// Package api provides HTTP handlers for the fetch_ml API server
package api

import (
	"encoding/json"
	"fmt"
	"net/http"

	"github.com/jfraeys/fetch_ml/internal/api/helpers"
	"github.com/jfraeys/fetch_ml/internal/auth"
	"github.com/jfraeys/fetch_ml/internal/experiment"
	"github.com/jfraeys/fetch_ml/internal/jupyter"
	"github.com/jfraeys/fetch_ml/internal/logging"
)

// Handlers groups all HTTP handlers
type Handlers struct {
	expManager        *experiment.Manager
	jupyterServiceMgr *jupyter.ServiceManager
	logger            *logging.Logger
}

// NewHandlers creates a new handler group
func NewHandlers(
	expManager *experiment.Manager,
	jupyterServiceMgr *jupyter.ServiceManager,
	logger *logging.Logger,
) *Handlers {
	return &Handlers{
		expManager:        expManager,
		jupyterServiceMgr: jupyterServiceMgr,
		logger:            logger,
	}
}

// RegisterHandlers registers all HTTP handlers with the mux
func (h *Handlers) RegisterHandlers(mux *http.ServeMux) {
	// Health check endpoints
	mux.HandleFunc("/db-status", h.handleDBStatus)

	// Jupyter service endpoints
	if h.jupyterServiceMgr != nil {
		mux.HandleFunc("/api/jupyter/services", h.handleJupyterServices)
		mux.HandleFunc("/api/jupyter/experiments/link", h.handleJupyterExperimentLink)
		mux.HandleFunc("/api/jupyter/experiments/sync", h.handleJupyterExperimentSync)
	}
}

// handleHealth responds with a simple health check
func (h *Handlers) handleHealth(w http.ResponseWriter, _ *http.Request) {
	w.WriteHeader(http.StatusOK)
	_, _ = fmt.Fprintf(w, "OK\n")
}

// handleDBStatus responds with database connection status
func (h *Handlers) handleDBStatus(w http.ResponseWriter, _ *http.Request) {
	w.Header().Set("Content-Type", "application/json")

	// This would need the DB instance passed to handlers
	// For now, return a basic response
	response := map[string]any{
		"status":  "unknown",
		"message": "Database status check not implemented",
	}

	w.WriteHeader(http.StatusOK)
	if _, err := w.Write(helpers.MarshalJSONOrEmpty(response)); err != nil {
		h.logger.Error("failed to write response", "error", err)
	}
}

// handleJupyterServices handles Jupyter service management requests
func (h *Handlers) handleJupyterServices(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	user := auth.GetUserFromContext(r.Context())
	if user == nil {
		http.Error(w, "Unauthorized: No user context", http.StatusUnauthorized)
		return
	}

	switch r.Method {
	case http.MethodGet:
		if !user.HasPermission("jupyter:read") {
			http.Error(w, "Forbidden: Insufficient permissions", http.StatusForbidden)
			return
		}
		h.listJupyterServices(w, r)
	case http.MethodPost:
		if !user.HasPermission("jupyter:manage") {
			http.Error(w, "Forbidden: Insufficient permissions", http.StatusForbidden)
			return
		}
		h.startJupyterService(w, r)
	case http.MethodDelete:
		if !user.HasPermission("jupyter:manage") {
			http.Error(w, "Forbidden: Insufficient permissions", http.StatusForbidden)
			return
		}
		h.stopJupyterService(w, r)
	default:
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
	}
}

// listJupyterServices lists all Jupyter services
func (h *Handlers) listJupyterServices(w http.ResponseWriter, _ *http.Request) {
	services := h.jupyterServiceMgr.ListServices()
	w.WriteHeader(http.StatusOK)
	if _, err := w.Write(helpers.MarshalJSONOrEmpty(services)); err != nil {
		h.logger.Error("failed to write response", "error", err)
	}
}

// startJupyterService starts a new Jupyter service
func (h *Handlers) startJupyterService(w http.ResponseWriter, r *http.Request) {
	var req jupyter.StartRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	ctx := r.Context()
	service, err := h.jupyterServiceMgr.StartService(ctx, &req)
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to start service: %v", err), http.StatusInternalServerError)
		return
	}

	w.WriteHeader(http.StatusCreated)
	if _, err := w.Write(helpers.MarshalJSONOrEmpty(service)); err != nil {
		h.logger.Error("failed to write response", "error", err)
	}
}

// stopJupyterService stops a Jupyter service
func (h *Handlers) stopJupyterService(w http.ResponseWriter, r *http.Request) {
	serviceID := r.URL.Query().Get("id")
	if serviceID == "" {
		http.Error(w, "Service ID is required", http.StatusBadRequest)
		return
	}

	ctx := r.Context()
	if err := h.jupyterServiceMgr.StopService(ctx, serviceID); err != nil {
		http.Error(w, fmt.Sprintf("Failed to stop service: %v", err), http.StatusInternalServerError)
		return
	}

	w.WriteHeader(http.StatusOK)
	if err := json.NewEncoder(w).Encode(map[string]string{
		"status": "stopped",
		"id":     serviceID,
	}); err != nil {
		h.logger.Error("failed to encode response", "error", err)
	}
}

// handleJupyterExperimentLink handles linking Jupyter workspaces with experiments
func (h *Handlers) handleJupyterExperimentLink(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	user := auth.GetUserFromContext(r.Context())
	if user == nil {
		http.Error(w, "Unauthorized: No user context", http.StatusUnauthorized)
		return
	}
	if !user.HasPermission("jupyter:manage") {
		http.Error(w, "Forbidden: Insufficient permissions", http.StatusForbidden)
		return
	}

	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req struct {
		Workspace    string `json:"workspace"`
		ExperimentID string `json:"experiment_id"`
		ServiceID    string `json:"service_id,omitempty"`
	}

	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	if req.Workspace == "" || req.ExperimentID == "" {
		http.Error(w, "Workspace and experiment_id are required", http.StatusBadRequest)
		return
	}

	if !h.expManager.ExperimentExists(req.ExperimentID) {
		http.Error(w, "Experiment not found", http.StatusNotFound)
		return
	}

	// Link workspace with experiment using service manager
	if err := h.jupyterServiceMgr.LinkWorkspaceWithExperiment(
		req.Workspace,
		req.ExperimentID,
		req.ServiceID,
	); err != nil {
		http.Error(w, fmt.Sprintf("Failed to link workspace: %v", err), http.StatusInternalServerError)
		return
	}

	// Get workspace metadata to return
	metadata, err := h.jupyterServiceMgr.GetWorkspaceMetadata(req.Workspace)
	if err != nil {
		http.Error(
			w,
			fmt.Sprintf("Failed to get workspace metadata: %v", err),
			http.StatusInternalServerError,
		)
		return
	}

	h.logger.Info("jupyter workspace linked with experiment",
		"workspace", req.Workspace,
		"experiment_id", req.ExperimentID,
		"service_id", req.ServiceID)

	w.WriteHeader(http.StatusCreated)
	if err := json.NewEncoder(w).Encode(map[string]interface{}{
		"status": "linked",
		"data":   metadata,
	}); err != nil {
		h.logger.Error("failed to encode response", "error", err)
	}
}

// handleJupyterExperimentSync handles synchronization between Jupyter workspaces and experiments
func (h *Handlers) handleJupyterExperimentSync(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	user := auth.GetUserFromContext(r.Context())
	if user == nil {
		http.Error(w, "Unauthorized: No user context", http.StatusUnauthorized)
		return
	}
	if !user.HasPermission("jupyter:manage") {
		http.Error(w, "Forbidden: Insufficient permissions", http.StatusForbidden)
		return
	}

	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req struct {
		Workspace    string `json:"workspace"`
		ExperimentID string `json:"experiment_id"`
		Direction    string `json:"direction"` // "pull" or "push"
		SyncType     string `json:"sync_type"` // "data", "notebooks", "all"
	}

	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	if req.Workspace == "" || req.ExperimentID == "" || req.Direction == "" {
		http.Error(w, "Workspace, experiment_id, and direction are required", http.StatusBadRequest)
		return
	}

	// Validate experiment exists
	if !h.expManager.ExperimentExists(req.ExperimentID) {
		http.Error(w, "Experiment not found", http.StatusNotFound)
		return
	}

	// Perform sync operation using service manager
	ctx := r.Context()
	if err := h.jupyterServiceMgr.SyncWorkspaceWithExperiment(
		ctx, req.Workspace, req.ExperimentID, req.Direction); err != nil {
		http.Error(w, fmt.Sprintf("Failed to sync workspace: %v", err), http.StatusInternalServerError)
		return
	}

	// Get updated metadata
	metadata, err := h.jupyterServiceMgr.GetWorkspaceMetadata(req.Workspace)
	if err != nil {
		http.Error(
			w,
			fmt.Sprintf("Failed to get workspace metadata: %v", err),
			http.StatusInternalServerError,
		)
		return
	}

	// Create sync result
	syncResult := map[string]interface{}{
		"workspace":     req.Workspace,
		"experiment_id": req.ExperimentID,
		"direction":     req.Direction,
		"sync_type":     req.SyncType,
		"synced_at":     metadata.LastSync,
		"status":        "completed",
		"metadata":      metadata,
	}

	h.logger.Info("jupyter workspace sync completed",
		"workspace", req.Workspace,
		"experiment_id", req.ExperimentID,
		"direction", req.Direction,
		"sync_type", req.SyncType)

	w.WriteHeader(http.StatusOK)
	if err := json.NewEncoder(w).Encode(syncResult); err != nil {
		h.logger.Error("failed to encode response", "error", err)
	}
}