import { type PropsWithChildren, useCallback, useContext, useInsertionEffect, useMemo } from 'react'
import {
	DISABLE_MOUSE_TRACKING,
	ENABLE_MOUSE_TRACKING,
	ENTER_ALT_SCREEN,
	EXIT_ALT_SCREEN,
} from '../../termio/dec.js'
import instances from '../instances.js'
import { TerminalWriteContext } from '../useTerminalNotification.js'
import Box from './Box.js'
import { TerminalSizeContext } from './TerminalSizeContext.js'

type Props = PropsWithChildren<{
	/** Enable SGR mouse tracking (wheel + click/drag). Default true. */
	mouseTracking?: boolean
}>

/**
 * Run children in the terminal's alternate screen buffer, constrained to
 * the viewport height. While mounted:
 *
 * - Enters the alt screen (DEC 1049), clears it, homes the cursor
 * - Constrains its own height to the terminal row count, so overflow must
 *   be handled via `overflow: scroll` / flexbox (no native scrollback)
 * - Optionally enables SGR mouse tracking (wheel + click/drag) — events
 *   surface as `ParsedKey` (wheel) and update the Ink instance's
 *   selection state (click/drag)
 *
 * On unmount, disables mouse tracking and exits the alt screen, restoring
 * the main screen's content. Safe for use in ctrl-o transcript overlays
 * and similar temporary fullscreen views — the main screen is preserved.
 *
 * Notifies the Ink instance via `setAltScreenActive()` so the renderer
 * keeps the cursor inside the viewport (preventing the cursor-restore LF
 * from scrolling content) and so signal-exit cleanup can exit the alt
 * screen if the component's own unmount doesn't run.
 */
export function AlternateScreen({ children, mouseTracking = true }: Props) {
	const size = useContext(TerminalSizeContext)
	const writeRaw = useContext(TerminalWriteContext)
	const effect = useCallback(() => {
		const ink = instances.get(process.stdout)
		if (!writeRaw) {
			return
		}
		writeRaw(ENTER_ALT_SCREEN + '\x1B[2J\x1B[H' + (mouseTracking ? ENABLE_MOUSE_TRACKING : ''))
		ink?.setAltScreenActive(true, mouseTracking)
		return () => {
			ink?.setAltScreenActive(false)
			ink?.clearTextSelection()
			writeRaw((mouseTracking ? DISABLE_MOUSE_TRACKING : '') + EXIT_ALT_SCREEN)
		}
	}, [writeRaw, mouseTracking])
	useInsertionEffect(effect, [effect])
	const height = size?.rows ?? 24
	return useMemo(
		() => (
			<Box flexDirection="column" height={height} width="100%" flexShrink={0}>
				{children}
			</Box>
		),
		[children, height],
	)
}