package handlers

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"

	"devone.aplikasi.web.id/gitea/mario/go-ohif-proxy/internal/api/middleware"
	"devone.aplikasi.web.id/gitea/mario/go-ohif-proxy/internal/auth"
	"devone.aplikasi.web.id/gitea/mario/go-ohif-proxy/internal/proxy"
	"github.com/go-chi/chi/v5"
	"go.uber.org/zap"
)

// DicomHandler handles DICOM Web requests
type DicomHandler struct {
	client *proxy.Client
	logger *zap.Logger
}

// NewDicomHandler creates a new DICOM handler
func NewDicomHandler(client *proxy.Client, logger *zap.Logger) *DicomHandler {
	return &DicomHandler{
		client: client,
		logger: logger,
	}
}

// buildRefDoctorFilter constructs a properly encoded query string for referring doctor filtering
func (h *DicomHandler) buildRefDoctorFilter(doctorName string, queryParams url.Values) string {
	// Extract basic parameters with fallbacks
	limit := queryParams.Get("limit")
	if limit == "" {
		limit = "101" // Default limit used by OHIF
	}

	offset := queryParams.Get("offset")
	if offset == "" {
		offset = "0" // Default offset
	}

	includeField := queryParams.Get("includefield")

	// Make sure includefield includes 00080090 (ReferringPhysician)
	if includeField != "" && !strings.Contains(includeField, "00080090") {
		includeField = includeField + ",00080090"
	} else if includeField == "" {
		includeField = "00081030,00080060,00080090"
	}

	// Properly encode the doctor's name
	encodedName := strings.ReplaceAll(doctorName, " ", "%20")
	encodedName = strings.ReplaceAll(encodedName, ",", "%2C")
	encodedName = strings.ReplaceAll(encodedName, ".", "%2E")

	// Construct query string manually to avoid double-encoding
	return fmt.Sprintf("limit=%s&offset=%s&fuzzymatching=false&includefield=%s&00080090=%s",
		limit, offset, includeField, encodedName)
}

// isStudyListRequest checks if a path refers to the top-level studies endpoint
func isStudyListRequest(path string) bool {
	// Normalize the path first
	if !strings.HasPrefix(path, "/") {
		path = "/" + path
	}

	// Check for exact match with "/studies"
	return path == "/studies"
}

// ForwardRequest forwards the request to Google Healthcare API
func (h *DicomHandler) ForwardRequest(w http.ResponseWriter, r *http.Request) {
	// Get claims from context if they exist
	var claims *auth.CustomClaims
	claimsValue := r.Context().Value(middleware.ClaimsKey)

	// Add detailed debug logging about claims
	if claimsValue == nil {
		h.logger.Warn("Claims not found in context",
			zap.String("path", r.URL.Path),
			zap.String("method", r.Method))
	} else {
		claims = claimsValue.(*auth.CustomClaims)
		h.logger.Debug("Claims retrieved from context",
			zap.String("userID", claims.UserID),
			zap.String("role", claims.Role),
			zap.String("userName", claims.UserName))
	}

	// Get the path after /dicomWeb
	urlPath := chi.URLParam(r, "*")

	// If the URL parameter is empty, try to extract it from the URL path
	if urlPath == "" {
		// Remove /dicomWeb prefix from the URL
		prefix := "/dicomWeb"
		if strings.HasPrefix(r.URL.Path, prefix) {
			urlPath = r.URL.Path[len(prefix):]
		}
	}

	// Normalize the path
	if !strings.HasPrefix(urlPath, "/") {
		urlPath = "/" + urlPath
	}

	h.logger.Debug("Forwarding request",
		zap.String("path", urlPath),
		zap.String("method", r.Method),
		zap.String("url", r.URL.String()))

	// Copy query parameters
	queryParams := r.URL.Query()
	queryString := ""

	// Apply role-specific query modifications
	if claims != nil {
		switch claims.Role {
		case "patient":
			// For patients requesting study list, filter to only show their studies
			if isStudyListRequest(urlPath) {
				// Check if studies are available in the claim
				if len(claims.StudyIUIDs) > 0 {
					// Remove existing StudyInstanceUID param if it exists
					queryParams.Del("StudyInstanceUID")

					// For DICOMweb, we can use comma-separated UIDs
					queryParams.Set("StudyInstanceUID", strings.Join(claims.StudyIUIDs, ","))

					h.logger.Debug("Filtering by studies",
						zap.Strings("studies", claims.StudyIUIDs))
				}
			} else if strings.HasPrefix(urlPath, "/studies/") {
				// This is a request for a specific study - check if the patient is authorized

				// Extract the study ID from the path
				// Format: /studies/{studyID}/...
				pathParts := strings.Split(strings.TrimPrefix(urlPath, "/"), "/")
				if len(pathParts) >= 2 {
					studyID := pathParts[1]

					// Check if this study is in the patient's authorized studies
					authorized := false

					// Check StudyIUIDs array
					for _, id := range claims.StudyIUIDs {
						if id == studyID {
							authorized = true
							break
						}
					}

					// If not authorized, return 403 Forbidden
					if !authorized {
						h.logger.Warn("Unauthorized study access attempt",
							zap.String("studyID", studyID),
							zap.String("patientID", claims.PatientID),
							zap.Strings("authorizedStudies", claims.StudyIUIDs),
						)
						http.Error(w, "Forbidden: You are not authorized to access this study", http.StatusForbidden)
						return
					}

					h.logger.Debug("Authorized access to specific study",
						zap.String("studyID", studyID),
						zap.String("patientID", claims.PatientID),
					)
				}
			}

			// Use standard query parameter encoding
			queryString = queryParams.Encode()

		case "ref_doctor":
			// For ref_doctor requesting study list, apply filter
			if isStudyListRequest(urlPath) {
				// Use our helper function to build the properly encoded query
				queryString = h.buildRefDoctorFilter(claims.UserName, queryParams)

				h.logger.Debug("Applied referring physician filter",
					zap.String("doctorName", claims.UserName),
					zap.String("queryString", queryString))
			} else {
				// For other paths, use standard query parameter encoding
				queryString = queryParams.Encode()
			}

		case "expertise_doctor":
			// No restrictions for expertise_doctor
			queryString = queryParams.Encode()
		}
	} else {
		// No claims, use standard query parameter encoding
		queryString = queryParams.Encode()
	}

	// Add the query string to the path
	if queryString != "" {
		urlPath = urlPath + "?" + queryString
	}

	// Read request body if present
	var bodyBytes []byte
	if r.Body != nil && r.ContentLength > 0 {
		var err error
		bodyBytes, err = io.ReadAll(r.Body)
		if err != nil {
			h.logger.Error("Failed to read request body", zap.Error(err))
			http.Error(w, "Failed to read request body", http.StatusInternalServerError)
			return
		}
	}

	// Get request headers
	headers := make(map[string]string)
	for k, v := range r.Header {
		if len(v) > 0 {
			headers[k] = v[0]
		}
	}

	// Forward the request to Healthcare API
	response, err := h.client.ForwardRequest(
		r.Context(),
		r.Method,
		urlPath,
		headers,
		bodyBytes)

	if err != nil {
		h.logger.Error("Request forwarding failed", zap.Error(err))
		http.Error(w, fmt.Sprintf("Request failed: %v", err), http.StatusInternalServerError)
		return
	}

	// Set response headers
	for k, v := range response.Headers {
		w.Header().Set(k, v)
	}

	// Set status and write response body
	w.WriteHeader(response.StatusCode)
	w.Write(response.Body)
}