stack/packages/mosaic/src/tui/components/bottom-bar.tsx

import React from 'react';
import { Box, Text } from 'ink';
import type { RoutingDecisionInfo } from '@mosaic/types';
import type { TokenUsage } from '../hooks/use-socket.js';
import type { GitInfo } from '../hooks/use-git-info.js';

export interface BottomBarProps {
  gitInfo: GitInfo;
  tokenUsage: TokenUsage;
  connected: boolean;
  connecting: boolean;
  modelName: string | null;
  providerName: string | null;
  thinkingLevel: string;
  conversationId: string | undefined;
  /** Routing decision info for transparency display (M4-008) */
  routingDecision?: RoutingDecisionInfo | null;
}

function formatTokens(n: number): string {
  if (n >= 1_000_000) return `${(n / 1_000_000).toFixed(1)}M`;
  if (n >= 1_000) return `${(n / 1_000).toFixed(0)}k`;
  return String(n);
}

/** Compact the cwd — replace home with ~ */
function compactCwd(cwd: string): string {
  const home = process.env['HOME'] ?? '';
  if (home && cwd.startsWith(home)) {
    return '~' + cwd.slice(home.length);
  }
  return cwd;
}

export function BottomBar({
  gitInfo,
  tokenUsage,
  connected,
  connecting,
  modelName,
  providerName,
  thinkingLevel,
  conversationId,
  routingDecision,
}: BottomBarProps) {
  const gatewayStatus = connected ? 'Connected' : connecting ? 'Connecting…' : 'Disconnected';
  const gatewayColor = connected ? 'green' : connecting ? 'yellow' : 'red';

  const hasTokens = tokenUsage.total > 0;

  return (
    <Box flexDirection="column" paddingX={0} marginTop={0}>
      {/* Line 0: keybinding hints */}
      <Box>
        <Text dimColor>^L sidebar · ^N new · ^K search · ^T thinking · PgUp/Dn scroll</Text>
      </Box>

      {/* Line 1: blank  ·····  Gateway: Status */}
      <Box justifyContent="space-between">
        <Box />
        <Box>
          <Text dimColor>Gateway: </Text>
          <Text color={gatewayColor}>{gatewayStatus}</Text>
        </Box>
      </Box>

      {/* Line 2: cwd (branch)  ·····  Session: id */}
      <Box justifyContent="space-between">
        <Box>
          <Text dimColor>{compactCwd(gitInfo.cwd)}</Text>
          {gitInfo.branch && <Text dimColor> ({gitInfo.branch})</Text>}
        </Box>
        <Box>
          <Text dimColor>
            {conversationId ? `Session: ${conversationId.slice(0, 8)}` : 'No session'}
          </Text>
        </Box>
      </Box>

      {/* Line 3: token stats  ·····  (provider) model */}
      <Box justifyContent="space-between" minHeight={1}>
        <Box>
          {hasTokens ? (
            <>
              <Text dimColor>↑{formatTokens(tokenUsage.input)}</Text>
              <Text dimColor>{'  '}</Text>
              <Text dimColor>↓{formatTokens(tokenUsage.output)}</Text>
              {tokenUsage.cacheRead > 0 && (
                <>
                  <Text dimColor>{'  '}</Text>
                  <Text dimColor>R{formatTokens(tokenUsage.cacheRead)}</Text>
                </>
              )}
              {tokenUsage.cacheWrite > 0 && (
                <>
                  <Text dimColor>{'  '}</Text>
                  <Text dimColor>W{formatTokens(tokenUsage.cacheWrite)}</Text>
                </>
              )}
              {tokenUsage.cost > 0 && (
                <>
                  <Text dimColor>{'  '}</Text>
                  <Text dimColor>${tokenUsage.cost.toFixed(3)}</Text>
                </>
              )}
              {tokenUsage.contextPercent > 0 && (
                <>
                  <Text dimColor>{'  '}</Text>
                  <Text dimColor>
                    {tokenUsage.contextPercent.toFixed(1)}%/{formatTokens(tokenUsage.contextWindow)}
                  </Text>
                </>
              )}
            </>
          ) : (
            <Text dimColor>↑0 ↓0 $0.000</Text>
          )}
        </Box>
        <Box>
          <Text dimColor>
            {providerName ? `(${providerName}) ` : ''}
            {modelName ?? 'awaiting model'}
            {thinkingLevel !== 'off' ? ` • ${thinkingLevel}` : ''}
          </Text>
        </Box>
      </Box>

      {/* Line 4: routing transparency (M4-008) — only shown when a routing decision is available */}
      {routingDecision && (
        <Box>
          <Text dimColor>
            Routed: {routingDecision.model} ({routingDecision.reason})
          </Text>
        </Box>
      )}
    </Box>
  );
}