package promptkit

import (
	"fmt"

	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
)

// Namespaces selects default resource namespaces for caller-supplied IDs.
// Empty fields leave that resource type unscoped.
type Namespaces struct {
	Prompt  string
	Profile string
	Backend string
}

// WithNamespaces returns an engine view that qualifies slashless caller-supplied
// prompt, profile, and backend selections with the supplied namespaces.
// Qualified selections pass through unchanged. It replaces all namespace
// defaults on the new view and leaves the receiver unchanged; resource
// existence is checked when selected. An empty field clears that resource's
// scope. Captured configuration references, defaults, and global configuration
// inspection are not rewritten. [Engine.ListNamespaces] and
// [Engine.ListCollections] remain global inventories. Invalid namespace syntax
// or a nil engine returns an error matching ErrInvalidConfig.
//
// The view shares the receiver's captured configuration, clients, backend-capacity
// pools, and prepared-execution owner. Prepared handles retain their captured
// selections whichever related view executes them.
func (e *Engine) WithNamespaces(namespaces Namespaces) (*Engine, error) {
	if e == nil || e.internal == nil {
		return nil, fmt.Errorf("%w: engine is nil", ErrInvalidConfig)
	}
	for _, namespace := range []struct {
		kind string
		name string
	}{
		{kind: "prompt", name: namespaces.Prompt},
		{kind: "profile", name: namespaces.Profile},
		{kind: "backend", name: namespaces.Backend},
	} {
		if namespace.name != "" && !domain.IsValidResourceNamespace(namespace.name) {
			return nil, fmt.Errorf("%w: invalid %s namespace %q", ErrInvalidConfig, namespace.kind, namespace.name)
		}
	}
	return &Engine{internal: e.internal.WithNamespaces(namespaces.Prompt, namespaces.Profile, namespaces.Backend)}, nil
}