import {
  appendDanglingToolIntentCorrection,
  buildChatToolSystemPrompt,
  executeToolCallAndBuildEvent,
  getEnabledChatTools,
  getUnstreamedText,
  looksLikeDanglingToolIntent,
  MAX_DANGLING_TOOL_INTENT_RETRIES,
  MAX_TOOL_ROUNDS,
  prepareToolCallExecution,
  type NormalizedToolCall,
  type ToolAwareCompletionParams,
  type ToolAwareCompletionResult,
  type ToolAwareStreamingEvent,
  type ToolAwareUsage,
  type ToolExecutionEvent,
} from "../chat-tools.js";
import {
  buildImageSummaryText,
  buildSystemPromptAugmentationMessage,
  buildTextAttachmentPrompt,
  getImageAttachments,
  getTextAttachments,
} from "../message-content.js";
import type { ChatMessage } from "../types.js";

function toResponsesTools(tools: any[]) {
  return tools.map((tool) => {
    if (tool?.type !== "function") return tool;
    return {
      type: "function",
      name: tool.function.name,
      description: tool.function.description,
      parameters: tool.function.parameters,
      strict: false,
    };
  });
}

function toContentParts(message: ChatMessage) {
  const imageAttachments = getImageAttachments(message);
  const textAttachments = getTextAttachments(message);
  if (!imageAttachments.length && !textAttachments.length) {
    return message.content;
  }

  const parts: Array<Record<string, unknown>> = [];
  for (const attachment of imageAttachments) {
    parts.push({
      type: "input_image",
      image_url: attachment.dataUrl,
      detail: "auto",
    });
  }

  const imageSummary = buildImageSummaryText(imageAttachments);
  if (imageSummary) {
    parts.push({ type: "input_text", text: imageSummary });
  }

  for (const attachment of textAttachments) {
    parts.push({ type: "input_text", text: buildTextAttachmentPrompt(attachment) });
  }

  if (message.content.trim()) {
    parts.push({ type: "input_text", text: message.content });
  }

  if (parts.length === 1 && parts[0]?.type === "input_text" && typeof parts[0].text === "string") {
    return parts[0].text;
  }

  return parts;
}

function buildInputMessage(message: ChatMessage) {
  if (message.role === "tool") {
    const name = message.name?.trim() || "tool";
    return {
      role: "user",
      content: `Tool output (${name}):\n${message.content}`,
    };
  }

  return {
    role: message.role,
    content: toContentParts(message),
  };
}

function normalizeInput(messages: ChatMessage[], userLocation?: string, params: Pick<ToolAwareCompletionParams, "enabledTools"> = {}) {
  const normalized = messages.map((message) => buildInputMessage(message));
  return [{ role: "system", content: buildChatToolSystemPrompt(params) }, buildSystemPromptAugmentationMessage(userLocation), ...normalized];
}

function mergeUsage(acc: Required<ToolAwareUsage>, usage: any) {
  if (!usage) return false;
  acc.inputTokens += usage.input_tokens ?? 0;
  acc.outputTokens += usage.output_tokens ?? 0;
  acc.totalTokens += usage.total_tokens ?? 0;
  return true;
}

function getOutputItems(response: any) {
  return Array.isArray(response?.output) ? response.output : [];
}

function extractText(response: any, fallback = "") {
  if (typeof response?.output_text === "string") return response.output_text;

  const parts: string[] = [];
  for (const item of getOutputItems(response)) {
    if (item?.type !== "message" || !Array.isArray(item.content)) continue;
    for (const content of item.content) {
      if (content?.type === "output_text" && typeof content.text === "string") {
        parts.push(content.text);
      } else if (content?.type === "refusal" && typeof content.refusal === "string") {
        parts.push(content.refusal);
      }
    }
  }
  return parts.join("") || fallback;
}

function getFailureMessage(response: any) {
  if (response?.status !== "failed" && response?.status !== "incomplete") return null;
  const errorMessage = typeof response?.error?.message === "string" ? response.error.message : null;
  const incompleteReason = typeof response?.incomplete_details?.reason === "string" ? response.incomplete_details.reason : null;
  return errorMessage ?? (incompleteReason ? `Response incomplete: ${incompleteReason}` : `Response ${response.status}.`);
}

function normalizeToolCalls(outputItems: any[], round: number): NormalizedToolCall[] {
  return outputItems
    .filter((item) => item?.type === "function_call")
    .map((call: any, index: number) => ({
      id: call.call_id ?? call.id ?? `tool_call_${round}_${index}`,
      name: call.name ?? "unknown_tool",
      arguments: call.arguments ?? "{}",
    }));
}

export async function completeWithResponsesApi(params: ToolAwareCompletionParams): Promise<ToolAwareCompletionResult> {
  const enabledTools = getEnabledChatTools(params);
  const input: any[] = normalizeInput(params.messages, params.userLocation, params);
  const rawResponses: unknown[] = [];
  const toolEvents: ToolExecutionEvent[] = [];
  const usageAcc: Required<ToolAwareUsage> = { inputTokens: 0, outputTokens: 0, totalTokens: 0 };
  let sawUsage = false;
  let totalToolCalls = 0;
  let danglingToolIntentRetries = 0;

  for (let round = 0; round < MAX_TOOL_ROUNDS; round += 1) {
    const response = await params.client.responses.create({
      model: params.model,
      input,
      temperature: params.temperature,
      max_output_tokens: params.maxTokens,
      tools: toResponsesTools(enabledTools),
      tool_choice: "auto",
      parallel_tool_calls: true,
      store: true,
    } as any);
    rawResponses.push(response);
    sawUsage = mergeUsage(usageAcc, response?.usage) || sawUsage;

    const failureMessage = getFailureMessage(response);
    if (failureMessage) {
      throw new Error(failureMessage);
    }

    const outputItems = getOutputItems(response);
    const normalizedToolCalls = normalizeToolCalls(outputItems, round);
    if (!normalizedToolCalls.length) {
      const text = extractText(response);
      if (danglingToolIntentRetries < MAX_DANGLING_TOOL_INTENT_RETRIES && looksLikeDanglingToolIntent(text)) {
        danglingToolIntentRetries += 1;
        appendDanglingToolIntentCorrection(input, text);
        continue;
      }
      return {
        text,
        usage: sawUsage ? usageAcc : undefined,
        raw: { responses: rawResponses, toolCallsUsed: totalToolCalls, api: "responses" },
        toolEvents,
      };
    }

    totalToolCalls += normalizedToolCalls.length;
    input.push(...outputItems);

    for (const call of normalizedToolCalls) {
      const { execution } = prepareToolCallExecution(call);
      const { event, toolResult } = await executeToolCallAndBuildEvent(call, execution, params);
      toolEvents.push(event);

      input.push({
        type: "function_call_output",
        call_id: call.id,
        output: JSON.stringify(toolResult),
      });
    }
  }

  return {
    text: "I reached the tool-call limit while gathering information. Please narrow the request and try again.",
    usage: sawUsage ? usageAcc : undefined,
    raw: { responses: rawResponses, toolCallsUsed: totalToolCalls, toolCallLimitReached: true, api: "responses" },
    toolEvents,
  };
}

export async function* streamWithResponsesApi(params: ToolAwareCompletionParams): AsyncGenerator<ToolAwareStreamingEvent> {
  const enabledTools = getEnabledChatTools(params);
  const input: any[] = normalizeInput(params.messages, params.userLocation, params);
  const rawResponses: unknown[] = [];
  const toolEvents: ToolExecutionEvent[] = [];
  const usageAcc: Required<ToolAwareUsage> = { inputTokens: 0, outputTokens: 0, totalTokens: 0 };
  let sawUsage = false;
  let totalToolCalls = 0;
  let danglingToolIntentRetries = 0;

  for (let round = 0; round < MAX_TOOL_ROUNDS; round += 1) {
    const stream = await params.client.responses.create({
      model: params.model,
      input,
      temperature: params.temperature,
      max_output_tokens: params.maxTokens,
      tools: toResponsesTools(enabledTools),
      tool_choice: "auto",
      parallel_tool_calls: true,
      store: true,
      stream: true,
    } as any);

    let roundText = "";
    let streamedRoundText = "";
    let roundHasToolCalls = false;
    let canStreamRoundText = false;
    let completedResponse: any | null = null;
    const completedOutputItems: any[] = [];

    for await (const event of stream as any as AsyncIterable<any>) {
      rawResponses.push(event);

      if (event?.type === "response.output_text.delta" && typeof event.delta === "string") {
        roundText += event.delta;
        if (canStreamRoundText && !roundHasToolCalls && event.delta.length) {
          streamedRoundText += event.delta;
          yield { type: "delta", text: event.delta };
        }
      } else if (event?.type === "response.output_item.added" && event.item) {
        if (event.item.type === "function_call") {
          roundHasToolCalls = true;
          canStreamRoundText = false;
        } else if (event.item.type === "message" && !roundHasToolCalls) {
          canStreamRoundText = true;
        }
      } else if (event?.type === "response.output_item.done" && event.item) {
        completedOutputItems[event.output_index ?? completedOutputItems.length] = event.item;
        if (event.item.type === "function_call") {
          roundHasToolCalls = true;
          canStreamRoundText = false;
        }
      } else if (event?.type === "response.completed") {
        completedResponse = event.response;
        sawUsage = mergeUsage(usageAcc, event.response?.usage) || sawUsage;
      } else if (event?.type === "response.failed" || event?.type === "response.incomplete") {
        completedResponse = event.response;
        sawUsage = mergeUsage(usageAcc, event.response?.usage) || sawUsage;
      } else if (event?.type === "error") {
        throw new Error(event.message ?? "Responses stream failed.");
      }
    }

    const failureMessage = getFailureMessage(completedResponse);
    if (failureMessage) {
      throw new Error(failureMessage);
    }

    const outputItems = getOutputItems(completedResponse);
    const responseOutputItems = outputItems.length ? outputItems : completedOutputItems.filter(Boolean);
    const normalizedToolCalls = normalizeToolCalls(responseOutputItems, round);
    if (!normalizedToolCalls.length) {
      const text = extractText(completedResponse, roundText);
      if (!streamedRoundText && danglingToolIntentRetries < MAX_DANGLING_TOOL_INTENT_RETRIES && looksLikeDanglingToolIntent(text)) {
        danglingToolIntentRetries += 1;
        appendDanglingToolIntentCorrection(input, text);
        continue;
      }
      const unstreamedText = getUnstreamedText(text, streamedRoundText);
      if (unstreamedText) {
        yield { type: "delta", text: unstreamedText };
      }
      yield {
        type: "done",
        result: {
          text,
          usage: sawUsage ? usageAcc : undefined,
          raw: { streamed: true, responses: rawResponses, toolCallsUsed: totalToolCalls, api: "responses" },
          toolEvents,
        },
      };
      return;
    }

    totalToolCalls += normalizedToolCalls.length;
    input.push(...responseOutputItems);

    for (const call of normalizedToolCalls) {
      const { event: initiatedEvent, execution } = prepareToolCallExecution(call);
      yield { type: "tool_call", event: initiatedEvent };
      const { event, toolResult } = await executeToolCallAndBuildEvent(call, execution, params);
      toolEvents.push(event);
      yield { type: "tool_call", event };
      input.push({
        type: "function_call_output",
        call_id: call.id,
        output: JSON.stringify(toolResult),
      });
    }
  }

  yield {
    type: "done",
    result: {
      text: "I reached the tool-call limit while gathering information. Please narrow the request and try again.",
      usage: sawUsage ? usageAcc : undefined,
      raw: { streamed: true, responses: rawResponses, toolCallsUsed: totalToolCalls, toolCallLimitReached: true, api: "responses" },
      toolEvents,
    },
  };
}