import type { Projection } from "./json-projection.ts";
import { isUnknownArray, recordAt, type UnknownRecord } from "./unknown.ts";

function resultField(path: readonly (string | number)[]): boolean {
  if (path.length === 2) {
    return path[0] === "result";
  }
  if (path.length === 3) {
    return path[0] === "results" && typeof path[1] === "number";
  }
  return (
    path.length === 4 &&
    path[0] === "children" &&
    typeof path[1] === "number" &&
    path[2] === "result"
  );
}
function summaryField(path: readonly (string | number)[]): boolean {
  return (
    (path.length === 1 && path[0] === "summary") ||
    (path.length === 3 &&
      path[0] === "children" &&
      typeof path[1] === "number" &&
      path[2] === "summary")
  );
}
export const ownerProjection: Projection = (path) => {
  const field = path.at(-1);
  if (resultField(path)) {
    if (field === "messages") {
      return false;
    }
    if (["output", "finalOutput", "initialOutput", "rawOutput"].includes(String(field))) {
      return 8192;
    }
  }
  return summaryField(path) ? 8192 : true;
};
const entryFields = new Set([
  "type",
  "id",
  "parentId",
  "timestamp",
  "version",
  "cwd",
  "parentSession",
  "checkpoint",
  "provider",
  "model",
  "modelId",
  "thinkingLevel",
  "customType",
  "usage",
  "firstKeptEntryId",
  "fromId",
]);
const messageFields = new Set([
  "role",
  "provider",
  "model",
  "responseModel",
  "thinkingLevel",
  "usage",
  "stopReason",
  "errorMessage",
  "timestamp",
  "toolCallId",
  "toolName",
  "isError",
  "content",
  "command",
  "output",
  "exitCode",
  "cancelled",
]);
function argumentCount(root: UnknownRecord | undefined, index: number): number {
  const content = recordAt(root, "message")?.content;
  const part = isUnknownArray(content) ? content[index] : undefined;
  return Object.keys(recordAt(part, "arguments") ?? {}).length;
}
function contentProjection(
  path: readonly (string | number)[],
  root?: UnknownRecord,
): boolean | number {
  if (path.length <= 3) {
    return 2048;
  }
  if (path[3] !== "arguments") {
    return ["type", "id", "name", "text", "thinking", "mimeType"].includes(String(path[3]))
      ? 2048
      : false;
  }
  if (path.length === 4) {
    return true;
  }
  if (path.length === 5) {
    return argumentCount(root, Number(path[2])) < 32 ? 2048 : false;
  }
  return path.length === 6 && path[5] === 0 ? 2048 : false;
}
/** Metadata/previews, never unrelated custom data, image bytes or raw tool details. */
function messageProjection(
  path: readonly (string | number)[],
  root?: UnknownRecord,
): boolean | number {
  if (path.length === 1) {
    return true;
  }
  if (!messageFields.has(String(path[1]))) {
    return false;
  }
  if (path[1] === "content") {
    return contentProjection(path, root);
  }
  return path[1] === "usage" ? true : 4096;
}
export const nativeProjection: Projection = (path, root) => {
  if (path.length === 0) {
    return true;
  }
  if (path[0] === "message") {
    return messageProjection(path, root);
  }
  if (path[0] === "summary" || path[0] === "content") {
    return 2048;
  }
  if (path[0] === "details") {
    return path.length === 1 || ["bodyText", "message", "from"].includes(String(path[1]))
      ? 2048
      : false;
  }
  return entryFields.has(String(path[0])) ? 4096 : false;
};