package socket_test

import (
	"context"
	"encoding/json"
	"path/filepath"
	"sync"
	"testing"
	"time"

	"gitea.alexandru.macocian.me/Charlie/sherlock/internal/rpc"
	"gitea.alexandru.macocian.me/Charlie/sherlock/internal/socket"
)

func newServer(t *testing.T, handler socket.Handler) (string, func()) {
	t.Helper()
	path := filepath.Join(t.TempDir(), "test.sock")
	srv, err := socket.Listen(path, handler)
	if err != nil {
		t.Fatalf("Listen: %v", err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan struct{})
	go func() {
		defer close(done)
		if err := srv.Serve(ctx); err != nil {
			t.Errorf("Serve: %v", err)
		}
	}()
	return path, func() {
		cancel()
		_ = srv.Close()
		<-done
	}
}

func TestRoundTrip_Success(t *testing.T) {
	handler := socket.HandlerFunc(func(_ context.Context, req rpc.Request) rpc.Response {
		if req.Method != "echo" {
			return rpc.Response{Error: rpc.NewError(rpc.CodeUnknownMethod, "nope")}
		}
		out, _ := rpc.MarshalResult(map[string]string{"got": "ok"})
		return rpc.Response{Result: out}
	})
	path, stop := newServer(t, handler)
	defer stop()

	c, err := socket.Dial(path)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer func() { _ = c.Close() }()

	var resp map[string]string
	if err := c.Call(context.Background(), "echo", nil, &resp); err != nil {
		t.Fatalf("Call: %v", err)
	}
	if resp["got"] != "ok" {
		t.Fatalf("got %v", resp)
	}
}

func TestRoundTrip_Error(t *testing.T) {
	handler := socket.HandlerFunc(func(_ context.Context, req rpc.Request) rpc.Response {
		return rpc.Response{Error: rpc.NewError(rpc.CodeNotLoggedIn, "session missing")}
	})
	path, stop := newServer(t, handler)
	defer stop()

	c, err := socket.Dial(path)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer func() { _ = c.Close() }()

	err = c.Call(context.Background(), "status", nil, nil)
	if err == nil {
		t.Fatal("expected error")
	}
	rpcErr, ok := err.(*rpc.Error)
	if !ok {
		t.Fatalf("expected *rpc.Error, got %T", err)
	}
	if rpcErr.Code != rpc.CodeNotLoggedIn {
		t.Fatalf("code = %v", rpcErr.Code)
	}
}

func TestRoundTrip_BadJSON(t *testing.T) {
	handler := socket.HandlerFunc(func(_ context.Context, req rpc.Request) rpc.Response {
		return rpc.Response{}
	})
	path, stop := newServer(t, handler)
	defer stop()

	// Send garbage directly so we exercise the server-side decode path.
	conn, err := dialRaw(path)
	if err != nil {
		t.Fatalf("dialRaw: %v", err)
	}
	defer func() { _ = conn.Close() }()

	if _, err := conn.Write([]byte("not json\n")); err != nil {
		t.Fatalf("Write: %v", err)
	}
	buf := make([]byte, 1024)
	n, err := conn.Read(buf)
	if err != nil {
		t.Fatalf("Read: %v", err)
	}
	var resp rpc.Response
	if err := json.Unmarshal(buf[:n], &resp); err != nil {
		t.Fatalf("Unmarshal: %v", err)
	}
	if resp.Error == nil || resp.Error.Code != rpc.CodeBadRequest {
		t.Fatalf("expected bad_request, got %+v", resp.Error)
	}
}

func TestConcurrentCalls(t *testing.T) {
	handler := socket.HandlerFunc(func(_ context.Context, req rpc.Request) rpc.Response {
		var in struct{ N int }
		_ = json.Unmarshal(req.Params, &in)
		out, _ := rpc.MarshalResult(map[string]int{"n": in.N})
		return rpc.Response{Result: out}
	})
	path, stop := newServer(t, handler)
	defer stop()

	const goroutines = 20
	const callsEach = 50

	var wg sync.WaitGroup
	for i := 0; i < goroutines; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			c, err := socket.Dial(path)
			if err != nil {
				t.Errorf("Dial: %v", err)
				return
			}
			defer func() { _ = c.Close() }()
			for j := 0; j < callsEach; j++ {
				var out map[string]int
				err := c.Call(context.Background(), "echo",
					map[string]int{"N": j}, &out)
				if err != nil {
					t.Errorf("Call: %v", err)
					return
				}
				if out["n"] != j {
					t.Errorf("got %d want %d", out["n"], j)
					return
				}
			}
		}()
	}
	doneCh := make(chan struct{})
	go func() { wg.Wait(); close(doneCh) }()
	select {
	case <-doneCh:
	case <-time.After(10 * time.Second):
		t.Fatal("concurrent calls timed out")
	}
}