package devtodev

import (
	"bytes"
	"compress/gzip"
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/klauspost/compress/zstd"
)

func TestSend_NoCompression(t *testing.T) {
	payload := samplePayload()
	expected, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("marshal payload: %v", err)
	}

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			t.Fatalf("method: %s", r.Method)
		}
		if ct := r.Header.Get("Content-Type"); ct != "application/json" {
			t.Fatalf("content-type: %s", ct)
		}
		if r.URL.Query().Get("appId") != "app-123" {
			t.Fatalf("appId: %s", r.URL.Query().Get("appId"))
		}
		got, err := io.ReadAll(r.Body)
		if err != nil {
			t.Fatalf("read body: %v", err)
		}
		if !bytes.Equal(got, expected) {
			t.Fatalf("body mismatch")
		}
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	client := NewClient("app-123")
	client.Endpoint = server.URL

	if err := client.Send(context.Background(), payload); err != nil {
		t.Fatalf("send: %v", err)
	}
}

func TestSend_GzipCompression(t *testing.T) {
	payload := samplePayload()
	expected, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("marshal payload: %v", err)
	}

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if ct := r.Header.Get("Content-Type"); ct != "application/gzip" {
			t.Fatalf("content-type: %s", ct)
		}
		zr, err := gzip.NewReader(r.Body)
		if err != nil {
			t.Fatalf("gzip reader: %v", err)
		}
		got, err := io.ReadAll(zr)
		if err != nil {
			t.Fatalf("read body: %v", err)
		}
		zr.Close()
		if !bytes.Equal(got, expected) {
			t.Fatalf("body mismatch")
		}
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	client := NewClient("app-123")
	client.Endpoint = server.URL
	client.Compression = CompressionGzip

	if err := client.Send(context.Background(), payload); err != nil {
		t.Fatalf("send: %v", err)
	}
}

func TestSend_ZstdCompression(t *testing.T) {
	payload := samplePayload()
	expected, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("marshal payload: %v", err)
	}

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if ct := r.Header.Get("Content-Type"); ct != "application/zstd" {
			t.Fatalf("content-type: %s", ct)
		}
		decoder, err := zstd.NewReader(r.Body)
		if err != nil {
			t.Fatalf("zstd reader: %v", err)
		}
		got, err := io.ReadAll(decoder)
		if err != nil {
			t.Fatalf("read body: %v", err)
		}
		decoder.Close()
		if !bytes.Equal(got, expected) {
			t.Fatalf("body mismatch")
		}
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	client := NewClient("app-123")
	client.Endpoint = server.URL
	client.Compression = CompressionZstd

	if err := client.Send(context.Background(), payload); err != nil {
		t.Fatalf("send: %v", err)
	}
}

func TestValidatePayload(t *testing.T) {
	cases := []struct {
		name    string
		payload Payload
		ok      bool
	}{
		{
			name:    "empty",
			payload: Payload{},
			ok:      false,
		},
		{
			name: "missing device id",
			payload: Payload{
				Reports: []Report{{}},
			},
			ok: false,
		},
		{
			name: "missing packages",
			payload: Payload{
				Reports: []Report{{DeviceID: "d1"}},
			},
			ok: false,
		},
		{
			name: "missing events",
			payload: Payload{
				Reports: []Report{{DeviceID: "d1", Packages: []Package{{}}}},
			},
			ok: false,
		},
		{
			name: "missing code",
			payload: Payload{
				Reports: []Report{{DeviceID: "d1", Packages: []Package{{Events: []Event{{"timestamp": int64(1)}}}}}},
			},
			ok: false,
		},
		{
			name: "missing timestamp",
			payload: Payload{
				Reports: []Report{{DeviceID: "d1", Packages: []Package{{Events: []Event{{"code": "ce"}}}}}},
			},
			ok: false,
		},
		{
			name: "ok",
			payload: Payload{
				Reports: []Report{{DeviceID: "d1", Packages: []Package{{Events: []Event{{"code": "ce", "timestamp": int64(1)}}}}}},
			},
			ok: true,
		},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			err := ValidatePayload(tc.payload)
			if tc.ok && err != nil {
				t.Fatalf("expected ok, got %v", err)
			}
			if !tc.ok && err == nil {
				t.Fatalf("expected error")
			}
		})
	}
}

func TestSendWithResponse_ParsesJSONError(t *testing.T) {
	payload := samplePayload()

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		_, _ = w.Write([]byte(`{"message":"bad request"}`))
	}))
	defer server.Close()

	client := NewClient("app-123")
	client.Endpoint = server.URL
	client.Retry.MaxAttempts = 1

	resp, err := client.SendWithResponse(context.Background(), payload)
	if err == nil {
		t.Fatalf("expected error")
	}
	if resp == nil || resp.StatusCode != http.StatusBadRequest {
		t.Fatalf("unexpected response: %+v", resp)
	}
	var apiErr *APIError
	if !errors.As(err, &apiErr) {
		t.Fatalf("expected APIError, got %T", err)
	}
	if apiErr.Message != "bad request" {
		t.Fatalf("unexpected message: %q", apiErr.Message)
	}
}

func samplePayload() Payload {
	return Payload{
		Reports: []Report{
			{
				DeviceID: "device-123",
				Packages: []Package{
					{
						Language: "en",
						Country:  "US",
						Events: []Event{
							{
								"code":      "ce",
								"timestamp": time.Now().UnixMilli(),
								"level":     5,
								"name":      "custom_event",
								"parameters": map[string]interface{}{
									"level": 5,
								},
							},
						},
					},
				},
			},
		},
	}
}