// Package iface defines IPFS Core API which is a set of interfaces used to
// interact with IPFS nodes.
package iface

import (
	"context"
	"errors"
	"io"
	"time"

	options "github.com/ipfs/go-ipfs/core/coreapi/interface/options"

	ipld "gx/ipfs/QmNwUEK7QbwSqyKBu3mMtToo8SUc6wQJ7gdZq4gGGJqfnf/go-ipld-format"
	cid "gx/ipfs/QmeSrf6pzut73u6zLQkRFQ3ygt3k6XFT2kjdYP8Tnkwwyg/go-cid"
)

// Path is a generic wrapper for paths used in the API. A path can be resolved
// to a CID using one of Resolve functions in the API.
type Path interface {
	String() string
	Cid() *cid.Cid
	Root() *cid.Cid
	Resolved() bool
}

// TODO: should we really copy these?
//       if we didn't, godoc would generate nice links straight to go-ipld-format
type Node ipld.Node
type Link ipld.Link

type IpnsEntry struct {
	Name  string
	Value Path
}

type Reader interface {
	io.ReadSeeker
	io.Closer
}

// CoreAPI defines an unified interface to IPFS for Go programs.
type CoreAPI interface {
	// Unixfs returns an implementation of Unixfs API
	Unixfs() UnixfsAPI
	Dag() DagAPI
	Name() NameAPI
	Key() KeyAPI

	// ResolvePath resolves the path using Unixfs resolver
	ResolvePath(context.Context, Path) (Path, error)

	// ResolveNode resolves the path (if not resolved already) using Unixfs
	// resolver, gets and returns the resolved Node
	ResolveNode(context.Context, Path) (Node, error)
}

// UnixfsAPI is the basic interface to immutable files in IPFS
type UnixfsAPI interface {
	// Add imports the data from the reader into merkledag file
	Add(context.Context, io.Reader) (Path, error)

	// Cat returns a reader for the file
	Cat(context.Context, Path) (Reader, error)

	// Ls returns the list of links in a directory
	Ls(context.Context, Path) ([]*Link, error)
}

// DagAPI specifies the interface to IPLD
type DagAPI interface {
	// Put inserts data using specified format and input encoding.
	// Unless used with WithCodec or WithHash, the defaults "dag-cbor" and
	// "sha256" are used.
	Put(ctx context.Context, src io.Reader, opts ...options.DagPutOption) (Path, error)

	// WithInputEnc is an option for Put which specifies the input encoding of the
	// data. Default is "json", most formats/codecs support "raw"
	WithInputEnc(enc string) options.DagPutOption

	// WithCodec is an option for Put which specifies the multicodec to use to
	// serialize the object. Default is cid.DagCBOR (0x71)
	WithCodec(codec uint64) options.DagPutOption

	// WithHash is an option for Put which specifies the multihash settings to use
	// when hashing the object. Default is based on the codec used
	// (mh.SHA2_256 (0x12) for DagCBOR). If mhLen is set to -1, default length for
	// the hash will be used
	WithHash(mhType uint64, mhLen int) options.DagPutOption

	// Get attempts to resolve and get the node specified by the path
	Get(ctx context.Context, path Path) (Node, error)

	// Tree returns list of paths within a node specified by the path.
	Tree(ctx context.Context, path Path, opts ...options.DagTreeOption) ([]Path, error)

	// WithDepth is an option for Tree which specifies maximum depth of the
	// returned tree. Default is -1 (no depth limit)
	WithDepth(depth int) options.DagTreeOption
}

type NameAPI interface {
	Publish(ctx context.Context, path Path, opts ...options.NamePublishOption) (*IpnsEntry, error)
	WithValidTime(validTime time.Duration) options.NamePublishOption
	WithKey(key string) options.NamePublishOption

	Resolve(ctx context.Context, name string, opts ...options.NameResolveOption) (Path, error)
	WithRecursive(recursive bool) options.NameResolveOption
	WithLocal(local bool) options.NameResolveOption
	WithNoCache(nocache bool) options.NameResolveOption
}

type KeyAPI interface {
	Generate(ctx context.Context, name string, opts ...options.KeyGenerateOption) (string, error)
	WithAlgorithm(algorithm string) options.KeyGenerateOption
	WithSize(size int) options.KeyGenerateOption

	Rename(ctx context.Context, oldName string, newName string, opts ...options.KeyRenameOption) (string, bool, error)
	WithForce(force bool) options.KeyRenameOption

	List(ctx context.Context) (map[string]string, error) //TODO: better key type?
	Remove(ctx context.Context, name string) (string, error)
}

// type ObjectAPI interface {
// 	New() (cid.Cid, Object)
// 	Get(string) (Object, error)
// 	Links(string) ([]*Link, error)
// 	Data(string) (Reader, error)
// 	Stat(string) (ObjectStat, error)
// 	Put(Object) (cid.Cid, error)
// 	SetData(string, Reader) (cid.Cid, error)
// 	AppendData(string, Data) (cid.Cid, error)
// 	AddLink(string, string, string) (cid.Cid, error)
// 	RmLink(string, string) (cid.Cid, error)
// }

// type ObjectStat struct {
// 	Cid            cid.Cid
// 	NumLinks       int
// 	BlockSize      int
// 	LinksSize      int
// 	DataSize       int
// 	CumulativeSize int
// }

var ErrIsDir = errors.New("object is a directory")
var ErrOffline = errors.New("can't resolve, ipfs node is offline")