httpauth/claims_provider.go

package httpauth

import (
	"context"
	"encoding/json"

	"code.nochebuena.dev/go/rbac"
)

type claimsPermissionProvider struct {
	claimsKey string
}

// NewClaimsPermissionProvider returns an rbac.PermissionProvider that reads
// pre-computed permission masks from JWT claims stored in the request context
// by SetTokenData. Expects claims[claimsKey] to be a map[string]any where each
// key is a resource name and the value is the bitmask as int64 or float64
// (JSON unmarshaling decodes numbers as float64).
// Returns 0 without error if the claim is absent — callers treat 0 as no access.
func NewClaimsPermissionProvider(claimsKey string) rbac.PermissionProvider {
	return &claimsPermissionProvider{claimsKey: claimsKey}
}

func (p *claimsPermissionProvider) ResolveMask(ctx context.Context, _, resource string) (rbac.PermissionMask, error) {
	claims, ok := getClaims(ctx)
	if !ok {
		return 0, nil
	}
	masks, ok := claims[p.claimsKey].(map[string]any)
	if !ok {
		return 0, nil
	}
	// Check specific resource first, then wildcard fallback.
	for _, key := range []string{resource, "*"} {
		switch v := masks[key].(type) {
		case int64:
			return rbac.PermissionMask(v), nil
		case float64:
			return rbac.PermissionMask(int64(v)), nil
		case json.Number:
			n, err := v.Int64()
			if err != nil {
				return 0, nil
			}
			return rbac.PermissionMask(n), nil
		}
	}
	return 0, nil
}