package ca_test

import (
	"context"
	"math"
	"testing"
	"time"

	"github.com/uopi/goca/proto"
	"github.com/uopi/goca/testca"
)

// TestGetDisconnectMidRequest covers the "circuit disconnected during GET" path
// in conn.go: the server drops the connection while a READ_NOTIFY is in flight,
// so the in-flight reply channel is closed by the reconnect loop and the waiter
// unblocks with ok=false.
func TestGetDisconnectMidRequest(t *testing.T) {
	srv := newTestServer(t)
	cli := newTestClient(t, srv)

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	// First GET establishes the channel/circuit successfully.
	if _, err := cli.Get(ctx, "TEST:DOUBLE"); err != nil {
		t.Fatalf("initial Get: %v", err)
	}

	// Arm a mid-request disconnect for the next READ_NOTIFY.
	srv.SetGetFault(testca.GetFaultDisconnect)

	if _, err := cli.Get(ctx, "TEST:DOUBLE"); err == nil {
		t.Fatal("Get with mid-request disconnect: want error")
	}
}

// TestGetCorruptReply covers the "failed to decode GET reply" path: the server
// answers READ_NOTIFY with a payload too short for DecodeTimeValue.
func TestGetCorruptReply(t *testing.T) {
	srv := newTestServer(t)
	cli := newTestClient(t, srv)

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	// Establish the channel first so resolution succeeds.
	if _, err := cli.Get(ctx, "TEST:DOUBLE"); err != nil {
		t.Fatalf("initial Get: %v", err)
	}

	srv.SetGetFault(testca.GetFaultCorrupt)

	if _, err := cli.Get(ctx, "TEST:DOUBLE"); err == nil {
		t.Fatal("Get with corrupt reply: want error")
	}
}

// TestServerDisconnectReconnects covers the CmdServerDisc dispatch branch and the
// reconnect loop: after an orderly server disconnect the client transparently
// reconnects, re-creates its channel, re-subscribes the monitor, and continues to
// receive updates.
func TestServerDisconnectReconnects(t *testing.T) {
	srv := newTestServer(t)
	cli := newTestClient(t, srv)

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	ch := make(chan proto.TimeValue, 16)
	unsub, err := cli.Subscribe(ctx, "TEST:DOUBLE", ch)
	if err != nil {
		t.Fatalf("Subscribe: %v", err)
	}
	defer unsub()

	// Drain the initial value.
	select {
	case <-ch:
	case <-ctx.Done():
		t.Fatal("timeout waiting for initial value")
	}

	// Force an orderly disconnect; the client must reconnect on its own.
	srv.Disconnect()

	// After the reconnect settles, push a fresh value and expect to see it.
	// The reconnect back-off is ~1s, so poll generously and re-arm the value
	// until it is observed (the re-subscribe also delivers an initial value).
	deadline := time.After(8 * time.Second)
	tick := time.NewTicker(300 * time.Millisecond)
	defer tick.Stop()
	for {
		select {
		case tv := <-ch:
			if math.Abs(tv.Double-88.8) < 1e-6 {
				return // reconnect succeeded and the update flowed through
			}
		case <-tick.C:
			_ = srv.SetValue("TEST:DOUBLE", 88.8)
		case <-deadline:
			t.Fatal("timeout waiting for post-reconnect update")
		}
	}
}