package handler

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"testing"

	"gcy_hpc_server/internal/service"
	"gcy_hpc_server/internal/slurm"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"go.uber.org/zap/zaptest/observer"
)

func setupClusterHandler(slurmHandler http.HandlerFunc) (*httptest.Server, *ClusterHandler) {
	srv := httptest.NewServer(slurmHandler)
	client, _ := slurm.NewClient(srv.URL, srv.Client())
	clusterSvc := service.NewClusterService(client, zap.NewNop())
	return srv, NewClusterHandler(clusterSvc, zap.NewNop())
}

func setupClusterHandlerWithObserver(slurmHandler http.HandlerFunc) (*httptest.Server, *ClusterHandler, *observer.ObservedLogs) {
	core, recorded := observer.New(zapcore.DebugLevel)
	l := zap.New(core)
	srv := httptest.NewServer(slurmHandler)
	client, _ := slurm.NewClient(srv.URL, srv.Client())
	clusterSvc := service.NewClusterService(client, l)
	return srv, NewClusterHandler(clusterSvc, l), recorded
}

func setupClusterRouter(h *ClusterHandler) *gin.Engine {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	v1 := r.Group("/api/v1")
	v1.GET("/nodes", h.GetNodes)
	v1.GET("/nodes/:name", h.GetNode)
	v1.GET("/partitions", h.GetPartitions)
	v1.GET("/partitions/:name", h.GetPartition)
	v1.GET("/diag", h.GetDiag)
	return r
}

func TestGetNodes_Success(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"nodes": []map[string]interface{}{
				{"name": "node1", "state": []string{"IDLE"}, "cpus": 64, "real_memory": 128000},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var resp map[string]interface{}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("failed to parse response: %v", err)
	}
	if resp["success"] != true {
		t.Fatal("expected success=true")
	}
}

func TestGetNode_Success(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"nodes": []map[string]interface{}{
				{"name": "node1", "state": []string{"IDLE"}, "cpus": 64, "real_memory": 128000},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes/node1", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var resp map[string]interface{}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("failed to parse response: %v", err)
	}
	if resp["success"] != true {
		t.Fatal("expected success=true")
	}
}

func TestGetNode_NotFound(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"nodes":       []map[string]interface{}{},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes/nonexistent", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}
}

func TestGetPartitions_Success(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"partitions": []map[string]interface{}{
				{
					"name": "normal",
					"partition": map[string]interface{}{
						"state": []string{"UP"},
					},
					"nodes": map[string]interface{}{
						"configured": "node[1-10]",
						"total":      int32(10),
					},
					"cpus": map[string]interface{}{
						"total": int32(640),
					},
					"maximums": map[string]interface{}{
						"time": map[string]interface{}{"number": int64(60)},
					},
				},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var resp map[string]interface{}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("failed to parse response: %v", err)
	}
	if resp["success"] != true {
		t.Fatal("expected success=true")
	}
}

func TestGetPartition_Success(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"partitions": []map[string]interface{}{
				{
					"name": "normal",
					"partition": map[string]interface{}{
						"state": []string{"UP"},
					},
					"nodes": map[string]interface{}{
						"configured": "node[1-10]",
						"total":      int32(10),
					},
					"cpus": map[string]interface{}{
						"total": int32(640),
					},
					"maximums": map[string]interface{}{
						"time": map[string]interface{}{"number": int64(60)},
					},
				},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions/normal", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var resp map[string]interface{}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("failed to parse response: %v", err)
	}
	if resp["success"] != true {
		t.Fatal("expected success=true")
	}
}

func TestGetPartition_NotFound(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"partitions":  []map[string]interface{}{},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions/nonexistent", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}
}

func TestGetDiag_Success(t *testing.T) {
	srv, h := setupClusterHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"statistics": map[string]interface{}{
				"server_thread_count":  3,
				"agent_queue_size":     0,
				"jobs_submitted":       100,
				"jobs_started":         90,
				"jobs_completed":       85,
				"schedule_cycle_last":  10,
				"schedule_cycle_total": 500,
			},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/diag", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var resp map[string]interface{}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("failed to parse response: %v", err)
	}
	if resp["success"] != true {
		t.Fatal("expected success=true")
	}
}

// --- Logging tests ---

func TestClusterHandler_GetNodes_InternalError_LogsError(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprint(w, `{"errors":[{"error":"internal"}]}`)
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d", w.Code)
	}

	handlerLogs := recorded.FilterMessage("handler error")
	if handlerLogs.Len() != 1 {
		t.Fatalf("expected 1 handler error log, got %d", handlerLogs.Len())
	}
	entry := handlerLogs.All()[0]
	if entry.Level != zapcore.ErrorLevel {
		t.Fatalf("expected Error level, got %v", entry.Level)
	}
	assertField(t, entry.Context, "method", "GetNodes")
}

func TestClusterHandler_GetNodes_Success_NoLogs(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"nodes": []map[string]interface{}{
				{"name": "node1"},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if recorded.Len() != 0 {
		t.Fatalf("expected 0 log entries on success, got %d", recorded.Len())
	}
}

func TestClusterHandler_GetNode_InternalError_LogsError(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprint(w, `{"errors":[{"error":"internal"}]}`)
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes/node1", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d", w.Code)
	}

	handlerLogs := recorded.FilterMessage("handler error")
	if handlerLogs.Len() != 1 {
		t.Fatalf("expected 1 handler error log, got %d", handlerLogs.Len())
	}
	entry := handlerLogs.All()[0]
	if entry.Level != zapcore.ErrorLevel {
		t.Fatalf("expected Error level, got %v", entry.Level)
	}
	assertField(t, entry.Context, "method", "GetNode")
}

func TestClusterHandler_GetNode_NotFound_LogsWarn(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"nodes":       []map[string]interface{}{},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes/nonexistent", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}

	if recorded.Len() != 1 {
		t.Fatalf("expected 1 log entry, got %d", recorded.Len())
	}
	entry := recorded.All()[0]
	if entry.Level != zapcore.WarnLevel {
		t.Fatalf("expected Warn level, got %v", entry.Level)
	}
	if entry.Message != "not found" {
		t.Fatalf("expected message 'not found', got %q", entry.Message)
	}
	assertField(t, entry.Context, "method", "GetNode")
	assertField(t, entry.Context, "name", "nonexistent")
}

func TestClusterHandler_GetNode_Success_NoLogs(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"nodes": []map[string]interface{}{
				{"name": "node1", "state": []string{"IDLE"}, "cpus": 64, "real_memory": 128000},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/nodes/node1", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if recorded.Len() != 0 {
		t.Fatalf("expected 0 log entries on success, got %d", recorded.Len())
	}
}

func TestClusterHandler_GetPartitions_InternalError_LogsError(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprint(w, `{"errors":[{"error":"internal"}]}`)
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d", w.Code)
	}

	handlerLogs := recorded.FilterMessage("handler error")
	if handlerLogs.Len() != 1 {
		t.Fatalf("expected 1 handler error log, got %d", handlerLogs.Len())
	}
	entry := handlerLogs.All()[0]
	if entry.Level != zapcore.ErrorLevel {
		t.Fatalf("expected Error level, got %v", entry.Level)
	}
	assertField(t, entry.Context, "method", "GetPartitions")
}

func TestClusterHandler_GetPartitions_Success_NoLogs(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"partitions": []map[string]interface{}{
				{"name": "normal"},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if recorded.Len() != 0 {
		t.Fatalf("expected 0 log entries on success, got %d", recorded.Len())
	}
}

func TestClusterHandler_GetPartition_InternalError_LogsError(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprint(w, `{"errors":[{"error":"internal"}]}`)
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions/normal", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d", w.Code)
	}

	handlerLogs := recorded.FilterMessage("handler error")
	if handlerLogs.Len() != 1 {
		t.Fatalf("expected 1 handler error log, got %d", handlerLogs.Len())
	}
	entry := handlerLogs.All()[0]
	if entry.Level != zapcore.ErrorLevel {
		t.Fatalf("expected Error level, got %v", entry.Level)
	}
	assertField(t, entry.Context, "method", "GetPartition")
}

func TestClusterHandler_GetPartition_NotFound_LogsWarn(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"partitions":  []map[string]interface{}{},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions/nonexistent", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}

	if recorded.Len() != 1 {
		t.Fatalf("expected 1 log entry, got %d", recorded.Len())
	}
	entry := recorded.All()[0]
	if entry.Level != zapcore.WarnLevel {
		t.Fatalf("expected Warn level, got %v", entry.Level)
	}
	if entry.Message != "not found" {
		t.Fatalf("expected message 'not found', got %q", entry.Message)
	}
	assertField(t, entry.Context, "method", "GetPartition")
	assertField(t, entry.Context, "name", "nonexistent")
}

func TestClusterHandler_GetPartition_Success_NoLogs(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"partitions": []map[string]interface{}{
				{
					"name": "normal",
					"partition": map[string]interface{}{
						"state": []string{"UP"},
					},
					"nodes": map[string]interface{}{
						"configured": "node[1-10]",
						"total":      int32(10),
					},
					"cpus": map[string]interface{}{
						"total": int32(640),
					},
					"maximums": map[string]interface{}{
						"time": map[string]interface{}{"number": int64(60)},
					},
				},
			},
			"last_update": map[string]interface{}{},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/partitions/normal", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if recorded.Len() != 0 {
		t.Fatalf("expected 0 log entries on success, got %d", recorded.Len())
	}
}

func TestClusterHandler_GetDiag_InternalError_LogsError(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprint(w, `{"errors":[{"error":"internal"}]}`)
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/diag", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d", w.Code)
	}

	handlerLogs := recorded.FilterMessage("handler error")
	if handlerLogs.Len() != 1 {
		t.Fatalf("expected 1 handler error log, got %d", handlerLogs.Len())
	}
	entry := handlerLogs.All()[0]
	if entry.Level != zapcore.ErrorLevel {
		t.Fatalf("expected Error level, got %v", entry.Level)
	}
	assertField(t, entry.Context, "method", "GetDiag")
}

func TestClusterHandler_GetDiag_Success_NoLogs(t *testing.T) {
	srv, h, recorded := setupClusterHandlerWithObserver(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"statistics": map[string]interface{}{
				"server_thread_count":  3,
				"agent_queue_size":     0,
				"jobs_submitted":       100,
				"jobs_started":         90,
				"jobs_completed":       85,
				"schedule_cycle_last":  10,
				"schedule_cycle_total": 500,
			},
		})
	}))
	defer srv.Close()

	router := setupClusterRouter(h)
	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/api/v1/diag", nil)
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	if recorded.Len() != 0 {
		t.Fatalf("expected 0 log entries on success, got %d", recorded.Len())
	}
}

// assertField checks that a zap Field slice contains a string field with the given key and value.
func assertField(t *testing.T, fields []zapcore.Field, key, value string) {
	t.Helper()
	for _, f := range fields {
		if f.Key == key && f.String == value {
			return
		}
	}
	t.Fatalf("expected field %q=%q in context, got %v", key, value, fields)
}