Request,
  rows: readonly number[],
) => {
  const indices = rows.slice(view.offset, view.offset + view.limit);
  const defaults =
    view.collection === "matches"
      ? [
          "match_id",
          "state",
          "basis",
          "reason",
          "left_count",
          "right_count",
          "compare_functions_input",
        ]
      : [
          "function_id",
          "match_id",
          "state",
          "side",
          "inventory_evidence_id",
          "source_index",
          "address",
          "name",
          "body_sha256",
          "structural_candidate_sha256",
          "body_bytes",
          "dossier_evidence_id",
          "evidence_links",
        ];
  const fields = new Set<string>(view.fields ?? defaults);
  const columns = (row: Readonly<Record<string, JsonValue>>) =>
    Object.fromEntries([...fields].map((field) => [field, row[field]!]));
  if (view.collection === "matches")
    return indices.map((index) => {
      const row = entry.report.matches[index]!,
        left_count = row.left.length,
        right_count = row.right.length;
      return {
        ...columns({ ...row, left_count, right_count }),
        match_id: row.match_id,
        state: row.state,
        left_count,
        right_count,
      };
    });
  const functions = functionRows(entry);
  return indices.map((index) => {
    const row = functions[index]!,
      member = row.member;
    return {
      ...columns({
        ...member,
        match_id: row.match_id,
        state: row.state,
        side: row.side,
      }),
      function_id: member.function_id,
      match_id: row.match_id,
      state: row.state,
      side: row.side,
      inventory_evidence_id: member.inventory_evidence_id,
      source_index: member.source_index,
      address: member.address,
      evidence_links: member.evidence_links,
    };
  });
};

/** Query immutable matching facts without copying full alias groups into selected pages. */
export const projectNativeFunctionMatchingView = (
  parent: AnalysisViewParent,
  view: AnalysisViewRequest,
): Result<UnsignedAnalysisView, AnalysisError> => {
  if (view.kind !== "summary" && view.kind !== "function-matches")
    return err(
      analysisViewInputError([
        {
          path: ["view"],
          reason: "invalid_value",
          message:
            "Native matching supports summary and function-matches pages",
        },
      ]),
    );
  const parsed = checkedReport(parent);
  if (!parsed.ok) return parsed;
  const entry = parsed.value;
  const {
    matches: _matches,
    limitations: _limitations,
    ...context
  } = entry.report;
  const shared = sharedContext(parent, entry.report);
  if (view.kind === "summary")
    return ok({
      kind: "summary",
      view,
      ...shared,
      summary: context,
      coverage: completeWithinViewCoverage(1, 1),
    });
  const rows = filterRows(entry, view),
    items = selectedItems(entry, view, rows);
  return ok({
    kind: "function-matches",
    view,
    ...shared,
    ...context,
    items,
    coverage: pageViewCoverage(view.offset, items.length, rows.length),
  });
};