config

type Config interface {
	// Load loads from the configured sources.
	Load() error
	// Watch invokes fn whenever the configuration changes.
	Watch(fn func(Config)) error
	// Close releases resources.
	Close() error
	Value(path string) Value
	Scan(v interface{}) error
	Reader() Reader
}

type KeyValue struct {
	Key    string
	Value  []byte
	Format string // "json", "yaml", "toml"; empty means auto-detect.
}

type Loader interface {
	Load(sources ...Source) error
}

type Option func(*config)

type Reader interface {
	// Merge decodes and merges raw key/values.
	Merge(kvs ...*KeyValue) error
	// Value returns the value at a dot-separated path, e.g. "a.b.c".
	Value(path string) Value
	// Source returns the merged raw bytes.
	Source() ([]byte, error)
}

type Source interface {
	// Load returns the current raw key/values.
	Load() ([]*KeyValue, error)
	// Watch returns a Watcher that emits raw changes.
	Watch() (Watcher, error)
}

type SourceFactory func(opts any) (Source, error)

type Value interface {
	String() string
	Int() int
	Int64() int64
	Float64() float64
	Bool() bool
	Duration() time.Duration
	Bytes() []byte
	// Scan unmarshals the value into v.
	Scan(v interface{}) error
}

type Watcher interface {
	Next() ([]*KeyValue, error)
	Stop() error
}