import { Part } from '@google/genai';
import { toolRegistry } from '../tools/tool-registry.js';
import {
  HistoryItem,
  IndividualToolCallDisplay,
  ToolCallEvent,
  ToolCallStatus,
  ToolConfirmationOutcome,
  ToolEditConfirmationDetails,
  ToolExecuteConfirmationDetails,
} from '../ui/types.js';
import { ToolResultDisplay } from '../tools/tools.js';

/**
 * Processes a tool call chunk and updates the history state accordingly.
 * Manages adding new tool groups or updating existing ones.
 * Resides here as its primary effect is updating history based on tool events.
 */
export const handleToolCallChunk = (
  chunk: ToolCallEvent,
  setHistory: React.Dispatch<React.SetStateAction<HistoryItem[]>>,
  submitQuery: (query: Part) => Promise<void>,
  getNextMessageId: () => number,
  currentToolGroupIdRef: React.MutableRefObject<number | null>,
): void => {
  const toolDefinition = toolRegistry.getTool(chunk.name);
  const description = toolDefinition?.getDescription
    ? toolDefinition.getDescription(chunk.args)
    : '';
  const toolDisplayName = toolDefinition?.displayName ?? chunk.name;
  let confirmationDetails = chunk.confirmationDetails;
  if (confirmationDetails) {
    const originalConfirmationDetails = confirmationDetails;
    const historyUpdatingConfirm = async (outcome: ToolConfirmationOutcome) => {
      originalConfirmationDetails.onConfirm(outcome);

      if (outcome === ToolConfirmationOutcome.Cancel) {
        let resultDisplay: ToolResultDisplay | undefined;
        if ('fileDiff' in originalConfirmationDetails) {
          resultDisplay = {
            fileDiff: (
              originalConfirmationDetails as ToolEditConfirmationDetails
            ).fileDiff,
          };
        } else {
          resultDisplay = `~~${(originalConfirmationDetails as ToolExecuteConfirmationDetails).command}~~`;
        }
        handleToolCallChunk(
          {
            ...chunk,
            status: ToolCallStatus.Canceled,
            confirmationDetails: undefined,
            resultDisplay,
          },
          setHistory,
          submitQuery,
          getNextMessageId,
          currentToolGroupIdRef,
        );
        const functionResponse: Part = {
          functionResponse: {
            name: chunk.name,
            response: { error: 'User rejected function call.' },
          },
        };
        await submitQuery(functionResponse);
      } else {
        const tool = toolRegistry.getTool(chunk.name);
        if (!tool) {
          throw new Error(
            `Tool "${chunk.name}" not found or is not registered.`,
          );
        }
        handleToolCallChunk(
          {
            ...chunk,
            status: ToolCallStatus.Invoked,
            resultDisplay: 'Executing...',
            confirmationDetails: undefined,
          },
          setHistory,
          submitQuery,
          getNextMessageId,
          currentToolGroupIdRef,
        );
        const result = await tool.execute(chunk.args);
        handleToolCallChunk(
          {
            ...chunk,
            status: ToolCallStatus.Invoked,
            resultDisplay: result.returnDisplay,
            confirmationDetails: undefined,
          },
          setHistory,
          submitQuery,
          getNextMessageId,
          currentToolGroupIdRef,
        );
        const functionResponse: Part = {
          functionResponse: {
            name: chunk.name,
            id: chunk.callId,
            response: { output: result.llmContent },
          },
        };
        await submitQuery(functionResponse);
      }
    };

    confirmationDetails = {
      ...originalConfirmationDetails,
      onConfirm: historyUpdatingConfirm,
    };
  }
  const toolDetail: IndividualToolCallDisplay = {
    callId: chunk.callId,
    name: toolDisplayName,
    description,
    resultDisplay: chunk.resultDisplay,
    status: chunk.status,
    confirmationDetails,
  };

  const activeGroupId = currentToolGroupIdRef.current;
  setHistory((prev) => {
    if (chunk.status === ToolCallStatus.Pending) {
      if (activeGroupId === null) {
        // Start a new tool group
        const newGroupId = getNextMessageId();
        currentToolGroupIdRef.current = newGroupId;
        return [
          ...prev,
          {
            id: newGroupId,
            type: 'tool_group',
            tools: [toolDetail],
          } as HistoryItem,
        ];
      }

      // Add to existing tool group
      return prev.map((item) =>
        item.id === activeGroupId && item.type === 'tool_group'
          ? item.tools.some((t) => t.callId === toolDetail.callId)
            ? item // Tool already listed as pending
            : { ...item, tools: [...item.tools, toolDetail] }
          : item,
      );
    }

    // Update the status of a pending tool within the active group
    if (activeGroupId === null) {
      // Log if an invoked tool arrives without an active group context
      console.warn(
        'Received invoked tool status without an active tool group ID:',
        chunk,
      );
      return prev;
    }

    return prev.map((item) =>
      item.id === activeGroupId && item.type === 'tool_group'
        ? {
            ...item,
            tools: item.tools.map((t) =>
              t.callId === toolDetail.callId
                ? { ...t, ...toolDetail, status: chunk.status } // Update details & status
                : t,
            ),
          }
        : item,
    );
  });
};

/**
 * Appends an error or informational message to the history, attempting to attach
 * it to the last non-user message or creating a new entry.
 */
export const addErrorMessageToHistory = (
  error: DOMException | Error,
  setHistory: React.Dispatch<React.SetStateAction<HistoryItem[]>>,
  getNextMessageId: () => number,
): void => {
  const isAbort = error.name === 'AbortError';
  const errorType = isAbort ? 'info' : 'error';
  const errorText = isAbort
    ? '[Request cancelled by user]'
    : `[Error: ${error.message || 'Unknown error'}]`;

  setHistory((prev) => {
    const reversedHistory = [...prev].reverse();
    // Find the last message that isn't from the user to append the error/info to
    const lastBotMessageIndex = reversedHistory.findIndex(
      (item) => item.type !== 'user',
    );
    const originalIndex =
      lastBotMessageIndex !== -1 ? prev.length - 1 - lastBotMessageIndex : -1;

    if (originalIndex !== -1) {
      // Append error to the last relevant message
      return prev.map((item, index) => {
        if (index === originalIndex) {
          let baseText = '';
          // Determine base text based on item type
          if (item.type === 'gemini') baseText = item.text ?? '';
          else if (item.type === 'tool_group')
            baseText = `Tool execution (${item.tools.length} calls)`;
          else if (item.type === 'error' || item.type === 'info')
            baseText = item.text ?? '';
          // Safely handle potential undefined text

          const updatedText = (
            baseText +
            (baseText && !baseText.endsWith('\n') ? '\n' : '') +
            errorText
          ).trim();
          // Reuse existing ID, update type and text
          return { ...item, type: errorType, text: updatedText };
        }
        return item;
      });
    } else {
      // No previous message to append to, add a new error item
      return [
        ...prev,
        {
          id: getNextMessageId(),
          type: errorType,
          text: errorText,
        } as HistoryItem,
      ];
    }
  });
};