package scheduler_test

import (
	"encoding/json"
	"net/http"
	"net/url"
	"testing"
	"time"

	"github.com/gorilla/websocket"
	"github.com/jfraeys/fetch_ml/internal/scheduler"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TestDistributedRoundTrip validates full job lifecycle through scheduler
func TestDistributedRoundTrip(t *testing.T) {
	// Create scheduler hub with token auth configured
	testToken := "test-token-123"
	hub, err := scheduler.NewHub(scheduler.HubConfig{
		BindAddr:              "localhost:0",
		StateDir:              t.TempDir(),
		DefaultBatchSlots:     4,
		AcceptanceTimeoutSecs: 5,
		WorkerTokens: map[string]string{
			testToken: "test-worker",
		},
	}, nil)
	require.NoError(t, err)
	defer hub.Stop()

	// Start scheduler
	err = hub.Start()
	require.NoError(t, err)

	// Get scheduler address - use the actual listening address
	u := &url.URL{Scheme: "ws", Host: hub.Addr(), Path: "/ws/worker"}
	wsURL := u.String()

	// Create mock worker connection with auth token
	workerID := "test-worker"
	headers := http.Header{}
	headers.Set("Authorization", "Bearer "+testToken)
	conn, _, err := websocket.DefaultDialer.Dial(wsURL, headers)
	require.NoError(t, err)
	defer conn.Close()

	// Start receive goroutine
	recvCh := make(chan scheduler.Message, 10)
	go func() {
		for {
			var msg scheduler.Message
			err := conn.ReadJSON(&msg)
			if err != nil {
				close(recvCh)
				return
			}
			recvCh <- msg
		}
	}()

	// Register worker
	err = conn.WriteJSON(scheduler.Message{
		Type: scheduler.MsgRegister,
		Payload: mustMarshal(scheduler.WorkerRegistration{
			ID: workerID,
			Capabilities: scheduler.WorkerCapabilities{
				GPUCount: 0,
				GPUType:  "",
			},
		}),
	})
	require.NoError(t, err)

	// Wait for ack
	select {
	case msg := <-recvCh:
		require.Equal(t, scheduler.MsgAck, msg.Type)
	case <-time.After(2 * time.Second):
		t.Fatal("timeout waiting for registration ack")
	}

	// Send heartbeat to show we're alive
	err = conn.WriteJSON(scheduler.Message{
		Type: scheduler.MsgHeartbeat,
		Payload: mustMarshal(scheduler.HeartbeatPayload{
			WorkerID: workerID,
			Slots: scheduler.SlotStatus{
				BatchTotal: 4,
				BatchInUse: 0,
			},
		}),
	})
	require.NoError(t, err)

	// Signal ready for work
	err = conn.WriteJSON(scheduler.Message{
		Type: scheduler.MsgReadyForWork,
		Payload: mustMarshal(scheduler.ReadyPayload{
			WorkerID: workerID,
			Slots: scheduler.SlotStatus{
				BatchTotal: 4,
				BatchInUse: 0,
			},
			Reason: "polling",
		}),
	})
	require.NoError(t, err)

	// Wait a bit and verify connection is still alive
	time.Sleep(200 * time.Millisecond)
}

// TestWorkerRegistration validates worker registration flow
func TestWorkerRegistration(t *testing.T) {
	testToken := "reg-test-token"
	hub, err := scheduler.NewHub(scheduler.HubConfig{
		BindAddr:          "localhost:0",
		StateDir:          t.TempDir(),
		DefaultBatchSlots: 4,
		WorkerTokens: map[string]string{
			testToken: "reg-test-worker",
		},
	}, nil)
	require.NoError(t, err)
	defer hub.Stop()

	// Start scheduler
	err = hub.Start()
	require.NoError(t, err)

	u := &url.URL{Scheme: "ws", Host: hub.Addr(), Path: "/ws/worker"}
	wsURL := u.String()

	// Connect worker with auth token
	headers := http.Header{}
	headers.Set("Authorization", "Bearer "+testToken)
	conn, _, err := websocket.DefaultDialer.Dial(wsURL, headers)
	require.NoError(t, err)
	defer conn.Close()

	// Receive channel
	recvCh := make(chan scheduler.Message, 10)
	go func() {
		for {
			var msg scheduler.Message
			err := conn.ReadJSON(&msg)
			if err != nil {
				close(recvCh)
				return
			}
			recvCh <- msg
		}
	}()

	// Register with capabilities
	workerID := "reg-test-worker"
	err = conn.WriteJSON(scheduler.Message{
		Type: scheduler.MsgRegister,
		Payload: mustMarshal(scheduler.WorkerRegistration{
			ID: workerID,
			Capabilities: scheduler.WorkerCapabilities{
				GPUCount: 2,
				GPUType:  "nvidia",
				CPUCount: 8,
				MemoryGB: 32.0,
			},
		}),
	})
	require.NoError(t, err)

	// Expect ack
	select {
	case msg := <-recvCh:
		assert.Equal(t, scheduler.MsgAck, msg.Type)
	case <-time.After(2 * time.Second):
		t.Fatal("timeout waiting for ack")
	}
}

// TestHeartbeat validates heartbeat slot reporting
func TestHeartbeat(t *testing.T) {
	testToken := "hb-test-token"
	hub, err := scheduler.NewHub(scheduler.HubConfig{
		BindAddr:          "localhost:0",
		StateDir:          t.TempDir(),
		DefaultBatchSlots: 4,
		WorkerTokens: map[string]string{
			testToken: "hb-test-worker",
		},
	}, nil)
	require.NoError(t, err)
	defer hub.Stop()

	// Start scheduler
	err = hub.Start()
	require.NoError(t, err)

	u := &url.URL{Scheme: "ws", Host: hub.Addr(), Path: "/ws/worker"}
	wsURL := u.String()

	headers := http.Header{}
	headers.Set("Authorization", "Bearer "+testToken)
	conn, _, err := websocket.DefaultDialer.Dial(wsURL, headers)
	require.NoError(t, err)
	defer conn.Close()

	workerID := "hb-test-worker"

	// Register first
	err = conn.WriteJSON(scheduler.Message{
		Type: scheduler.MsgRegister,
		Payload: mustMarshal(scheduler.WorkerRegistration{
			ID: workerID,
			Capabilities: scheduler.WorkerCapabilities{
				GPUCount: 0,
			},
		}),
	})
	require.NoError(t, err)

	// Send multiple heartbeats
	slots := []scheduler.SlotStatus{
		{BatchTotal: 4, BatchInUse: 0},
		{BatchTotal: 4, BatchInUse: 1},
		{BatchTotal: 4, BatchInUse: 2},
	}

	for _, slot := range slots {
		err = conn.WriteJSON(scheduler.Message{
			Type: scheduler.MsgHeartbeat,
			Payload: mustMarshal(scheduler.HeartbeatPayload{
				WorkerID: workerID,
				Slots:    slot,
			}),
		})
		require.NoError(t, err)
		time.Sleep(50 * time.Millisecond)
	}

	// Connection should remain healthy
	time.Sleep(100 * time.Millisecond)
}

func mustMarshal(v any) []byte {
	b, _ := json.Marshal(v)
	return b
}