package configkit

import (
	"io"
	"io/fs"

	"gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
)

// Source is an opaque configuration input. Construct sources with File,
// Filesystem.File, SearchConfig, Bytes, Reader, Mapping, or NoSource; the zero
// value is invalid. SearchConfig selects a host file when a load consumes it.
type Source struct{ value engine.Source }

// Filesystem is a reusable opaque namespace for a caller-owned fs.FS. Copies
// preserve identity; separately constructed values are distinct even if their
// labels or underlying filesystems match. The filesystem is never closed.
type Filesystem struct{ value engine.Filesystem }

// NewFilesystem borrows filesystem without opening it. Label must be nonempty
// and safe to display; a nil filesystem or invalid label is reported when a
// source from the returned namespace is consumed.
func NewFilesystem(label string, filesystem fs.FS) Filesystem {
	return Filesystem{value: engine.NewFilesystem(label, filesystem)}
}

// File selects a non-root fs.ValidPath name in this filesystem. Each load
// reopens the file; constructor problems are reported when the source is used.
func (f Filesystem) File(name string) Source { return Source{value: f.value.File(name)} }

// File returns a source that reopens path for every load attempt.
func File(path string) Source { return Source{value: engine.File(path)} }

// Bytes snapshots data immediately. Label must be nonempty and safe to display;
// constructor problems are reported when the source is consumed.
func Bytes(label string, data []byte) Source { return Source{value: engine.Bytes(label, data)} }

// Reader returns a single-use source. ConfigKit consumes input but never closes it.
// Copies of the returned Source share the same single-use claim.
func Reader(label string, input io.Reader) Source { return Source{value: engine.Reader(label, input)} }

// Mapping snapshots supported built-in values immediately. A nil root map is
// invalid; an empty map is a valid empty document. Values may be nil, built-in
// scalars, []any, or map[string]any recursively. Unsupported values and cycles
// are reported when the source is consumed. Label must be nonempty and safe to
// display. Later caller mutation cannot change the captured document.
func Mapping(label string, values map[string]any) Source {
	return Source{value: engine.Mapping(label, values)}
}

// NoSource selects an absent input for defaults and resolution. It creates no
// source record and has no main declarations to traverse when imports are enabled.
// An active overlay requires explicit filesystem context.
func NoSource() Source { return Source{value: engine.NoSource()} }

func (s Source) toEngine() engine.Source { return s.value }