// construct-render-4.ts

import { $RENDER } from "../../../core/constants.js";
import { make_string } from "../../../core/stringify.js";
import { serialize_hson } from "../serializers/serialize-hson.js";
import { serialize_json } from "../serializers/serialize-json.js";
import type {
  TransformFrameRender,
  TransformHsonSerialize,
  TransformJsonValue,
  TransformOutputRenderFormat,
  TransformSerialize,
} from "../transform.types.js";
import { ROOT_TAG } from "../../../core/constants.js";
import { detach_hson_root_value } from "../utils/node-utils/detach-hson-root-value.js";
import { admit_projected_value } from "../../../core/projected-value-admission.js";
import { materialize_projected_value } from "../../../core/projected-value-materialization.js";
import { sha256_text } from "../sha256.js";

/**
 * Hson pipeline, stage 4: finalize the selected output.
 *
 * This is the terminal stage of the transformer chain. The incoming context
 * already contains:
 * - the chosen render format,
 * - the materialized representation on the frame,
 * - and any formatting options applied in stage 3.
 *
 * This stage exposes the final data operations:
 * - `serialize()` → string output in the chosen format
 * - JSON `value()` → the in-memory JsonValue projection
 *
 * Hson and HTML use serialization-only finalizers. Canonical graph access is
 * handled uniformly by the source constructor's `toNode()` terminal.
 *
 * LiveTree creation is not part of this final render stage.
 *
 * @param context - Render context containing the frame and chosen format.
 * @returns Stage-4 terminal render API.
 */
function serialize_render(context: TransformFrameRender<TransformOutputRenderFormat>): string {
  const { frame, output } = context;

  switch (output) {
    case $RENDER.JSON:
      if (frame.json === undefined) throw new Error("serialize(): frame is missing JSON data");
      // Text emission must retain the canonical graph's property sequence.
      // The public `.value()` projection is an ordinary JavaScript value and
      // cannot carry source order for integer-index property names.
      return serialize_json(frame.node);
    case $RENDER.HTML:
      if (frame.html == null) throw new Error("serialize(): frame is missing HTML data");
      return typeof frame.html === "string" ? frame.html : make_string(frame.html);
  }
}

/** Hson output is serialization-only; graph access belongs to source `.toNode()`. */
export function construct_hson_render_4(
  context: TransformFrameRender<(typeof $RENDER)["Hson"]>,
): TransformHsonSerialize {
  const serialize = () => {
    const origin = context.frame.meta?.origin;
    const parserOwnsRoot = origin === "json" || origin === "html";
    const node = parserOwnsRoot && context.frame.node.$_tag === ROOT_TAG
      ? detach_hson_root_value(context.frame.node)
      : context.frame.node;
    return serialize_hson(node, {
      noBreak: context.frame.options?.noBreak ?? false,
      noQuid: context.frame.options?.noQuid ?? false,
    });
  };
  return {
    serialize,
    sha256: () => sha256_text(serialize()),
  };
}

export function construct_html_render_4(
  context: TransformFrameRender<(typeof $RENDER)["HTML"]>,
): TransformSerialize {
  const serialize = () => serialize_render(context);
  return {
    serialize,
    sha256: () => sha256_text(serialize()),
  };
}

export function construct_json_render_4(
  context: TransformFrameRender<(typeof $RENDER)["JSON"]>,
): TransformJsonValue {
  const serialize = () => serialize_render(context);
  return {
    serialize,
    sha256: () => sha256_text(serialize()),
    value: () => {
      if (context.frame.json === undefined) {
        throw new Error("value(): frame is missing JSON data");
      }
      return materialize_projected_value(admit_projected_value(context.frame.json));
    },
  };
}