package sitemap_test

import (
	"context"
	"slices"
	"sync"
	"testing"
	"time"

	"git.golem15.com/golem15/sm-sitemap-plugin/classes"
	"git.golem15.com/golem15/summercms/modules/pact"
)

// rebuildResult is the outcome of one classes.Rebuild run in a goroutine.
type rebuildResult struct {
	res classes.RebuildResult
	err error
}

// waitFor polls cond until it holds or the deadline passes.
func waitFor(t *testing.T, what string, cond func() bool) {
	t.Helper()
	deadline := time.Now().Add(15 * time.Second)
	for !cond() {
		if time.Now().After(deadline) {
			t.Fatalf("timed out waiting for %s", what)
		}
		time.Sleep(20 * time.Millisecond)
	}
}

// TestConcurrentRebuilds pins L2 WR-02 (D-30, P33-63): a second rebuild
// waits on the rebuild's advisory lock while the first one collects, so it
// collects only after the first has committed; a record published while
// the first rebuild ran is listed afterwards and never sent to IndexNow as
// removed.
func TestConcurrentRebuilds(t *testing.T) {
	e := bootIndex(t, filterPluginID)
	mod := time.Date(2026, 10, 1, 8, 0, 0, 0, time.UTC)
	contentStore.put(pageType, page1(1, "a", mod))
	if _, err := classes.Rebuild(t.Context(), e.app); err != nil {
		t.Fatal(err)
	}

	entered, release := make(chan struct{}), make(chan struct{})
	var once sync.Once
	theFilter.setHook(t, func() {
		first := false
		once.Do(func() { first = true; close(entered) })
		if first {
			<-release
		}
	})
	run := func() <-chan rebuildResult {
		out := make(chan rebuildResult, 1)
		go func() {
			res, err := classes.Rebuild(context.Background(), e.app)
			out <- rebuildResult{res, err}
		}()
		return out
	}
	a := run()
	select {
	case <-entered:
	case <-time.After(15 * time.Second):
		t.Fatal("rebuild A never asked the filter")
	}
	contentStore.put(pageType, page1(2, "x", mod))
	b := run()
	waitFor(t, "rebuild B to wait on the advisory lock", func() bool {
		var waiting int64
		e.gdb.Raw(`SELECT COUNT(*) FROM pg_locks WHERE locktype = 'advisory' AND NOT granted`).Scan(&waiting)
		return waiting > 0
	})
	close(release)
	ra, rb := <-a, <-b
	if ra.err != nil || rb.err != nil {
		t.Fatalf("rebuilds: %v, %v", ra.err, rb.err)
	}
	var reason []string
	e.gdb.Raw(`SELECT excluded_reason FROM golem15_sitemap_urls WHERE type_key = ? AND record_id = '2'`, pageType).Scan(&reason)
	if len(reason) != 1 || reason[0] != "" {
		t.Fatalf("record x after both rebuilds = %v, want listed", reason)
	}
	x := "https://api.example.test/pages/x"
	if slices.Contains(ra.res.Removed, x) || slices.Contains(rb.res.Removed, x) {
		t.Fatalf("x sent as removed: A %v, B %v", ra.res.Removed, rb.res.Removed)
	}
	if !slices.Contains(rb.res.Added, x) {
		t.Fatalf("rebuild B added %v, want x", rb.res.Added)
	}
}

// TestRebuildKeepsMovedLastmod pins L2 WR-03 (D-30): a lastmod that
// RecordSaved moves while a rebuild runs stays, also when the same rebuild
// rewrites the row for another change (its title).
func TestRebuildKeepsMovedLastmod(t *testing.T) {
	e := bootIndex(t)
	old := time.Date(2026, 10, 1, 8, 0, 0, 0, time.UTC)
	contentStore.put(pageType, page1(1, "a", old))
	if _, err := classes.Rebuild(t.Context(), e.app); err != nil {
		t.Fatal(err)
	}
	renamed := page1(1, "a", old)
	renamed.Locales[0].Title = "Page a, renamed"
	contentStore.put(pageType, renamed)

	lastmod := func() time.Time {
		var at time.Time
		e.gdb.Raw(`SELECT lastmod FROM golem15_sitemap_urls WHERE type_key = ? AND record_id = '1'`, pageType).Scan(&at)
		return at
	}
	saved := make(chan error, 1)
	ctx := classes.WithAfterSlotRead(t.Context(), func() {
		go func() {
			saved <- e.app.Events.Fire(context.Background(), &pact.RecordSaved{Model: pageModel, ID: "1", Changes: []pact.RecordChange{{Attribute: "title"}}})
		}()
		waitFor(t, "RecordSaved to move the lastmod", func() bool { return !lastmod().Equal(old) })
	})
	if _, err := classes.Rebuild(ctx, e.app); err != nil {
		t.Fatal(err)
	}
	if err := <-saved; err != nil {
		t.Fatal(err)
	}
	if got := lastmod(); got.Equal(old) {
		t.Fatal("the rebuild wrote the lastmod it read back over the moved one")
	}
	var title string
	e.gdb.Raw(`SELECT title FROM golem15_sitemap_urls WHERE type_key = ? AND record_id = '1'`, pageType).Scan(&title)
	if title != "Page a, renamed" {
		t.Fatalf("title = %q, want the rebuild's change", title)
	}
}