package monitoring

import (
	"context"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"
)

func TestPrometheusClient_Query(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/api/v1/query" {
			t.Errorf("unexpected path: %s", r.URL.Path)
		}
		if r.URL.Query().Get("query") != "up" {
			t.Errorf("unexpected query param: %s", r.URL.Query().Get("query"))
		}

		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{
			"status": "success",
			"data": {
				"resultType": "vector",
				"result": [
					{
						"metric": {"__name__": "up", "job": "prometheus", "instance": "localhost:9090"},
						"value": [1234567890, "1"]
					},
					{
						"metric": {"__name__": "up", "job": "node", "instance": "localhost:9100"},
						"value": [1234567890, "0"]
					}
				]
			}
		}`))
	}))
	defer srv.Close()

	client := NewPrometheusClient(srv.URL)
	data, err := client.Query(context.Background(), "up", time.Time{})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if data.ResultType != "vector" {
		t.Errorf("expected resultType=vector, got %s", data.ResultType)
	}
	if len(data.Result) != 2 {
		t.Fatalf("expected 2 results, got %d", len(data.Result))
	}
	if data.Result[0].Metric["job"] != "prometheus" {
		t.Errorf("expected job=prometheus, got %s", data.Result[0].Metric["job"])
	}
}

func TestPrometheusClient_QueryError(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{
			"status": "error",
			"errorType": "bad_data",
			"error": "invalid expression"
		}`))
	}))
	defer srv.Close()

	client := NewPrometheusClient(srv.URL)
	_, err := client.Query(context.Background(), "invalid{", time.Time{})
	if err == nil {
		t.Fatal("expected error, got nil")
	}
	if !contains(err.Error(), "invalid expression") {
		t.Errorf("expected error to contain 'invalid expression', got: %s", err.Error())
	}
}

func TestPrometheusClient_LabelValues(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/api/v1/label/__name__/values" {
			t.Errorf("unexpected path: %s", r.URL.Path)
		}

		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{
			"status": "success",
			"data": ["up", "node_cpu_seconds_total", "prometheus_build_info"]
		}`))
	}))
	defer srv.Close()

	client := NewPrometheusClient(srv.URL)
	values, err := client.LabelValues(context.Background(), "__name__")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if len(values) != 3 {
		t.Fatalf("expected 3 values, got %d", len(values))
	}
	if values[0] != "up" {
		t.Errorf("expected first value=up, got %s", values[0])
	}
}

func TestPrometheusClient_Metadata(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/api/v1/metadata" {
			t.Errorf("unexpected path: %s", r.URL.Path)
		}

		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{
			"status": "success",
			"data": {
				"up": [{"type": "gauge", "help": "Whether the target is up.", "unit": ""}],
				"node_cpu_seconds_total": [{"type": "counter", "help": "CPU seconds spent.", "unit": "seconds"}]
			}
		}`))
	}))
	defer srv.Close()

	client := NewPrometheusClient(srv.URL)
	metadata, err := client.Metadata(context.Background(), "")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if len(metadata) != 2 {
		t.Fatalf("expected 2 metrics, got %d", len(metadata))
	}
	if metadata["up"][0].Type != "gauge" {
		t.Errorf("expected up type=gauge, got %s", metadata["up"][0].Type)
	}
}

func TestPrometheusClient_Targets(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/api/v1/targets" {
			t.Errorf("unexpected path: %s", r.URL.Path)
		}

		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{
			"status": "success",
			"data": {
				"activeTargets": [
					{
						"labels": {"instance": "localhost:9090", "job": "prometheus"},
						"scrapePool": "prometheus",
						"scrapeUrl": "http://localhost:9090/metrics",
						"globalUrl": "http://localhost:9090/metrics",
						"lastError": "",
						"lastScrape": "2024-01-01T00:00:00Z",
						"lastScrapeDuration": 0.01,
						"health": "up",
						"scrapeInterval": "15s",
						"scrapeTimeout": "10s"
					}
				],
				"droppedTargets": []
			}
		}`))
	}))
	defer srv.Close()

	client := NewPrometheusClient(srv.URL)
	data, err := client.Targets(context.Background())
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if len(data.ActiveTargets) != 1 {
		t.Fatalf("expected 1 active target, got %d", len(data.ActiveTargets))
	}
	if data.ActiveTargets[0].Health != "up" {
		t.Errorf("expected health=up, got %s", data.ActiveTargets[0].Health)
	}
}

func TestPrometheusClient_HTTPError(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
		_, _ = w.Write([]byte("internal error"))
	}))
	defer srv.Close()

	client := NewPrometheusClient(srv.URL)
	_, err := client.Query(context.Background(), "up", time.Time{})
	if err == nil {
		t.Fatal("expected error, got nil")
	}
	if !contains(err.Error(), "500") {
		t.Errorf("expected error to contain status code, got: %s", err.Error())
	}
}

func contains(s, substr string) bool {
	return len(s) >= len(substr) && searchString(s, substr)
}

func searchString(s, substr string) bool {
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}