package engine

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"

	"github.com/cdnutter/playlink/internal/notify"
	"github.com/cdnutter/playlink/internal/store"
)

// events records what the engine would notify about.
type events struct {
	mu  sync.Mutex
	got []notify.Event
}

func (ev *env) captureEvents() *events {
	r := &events{}
	ev.e.SetNotify(func(_ context.Context, e notify.Event) {
		r.mu.Lock()
		r.got = append(r.got, e)
		r.mu.Unlock()
	})
	return r
}

func (r *events) take() []notify.Event {
	r.mu.Lock()
	defer r.mu.Unlock()
	out := r.got
	r.got = nil
	return out
}

func kinds(es []notify.Event) string {
	var k []string
	for _, e := range es {
		k = append(k, e.Kind)
	}
	return strings.Join(k, ",")
}

func (ev *env) automate(t *testing.T, settle int) {
	t.Helper()
	ev.pair.AutoLinkIdentical, ev.pair.AutoCleanupEmpty, ev.pair.SettleMinutes = true, true, settle
	if err := ev.st.SavePair(ctx, &ev.pair); err != nil {
		t.Fatal(err)
	}
}

func TestAutoCleanupRemovesOnlyEmptyFolders(t *testing.T) {
	ev := setup(t, false)
	ev.automate(t, 0)
	rec := ev.captureEvents()
	ev.write(ev.master, "A/Same/1 Song.flac", "same")
	ev.write(ev.slave, "A/Same/1 Song.flac", "same")
	ev.write(ev.master, "A/Diff/1 Song.flac", "master")
	ev.write(ev.slave, "A/Diff/1 Song.flac", "slave!")
	os.MkdirAll(filepath.Join(ev.slave, "B/Empty/Disc 1"), 0o755)
	ev.write(ev.slave, "C/Art/cover.jpg", "art")
	ev.write(ev.slave, "D/.DS_Store", "x") // any file at all keeps the folder

	ev.scan()
	if exists(filepath.Join(ev.slave, "B")) {
		t.Fatal("empty folder B should have been removed")
	}
	for _, keep := range []string{"C/Art/cover.jpg", "D/.DS_Store", "A/Same/1 Song.flac"} {
		if !exists(filepath.Join(ev.slave, keep)) {
			t.Fatalf("%s should be kept", keep)
		}
	}
	es := rec.take()
	if kinds(es) != "review,linked,cleanup" {
		t.Fatalf("events = %s", kinds(es))
	}
	if es[0].Message != "1 song needs review." || es[0].PairID != ev.pair.ID {
		t.Fatalf("review event: %+v", es[0])
	}
	if !strings.Contains(es[1].Message, "1 identical file") {
		t.Fatalf("linked event: %+v", es[1])
	}
	if !strings.Contains(es[2].Message, "1 empty folder") || !strings.Contains(es[2].Message, "2 folders without music still hold files") {
		t.Fatalf("cleanup event: %+v", es[2])
	}
	// Removed folders are quarantined and listed in History like manual ones.
	ops, _, err := ev.st.Ops(ctx, store.OpFilter{PairID: ev.pair.ID, Limit: 100})
	if err != nil {
		t.Fatal(err)
	}
	var found bool
	for _, o := range ops {
		if o.Action == "remove-folder" && o.RelSlave == "B" && strings.HasPrefix(o.Trigger, "auto:") && exists(o.QuarantinePath) {
			found = true
		}
	}
	if !found {
		t.Fatalf("no quarantined auto removal of B in %+v", ops)
	}

	// Nothing new: a second scan stays quiet.
	ev.scan()
	if es := rec.take(); len(es) != 0 {
		t.Fatalf("second scan notified: %s", kinds(es))
	}
}

func TestAutoCleanupWaitsForSettleAndDryRun(t *testing.T) {
	ev := setup(t, false)
	ev.automate(t, 10)
	rec := ev.captureEvents()
	os.MkdirAll(filepath.Join(ev.slave, "Fresh"), 0o755)
	ev.write(ev.slave, "A/1 Song.flac", "x")
	ev.scan()
	if !exists(filepath.Join(ev.slave, "Fresh")) {
		t.Fatal("a folder changed within the settle time must be left alone")
	}
	if es := rec.take(); len(es) != 0 {
		t.Fatalf("events = %s", kinds(es))
	}

	dry := setup(t, true)
	dry.automate(t, 0)
	rec = dry.captureEvents()
	os.MkdirAll(filepath.Join(dry.slave, "Empty"), 0o755)
	dry.write(dry.slave, "A/1 Song.flac", "x")
	dry.scan()
	if !exists(filepath.Join(dry.slave, "Empty")) {
		t.Fatal("dry run removed a folder")
	}
	if es := rec.take(); len(es) != 0 {
		t.Fatalf("dry run notified: %s", kinds(es))
	}
}