// src/plugin/hooks/useReamsActiveFile.ts
import { useState, useEffect } from 'react'
import type { App } from '../app'
import type { TFile } from '../files'

/**
 * React hook that returns the currently active file via workspace 'file-open' event.
 * Used by panel components to track which document is active without coupling to
 * LayoutContext.
 *
 * The workspace is the single source of truth for active file — this hook only reads.
 *
 * @internal Built-in UI uses this for React integration. External plugins should
 * use `app.workspace.getActiveFile()` and `app.workspace.on('file-open', ...)` directly.
 */
export function useReamsActiveFile(app: App): TFile | null {
  const [activeFile, setActiveFile] = useState<TFile | null>(
    () => app.workspace.getActiveFile()
  )

  useEffect(() => {
    // Sync on mount in case state changed between initial render and effect
    setActiveFile(app.workspace.getActiveFile())

    const ref = app.workspace.on('file-open', (file) => {
      setActiveFile(file)
    })

    return () => { app.workspace.offref(ref) }
  }, [app])

  return activeFile
}