// Package ulreq implements encoding and decoding upload-request
// messages from a git-upload-pack command.
package ulreq

import (
	"time"

	"gopkg.in/src-d/go-git.v4/core"
	"gopkg.in/src-d/go-git.v4/formats/packp"
)

// UlReq values represent the information transmitted on a
// upload-request message.  Values from this type are not zero-value
// safe, use the New function instead.
type UlReq struct {
	Capabilities *packp.Capabilities
	Wants        []core.Hash
	Shallows     []core.Hash
	Depth        Depth
}

// Depth values stores the desired depth of the requested packfile: see
// DepthCommit, DepthSince and DepthReference.
type Depth interface {
	isDepth()
}

// DepthCommits values stores the maximum number of requested commits in
// the packfile.  Zero means infinite.  A negative value will have
// undefined consecuences.
type DepthCommits int

func (d DepthCommits) isDepth() {}

// DepthSince values requests only commits newer than the specified time.
type DepthSince time.Time

func (d DepthSince) isDepth() {}

// DepthReference requests only commits not to found in the specified reference.
type DepthReference string

func (d DepthReference) isDepth() {}

// New returns a pointer to a new UlReq value, ready to be used.  It has
// no capabilities, wants or shallows and an infinite depth.  Please
// note that to encode an upload-request it has to have at least one
// wanted hash.
func New() *UlReq {
	return &UlReq{
		Capabilities: packp.NewCapabilities(),
		Wants:        []core.Hash{},
		Shallows:     []core.Hash{},
		Depth:        DepthCommits(0),
	}
}