package userroles

import (
	"context"
	"errors"
	"sync"
	"time"

	cs3 "github.com/cs3org/go-cs3apis/cs3/identity/user/v1beta1"
	"github.com/qsfera/server/pkg/middleware"
	"github.com/qsfera/server/pkg/oidc"
	settingssvc "github.com/qsfera/server/protogen/gen/qsfera/services/settings/v0"
	"github.com/opencloud-eu/reva/v2/pkg/utils"
	"go-micro.dev/v4/metadata"
)

type oidcRoleAssigner struct {
	Options
}

// NewOIDCRoleAssigner returns an implementation of the UserRoleAssigner interface
func NewOIDCRoleAssigner(opts ...Option) UserRoleAssigner {
	opt := Options{}
	for _, o := range opts {
		o(&opt)
	}

	return oidcRoleAssigner{
		Options: opt,
	}
}

func extractRoles(rolesClaim string, claims map[string]any) (map[string]struct{}, error) {

	claimRoles := map[string]struct{}{}
	// happy path
	value, _ := claims[rolesClaim].(string)
	if value != "" {
		claimRoles[value] = struct{}{}
		return claimRoles, nil
	}

	claim, err := oidc.WalkSegments(oidc.SplitWithEscaping(rolesClaim, ".", "\\"), claims)
	if err != nil {
		return nil, err
	}

	switch v := claim.(type) {
	case []string:
		for _, cr := range v {
			claimRoles[cr] = struct{}{}
		}
	case []any:
		for _, cri := range v {
			cr, ok := cri.(string)
			if !ok {
				err := errors.New("invalid role in claims")
				return nil, err
			}

			claimRoles[cr] = struct{}{}
		}
	case string:
		claimRoles[v] = struct{}{}
	default:
		return nil, errors.New("no roles in user claims")
	}

	return claimRoles, nil
}

// UpdateUserRoleAssignment assigns the role "User" to the supplied user. Unless the user
// already has a different role assigned.
func (ra oidcRoleAssigner) UpdateUserRoleAssignment(ctx context.Context, user *cs3.User, claims map[string]any) (*cs3.User, error) {
	logger := ra.logger.SubloggerWithRequestID(ctx).With().Str("userid", user.GetId().GetOpaqueId()).Logger()
	roleNamesToRoleIDs, err := ra.roleNamesToRoleIDs()
	if err != nil {
		logger.Error().Err(err).Msg("Error mapping role names to role ids")
		return nil, err
	}

	claimRoles, err := extractRoles(ra.rolesClaim, claims)
	if err != nil {
		logger.Error().Err(err).Msg("Error mapping role names to role ids")
		return nil, err
	}

	if len(claimRoles) == 0 {
		err := errors.New("no roles set in claim")
		logger.Error().Err(err).Msg("")
		return nil, err
	}

	// the roleMapping config is supposed to have the role mappings ordered from the highest privileged role
	// down to the lowest privileged role. Since КуСфера currently only can handle a single role assignment we
	// pick the highest privileged role that matches a value from the claims
	roleIDFromClaim := ""
	for _, mapping := range ra.Options.roleMapping {
		if _, ok := claimRoles[mapping.ClaimValue]; ok {
			logger.Debug().Str("qsferaRole", mapping.RoleName).Str("role id", roleNamesToRoleIDs[mapping.RoleName]).Msg("first matching role")
			roleIDFromClaim = roleNamesToRoleIDs[mapping.RoleName]
			break
		}
	}

	if roleIDFromClaim == "" {
		err := errors.New("no role in claim maps to an КуСфера role")
		logger.Error().Err(err).Msg("")
		return nil, err
	}

	assignedRoles, err := loadRolesIDs(ctx, user.GetId().GetOpaqueId(), ra.roleService)
	if err != nil {
		logger.Error().Err(err).Msg("Could not load roles")
		return nil, err
	}
	if len(assignedRoles) > 1 {
		logger.Error().Str("userID", user.GetId().GetOpaqueId()).Int("numRoles", len(assignedRoles)).Msg("The user has too many roles assigned")
	}
	logger.Debug().Interface("assignedRoleIds", assignedRoles).Msg("Currently assigned roles")

	if len(assignedRoles) != 1 || (assignedRoles[0] != roleIDFromClaim) {
		logger.Debug().Interface("assignedRoleIds", assignedRoles).Interface("newRoleId", roleIDFromClaim).Msg("Updating role assignment for user")
		newctx, err := ra.prepareAdminContext()
		if err != nil {
			logger.Error().Err(err).Msg("Error creating admin context")
			return nil, err
		}
		if _, err = ra.roleService.AssignRoleToUser(newctx, &settingssvc.AssignRoleToUserRequest{
			AccountUuid: user.GetId().GetOpaqueId(),
			RoleId:      roleIDFromClaim,
		}); err != nil {
			logger.Error().Err(err).Msg("Role assignment failed")
			return nil, err
		}
	}

	user.Opaque = utils.AppendJSONToOpaque(user.Opaque, "roles", []string{roleIDFromClaim})
	return user, nil
}

// ApplyUserRole it looks up the user's role in the settings service and adds it
// user's opaque data
func (ra oidcRoleAssigner) ApplyUserRole(ctx context.Context, user *cs3.User) (*cs3.User, error) {
	roleIDs, err := loadRolesIDs(ctx, user.Id.OpaqueId, ra.roleService)
	if err != nil {
		ra.logger.Error().Err(err).Msg("Could not load roles")
		return nil, err
	}

	user.Opaque = utils.AppendJSONToOpaque(user.Opaque, "roles", roleIDs)
	return user, nil
}

func (ra oidcRoleAssigner) prepareAdminContext() (context.Context, error) {
	gatewayClient, err := ra.gatewaySelector.Next()
	if err != nil {
		ra.logger.Error().Err(err).Msg("could not select next gateway client")
		return nil, err
	}
	newctx, err := utils.GetServiceUserContext(ra.serviceAccount.ServiceAccountID, gatewayClient, ra.serviceAccount.ServiceAccountSecret)
	if err != nil {
		ra.logger.Error().Err(err).Msg("Error preparing request context for provisioning role assignments.")
		return nil, err
	}

	newctx = metadata.Set(newctx, middleware.AccountID, ra.serviceAccount.ServiceAccountID)
	return newctx, nil
}

type roleNameToIDCache struct {
	roleNameToID map[string]string
	lastRead     time.Time
	lock         sync.RWMutex
}

var roleNameToID roleNameToIDCache

func (ra oidcRoleAssigner) roleNamesToRoleIDs() (map[string]string, error) {
	cacheTTL := 5 * time.Minute
	roleNameToID.lock.RLock()

	if !roleNameToID.lastRead.IsZero() && time.Since(roleNameToID.lastRead) < cacheTTL {
		defer roleNameToID.lock.RUnlock()
		return roleNameToID.roleNameToID, nil
	}
	ra.logger.Debug().Msg("refreshing roles ids")

	// cache needs Refresh get a write lock
	roleNameToID.lock.RUnlock()
	roleNameToID.lock.Lock()
	defer roleNameToID.lock.Unlock()

	// check again, another goroutine might have updated while we "upgraded" the lock
	if !roleNameToID.lastRead.IsZero() && time.Since(roleNameToID.lastRead) < cacheTTL {
		return roleNameToID.roleNameToID, nil
	}

	// Get all roles to find the role IDs.
	// To list roles we need some elevated access to the settings service
	// prepare a new request context for that until we have service accounts
	ctx, err := ra.prepareAdminContext()
	if err != nil {
		ra.logger.Error().Err(err).Msg("Error creating admin context")
		return nil, err
	}

	req := &settingssvc.ListBundlesRequest{}
	res, err := ra.roleService.ListRoles(ctx, req)
	if err != nil {
		ra.logger.Error().Err(err).Msg("Failed to list all roles")
		return map[string]string{}, err
	}

	newIDs := map[string]string{}
	for _, role := range res.Bundles {
		ra.logger.Debug().Str("role", role.Name).Str("id", role.Id).Msg("Got Role")
		newIDs[role.Name] = role.Id
	}
	ra.logger.Debug().Interface("roleMap", newIDs).Msg("Role Name to role ID map")
	roleNameToID.roleNameToID = newIDs
	roleNameToID.lastRead = time.Now()
	return roleNameToID.roleNameToID, nil
}