package httpapi

import (
	"log/slog"
	"net/http"
	"time"

	"github.com/google/uuid"
	"github.com/syncova/syncova/packages/audit"
	"github.com/syncova/syncova/packages/auth"
	"github.com/syncova/syncova/packages/platform/logging"
)

// roleHandler bedient Rollen und Berechtigungen (SYNCOVA_API.md §5).
type roleHandler struct {
	// repository ist die Datenzugriffsschicht der Identitätsverwaltung.
	repository *auth.Repository
	// auditRecorder protokolliert Änderungen an Rollen.
	auditRecorder audit.Recorder
	// logger protokolliert technische Fehler.
	logger *slog.Logger
}

// roleRequest ist der Rumpf von POST und PATCH auf /roles.
type roleRequest struct {
	// Name ist der technische Name der Rolle (nur beim Anlegen ausgewertet).
	Name string `json:"name"`
	// Description erklärt den Zweck der Rolle.
	Description *string `json:"description"`
	// Permissions sind die zuzuordnenden Berechtigungen.
	Permissions []string `json:"permissions"`
}

// handleListRoles bedient GET /roles.
func (handler *roleHandler) handleListRoles(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)

	loadedRoles, listError := handler.repository.ListRoles(request.Context())
	if listError != nil {
		WriteError(responseWriter, request, requestLogger, NewInternalError(listError))
		return
	}

	WriteSuccess(responseWriter, request, http.StatusOK, loadedRoles)
}

// handleGetRole bedient GET /roles/{id}.
func (handler *roleHandler) handleGetRole(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)

	roleID, parseError := parsePathUUID(request, "id")
	if parseError != nil {
		WriteError(responseWriter, request, requestLogger, parseError)
		return
	}

	loadedRole, loadError := handler.repository.FindRoleByID(request.Context(), roleID)
	if loadError != nil {
		WriteError(responseWriter, request, requestLogger, translateAuthError(loadError))
		return
	}

	WriteSuccess(responseWriter, request, http.StatusOK, loadedRole)
}

// handleCreateRole bedient POST /roles.
func (handler *roleHandler) handleCreateRole(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)
	actingUser, _ := AuthenticatedUserFromContext(request.Context())

	var rolePayload roleRequest
	if decodeError := decodeJSONBody(request, &rolePayload); decodeError != nil {
		WriteError(responseWriter, request, requestLogger, decodeError)
		return
	}

	if rolePayload.Name == "" {
		WriteError(responseWriter, request, requestLogger, NewValidationError("Der Rollenname ist erforderlich."))
		return
	}

	// Eine Rolle ohne Berechtigungen wäre wirkungslos und fast immer ein Versehen.
	if len(rolePayload.Permissions) == 0 {
		WriteError(responseWriter, request, requestLogger,
			NewValidationError("Es muss mindestens eine Berechtigung zugeordnet werden."))
		return
	}

	description := ""
	if rolePayload.Description != nil {
		description = *rolePayload.Description
	}

	createdRoleID, createError := handler.repository.CreateRole(
		request.Context(), rolePayload.Name, description, rolePayload.Permissions)
	if createError != nil {
		WriteError(responseWriter, request, requestLogger, translateAuthError(createError))
		return
	}

	handler.recordRoleAudit(request, audit.ActionRoleCreated, createdRoleID, actingUser, map[string]any{
		"name":           rolePayload.Name,
		"berechtigungen": rolePayload.Permissions,
	})

	createdRole, loadError := handler.repository.FindRoleByID(request.Context(), createdRoleID)
	if loadError != nil {
		WriteError(responseWriter, request, requestLogger, NewInternalError(loadError))
		return
	}

	WriteSuccess(responseWriter, request, http.StatusCreated, createdRole)
}

// handleUpdateRole bedient PATCH /roles/{id}.
func (handler *roleHandler) handleUpdateRole(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)
	actingUser, _ := AuthenticatedUserFromContext(request.Context())

	roleID, parseError := parsePathUUID(request, "id")
	if parseError != nil {
		WriteError(responseWriter, request, requestLogger, parseError)
		return
	}

	var rolePayload roleRequest
	if decodeError := decodeJSONBody(request, &rolePayload); decodeError != nil {
		WriteError(responseWriter, request, requestLogger, decodeError)
		return
	}

	if updateError := handler.repository.UpdateRole(
		request.Context(), roleID, rolePayload.Description, rolePayload.Permissions); updateError != nil {
		WriteError(responseWriter, request, requestLogger, translateAuthError(updateError))
		return
	}

	handler.recordRoleAudit(request, audit.ActionRoleUpdated, roleID, actingUser, map[string]any{
		"berechtigungen": rolePayload.Permissions,
	})

	updatedRole, loadError := handler.repository.FindRoleByID(request.Context(), roleID)
	if loadError != nil {
		WriteError(responseWriter, request, requestLogger, NewInternalError(loadError))
		return
	}

	WriteSuccess(responseWriter, request, http.StatusOK, updatedRole)
}

// handleDeleteRole bedient DELETE /roles/{id}.
func (handler *roleHandler) handleDeleteRole(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)
	actingUser, _ := AuthenticatedUserFromContext(request.Context())

	roleID, parseError := parsePathUUID(request, "id")
	if parseError != nil {
		WriteError(responseWriter, request, requestLogger, parseError)
		return
	}

	if deleteError := handler.repository.DeleteRole(request.Context(), roleID); deleteError != nil {
		WriteError(responseWriter, request, requestLogger, translateAuthError(deleteError))
		return
	}

	handler.recordRoleAudit(request, audit.ActionRoleDeleted, roleID, actingUser, nil)

	WriteSuccess(responseWriter, request, http.StatusNoContent, nil)
}

// handleListPermissions bedient GET /permissions.
func (handler *roleHandler) handleListPermissions(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)

	loadedPermissions, listError := handler.repository.ListPermissions(request.Context())
	if listError != nil {
		WriteError(responseWriter, request, requestLogger, NewInternalError(listError))
		return
	}

	WriteSuccess(responseWriter, request, http.StatusOK, loadedPermissions)
}

// recordRoleAudit protokolliert eine Rollenänderung.
func (handler *roleHandler) recordRoleAudit(request *http.Request, auditAction audit.Action, roleID uuid.UUID, actingUser auth.User, auditDetails map[string]any) {
	correlationID, _ := logging.CorrelationIDFromContext(request.Context())

	if recordError := handler.auditRecorder.Record(request.Context(), audit.Event{
		UserID:        &actingUser.ID,
		ActorUsername: actingUser.Username,
		Action:        auditAction,
		EntityType:    "role",
		EntityID:      &roleID,
		Result:        audit.ResultSuccess,
		IPAddress:     clientIPAddress(request),
		UserAgent:     request.UserAgent(),
		CorrelationID: correlationID,
		Details:       auditDetails,
	}); recordError != nil {
		logging.WithContext(request.Context(), handler.logger).Error(
			"rollenänderung konnte nicht protokolliert werden",
			slog.String("action", string(auditAction)),
			slog.String("error", recordError.Error()))
	}
}

// ---------------------------------------------------------------------------
// Auditprotokoll
// ---------------------------------------------------------------------------

// auditHandler bedient die Auditabfrage (SYNCOVA_API.md §17).
type auditHandler struct {
	// auditRecorder liest die protokollierten Ereignisse.
	auditRecorder audit.Recorder
	// logger protokolliert technische Fehler.
	logger *slog.Logger
}

// handleListAuditEvents bedient GET /audit-events.
func (handler *auditHandler) handleListAuditEvents(responseWriter http.ResponseWriter, request *http.Request) {
	requestLogger := logging.WithContext(request.Context(), handler.logger)

	page, pageSize := parsePagination(request)
	queryParameters := request.URL.Query()

	queryFilter := audit.Filter{
		Action:   queryParameters.Get("action"),
		Result:   queryParameters.Get("result"),
		Page:     page,
		PageSize: pageSize,
	}

	if rawUserID := queryParameters.Get("user_id"); rawUserID != "" {
		parsedUserID, parseError := uuid.Parse(rawUserID)
		if parseError != nil {
			WriteError(responseWriter, request, requestLogger,
				NewBadRequestError("Der Parameter user_id ist keine gültige UUID."))
			return
		}

		queryFilter.UserID = &parsedUserID
	}

	// Zeitangaben werden in ISO 8601 erwartet, passend zur Ausgabe der API.
	if rawFrom := queryParameters.Get("from"); rawFrom != "" {
		parsedFrom, parseError := time.Parse(time.RFC3339, rawFrom)
		if parseError != nil {
			WriteError(responseWriter, request, requestLogger,
				NewBadRequestError("Der Parameter from muss im Format RFC 3339 angegeben werden."))
			return
		}

		queryFilter.From = &parsedFrom
	}

	if rawTo := queryParameters.Get("to"); rawTo != "" {
		parsedTo, parseError := time.Parse(time.RFC3339, rawTo)
		if parseError != nil {
			WriteError(responseWriter, request, requestLogger,
				NewBadRequestError("Der Parameter to muss im Format RFC 3339 angegeben werden."))
			return
		}

		queryFilter.To = &parsedTo
	}

	auditEvents, totalCount, queryError := handler.auditRecorder.Query(request.Context(), queryFilter)
	if queryError != nil {
		WriteError(responseWriter, request, requestLogger, NewInternalError(queryError))
		return
	}

	WritePaginatedSuccess(responseWriter, request, auditEvents, PaginationMeta{
		Page: page, PageSize: pageSize, Total: totalCount,
	})
}