package httpclient

import (
	"errors"
	"io"
	"net/http"
	"strings"
	"sync/atomic"
	"testing"
	"time"

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

type roundTripFunc func(*http.Request) (*http.Response, error)

func (f roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
	return f(req)
}

func TestValidatedTransport_CacheHostValidation(t *testing.T) {
	originalValidate := validateResolvedIP
	defer func() { validateResolvedIP = originalValidate }()

	var validateCalls int32
	validateResolvedIP = func(host string) error {
		atomic.AddInt32(&validateCalls, 1)
		require.Equal(t, "api.openai.com", host)
		return nil
	}

	var baseCalls int32
	base := roundTripFunc(func(_ *http.Request) (*http.Response, error) {
		atomic.AddInt32(&baseCalls, 1)
		return &http.Response{
			StatusCode: http.StatusOK,
			Body:       io.NopCloser(strings.NewReader(`{}`)),
			Header:     make(http.Header),
		}, nil
	})

	now := time.Unix(1730000000, 0)
	transport := newValidatedTransport(base)
	transport.now = func() time.Time { return now }

	req, err := http.NewRequest(http.MethodGet, "https://api.openai.com/v1/responses", nil)
	require.NoError(t, err)

	_, err = transport.RoundTrip(req)
	require.NoError(t, err)
	_, err = transport.RoundTrip(req)
	require.NoError(t, err)

	require.Equal(t, int32(1), atomic.LoadInt32(&validateCalls))
	require.Equal(t, int32(2), atomic.LoadInt32(&baseCalls))
}

func TestValidatedTransport_ExpiredCacheTriggersRevalidation(t *testing.T) {
	originalValidate := validateResolvedIP
	defer func() { validateResolvedIP = originalValidate }()

	var validateCalls int32
	validateResolvedIP = func(_ string) error {
		atomic.AddInt32(&validateCalls, 1)
		return nil
	}

	base := roundTripFunc(func(_ *http.Request) (*http.Response, error) {
		return &http.Response{
			StatusCode: http.StatusOK,
			Body:       io.NopCloser(strings.NewReader(`{}`)),
			Header:     make(http.Header),
		}, nil
	})

	now := time.Unix(1730001000, 0)
	transport := newValidatedTransport(base)
	transport.now = func() time.Time { return now }

	req, err := http.NewRequest(http.MethodGet, "https://api.openai.com/v1/responses", nil)
	require.NoError(t, err)

	_, err = transport.RoundTrip(req)
	require.NoError(t, err)

	now = now.Add(validatedHostTTL + time.Second)
	_, err = transport.RoundTrip(req)
	require.NoError(t, err)

	require.Equal(t, int32(2), atomic.LoadInt32(&validateCalls))
}

func TestValidatedTransport_ValidationErrorStopsRoundTrip(t *testing.T) {
	originalValidate := validateResolvedIP
	defer func() { validateResolvedIP = originalValidate }()

	expectedErr := errors.New("dns rebinding rejected")
	validateResolvedIP = func(_ string) error {
		return expectedErr
	}

	var baseCalls int32
	base := roundTripFunc(func(_ *http.Request) (*http.Response, error) {
		atomic.AddInt32(&baseCalls, 1)
		return &http.Response{StatusCode: http.StatusOK, Body: io.NopCloser(strings.NewReader(`{}`))}, nil
	})

	transport := newValidatedTransport(base)
	req, err := http.NewRequest(http.MethodGet, "https://api.openai.com/v1/responses", nil)
	require.NoError(t, err)

	_, err = transport.RoundTrip(req)
	require.ErrorIs(t, err, expectedErr)
	require.Equal(t, int32(0), atomic.LoadInt32(&baseCalls))
}

func TestBuildClientKey(t *testing.T) {
	opts1 := Options{
		ProxyURL:              "http://proxy:8080",
		Timeout:               30 * time.Second,
		ResponseHeaderTimeout: 10 * time.Second,
		InsecureSkipVerify:    false,
		ValidateResolvedIP:    true,
		AllowPrivateHosts:     false,
		MaxIdleConns:          100,
		MaxIdleConnsPerHost:   10,
		MaxConnsPerHost:       0,
	}

	key1 := buildClientKey(opts1)
	require.NotEmpty(t, key1)

	// Same options should produce same key
	key2 := buildClientKey(opts1)
	require.Equal(t, key1, key2)

	// Different options should produce different key
	opts2 := opts1
	opts2.Timeout = 60 * time.Second
	key3 := buildClientKey(opts2)
	require.NotEqual(t, key1, key3)
}

func TestBuildClientKeyTrimsSpaces(t *testing.T) {
	opts1 := Options{ProxyURL: "http://proxy:8080"}
	opts2 := Options{ProxyURL: "  http://proxy:8080  "}

	key1 := buildClientKey(opts1)
	key2 := buildClientKey(opts2)

	require.Equal(t, key1, key2)
}

func TestIsValidatedHost(t *testing.T) {
	base := roundTripFunc(func(_ *http.Request) (*http.Response, error) {
		return &http.Response{StatusCode: http.StatusOK}, nil
	})

	transport := newValidatedTransport(base)
	now := time.Unix(1730000000, 0)
	transport.now = func() time.Time { return now }

	host := "example.com"
	transport.validatedHosts.Store(host, now.Add(validatedHostTTL))

	require.True(t, transport.isValidatedHost(host, now))
	require.False(t, transport.isValidatedHost(host, now.Add(validatedHostTTL+1)))
	require.False(t, transport.isValidatedHost("other.com", now))
}

func TestIsValidatedHostNilTransport(t *testing.T) {
	var transport *validatedTransport
	now := time.Now()
	require.False(t, transport.isValidatedHost("example.com", now))
}

func TestNewValidatedTransport(t *testing.T) {
	base := roundTripFunc(func(_ *http.Request) (*http.Response, error) {
		return &http.Response{StatusCode: http.StatusOK}, nil
	})

	transport := newValidatedTransport(base)
	require.NotNil(t, transport)
	require.NotNil(t, transport.base)
	require.NotNil(t, transport.now)
}

func TestBuildClient(t *testing.T) {
	t.Run("valid options", func(t *testing.T) {
		opts := Options{
			Timeout:            30 * time.Second,
			MaxIdleConns:       100,
			MaxIdleConnsPerHost: 10,
		}

		client, err := buildClient(opts)
		require.NoError(t, err)
		require.NotNil(t, client)
	})

	t.Run("insecure skip verify not allowed", func(t *testing.T) {
		opts := Options{
			InsecureSkipVerify: true,
		}

		_, err := buildClient(opts)
		require.Error(t, err)
		require.Contains(t, err.Error(), "insecure_skip_verify is not allowed")
	})
}

func TestBuildTransport(t *testing.T) {
	t.Run("default values", func(t *testing.T) {
		opts := Options{}
		transport, err := buildTransport(opts)
		require.NoError(t, err)
		require.NotNil(t, transport)
		require.Equal(t, defaultMaxIdleConns, transport.MaxIdleConns)
		require.Equal(t, defaultMaxIdleConnsPerHost, transport.MaxIdleConnsPerHost)
	})

	t.Run("custom values", func(t *testing.T) {
		opts := Options{
			MaxIdleConns:        50,
			MaxIdleConnsPerHost: 5,
		}
		transport, err := buildTransport(opts)
		require.NoError(t, err)
		require.NotNil(t, transport)
		require.Equal(t, 50, transport.MaxIdleConns)
		require.Equal(t, 5, transport.MaxIdleConnsPerHost)
	})
}