package delivery

import (
	"encoding/json"
	"fmt"

	"git.novox.be/novox/mesh-sdk/go/catalogue"
)

// A node's record is what the machine observes of itself (issue 1126, ADR 0555 §3), written by its own agent in its
// own have key, `<node>.node` of the node-engine's have bucket (HaveNode.Record), whenever an observed fact changes and
// only when the value differs. The key's change is the event its readers hear: every node and the parts that compose
// watch it. Where a module runs, and every fact a person decides of the node (its endpoint, site, hub, address on the
// private network, public domain, accounts, the tunnel found at adoption), are the catalogue's placement
// (placement.go). Nothing in it is secret: its keys are public halves.

// RecordTunnel is a tunnel found on a node when it was adopted, as compose.Tunnel holds it: public keys and addresses
// only. After the node took it over the tunnel is no longer there to observe, so it is kept as what was decided at
// adoption, in the node's placement (NodeDecided.Tunnel).
type RecordTunnel struct {
	Interface string             `json:"interface"`
	Unit      string             `json:"unit,omitempty"`
	Config    string             `json:"config,omitempty"`
	Port      int                `json:"port,omitempty"`
	MTU       int                `json:"mtu,omitempty"`
	Address   string             `json:"address,omitempty"`
	Range     string             `json:"range,omitempty"`
	PublicKey string             `json:"public-key,omitempty"`
	Peers     []RecordTunnelPeer `json:"peers,omitempty"`
}

// RecordTunnelPeer is one peer of a found tunnel.
type RecordTunnelPeer struct {
	PublicKey string `json:"public-key"`
	Address   string `json:"address,omitempty"`
}

// NodeRecord is one node's record: what the machine observes of itself (issue 1126, ADR 0555: what a person decides
// lives in the catalogue's placement file, Placement.Decided; what the machine observes lives here). TunnelKey is the
// public key of its private-network tunnel; Certificate the one the mesh issued for its internal name, public, as the
// node holds it. The tunnel found at adoption and the names given to its peers are decisions kept in the placement;
// whether the hub took its found tunnel over, and which node enrolled under a carried peer's key, are read from both.
type NodeRecord struct {
	V            int                         `json:"v"`
	Node         string                      `json:"node"`
	TunnelKey    string                      `json:"tunnel-key,omitempty"`
	Capabilities []string                    `json:"capabilities,omitempty"`
	SealingKey   string                      `json:"sealing-key,omitempty"`
	ServingKey   string                      `json:"serving-key,omitempty"`
	Certificate  string                      `json:"certificate,omitempty"`
	OutwardLinks []string                    `json:"outward-links,omitempty"`
	Networks     []catalogue.AttachedNetwork `json:"networks,omitempty"`
	NetworksSaid bool                        `json:"networks-said,omitempty"`
	Contract     int                         `json:"contract,omitempty"`
	// Authority is the mesh's own certificate as this machine holds it (public): the one its declaration last wrote where
	// a module asked for it. A node composing its own composes a certificate with it (compose.Input.Authority).
	Authority string `json:"authority,omitempty"`
}

func (r NodeRecord) check() error {
	if err := checkName("node", r.Node); err != nil {
		return err
	}
	for _, c := range r.Capabilities {
		if c == "" {
			return fmt.Errorf("delivery: the record of %s names an empty capability", r.Node)
		}
	}
	return nil
}

// EncodeNodeRecord is r as JSON at Version; it refuses what DecodeNodeRecord refuses.
func EncodeNodeRecord(r NodeRecord) ([]byte, error) {
	if err := r.check(); err != nil {
		return nil, err
	}
	r.V = Version
	return json.Marshal(r)
}

// DecodeNodeRecord reads a node record; it refuses an unknown version (ErrUnknownVersion), a node that is not a name, and
// an empty capability.
func DecodeNodeRecord(data []byte) (NodeRecord, error) {
	var r NodeRecord
	if err := decode(data, &r); err != nil {
		return NodeRecord{}, err
	}
	if err := r.check(); err != nil {
		return NodeRecord{}, err
	}
	return r, nil
}

// SameNodeRecord says whether two records are the same value, so the agent writes only when they differ.
func SameNodeRecord(a, b NodeRecord) bool {
	a.V, b.V = 0, 0
	return jsonEqual(a, b)
}