package vllm

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"

	"go.uber.org/zap"

	"iop/apps/node/internal/runtime"
	"iop/packages/go/config"
)

type fakeSink struct {
	mu     sync.Mutex
	events []runtime.RuntimeEvent
}

func (s *fakeSink) Emit(_ context.Context, event runtime.RuntimeEvent) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.events = append(s.events, event)
	return nil
}

func (s *fakeSink) all() []runtime.RuntimeEvent {
	s.mu.Lock()
	defer s.mu.Unlock()
	return append([]runtime.RuntimeEvent(nil), s.events...)
}

func TestVllmCapabilitiesQueryModels(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/v1/models" {
			t.Fatalf("unexpected path %s", r.URL.Path)
		}
		_, _ = w.Write([]byte(`{"object":"list","data":[{"id":"model-a"},{"id":"model-b"}]}`))
	}))
	defer server.Close()

	adapter := New(config.VllmConf{
		Endpoint:         server.URL,
		Capacity:         10,
		MaxQueue:         20,
		QueueTimeoutMS:   5000,
		RequestTimeoutMS: 10000,
	}, zap.NewNop())
	caps, err := adapter.Capabilities(context.Background())
	if err != nil {
		t.Fatalf("Capabilities failed: %v", err)
	}
	if got := strings.Join(caps.Targets, ","); got != "model-a,model-b" {
		t.Fatalf("targets: got %q", got)
	}
	if caps.MaxConcurrency != 10 {
		t.Fatalf("expected MaxConcurrency 10, got %d", caps.MaxConcurrency)
	}
	if caps.MaxQueue != 20 {
		t.Fatalf("expected MaxQueue 20, got %d", caps.MaxQueue)
	}
	if caps.QueueTimeoutMS != 5000 {
		t.Fatalf("expected QueueTimeoutMS 5000, got %d", caps.QueueTimeoutMS)
	}
	if caps.RequestTimeoutMS != 10000 {
		t.Fatalf("expected RequestTimeoutMS 10000, got %d", caps.RequestTimeoutMS)
	}

	// Verify default capacity fallback
	adapterDefault := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
	capsDefault, err := adapterDefault.Capabilities(context.Background())
	if err != nil {
		t.Fatalf("Capabilities failed: %v", err)
	}
	if capsDefault.MaxConcurrency != 8 {
		t.Fatalf("expected default MaxConcurrency 8, got %d", capsDefault.MaxConcurrency)
	}
}

func TestVllmExecuteStreamsDeltas(t *testing.T) {
	var gotModel string
	var gotMessages int
	var gotStream bool
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/v1/chat/completions" {
			t.Fatalf("unexpected path %s", r.URL.Path)
		}
		var req struct {
			Model    string `json:"model"`
			Messages []any  `json:"messages"`
			Stream   bool   `json:"stream"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Fatalf("decode request: %v", err)
		}
		gotModel = req.Model
		gotMessages = len(req.Messages)
		gotStream = req.Stream
		w.Header().Set("Content-Type", "text/event-stream")
		_, _ = fmt.Fprintf(w, "data: %s\n\n", `{"choices":[{"delta":{"content":"hello "}}]}`)
		_, _ = fmt.Fprintf(w, "data: %s\n\n", `{"choices":[{"delta":{"content":"world"}}]}`)
		_, _ = fmt.Fprintf(w, "data: [DONE]\n\n")
	}))
	defer server.Close()

	adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
	sink := &fakeSink{}
	err := adapter.Execute(context.Background(), runtime.ExecutionSpec{
		RunID:  "run-1",
		Target: "llama-3",
		Input:  map[string]any{"prompt": "say hello"},
	}, sink)
	if err != nil {
		t.Fatalf("Execute failed: %v", err)
	}
	if gotModel != "llama-3" {
		t.Fatalf("model: got %q", gotModel)
	}
	if gotMessages != 1 {
		t.Fatalf("messages: got %d", gotMessages)
	}
	if !gotStream {
		t.Fatal("expected stream=true")
	}

	events := sink.all()
	if len(events) != 4 {
		t.Fatalf("expected 4 events (start+delta+delta+complete), got %d: %+v", len(events), events)
	}
	if events[0].Type != runtime.EventTypeStart {
		t.Fatalf("expected start event, got %+v", events[0])
	}
	if events[1].Delta+events[2].Delta != "hello world" {
		t.Fatalf("unexpected deltas: %q + %q", events[1].Delta, events[2].Delta)
	}
	if events[3].Type != runtime.EventTypeComplete {
		t.Fatalf("expected complete event, got %+v", events[3])
	}
}

func TestVllmExecuteUsesMessagesInput(t *testing.T) {
	var gotMessages []map[string]any
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Messages []map[string]any `json:"messages"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Fatalf("decode request: %v", err)
		}
		gotMessages = req.Messages
		w.Header().Set("Content-Type", "text/event-stream")
		_, _ = fmt.Fprintf(w, "data: %s\n\n", `{"choices":[{"delta":{"content":"ok"}}]}`)
		_, _ = fmt.Fprintf(w, "data: [DONE]\n\n")
	}))
	defer server.Close()

	adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
	sink := &fakeSink{}
	err := adapter.Execute(context.Background(), runtime.ExecutionSpec{
		RunID:  "run-2",
		Target: "llama-3",
		Input: map[string]any{
			"messages": []any{
				map[string]any{"role": "system", "content": "You are helpful."},
				map[string]any{"role": "user", "content": "hi"},
			},
		},
	}, sink)
	if err != nil {
		t.Fatalf("Execute failed: %v", err)
	}
	if len(gotMessages) != 2 {
		t.Fatalf("messages: got %d", len(gotMessages))
	}
	if gotMessages[0]["role"] != "system" || gotMessages[1]["role"] != "user" {
		t.Fatalf("unexpected messages: %+v", gotMessages)
	}
}

func TestVllmExecuteEmitsErrorForHTTPFailure(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		http.Error(w, "service unavailable", http.StatusServiceUnavailable)
	}))
	defer server.Close()

	adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
	sink := &fakeSink{}
	err := adapter.Execute(context.Background(), runtime.ExecutionSpec{
		RunID:  "run-err",
		Target: "llama-3",
		Input:  map[string]any{"prompt": "hi"},
	}, sink)
	if err == nil {
		t.Fatal("expected error")
	}
	events := sink.all()
	if len(events) < 2 || events[1].Type != runtime.EventTypeError {
		t.Fatalf("expected error event after start, got %+v", events)
	}
	if !strings.Contains(events[1].Error, "503") {
		t.Fatalf("expected status in error, got %q", events[1].Error)
	}
}

func TestVllmInstanceKey(t *testing.T) {
	adapter := New(config.VllmConf{Endpoint: "http://localhost:8000"}, zap.NewNop(), "vllm-gpu")
	caps, _ := adapter.Capabilities(context.Background())
	if caps.InstanceKey != "vllm-gpu" {
		t.Fatalf("InstanceKey: got %q, want vllm-gpu", caps.InstanceKey)
	}
	if caps.AdapterName != Name {
		t.Fatalf("AdapterName: got %q, want %q", caps.AdapterName, Name)
	}
}

func TestVllmProbeProviderAvailability(t *testing.T) {
	t.Run("200_ok_and_target_hit", func(t *testing.T) {
		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if r.URL.Path != "/v1/models" {
				t.Fatalf("unexpected path %s", r.URL.Path)
			}
			_, _ = w.Write([]byte(`{"object":"list","data":[{"id":"model-a"},{"id":"model-b"}]}`))
		}))
		defer server.Close()

		adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
		res, err := adapter.ProbeProvider(context.Background(), "model-a")
		if err != nil {
			t.Fatalf("ProbeProvider failed: %v", err)
		}
		if res.Status != runtime.ProviderStatusAvailable {
			t.Errorf("expected Status available, got %s", res.Status)
		}
		if len(res.Targets) != 2 || res.Targets[0] != "model-a" {
			t.Errorf("unexpected Targets: %+v", res.Targets)
		}
	})

	t.Run("200_ok_and_target_miss", func(t *testing.T) {
		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			_, _ = w.Write([]byte(`{"object":"list","data":[{"id":"model-a"}]}`))
		}))
		defer server.Close()

		adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
		res, err := adapter.ProbeProvider(context.Background(), "model-b")
		if err != nil {
			t.Fatalf("ProbeProvider failed: %v", err)
		}
		if res.Status != runtime.ProviderStatusUnavailable {
			t.Errorf("expected Status unavailable, got %s", res.Status)
		}
		if !strings.Contains(res.Detail, "not found") {
			t.Errorf("expected 'not found' in detail, got %s", res.Detail)
		}
	})

	t.Run("500_internal_error", func(t *testing.T) {
		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(http.StatusInternalServerError)
		}))
		defer server.Close()

		adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
		res, err := adapter.ProbeProvider(context.Background(), "model-a")
		if err != nil {
			t.Fatalf("ProbeProvider failed: %v", err)
		}
		if res.Status != runtime.ProviderStatusUnavailable {
			t.Errorf("expected Status unavailable, got %s", res.Status)
		}
	})

	t.Run("empty_target", func(t *testing.T) {
		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			_, _ = w.Write([]byte(`{"object":"list","data":[{"id":"model-a"}]}`))
		}))
		defer server.Close()

		adapter := New(config.VllmConf{Endpoint: server.URL}, zap.NewNop())
		res, err := adapter.ProbeProvider(context.Background(), "")
		if err != nil {
			t.Fatalf("ProbeProvider failed: %v", err)
		}
		if res.Status != runtime.ProviderStatusAvailable {
			t.Errorf("expected Status available, got %s", res.Status)
		}
	})
}