/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import type React from 'react';
import { useMemo } from 'react';
import { Box, Text } from 'ink';
import type { ThoughtSummary } from '@google/gemini-cli-core';
import { theme } from '../../semantic-colors.js';
import { normalizeEscapedNewlines } from '../../utils/textUtils.js';

interface ThinkingMessageProps {
  thought: ThoughtSummary;
  terminalWidth: number;
  isFirstThinking?: boolean;
}

const THINKING_LEFT_PADDING = 1;

function normalizeThoughtLines(thought: ThoughtSummary): string[] {
  const subject = normalizeEscapedNewlines(thought.subject).trim();
  const description = normalizeEscapedNewlines(thought.description).trim();

  if (!subject && !description) {
    return [];
  }

  if (!subject) {
    return description.split('\n');
  }

  if (!description) {
    return [subject];
  }

  const bodyLines = description.split('\n');
  return [subject, ...bodyLines];
}

/**
 * Renders a model's thought as a distinct bubble.
 * Leverages Ink layout for wrapping and borders.
 */
export const ThinkingMessage: React.FC<ThinkingMessageProps> = ({
  thought,
  terminalWidth,
  isFirstThinking,
}) => {
  const fullLines = useMemo(() => normalizeThoughtLines(thought), [thought]);

  if (fullLines.length === 0) {
    return null;
  }

  return (
    <Box width={terminalWidth} flexDirection="column">
      {isFirstThinking && (
        <Text color={theme.text.primary} italic>
          {' '}
          Thinking...{' '}
        </Text>
      )}

      <Box
        marginLeft={THINKING_LEFT_PADDING}
        paddingLeft={1}
        borderStyle="single"
        borderLeft={true}
        borderRight={false}
        borderTop={false}
        borderBottom={false}
        borderColor={theme.text.secondary}
        flexDirection="column"
      >
        <Text> </Text>
        {fullLines.length > 0 && (
          <Text color={theme.text.primary} bold italic>
            {fullLines[0]}
          </Text>
        )}
        {fullLines.slice(1).map((line, index) => (
          <Text key={`body-line-${index}`} color={theme.text.secondary} italic>
            {line}
          </Text>
        ))}
      </Box>
    </Box>
  );
};
