package httpapi

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/easyai/easyai-ai-gateway/apps/api/internal/auth"
	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
)

func (s *Server) health(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]any{
		"ok":           true,
		"service":      "easyai-ai-gateway",
		"env":          s.cfg.AppEnv,
		"identityMode": s.cfg.IdentityMode,
	})
}

func (s *Server) ready(w http.ResponseWriter, r *http.Request) {
	if err := s.store.Ping(r.Context()); err != nil {
		writeError(w, http.StatusServiceUnavailable, "postgres unavailable")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"ok": true})
}

func (s *Server) me(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	writeJSON(w, http.StatusOK, user)
}

func (s *Server) register(w http.ResponseWriter, r *http.Request) {
	if !s.localIdentityEnabled() {
		writeError(w, http.StatusForbidden, "local registration is disabled")
		return
	}
	var input store.LocalRegisterInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	user, err := s.store.RegisterLocalUser(r.Context(), input)
	if err != nil {
		if errors.Is(err, store.ErrWeakPassword) {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if errors.Is(err, store.ErrInvalidInvitation) {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if errors.Is(err, store.ErrUserAlreadyExists) {
			writeError(w, http.StatusConflict, err.Error())
			return
		}
		s.logger.Error("register local user failed", "error", err)
		writeError(w, http.StatusInternalServerError, "register local user failed")
		return
	}
	s.writeAuthResponse(w, http.StatusCreated, user)
}

func (s *Server) login(w http.ResponseWriter, r *http.Request) {
	if !s.localIdentityEnabled() {
		writeError(w, http.StatusForbidden, "local login is disabled")
		return
	}
	var input store.LocalLoginInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	user, err := s.store.AuthenticateLocalUser(r.Context(), input)
	if err != nil {
		if errors.Is(err, store.ErrInvalidCredentials) {
			writeError(w, http.StatusUnauthorized, "invalid account or password")
			return
		}
		s.logger.Error("login local user failed", "error", err)
		writeError(w, http.StatusInternalServerError, "login failed")
		return
	}
	s.writeAuthResponse(w, http.StatusOK, user)
}

func (s *Server) localIdentityEnabled() bool {
	mode := strings.ToLower(strings.TrimSpace(s.cfg.IdentityMode))
	return mode == "" || mode == "standalone" || mode == "hybrid"
}

func (s *Server) writeAuthResponse(w http.ResponseWriter, status int, user store.GatewayUser) {
	authUser := authUserFromGatewayUser(user)
	const ttl = 24 * time.Hour
	token, err := s.auth.SignJWT(authUser, ttl)
	if err != nil {
		s.logger.Error("sign local jwt failed", "error", err)
		writeError(w, http.StatusInternalServerError, "token sign failed")
		return
	}
	writeJSON(w, status, map[string]any{
		"accessToken": token,
		"tokenType":   "Bearer",
		"expiresIn":   int(ttl.Seconds()),
		"user":        authUser,
	})
}

func authUserFromGatewayUser(user store.GatewayUser) *auth.User {
	roles := user.Roles
	if len(roles) == 0 {
		roles = []string{"user"}
	}
	tenantID := user.TenantID
	if tenantID == "" {
		tenantID = user.TenantKey
	}
	return &auth.User{
		ID:              user.ID,
		Username:        user.Username,
		Roles:           roles,
		TenantID:        tenantID,
		GatewayTenantID: user.GatewayTenantID,
		TenantKey:       user.TenantKey,
		Source:          "gateway",
		GatewayUserID:   user.ID,
		UserGroupID:     user.DefaultUserGroupID,
	}
}

func (s *Server) listPlatforms(w http.ResponseWriter, r *http.Request) {
	platforms, err := s.store.ListPlatforms(r.Context())
	if err != nil {
		s.logger.Error("list platforms failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list platforms failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": platforms})
}

func (s *Server) createPlatform(w http.ResponseWriter, r *http.Request) {
	var input store.CreatePlatformInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	input.Provider = strings.TrimSpace(input.Provider)
	input.Name = strings.TrimSpace(input.Name)
	input.InternalName = strings.TrimSpace(input.InternalName)
	if input.Provider == "" || input.Name == "" {
		writeError(w, http.StatusBadRequest, "provider and name are required")
		return
	}
	if input.AuthType == "" {
		input.AuthType = "bearer"
	}
	platform, err := s.store.CreatePlatform(r.Context(), input)
	if err != nil {
		s.logger.Error("create platform failed", "error", err)
		writeError(w, http.StatusInternalServerError, "create platform failed")
		return
	}
	writeJSON(w, http.StatusCreated, platform)
}

func (s *Server) updatePlatform(w http.ResponseWriter, r *http.Request) {
	var input store.CreatePlatformInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	input.Provider = strings.TrimSpace(input.Provider)
	input.Name = strings.TrimSpace(input.Name)
	input.InternalName = strings.TrimSpace(input.InternalName)
	if input.Provider == "" || input.Name == "" {
		writeError(w, http.StatusBadRequest, "provider and name are required")
		return
	}
	if input.AuthType == "" {
		input.AuthType = "bearer"
	}
	platform, err := s.store.UpdatePlatform(r.Context(), r.PathValue("platformID"), input)
	if err != nil {
		if store.IsNotFound(err) {
			writeError(w, http.StatusNotFound, "platform not found")
			return
		}
		if store.IsUniqueViolation(err) {
			writeError(w, http.StatusConflict, "platform key already exists")
			return
		}
		s.logger.Error("update platform failed", "error", err)
		writeError(w, http.StatusInternalServerError, "update platform failed")
		return
	}
	writeJSON(w, http.StatusOK, platform)
}

func (s *Server) deletePlatform(w http.ResponseWriter, r *http.Request) {
	if err := s.store.DeletePlatform(r.Context(), r.PathValue("platformID")); err != nil {
		if store.IsNotFound(err) {
			writeError(w, http.StatusNotFound, "platform not found")
			return
		}
		s.logger.Error("delete platform failed", "error", err)
		writeError(w, http.StatusInternalServerError, "delete platform failed")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (s *Server) createPlatformModel(w http.ResponseWriter, r *http.Request) {
	var input store.CreatePlatformModelInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	if pathPlatformID := r.PathValue("platformID"); pathPlatformID != "" {
		input.PlatformID = pathPlatformID
	}
	if input.PlatformID == "" {
		writeError(w, http.StatusBadRequest, "platformId is required")
		return
	}
	model, err := s.store.CreatePlatformModel(r.Context(), input)
	if err != nil {
		if store.IsNotFound(err) {
			writeError(w, http.StatusNotFound, "base model not found")
			return
		}
		s.logger.Error("create platform model failed", "error", err)
		writeError(w, http.StatusInternalServerError, "create platform model failed")
		return
	}
	writeJSON(w, http.StatusCreated, model)
}

func (s *Server) replacePlatformModels(w http.ResponseWriter, r *http.Request) {
	platformID := r.PathValue("platformID")
	if platformID == "" {
		writeError(w, http.StatusBadRequest, "platformId is required")
		return
	}

	var input struct {
		Models []store.CreatePlatformModelInput `json:"models"`
	}
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}

	models, err := s.store.ReplacePlatformModels(r.Context(), platformID, input.Models)
	if err != nil {
		if store.IsNotFound(err) {
			writeError(w, http.StatusNotFound, "base model not found")
			return
		}
		s.logger.Error("replace platform models failed", "error", err)
		writeError(w, http.StatusInternalServerError, "replace platform models failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": models})
}

func (s *Server) deletePlatformModel(w http.ResponseWriter, r *http.Request) {
	if err := s.store.DeletePlatformModel(r.Context(), r.PathValue("modelID")); err != nil {
		if store.IsNotFound(err) {
			writeError(w, http.StatusNotFound, "platform model not found")
			return
		}
		s.logger.Error("delete platform model failed", "error", err)
		writeError(w, http.StatusInternalServerError, "delete platform model failed")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (s *Server) listModels(w http.ResponseWriter, r *http.Request) {
	models, err := s.store.ListModels(r.Context())
	if err != nil {
		s.logger.Error("list models failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list models failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": models})
}

func (s *Server) listPlayableModels(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	models, err := s.store.ListAccessiblePlatformModels(r.Context(), user)
	if err != nil {
		s.logger.Error("list playable models failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list playable models failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": models})
}

func (s *Server) listPricingRules(w http.ResponseWriter, r *http.Request) {
	items, err := s.store.ListPricingRules(r.Context())
	if err != nil {
		s.logger.Error("list pricing rules failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list pricing rules failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) listTenants(w http.ResponseWriter, r *http.Request) {
	items, err := s.store.ListTenants(r.Context())
	if err != nil {
		s.logger.Error("list tenants failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list tenants failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) listUsers(w http.ResponseWriter, r *http.Request) {
	items, err := s.store.ListUsers(r.Context())
	if err != nil {
		s.logger.Error("list users failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list users failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) listUserGroups(w http.ResponseWriter, r *http.Request) {
	items, err := s.store.ListUserGroups(r.Context())
	if err != nil {
		s.logger.Error("list user groups failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list user groups failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) listAPIKeys(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	items, err := s.store.ListAPIKeys(r.Context(), user)
	if err != nil {
		s.logger.Error("list api keys failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list api keys failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) listPlayableAPIKeys(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	items, err := s.store.ListPlayableAPIKeys(r.Context(), user)
	if err != nil {
		if errors.Is(err, store.ErrLocalUserRequired) {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		s.logger.Error("list playable api keys failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list playable api keys failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) createAPIKey(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	var input store.CreateAPIKeyInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	created, err := s.store.CreateAPIKey(r.Context(), input, user)
	if err != nil {
		if errors.Is(err, store.ErrLocalUserRequired) {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		s.logger.Error("create api key failed", "error", err)
		writeError(w, http.StatusInternalServerError, "create api key failed")
		return
	}
	writeJSON(w, http.StatusCreated, created)
}

func (s *Server) disableAPIKey(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	item, err := s.store.DisableAPIKey(r.Context(), r.PathValue("apiKeyID"), user)
	if err == nil {
		writeJSON(w, http.StatusOK, item)
		return
	}
	if errors.Is(err, store.ErrLocalUserRequired) {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}
	if store.IsNotFound(err) {
		writeError(w, http.StatusNotFound, "api key not found")
		return
	}
	s.logger.Error("disable api key failed", "error", err)
	writeError(w, http.StatusInternalServerError, "disable api key failed")
}

func (s *Server) estimatePricing(w http.ResponseWriter, r *http.Request) {
	user, _ := auth.UserFromContext(r.Context())
	var body map[string]any
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json body")
		return
	}
	model, _ := body["model"].(string)
	kind, _ := body["kind"].(string)
	if kind == "" {
		kind = "chat.completions"
	}
	if model == "" {
		writeError(w, http.StatusBadRequest, "model is required")
		return
	}
	estimate, err := s.runner.Estimate(r.Context(), kind, model, body, user)
	if err != nil {
		if errors.Is(err, store.ErrNoModelCandidate) {
			writeError(w, http.StatusNotFound, "no enabled platform model matches request")
			return
		}
		s.logger.Error("estimate pricing failed", "error", err)
		writeError(w, http.StatusInternalServerError, "estimate pricing failed")
		return
	}
	writeJSON(w, http.StatusOK, estimate)
}

func (s *Server) listRateLimitWindows(w http.ResponseWriter, r *http.Request) {
	items, err := s.store.ListRateLimitWindows(r.Context())
	if err != nil {
		s.logger.Error("list rate limit windows failed", "error", err)
		writeError(w, http.StatusInternalServerError, "list rate limit windows failed")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

func (s *Server) createTask(kind string, compatible bool) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		user, ok := auth.UserFromContext(r.Context())
		if !ok {
			writeError(w, http.StatusUnauthorized, "unauthorized")
			return
		}

		var body map[string]any
		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
			writeError(w, http.StatusBadRequest, "invalid json body")
			return
		}
		model, _ := body["model"].(string)
		if model == "" {
			writeError(w, http.StatusBadRequest, "model is required")
			return
		}

		task, err := s.store.CreateTask(r.Context(), store.CreateTaskInput{
			Kind:    kind,
			Model:   model,
			RunMode: runModeFromRequest(body),
			Request: body,
		}, user)
		if err != nil {
			s.logger.Error("create task failed", "kind", kind, "error", err)
			writeError(w, http.StatusInternalServerError, "create task failed")
			return
		}
		if compatible {
			if boolValue(body, "stream") {
				flusher := prepareCompatibleStream(w)
				result, runErr := s.runner.ExecuteStream(r.Context(), task, user, func(delta string) error {
					writeCompatibleDelta(w, kind, model, delta)
					if flusher != nil {
						flusher.Flush()
					}
					return nil
				})
				if runErr != nil {
					sendSSE(w, "error", map[string]any{"error": map[string]any{"message": runErr.Error(), "status": statusFromRunError(runErr)}})
					if flusher != nil {
						flusher.Flush()
					}
					return
				}
				writeCompatibleDone(w, kind, model, result.Output)
				if flusher != nil {
					flusher.Flush()
				}
				return
			}
			result, runErr := s.runner.Execute(r.Context(), task, user)
			if runErr != nil {
				writeError(w, statusFromRunError(runErr), runErr.Error())
				return
			}
			writeJSON(w, http.StatusOK, result.Output)
			return
		}
		result, runErr := s.runner.Execute(r.Context(), task, user)
		if runErr != nil {
			s.logger.Warn("task completed with failure", "kind", kind, "taskId", task.ID, "error", runErr)
		}

		writeJSON(w, http.StatusAccepted, map[string]any{
			"task": result.Task,
			"next": map[string]string{
				"events": fmt.Sprintf("/api/v1/tasks/%s/events", task.ID),
				"detail": fmt.Sprintf("/api/v1/tasks/%s", task.ID),
			},
		})
	})
}

func statusFromRunError(err error) int {
	switch {
	case errors.Is(err, store.ErrNoModelCandidate):
		return http.StatusNotFound
	case errors.Is(err, store.ErrRateLimited):
		return http.StatusTooManyRequests
	default:
		return http.StatusBadGateway
	}
}

func boolValue(body map[string]any, key string) bool {
	value, _ := body[key].(bool)
	return value
}

func (s *Server) getTask(w http.ResponseWriter, r *http.Request) {
	task, err := s.store.GetTask(r.Context(), r.PathValue("taskID"))
	if err == nil {
		writeJSON(w, http.StatusOK, task)
		return
	}
	if store.IsNotFound(err) {
		writeError(w, http.StatusNotFound, "task not found")
		return
	}
	s.logger.Error("get task failed", "error", err)
	writeError(w, http.StatusInternalServerError, "get task failed")
}

func (s *Server) taskEvents(w http.ResponseWriter, r *http.Request) {
	task, err := s.store.GetTask(r.Context(), r.PathValue("taskID"))
	if err != nil {
		if store.IsNotFound(err) {
			writeError(w, http.StatusNotFound, "task not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "get task failed")
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")

	events, err := s.store.ListTaskEvents(r.Context(), task.ID)
	if err != nil {
		s.logger.Error("list task events failed", "error", err)
		return
	}
	for _, event := range events {
		sendSSE(w, event.EventType, event)
		if flusher, ok := w.(http.Flusher); ok {
			flusher.Flush()
		}
	}
	if len(events) == 0 {
		sendSSE(w, "task.accepted", map[string]any{
			"taskId": task.ID,
			"status": task.Status,
		})
	}
}

func runModeFromRequest(body map[string]any) string {
	if value, ok := body["runMode"].(string); ok {
		return value
	}
	if value, ok := body["mode"].(string); ok {
		return value
	}
	if value, ok := body["simulation"].(bool); ok && value {
		return "simulation"
	}
	if value, ok := body["testMode"].(bool); ok && value {
		return "simulation"
	}
	return ""
}