package page

import (
	"testing"

	"rhemawavetech.com/rhemawave/internal/download"
)

// Regression: DownloadDone was closed twice when checkState() re-navigated
// to HOME on the DOWNLOADING_ASSETS -> READY transition. The new Home page
// saw the already-closed MessageChannel and tried to close DownloadDone
// again, causing panic: close of closed channel.
//
// Primary fix: checkState() now skips navigation when transitioning between
// states that both map to the HOME page. The downloadDone flag on Home is
// defense-in-depth.

// TestHomeDownloadDoneGuardPreventsDoubleClose verifies that the per-instance
// downloadDone flag prevents closing DownloadDone more than once, even if a
// new Home page somehow reaches the close path.
func TestHomeDownloadDoneGuardPreventsDoubleClose(t *testing.T) {
	downloadDone := make(chan struct{})

	// First Home closes DownloadDone.
	h1 := &Home{downloadDone: false}
	h1.Context = &PageCtx{DownloadDone: downloadDone}
	if !h1.downloadDone {
		h1.downloadDone = true
		close(h1.Context.DownloadDone)
	}

	// Second Home with guard already set (simulates defense-in-depth).
	h2 := &Home{downloadDone: true}
	h2.Context = &PageCtx{DownloadDone: downloadDone}
	if !h2.downloadDone {
		h2.downloadDone = true
		close(h2.Context.DownloadDone) // would panic without guard
	}
}

// TestHomeDownloadDoneGuardUnsetWouldPanic proves that without the
// downloadDone guard, closing DownloadDone a second time panics.
func TestHomeDownloadDoneGuardUnsetWouldPanic(t *testing.T) {
	downloadDone := make(chan struct{})
	close(downloadDone) // pre-close

	defer func() {
		if r := recover(); r == nil {
			t.Error("expected panic when closing already-closed channel")
		}
	}()

	// New Home with downloadDone=false tries to close an already-closed channel.
	h := &Home{downloadDone: false}
	h.Context = &PageCtx{DownloadDone: downloadDone}
	if !h.downloadDone {
		h.downloadDone = true
		close(h.Context.DownloadDone) // panics
	}
}

// TestHomeDownloadFailedDoesNotClose verifies that when a download fails,
// DownloadDone is NOT closed (the error path should not signal success).
func TestHomeDownloadFailedDoesNotClose(t *testing.T) {
	downloadDone := make(chan struct{})

	h := &Home{
		downloadFailed: true,
		downloadDone:    false,
	}
	h.Context = &PageCtx{
		MessageChannel: make(chan download.DownloadStatus),
		DownloadDone:   downloadDone,
	}

	// Simulate the Update logic: on failure, downloadDone should not be set
	// and DownloadDone should not be closed.
	if h.downloadFailed {
		// Error path: do not close DownloadDone.
	} else if !h.downloadDone {
		h.downloadDone = true
		close(h.Context.DownloadDone)
	}

	select {
	case <-downloadDone:
		t.Error("DownloadDone should not be closed on download failure")
	default:
		// Correct: channel is still open.
	}
}

// TestHomeDownloadDoneAlreadyClosed verifies that a Home page with
// downloadDone=true never attempts to close the channel.
func TestHomeDownloadDoneAlreadyClosed(t *testing.T) {
	downloadDone := make(chan struct{})
	close(downloadDone)

	h := &Home{downloadDone: true}
	h.Context = &PageCtx{DownloadDone: downloadDone}

	// Guard should prevent any close attempt.
	if !h.downloadDone {
		h.downloadDone = true
		close(h.Context.DownloadDone)
	}
}