package uv

import (
	"io"
	"reflect"
	"strings"
	"testing"
	"time"
)

// Control strings split across reads, the way a large OSC 5522 clipboard
// reply arrives over ssh.

// stalledReader returns one chunk per Read, pausing before each like a slow
// network link.
type stalledReader struct {
	chunks []string
	pause  time.Duration
}

func (r *stalledReader) Read(p []byte) (int, error) {
	if len(r.chunks) == 0 {
		return 0, io.EOF
	}
	time.Sleep(r.pause)
	n := copy(p, r.chunks[0])
	r.chunks = r.chunks[1:]
	return n, nil
}

func TestDecodeWaitsForSplitStringTerminator(t *testing.T) {
	for name, seq := range map[string]string{
		"osc": "\x1b]5522;type=read:status=DATA;QUJD\x1b",
		"apc": "\x1b_Gi=1;OK\x1b",
		"dcs": "\x1bP1+r5463=31\x1b",
	} {
		t.Run(name, func(t *testing.T) {
			var d EventDecoder
			n, ev := d.Decode([]byte(seq))
			if _, ok := ev.(UnknownEvent); !ok || n != len(seq) {
				t.Fatalf("Decode(%q) = %d, %T; want an incomplete UnknownEvent over the whole buffer", seq, n, ev)
			}
		})
	}
}

func TestStreamEventsKeepsOscAcrossStalledReads(t *testing.T) {
	payload := strings.Repeat("QUJD", 2000)
	osc := "\x1b]5522;type=read:status=DATA:id=x;" + payload + "\x1b\\"
	half := len(osc) / 2
	chunks := []string{
		osc[:half],             // stall mid payload
		osc[half : len(osc)-1], // stall between ESC and the backslash of ST
		osc[len(osc)-1:] + "a",
	}
	events := testReadInputs(t, &stalledReader{chunks: chunks, pause: 4 * DefaultEscTimeout})
	want := []Event{UnknownOscEvent(osc), KeyPressEvent{Code: 'a', Text: "a"}}
	if !reflect.DeepEqual(events, want) {
		t.Fatalf("events = %#v\nwant %#v", events, want)
	}
}

func TestStreamEventsFlushesStalledClipboardOscAfterItsTimeout(t *testing.T) {
	saved := pendingClipboardOscTimeout
	pendingClipboardOscTimeout = 2 * DefaultEscTimeout
	t.Cleanup(func() { pendingClipboardOscTimeout = saved })

	head := "\x1b]5522;type=read:status=DATA:id=x;QUJD"
	events := testReadInputs(t, &stalledReader{chunks: []string{head, "a"}, pause: 6 * DefaultEscTimeout})
	want := []Event{UnknownEvent(head), KeyPressEvent{Code: 'a', Text: "a"}}
	if !reflect.DeepEqual(events, want) {
		t.Fatalf("events = %#v\nwant %#v", events, want)
	}
}