import type { StreamFn } from "@mariozechner/pi-agent-core";
import { streamSimple } from "@mariozechner/pi-ai";

function stripUnsupportedStrictFlag(tool: unknown): unknown {
  if (!tool || typeof tool !== "object") {
    return tool;
  }
  const toolObj = tool as Record<string, unknown>;
  const fn = toolObj.function;
  if (!fn || typeof fn !== "object") {
    return tool;
  }
  const fnObj = fn as Record<string, unknown>;
  if (typeof fnObj.strict !== "boolean") {
    return tool;
  }
  const nextFunction = { ...fnObj };
  delete nextFunction.strict;
  return { ...toolObj, function: nextFunction };
}

export function createXaiToolPayloadCompatibilityWrapper(
  baseStreamFn: StreamFn | undefined,
): StreamFn {
  const underlying = baseStreamFn ?? streamSimple;
  return (model, context, options) => {
    const originalOnPayload = options?.onPayload;
    return underlying(model, context, {
      ...options,
      onPayload: (payload) => {
        if (payload && typeof payload === "object") {
          const payloadObj = payload as Record<string, unknown>;
          if (Array.isArray(payloadObj.tools)) {
            payloadObj.tools = payloadObj.tools.map((tool) => stripUnsupportedStrictFlag(tool));
          }
        }
        return originalOnPayload?.(payload, model);
      },
    });
  };
}

function decodeHtmlEntities(value: string): string {
  return value
    .replaceAll("&quot;", '"')
    .replaceAll("&#34;", '"')
    .replaceAll("&apos;", "'")
    .replaceAll("&#39;", "'")
    .replaceAll("&lt;", "<")
    .replaceAll("&#60;", "<")
    .replaceAll("&gt;", ">")
    .replaceAll("&#62;", ">")
    .replaceAll("&amp;", "&")
    .replaceAll("&#38;", "&");
}

function decodeHtmlEntitiesInObject(value: unknown): unknown {
  if (typeof value === "string") {
    return decodeHtmlEntities(value);
  }
  if (!value || typeof value !== "object") {
    return value;
  }
  if (Array.isArray(value)) {
    return value.map((entry) => decodeHtmlEntitiesInObject(entry));
  }
  const record = value as Record<string, unknown>;
  for (const [key, entry] of Object.entries(record)) {
    record[key] = decodeHtmlEntitiesInObject(entry);
  }
  return record;
}

function decodeXaiToolCallArgumentsInMessage(message: unknown): void {
  if (!message || typeof message !== "object") {
    return;
  }
  const content = (message as { content?: unknown }).content;
  if (!Array.isArray(content)) {
    return;
  }
  for (const block of content) {
    if (!block || typeof block !== "object") {
      continue;
    }
    const typedBlock = block as { type?: unknown; arguments?: unknown };
    if (typedBlock.type !== "toolCall" || !typedBlock.arguments) {
      continue;
    }
    if (typeof typedBlock.arguments === "object") {
      typedBlock.arguments = decodeHtmlEntitiesInObject(typedBlock.arguments);
    }
  }
}

function wrapStreamDecodeXaiToolCallArguments(
  stream: ReturnType<typeof streamSimple>,
): ReturnType<typeof streamSimple> {
  const originalResult = stream.result.bind(stream);
  stream.result = async () => {
    const message = await originalResult();
    decodeXaiToolCallArgumentsInMessage(message);
    return message;
  };

  const originalAsyncIterator = stream[Symbol.asyncIterator].bind(stream);
  (stream as { [Symbol.asyncIterator]: typeof originalAsyncIterator })[Symbol.asyncIterator] =
    function () {
      const iterator = originalAsyncIterator();
      return {
        async next() {
          const result = await iterator.next();
          if (!result.done && result.value && typeof result.value === "object") {
            const event = result.value as { partial?: unknown; message?: unknown };
            decodeXaiToolCallArgumentsInMessage(event.partial);
            decodeXaiToolCallArgumentsInMessage(event.message);
          }
          return result;
        },
        async return(value?: unknown) {
          return iterator.return?.(value) ?? { done: true as const, value: undefined };
        },
        async throw(error?: unknown) {
          return iterator.throw?.(error) ?? { done: true as const, value: undefined };
        },
      };
    };
  return stream;
}

export function createXaiToolCallArgumentDecodingWrapper(baseStreamFn: StreamFn): StreamFn {
  return (model, context, options) => {
    const maybeStream = baseStreamFn(model, context, options);
    if (maybeStream && typeof maybeStream === "object" && "then" in maybeStream) {
      return Promise.resolve(maybeStream).then((stream) =>
        wrapStreamDecodeXaiToolCallArguments(stream),
      );
    }
    return wrapStreamDecodeXaiToolCallArguments(maybeStream);
  };
}