package caddytest

import (
	"bytes"
	"context"
	"crypto/tls"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"log"
	"net"
	"net/http"
	"net/http/cookiejar"
	"os"
	"path"
	"reflect"
	"regexp"
	"runtime"
	"strings"
	"testing"
	"time"

	"github.com/aryann/difflib"

	caddycmd "github.com/caddyserver/caddy/v2/cmd"

	"github.com/caddyserver/caddy/v2/caddyconfig"
	// plug in Caddy modules here
	_ "github.com/caddyserver/caddy/v2/modules/standard"
)

// Config store any configuration required to make the tests run
type Config struct {
	// Port we expect caddy to listening on
	AdminPort int
	// Certificates we expect to be loaded before attempting to run the tests
	Certificates []string
	// TestRequestTimeout is the time to wait for a http request to
	TestRequestTimeout time.Duration
	// LoadRequestTimeout is the time to wait for the config to be loaded against the caddy server
	LoadRequestTimeout time.Duration
}

// Default testing values
var Default = Config{
	AdminPort:          2999, // different from what a real server also running on a developer's machine might be
	Certificates:       []string{"/caddy.localhost.crt", "/caddy.localhost.key"},
	TestRequestTimeout: 5 * time.Second,
	LoadRequestTimeout: 5 * time.Second,
}

var (
	matchKey  = regexp.MustCompile(`(/[\w\d\.]+\.key)`)
	matchCert = regexp.MustCompile(`(/[\w\d\.]+\.crt)`)
)

// Tester represents an instance of a test client.
type Tester struct {
	Client       *http.Client
	configLoaded bool
	t            testing.TB
	config       Config
}

// NewTester will create a new testing client with an attached cookie jar
func NewTester(t testing.TB) *Tester {
	jar, err := cookiejar.New(nil)
	if err != nil {
		t.Fatalf("failed to create cookiejar: %s", err)
	}

	return &Tester{
		Client: &http.Client{
			Transport: CreateTestingTransport(),
			Jar:       jar,
			Timeout:   Default.TestRequestTimeout,
		},
		configLoaded: false,
		t:            t,
		config:       Default,
	}
}

// WithDefaultOverrides this will override the default test configuration with the provided values.
func (tc *Tester) WithDefaultOverrides(overrides Config) *Tester {
	if overrides.AdminPort != 0 {
		tc.config.AdminPort = overrides.AdminPort
	}
	if len(overrides.Certificates) > 0 {
		tc.config.Certificates = overrides.Certificates
	}
	if overrides.TestRequestTimeout != 0 {
		tc.config.TestRequestTimeout = overrides.TestRequestTimeout
		tc.Client.Timeout = overrides.TestRequestTimeout
	}
	if overrides.LoadRequestTimeout != 0 {
		tc.config.LoadRequestTimeout = overrides.LoadRequestTimeout
	}

	return tc
}

type configLoadError struct {
	Response string
}

func (e configLoadError) Error() string { return e.Response }

func timeElapsed(start time.Time, name string) {
	elapsed := time.Since(start)
	log.Printf("%s took %s", name, elapsed)
}

// InitServer this will configure the server with a configurion of a specific
// type. The configType must be either "json" or the adapter type.
func (tc *Tester) InitServer(rawConfig string, configType string) {
	if err := tc.initServer(rawConfig, configType); err != nil {
		tc.t.Logf("failed to load config: %s", err)
		tc.t.Fail()
	}
	if err := tc.ensureConfigRunning(rawConfig, configType); err != nil {
		tc.t.Logf("failed ensuring config is running: %s", err)
		tc.t.Fail()
	}
}

// InitServer this will configure the server with a configurion of a specific
// type. The configType must be either "json" or the adapter type.
func (tc *Tester) initServer(rawConfig string, configType string) error {
	if testing.Short() {
		tc.t.SkipNow()
		return nil
	}

	err := validateTestPrerequisites(tc)
	if err != nil {
		tc.t.Skipf("skipping tests as failed integration prerequisites. %s", err)
		return nil
	}

	tc.t.Cleanup(func() {
		if tc.t.Failed() && tc.configLoaded {
			res, err := http.Get(fmt.Sprintf("http://localhost:%d/config/", tc.config.AdminPort))
			if err != nil {
				tc.t.Log("unable to read the current config")
				return
			}
			defer res.Body.Close()
			body, _ := io.ReadAll(res.Body)

			var out bytes.Buffer
			_ = json.Indent(&out, body, "", "  ")
			tc.t.Logf("----------- failed with config -----------\n%s", out.String())
		}
	})

	rawConfig = prependCaddyFilePath(rawConfig)
	// normalize JSON config
	if configType == "json" {
		tc.t.Logf("Before: %s", rawConfig)
		var conf any
		if err := json.Unmarshal([]byte(rawConfig), &conf); err != nil {
			return err
		}
		c, err := json.Marshal(conf)
		if err != nil {
			return err
		}
		rawConfig = string(c)
		tc.t.Logf("After: %s", rawConfig)
	}
	client := &http.Client{
		Timeout: tc.config.LoadRequestTimeout,
	}
	start := time.Now()
	req, err := http.NewRequest("POST", fmt.Sprintf("http://localhost:%d/load", tc.config.AdminPort), strings.NewReader(rawConfig))
	if err != nil {
		tc.t.Errorf("failed to create request. %s", err)
		return err
	}

	if configType == "json" {
		req.Header.Add("Content-Type", "application/json")
	} else {
		req.Header.Add("Content-Type", "text/"+configType)
	}

	res, err := client.Do(req) //nolint:gosec // no SSRF because URL is hard-coded to localhost, and port comes from config
	if err != nil {
		tc.t.Errorf("unable to contact caddy server. %s", err)
		return err
	}
	timeElapsed(start, "caddytest: config load time")

	defer res.Body.Close()
	body, err := io.ReadAll(res.Body)
	if err != nil {
		tc.t.Errorf("unable to read response. %s", err)
		return err
	}

	if res.StatusCode != 200 {
		return configLoadError{Response: string(body)}
	}

	tc.configLoaded = true
	return nil
}

func (tc *Tester) ensureConfigRunning(rawConfig string, configType string) error {
	expectedBytes := []byte(prependCaddyFilePath(rawConfig))
	if configType != "json" {
		adapter := caddyconfig.GetAdapter(configType)
		if adapter == nil {
			return fmt.Errorf("adapter of config type is missing: %s", configType)
		}
		expectedBytes, _, _ = adapter.Adapt([]byte(rawConfig), nil)
	}

	var expected any
	err := json.Unmarshal(expectedBytes, &expected)
	if err != nil {
		return err
	}

	client := &http.Client{
		Timeout: tc.config.LoadRequestTimeout,
	}

	fetchConfig := func(client *http.Client) any {
		resp, err := client.Get(fmt.Sprintf("http://localhost:%d/config/", tc.config.AdminPort))
		if err != nil {
			return nil
		}
		defer resp.Body.Close()
		actualBytes, err := io.ReadAll(resp.Body)
		if err != nil {
			return nil
		}
		var actual any
		err = json.Unmarshal(actualBytes, &actual)
		if err != nil {
			return nil
		}
		return actual
	}

	for retries := 10; retries > 0; retries-- {
		if reflect.DeepEqual(expected, fetchConfig(client)) {
			return nil
		}
		time.Sleep(1 * time.Second)
	}
	tc.t.Errorf("POSTed configuration isn't active")
	return errors.New("EnsureConfigRunning: POSTed configuration isn't active")
}

const initConfig = `{
	admin localhost:%d
}
`

// validateTestPrerequisites ensures the certificates are available in the
// designated path and Caddy sub-process is running.
func validateTestPrerequisites(tc *Tester) error {
	// check certificates are found
	for _, certName := range tc.config.Certificates {
		if _, err := os.Stat(getIntegrationDir() + certName); errors.Is(err, fs.ErrNotExist) {
			return fmt.Errorf("caddy integration test certificates (%s) not found", certName)
		}
	}

	if isCaddyAdminRunning(tc) != nil {
		// setup the init config file, and set the cleanup afterwards
		f, err := os.CreateTemp("", "")
		if err != nil {
			return err
		}
		tc.t.Cleanup(func() {
			os.Remove(f.Name()) //nolint:gosec // false positive, filename comes from std lib, no path traversal
		})
		if _, err := fmt.Fprintf(f, initConfig, tc.config.AdminPort); err != nil {
			return err
		}

		// start inprocess caddy server
		os.Args = []string{"caddy", "run", "--config", f.Name(), "--adapter", "caddyfile"}
		go func() {
			caddycmd.Main()
		}()

		// wait for caddy to start serving the initial config
		for retries := 10; retries > 0 && isCaddyAdminRunning(tc) != nil; retries-- {
			time.Sleep(1 * time.Second)
		}
	}

	// one more time to return the error
	return isCaddyAdminRunning(tc)
}

func isCaddyAdminRunning(tc *Tester) error {
	// assert that caddy is running
	client := &http.Client{
		Timeout: tc.config.LoadRequestTimeout,
	}
	resp, err := client.Get(fmt.Sprintf("http://localhost:%d/config/", tc.config.AdminPort))
	if err != nil {
		return fmt.Errorf("caddy integration test caddy server not running. Expected to be listening on localhost:%d", tc.config.AdminPort)
	}
	resp.Body.Close()

	return nil
}

func getIntegrationDir() string {
	_, filename, _, ok := runtime.Caller(1)
	if !ok {
		panic("unable to determine the current file path")
	}

	return path.Dir(filename)
}

// use the convention to replace /[certificatename].[crt|key] with the full path
// this helps reduce the noise in test configurations and also allow this
// to run in any path
func prependCaddyFilePath(rawConfig string) string {
	r := matchKey.ReplaceAllString(rawConfig, getIntegrationDir()+"$1")
	r = matchCert.ReplaceAllString(r, getIntegrationDir()+"$1")
	return r
}

// CreateTestingTransport creates a testing transport that forces call dialing connections to happen locally
func CreateTestingTransport() *http.Transport {
	dialer := net.Dialer{
		Timeout:   5 * time.Second,
		KeepAlive: 5 * time.Second,
		DualStack: true,
	}

	dialContext := func(ctx context.Context, network, addr string) (net.Conn, error) {
		parts := strings.Split(addr, ":")
		destAddr := fmt.Sprintf("127.0.0.1:%s", parts[1])
		log.Printf("caddytest: redirecting the dialer from %s to %s", addr, destAddr)
		return dialer.DialContext(ctx, network, destAddr)
	}

	return &http.Transport{
		Proxy:                 http.ProxyFromEnvironment,
		DialContext:           dialContext,
		ForceAttemptHTTP2:     true,
		MaxIdleConns:          100,
		IdleConnTimeout:       90 * time.Second,
		TLSHandshakeTimeout:   5 * time.Second,
		ExpectContinueTimeout: 1 * time.Second,
		TLSClientConfig:       &tls.Config{InsecureSkipVerify: true}, //nolint:gosec
	}
}

// AssertLoadError will load a config and expect an error
func AssertLoadError(t *testing.T, rawConfig string, configType string, expectedError string) {
	t.Helper()

	tc := NewTester(t)

	err := tc.initServer(rawConfig, configType)
	if !strings.Contains(err.Error(), expectedError) {
		t.Errorf("expected error \"%s\" but got \"%s\"", expectedError, err.Error())
	}
}

// AssertRedirect makes a request and asserts the redirection happens
func (tc *Tester) AssertRedirect(requestURI string, expectedToLocation string, expectedStatusCode int) *http.Response {
	tc.t.Helper()

	redirectPolicyFunc := func(req *http.Request, via []*http.Request) error {
		return http.ErrUseLastResponse
	}

	// using the existing client, we override the check redirect policy for this test
	old := tc.Client.CheckRedirect
	tc.Client.CheckRedirect = redirectPolicyFunc
	defer func() { tc.Client.CheckRedirect = old }()

	resp, err := tc.Client.Get(requestURI)
	if err != nil {
		tc.t.Errorf("failed to call server %s", err)
		return nil
	}

	if expectedStatusCode != resp.StatusCode {
		tc.t.Errorf("requesting \"%s\" expected status code: %d but got %d", requestURI, expectedStatusCode, resp.StatusCode)
	}

	loc, err := resp.Location()
	if err != nil {
		tc.t.Errorf("requesting \"%s\" expected location: \"%s\" but got error: %s", requestURI, expectedToLocation, err)
	}
	if loc == nil && expectedToLocation != "" {
		tc.t.Errorf("requesting \"%s\" expected a Location header, but didn't get one", requestURI)
	}
	if loc != nil {
		if expectedToLocation != loc.String() {
			tc.t.Errorf("requesting \"%s\" expected location: \"%s\" but got \"%s\"", requestURI, expectedToLocation, loc.String())
		}
	}

	return resp
}

// CompareAdapt adapts a config and then compares it against an expected result
func CompareAdapt(t testing.TB, filename, rawConfig string, adapterName string, expectedResponse string) bool {
	t.Helper()

	cfgAdapter := caddyconfig.GetAdapter(adapterName)
	if cfgAdapter == nil {
		t.Logf("unrecognized config adapter '%s'", adapterName)
		return false
	}

	options := make(map[string]any)

	result, warnings, err := cfgAdapter.Adapt([]byte(rawConfig), options)
	if err != nil {
		t.Logf("adapting config using %s adapter: %v", adapterName, err)
		return false
	}

	// prettify results to keep tests human-manageable
	var prettyBuf bytes.Buffer
	err = json.Indent(&prettyBuf, result, "", "\t")
	if err != nil {
		return false
	}
	result = prettyBuf.Bytes()

	if len(warnings) > 0 {
		for _, w := range warnings {
			t.Logf("warning: %s:%d: %s: %s", filename, w.Line, w.Directive, w.Message)
		}
	}

	diff := difflib.Diff(
		strings.Split(expectedResponse, "\n"),
		strings.Split(string(result), "\n"))

	// scan for failure
	failed := false
	for _, d := range diff {
		if d.Delta != difflib.Common {
			failed = true
			break
		}
	}

	if failed {
		for _, d := range diff {
			switch d.Delta {
			case difflib.Common:
				fmt.Printf("  %s\n", d.Payload)
			case difflib.LeftOnly:
				fmt.Printf(" - %s\n", d.Payload)
			case difflib.RightOnly:
				fmt.Printf(" + %s\n", d.Payload)
			}
		}
		return false
	}
	return true
}

// AssertAdapt adapts a config and then tests it against an expected result
func AssertAdapt(t testing.TB, rawConfig string, adapterName string, expectedResponse string) {
	t.Helper()

	ok := CompareAdapt(t, "Caddyfile", rawConfig, adapterName, expectedResponse)
	if !ok {
		t.Fail()
	}
}

// Generic request functions

func applyHeaders(t testing.TB, req *http.Request, requestHeaders []string) {
	requestContentType := ""
	for _, requestHeader := range requestHeaders {
		arr := strings.SplitAfterN(requestHeader, ":", 2)
		k := strings.TrimRight(arr[0], ":")
		v := strings.TrimSpace(arr[1])
		if k == "Content-Type" {
			requestContentType = v
		}
		t.Logf("Request header: %s => %s", k, v)
		req.Header.Set(k, v)
	}

	if requestContentType == "" {
		t.Logf("Content-Type header not provided")
	}
}

// AssertResponseCode will execute the request and verify the status code, returns a response for additional assertions
func (tc *Tester) AssertResponseCode(req *http.Request, expectedStatusCode int) *http.Response {
	tc.t.Helper()

	resp, err := tc.Client.Do(req) //nolint:gosec // no SSRFs demonstrated
	if err != nil {
		tc.t.Fatalf("failed to call server %s", err)
	}

	if expectedStatusCode != resp.StatusCode {
		tc.t.Errorf("requesting \"%s\" expected status code: %d but got %d", req.URL.RequestURI(), expectedStatusCode, resp.StatusCode)
	}

	return resp
}

// AssertResponse requests a URI and asserts the status code and body.
func (tc *Tester) AssertResponse(req *http.Request, expectedStatusCode int, expectedBody string) (*http.Response, string) {
	tc.t.Helper()

	resp := tc.AssertResponseCode(req, expectedStatusCode)

	defer resp.Body.Close()
	bytes, err := io.ReadAll(resp.Body)
	if err != nil {
		tc.t.Fatalf("unable to read the response body %s", err)
	}

	body := string(bytes)

	if body != expectedBody {
		tc.t.Errorf("requesting \"%s\" expected response body \"%s\" but got \"%s\"", req.RequestURI, expectedBody, body)
	}

	return resp, body
}

// Verb specific test functions

// AssertGetResponse requests a URI with GET and expects a status code and body text.
func (tc *Tester) AssertGetResponse(requestURI string, expectedStatusCode int, expectedBody string) (*http.Response, string) {
	tc.t.Helper()

	req, err := http.NewRequest("GET", requestURI, nil)
	if err != nil {
		tc.t.Fatalf("unable to create request %s", err)
	}

	return tc.AssertResponse(req, expectedStatusCode, expectedBody)
}

// AssertDeleteResponse requests a URI with DELETE and expects a status code and body text.
func (tc *Tester) AssertDeleteResponse(requestURI string, expectedStatusCode int, expectedBody string) (*http.Response, string) {
	tc.t.Helper()

	req, err := http.NewRequest("DELETE", requestURI, nil)
	if err != nil {
		tc.t.Fatalf("unable to create request %s", err)
	}

	return tc.AssertResponse(req, expectedStatusCode, expectedBody)
}

// AssertPostResponseBody requests a URI with POST and asserts the response code and body.
func (tc *Tester) AssertPostResponseBody(requestURI string, requestHeaders []string, requestBody *bytes.Buffer, expectedStatusCode int, expectedBody string) (*http.Response, string) {
	tc.t.Helper()

	req, err := http.NewRequest("POST", requestURI, requestBody)
	if err != nil {
		tc.t.Errorf("failed to create request %s", err)
		return nil, ""
	}

	applyHeaders(tc.t, req, requestHeaders)

	return tc.AssertResponse(req, expectedStatusCode, expectedBody)
}

// AssertPutResponseBody requests a URI with PUT and asserts the response code and body.
func (tc *Tester) AssertPutResponseBody(requestURI string, requestHeaders []string, requestBody *bytes.Buffer, expectedStatusCode int, expectedBody string) (*http.Response, string) {
	tc.t.Helper()

	req, err := http.NewRequest("PUT", requestURI, requestBody)
	if err != nil {
		tc.t.Errorf("failed to create request %s", err)
		return nil, ""
	}

	applyHeaders(tc.t, req, requestHeaders)

	return tc.AssertResponse(req, expectedStatusCode, expectedBody)
}

// AssertPatchResponseBody requests a URI with PATCH and asserts the response code and body.
func (tc *Tester) AssertPatchResponseBody(requestURI string, requestHeaders []string, requestBody *bytes.Buffer, expectedStatusCode int, expectedBody string) (*http.Response, string) {
	tc.t.Helper()

	req, err := http.NewRequest("PATCH", requestURI, requestBody)
	if err != nil {
		tc.t.Errorf("failed to create request %s", err)
		return nil, ""
	}

	applyHeaders(tc.t, req, requestHeaders)

	return tc.AssertResponse(req, expectedStatusCode, expectedBody)
}
