package provider

import (
	"context"
	"fmt"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"nex/backend/internal/conversion"
)

func TestNewClient(t *testing.T) {
	client := NewClient()
	require.NotNil(t, client)
	assert.NotNil(t, client.httpClient)
	assert.Equal(t, 4096, client.streamCfg.InitialBufferSize)
	assert.Equal(t, 65536, client.streamCfg.MaxBufferSize)
	assert.Equal(t, 100, client.streamCfg.ChannelBufferSize)
}

func TestDefaultStreamConfig(t *testing.T) {
	cfg := DefaultStreamConfig()
	assert.Equal(t, 4096, cfg.InitialBufferSize)
	assert.Equal(t, 65536, cfg.MaxBufferSize)
	assert.Equal(t, 100, cfg.ChannelBufferSize)
}

func TestClient_Send_Success(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		assert.Equal(t, "POST", r.Method)
		assert.Equal(t, "application/json", r.Header.Get("Content-Type"))
		assert.Equal(t, "Bearer test-key", r.Header.Get("Authorization"))
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		w.Write([]byte(`{"id":"test","model":"gpt-4"}`))
	}))
	defer server.Close()

	client := NewClient()
	spec := conversion.HTTPRequestSpec{
		URL:    server.URL + "/v1/chat/completions",
		Method: "POST",
		Headers: map[string]string{
			"Authorization": "Bearer test-key",
			"Content-Type":  "application/json",
		},
		Body: []byte(`{"model":"gpt-4","messages":[]}`),
	}

	result, err := client.Send(context.Background(), spec)
	require.NoError(t, err)
	assert.Equal(t, 200, result.StatusCode)
	assert.Contains(t, string(result.Body), "test")
}

func TestClient_Send_ErrorResponse(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusUnauthorized)
		w.Write([]byte(`{"error":{"message":"Invalid API key"}}`))
	}))
	defer server.Close()

	client := NewClient()
	spec := conversion.HTTPRequestSpec{
		URL:     server.URL + "/v1/chat/completions",
		Method:  "POST",
		Headers: map[string]string{"Authorization": "Bearer bad-key"},
		Body:    []byte(`{}`),
	}

	result, err := client.Send(context.Background(), spec)
	require.NoError(t, err)
	assert.Equal(t, 401, result.StatusCode)
}

func TestClient_Send_ConnectionError(t *testing.T) {
	client := NewClient()
	spec := conversion.HTTPRequestSpec{
		URL:    "http://localhost:1/v1/chat/completions",
		Method: "POST",
	}

	_, err := client.Send(context.Background(), spec)
	assert.Error(t, err)
}

func TestClient_SendStream_CreatesChannel(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	client := NewClient()
	spec := conversion.HTTPRequestSpec{
		URL:     server.URL + "/v1/chat/completions",
		Method:  "POST",
		Headers: map[string]string{"Authorization": "Bearer test-key"},
		Body:    []byte(`{}`),
	}

	eventChan, err := client.SendStream(context.Background(), spec)
	require.NoError(t, err)
	require.NotNil(t, eventChan)

	for range eventChan {
	}
}

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

	client := NewClient()
	spec := conversion.HTTPRequestSpec{
		URL:     server.URL + "/v1/chat/completions",
		Method:  "POST",
		Headers: map[string]string{"Authorization": "Bearer key"},
		Body:    []byte(`{}`),
	}

	_, err := client.SendStream(context.Background(), spec)
	assert.Error(t, err)
}

func TestIsNetworkError(t *testing.T) {
	tests := []struct {
		input string
		want  bool
	}{
		{"connection reset by peer", true},
		{"broken pipe", true},
		{"network is unreachable", true},
		{"timeout waiting for response", true},
		{"unexpected EOF", true},
		{"normal error", false},
		{"", false},
	}
	for _, tt := range tests {
		err := fmt.Errorf("%s", tt.input)
		assert.Equal(t, tt.want, isNetworkError(err), "isNetworkError(%q)", tt.input)
	}
}