package api

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"

	"fission-console/internal/fission"
	"fission-console/internal/model"
	"fission-console/internal/runtime"

	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
)

// validFuncName — RFC 1123 subdomain label: строчные буквы+цифры+дефис, без дефиса в начале/конце.
// Максимум 57 символов (не 63): самый длинный суффикс "-route" (HTTPTrigger) = 6 символов.
// 63 - 6 = 57. Fission webhook требует все связанные объекты <= 63 символов.
var validFuncName = regexp.MustCompile(`^[a-z0-9]([a-z0-9-]*[a-z0-9])?$`)

// maxCodeSize — максимальный размер кода функции (1 MB).
// Выше — не имеет смысла для inline функции; лучше использовать Package с URL.
const maxCodeSize = 1 << 20

// defaultFunctionInvokeTimeout совпадает с дефолтом Fission для spec.functionTimeout.
const defaultFunctionInvokeTimeout = 60 * time.Second





func (s *Server) handleCreateFunction(w http.ResponseWriter, r *http.Request) {
	ns := s.userNS(r)

	var req model.CreateFunctionRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("decode request: %v", err))
		return
	}

	// Гарантируем namespace — на случай прямого вызова API без handleAuth
	nsCtx, nsCancel := context.WithTimeout(r.Context(), 60*time.Second)
	defer nsCancel()
	if err := s.nsManager.EnsureUserNS(nsCtx, ns); err != nil {
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("ensure namespace: %v", err))
		return
	}

	req.Name = strings.TrimSpace(req.Name)
	req.Language = strings.TrimSpace(req.Language)
	req.Environment = strings.TrimSpace(req.Environment)
	req.Code = strings.TrimSpace(req.Code)
	req.Entrypoint = strings.TrimSpace(req.Entrypoint)
	req.Route = strings.TrimSpace(req.Route)

	// Валидация имени
	if req.Name != "" && (!validFuncName.MatchString(req.Name) || len(req.Name) > 57) {
		writeJSONError(w, http.StatusBadRequest, "invalid function name: must match ^[a-z0-9]([a-z0-9-]*[a-z0-9])?$ and be <= 57 chars")
		return
	}
	if len(req.Code) > maxCodeSize {
		writeJSONError(w, http.StatusBadRequest, "code exceeds 1MB limit")
		return
	}

	// Lazy создание Environment по языку (если язык указан явно)
	if req.Language != "" {
		envCtx, envCancel := context.WithTimeout(r.Context(), 15*time.Second)
		defer envCancel()
		envName, err := fission.EnsureEnvironment(envCtx, s.dyn, ns, req.Language)
		if err != nil {
			if strings.Contains(err.Error(), "unsupported language") {
				writeJSONError(w, http.StatusBadRequest, err.Error())
			} else {
				writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("ensure environment: %v", err))
			}
			return
		}
		req.Environment = envName
	}

	if req.Name == "" || req.Environment == "" || req.Code == "" {
		writeJSONError(w, http.StatusBadRequest, "name, environment/language and code are required")
		return
	}
	if req.Entrypoint == "" {
		req.Entrypoint = runtime.DefaultEntrypoint(req.Language)
	}
	if req.Route == "" {
		// Namespace-prefix route: избегаем коллизий между пользователями
		// (разные пользователи могут создать функцию с одинаковым именем)
		nsShort := ns
		if len(nsShort) > 12 {
			nsShort = nsShort[len(nsShort)-12:]
		}
		req.Route = "/" + nsShort + "/" + req.Name
	}
	if !strings.HasPrefix(req.Route, "/") {
		req.Route = "/" + req.Route
	}
	req.Methods = normalizeMethods(req.Methods)
	req.Timeout = normalizeFunctionTimeout(req.Timeout)

	ctx, cancel := context.WithTimeout(r.Context(), 20*time.Second)
	defer cancel()

	// Проверяем что environment существует (мог быть задан явно без language)
	if _, err := s.dyn.Resource(fission.EnvironmentGVR).Namespace(ns).Get(ctx, req.Environment, metav1.GetOptions{}); err != nil {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("environment %q not found: %v", req.Environment, err))
		return
	}

	result, err := fission.CreateFunction(ctx, s.dyn, ns, req)
	if err != nil {
		status := http.StatusBadGateway
		if apierrors.IsAlreadyExists(err) {
			status = http.StatusConflict
		} else if apierrors.IsInvalid(err) {
			status = http.StatusBadRequest
		}
		writeJSONError(w, status, err.Error())
		return
	}

	writeAnyJSON(w, http.StatusCreated, result)
}

// handleGetFunction возвращает детали функции: код, environment, route, methods.
func (s *Server) handleGetFunction(w http.ResponseWriter, r *http.Request, name string) {
	ctx, cancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer cancel()
	ns := s.userNS(r)

	fn, err := s.dyn.Resource(fission.FunctionGVR).Namespace(ns).Get(ctx, name, metav1.GetOptions{})
	if err != nil {
		status := http.StatusBadGateway
		if apierrors.IsNotFound(err) {
			status = http.StatusNotFound
		}
		writeJSONError(w, status, fmt.Sprintf("get function %q: %v", name, err))
		return
	}

	packageName, _, _ := unstructured.NestedString(fn.Object, "spec", "package", "packageref", "name")
	environment, _, _ := unstructured.NestedString(fn.Object, "spec", "environment", "name")
	entrypoint, _, _ := unstructured.NestedString(fn.Object, "spec", "package", "functionName")
	functionTimeout, foundTimeout, _ := unstructured.NestedInt64(fn.Object, "spec", "functionTimeout")
	if !foundTimeout || functionTimeout <= 0 {
		functionTimeout = int64(defaultFunctionInvokeTimeout / time.Second)
	}

	// Извлекаем исходный код из Package (пробуем source.literal, потом deployment.literal, потом url)
	code := ""
	if packageName != "" {
		pkg, pkgErr := s.dyn.Resource(fission.PackageGVR).Namespace(ns).Get(ctx, packageName, metav1.GetOptions{})
		if pkgErr == nil {
			code = extractPackageSourceCode(ctx, s.http, pkg)
		}
	}

	// Ищем HTTPTrigger для получения route и methods
	route := ""
	methods := []string{}
	triggers, trigErr := s.dyn.Resource(fission.HTTPTrigGVR).Namespace(ns).List(ctx, metav1.ListOptions{})
	if trigErr == nil {
		for _, trig := range triggers.Items {
			refName, _, _ := unstructured.NestedString(trig.Object, "spec", "functionref", "name")
			if refName != name {
				continue
			}
			route, _, _ = unstructured.NestedString(trig.Object, "spec", "relativeurl")
			methods, _, _ = unstructured.NestedStringSlice(trig.Object, "spec", "methods")
			break
		}
	}

	writeAnyJSON(w, http.StatusOK, map[string]any{
		"name":        name,
		"namespace":   ns,
		"environment": environment,
		"package":     packageName,
		"entrypoint":  entrypoint,
		"timeout":     functionTimeout,
		"created_at":  functionTimestampResponse(fn)["created_at"],
		"updated_at":  functionTimestampResponse(fn)["updated_at"],
		"code":        code,
		"route":       route,
		"methods":     methods,
		"raw":         fn.Object,
	})
}

func (s *Server) handleUpdateFunctionCode(w http.ResponseWriter, r *http.Request, name string) {
	var req model.UpdateCodeRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("decode request: %v", err))
		return
	}
	req.Code = strings.TrimSpace(req.Code)
	if req.Code == "" {
		writeJSONError(w, http.StatusBadRequest, "code is required")
		return
	}
	if req.Timeout <= 0 {
		req.Timeout = int64(defaultFunctionInvokeTimeout / time.Second)
	}

	ctx, cancel := context.WithTimeout(r.Context(), 20*time.Second)
	defer cancel()
	ns := s.userNS(r)

	result, err := fission.UpdateFunctionCode(ctx, s.dyn, ns, name, req)
	if err != nil {
		status := http.StatusBadGateway
		if apierrors.IsNotFound(err) {
			status = http.StatusNotFound
		}
		writeJSONError(w, status, err.Error())
		return
	}

	writeAnyJSON(w, http.StatusOK, result)
}

// handleInvokeFunction вызывает функцию через Fission router.
// Определяет реальный URL из HTTPTrigger, выбирает метод (POST/GET).
func (s *Server) handleInvokeFunction(w http.ResponseWriter, r *http.Request, name string) {
	bodyBytes, err := io.ReadAll(r.Body)
	if err != nil {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("read request body: %v", err))
		return
	}
	if len(bytes.TrimSpace(bodyBytes)) == 0 {
		bodyBytes = []byte("{}")
	}

	ns := s.userNS(r)
	lookupCtx, lookupCancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer lookupCancel()

	// Проверяем существование функции до вызова — лучше 404 чем непонятный timeout
	fn, err2 := s.dyn.Resource(fission.FunctionGVR).Namespace(ns).Get(lookupCtx, name, metav1.GetOptions{})
	if err2 != nil {
		if apierrors.IsNotFound(err2) {
			writeJSONError(w, http.StatusNotFound, fmt.Sprintf("function %q not found", name))
			return
		}
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("get function %q: %v", name, err2))
		return
	}

	invokeTimeout := s.resolveInvokeTimeout(fn)
	ctx, cancel := context.WithTimeout(r.Context(), invokeTimeout)
	defer cancel()

	// Ищем HTTPTrigger чтобы получить реальный URL и метод
	invokeURL := buildInternalInvokeURL(s.routerURL, ns, name)
	invokeMethod := http.MethodPost
	triggers, err := s.dyn.Resource(fission.HTTPTrigGVR).Namespace(ns).List(ctx, metav1.ListOptions{})
	if err == nil {
		for _, trig := range triggers.Items {
			refName, _, _ := unstructured.NestedString(trig.Object, "spec", "functionref", "name")
			if refName != name {
				continue
			}
			route, _, _ := unstructured.NestedString(trig.Object, "spec", "relativeurl")
			methods, _, _ := unstructured.NestedStringSlice(trig.Object, "spec", "methods")
			hasPost, hasGet := false, false
			for _, m := range methods {
				switch strings.ToUpper(strings.TrimSpace(m)) {
				case http.MethodPost:
					hasPost = true
				case http.MethodGet:
					hasGet = true
				}
			}
			if route != "" {
				if !strings.HasPrefix(route, "/") {
					route = "/" + route
				}
				invokeURL = s.routerURL + route
				// Если функция поддерживает только GET — используем GET
				if !hasPost && hasGet {
					invokeMethod = http.MethodGet
				}
				break
			}
		}
	}

	start := time.Now()
	var invokeBody io.Reader
	if invokeMethod == http.MethodPost {
		invokeBody = bytes.NewReader(bodyBytes)
	}

	req, err := http.NewRequestWithContext(ctx, invokeMethod, invokeURL, invokeBody)
	if err != nil {
		writeJSONError(w, http.StatusInternalServerError, fmt.Sprintf("build invoke request: %v", err))
		return
	}
	if invokeMethod == http.MethodPost {
		req.Header.Set("Content-Type", "application/json")
	}
	if token := s.getRouterToken(); token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}

	resp, err := doRequestWithContextTimeout(s.http, req)
	if err != nil {
		// Отличаем timeout от сетевой ошибки.
		if errors.Is(err, context.DeadlineExceeded) {
			writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke %q timeout after %s", name, invokeTimeout))
			return
		}
		var netErr net.Error
		if errors.As(err, &netErr) && netErr.Timeout() {
			writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke %q timeout after %s", name, invokeTimeout))
			return
		}
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke %q: %v", name, err))
		return
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)
	writeAnyJSON(w, http.StatusOK, map[string]any{
		"status":       resp.StatusCode,
		"latency_ms":   time.Since(start).Milliseconds(),
		"invoke_url":   invokeURL,
		"response_raw": string(respBody),
	})
}

func buildInternalInvokeURL(routerURL, namespace, functionName string) string {
	if namespace == "default" || namespace == "" {
		return fmt.Sprintf("%s/fission-function/%s", routerURL, functionName)
	}
	return fmt.Sprintf("%s/fission-function/%s/%s", routerURL, namespace, functionName)
}

// handleFissionFunctionGateway принимает внутренние invoke-запросы timer/router
// и проксирует их через console в upstream router с корректным router JWT.
func (s *Server) handleFissionFunctionGateway(w http.ResponseWriter, r *http.Request) {
	rawPath := strings.Trim(strings.TrimPrefix(r.URL.Path, "/fission-function"), "/")
	if rawPath == "" {
		http.NotFound(w, r)
		return
	}

	parts := strings.Split(rawPath, "/")
	namespace := s.ns
	functionName := ""
	remainingPath := ""

	if len(parts) == 1 {
		functionName = strings.TrimSpace(parts[0])
	} else {
		namespace = strings.TrimSpace(parts[0])
		functionName = strings.TrimSpace(parts[1])
		if len(parts) > 2 {
			remainingPath = "/" + strings.Join(parts[2:], "/")
		}
	}

	if namespace == "" || functionName == "" {
		writeJSONError(w, http.StatusBadRequest, "namespace and function name are required")
		return
	}

	s.invokeInternalFunction(w, r, namespace, functionName, remainingPath)
}

func (s *Server) invokeInternalFunction(w http.ResponseWriter, r *http.Request, namespace, functionName, extraPath string) {
	bodyBytes, err := io.ReadAll(r.Body)
	if err != nil {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("read request body: %v", err))
		return
	}
	if len(bytes.TrimSpace(bodyBytes)) == 0 {
		bodyBytes = []byte("{}")
	}

	lookupCtx, lookupCancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer lookupCancel()

	fn, err := s.dyn.Resource(fission.FunctionGVR).Namespace(namespace).Get(lookupCtx, functionName, metav1.GetOptions{})
	if err != nil {
		if apierrors.IsNotFound(err) {
			writeJSONError(w, http.StatusNotFound, fmt.Sprintf("function %q not found", functionName))
			return
		}
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("get function %q: %v", functionName, err))
		return
	}

	invokeTimeout := s.resolveInvokeTimeout(fn)
	ctx, cancel := context.WithTimeout(r.Context(), invokeTimeout)
	defer cancel()

	invokeURL := buildInternalInvokeURL(s.routerURL, namespace, functionName) + extraPath
	if r.URL.RawQuery != "" {
		invokeURL += "?" + r.URL.RawQuery
	}

	var invokeBody io.Reader
	if shouldForwardRequestBody(r.Method) {
		invokeBody = bytes.NewReader(bodyBytes)
	}

	req, err := http.NewRequestWithContext(ctx, r.Method, invokeURL, invokeBody)
	if err != nil {
		writeJSONError(w, http.StatusInternalServerError, fmt.Sprintf("build invoke request: %v", err))
		return
	}
	if shouldForwardRequestBody(r.Method) {
		req.Header.Set("Content-Type", "application/json")
	}
	copyProxyRequestHeaders(req.Header, r.Header)
	if token := s.getRouterToken(); token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}

	start := time.Now()
	resp, err := doRequestWithContextTimeout(s.http, req)
	if err != nil {
		if errors.Is(err, context.DeadlineExceeded) {
			writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke %q timeout after %s", functionName, invokeTimeout))
			return
		}
		var netErr net.Error
		if errors.As(err, &netErr) && netErr.Timeout() {
			writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke %q timeout after %s", functionName, invokeTimeout))
			return
		}
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke %q: %v", functionName, err))
		return
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)
	writeAnyJSON(w, http.StatusOK, map[string]any{
		"status":       resp.StatusCode,
		"latency_ms":   time.Since(start).Milliseconds(),
		"invoke_url":   invokeURL,
		"response_raw": string(respBody),
	})
}

// handleInvokeRoute даёт пользователю прямой HTTP gateway к своей функции по route.
// Внешний контракт: /fn/<route> + Authorization: Bearer <user-token>.
func (s *Server) handleInvokeRoute(w http.ResponseWriter, r *http.Request) {
	route := normalizeRoute(strings.TrimPrefix(r.URL.Path, "/fn"))
	if route == "/" {
		writeJSONError(w, http.StatusBadRequest, "route is required")
		return
	}

	ns := s.userNS(r)
	lookupCtx, lookupCancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer lookupCancel()

	triggers, err := s.dyn.Resource(fission.HTTPTrigGVR).Namespace(ns).List(lookupCtx, metav1.ListOptions{})
	if err != nil {
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("list httptriggers: %v", err))
		return
	}

	matchedFunction := ""
	allowedMethods := make([]string, 0, 4)
	for _, trig := range triggers.Items {
		trigRoute, _, _ := unstructured.NestedString(trig.Object, "spec", "relativeurl")
		if normalizeRoute(trigRoute) != route {
			continue
		}
		methods, _, _ := unstructured.NestedStringSlice(trig.Object, "spec", "methods")
		allowedMethods = appendUniqueMethods(allowedMethods, methods)
		if !routeAllowsMethod(methods, r.Method) {
			continue
		}
		matchedFunction, _, _ = unstructured.NestedString(trig.Object, "spec", "functionref", "name")
		if matchedFunction != "" {
			break
		}
	}

	if matchedFunction == "" {
		if len(allowedMethods) > 0 {
			w.Header().Set("Allow", strings.Join(allowedMethods, ", "))
			writeJSONError(w, http.StatusMethodNotAllowed, fmt.Sprintf("route %q does not allow method %s", route, r.Method))
			return
		}
		writeJSONError(w, http.StatusNotFound, fmt.Sprintf("route %q not found", route))
		return
	}

	fn, err := s.dyn.Resource(fission.FunctionGVR).Namespace(ns).Get(lookupCtx, matchedFunction, metav1.GetOptions{})
	if err != nil {
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("get function %q: %v", matchedFunction, err))
		return
	}

	bodyBytes, err := io.ReadAll(r.Body)
	if err != nil {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("read request body: %v", err))
		return
	}

	invokeTimeout := s.resolveInvokeTimeout(fn)
	ctx, cancel := context.WithTimeout(r.Context(), invokeTimeout)
	defer cancel()

	invokeURL := s.routerURL + route
	if r.URL.RawQuery != "" {
		invokeURL += "?" + r.URL.RawQuery
	}

	var invokeBody io.Reader
	if shouldForwardRequestBody(r.Method) {
		invokeBody = bytes.NewReader(bodyBytes)
	}

	req, err := http.NewRequestWithContext(ctx, r.Method, invokeURL, invokeBody)
	if err != nil {
		writeJSONError(w, http.StatusInternalServerError, fmt.Sprintf("build invoke request: %v", err))
		return
	}
	copyProxyRequestHeaders(req.Header, r.Header)
	if token := s.getRouterToken(); token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}

	resp, err := doRequestWithContextTimeout(s.http, req)
	if err != nil {
		if errors.Is(err, context.DeadlineExceeded) {
			writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke route %q timeout after %s", route, invokeTimeout))
			return
		}
		var netErr net.Error
		if errors.As(err, &netErr) && netErr.Timeout() {
			writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke route %q timeout after %s", route, invokeTimeout))
			return
		}
		writeJSONError(w, http.StatusBadGateway, fmt.Sprintf("invoke route %q: %v", route, err))
		return
	}
	defer resp.Body.Close()

	copyProxyResponseHeaders(w.Header(), resp.Header)
	w.WriteHeader(resp.StatusCode)
	_, _ = io.Copy(w, resp.Body)
}

func (s *Server) handleDeleteFunction(w http.ResponseWriter, r *http.Request, name string) {
	ctx, cancel := context.WithTimeout(r.Context(), 20*time.Second)
	defer cancel()
	ns := s.userNS(r)

	if err := fission.DeleteFunction(ctx, s.dyn, ns, name); err != nil {
		status := http.StatusBadGateway
		if apierrors.IsNotFound(err) {
			status = http.StatusNotFound
		}
		writeJSONError(w, status, err.Error())
		return
	}

	writeAnyJSON(w, http.StatusOK, map[string]any{"deleted": true, "name": name})
}

// handleAuth обрабатывает POST /console/api/auth.
// Валидирует токен, создаёт namespace, возвращает namespace пользователя.


// parseTTL парсит строку TTL и возвращает время истечения.
// Поддерживаемые форматы: Go duration (1h, 30m, 24h) и дни (1d, 7d, 30d).
// Суффикс "d" не поддерживается стандартным time.ParseDuration — обрабатываем отдельно.
func parseTTL(ttl string) (time.Time, error) {
	if strings.HasSuffix(ttl, "d") {
		days, err := strconv.Atoi(strings.TrimSuffix(ttl, "d"))
		if err != nil || days <= 0 {
			return time.Time{}, fmt.Errorf("invalid days value: %q", ttl)
		}
		return time.Now().Add(time.Duration(days) * 24 * time.Hour), nil
	}
	d, err := time.ParseDuration(ttl)
	if err != nil {
		return time.Time{}, err
	}
	if d <= 0 {
		return time.Time{}, fmt.Errorf("ttl must be positive")
	}
	return time.Now().Add(d), nil
}

// normalizeMethods приводит список HTTP методов к верхнему регистру, убирает дубли.
// Если список пустой или все элементы пустые — возвращает ["GET"].