// Package nodesync replicates the system configuration of one PVE node (the
// master) to other nodes (the targets), of the same cluster or not. It is the
// second replication mode of pve-confsync, next to the cluster to cluster one
// (package engine). What the PVE API covers goes through the API: the network
// interfaces (/nodes/{node}/network, written in interfaces.new then reloaded)
// and the DNS servers (/nodes/{node}/dns). The other files go through SSH as
// root on the node: multipath, chrony, sysctl, interfaces.d. Same pipeline as
// the engine: read, normalize, diff, plan, apply with backup, reload, verify.
package nodesync

import "fmt"

// ItemKind tells how an item is read and written.
type ItemKind string

const (
	KindNetwork ItemKind = "network" // API /nodes/{node}/network
	KindDNS     ItemKind = "dns"     // API /nodes/{node}/dns
	KindFile    ItemKind = "file"    // files over SSH
)

// Item is one replicable element.
type Item struct {
	ID   string   `json:"id"`
	Kind ItemKind `json:"kind"`
	// Files: paths or glob patterns read on the nodes, and paths never touched.
	Paths   []string `json:"paths,omitempty"`
	Exclude []string `json:"exclude,omitempty"`
	// Glob items hold several files: a file only on the target is kept, or
	// deleted with the prune option. Single file items are never deleted.
	Glob bool `json:"glob,omitempty"`
	// Additive files (multipath wwids) only get the lines of the master they
	// miss: nothing is removed from the target.
	Additive bool `json:"additive,omitempty"`
	// Reload is the command run on the node after a write (empty: none).
	Reload string `json:"reload,omitempty"`
	// Network items reload the network of the node: typed confirmation,
	// automatic restore when the node is unreachable afterwards.
	Network bool `json:"network,omitempty"`
}

// Items is the catalog, in apply order (reloads follow this order, the
// network last).
var Items = []Item{
	{ID: "sysctl", Kind: KindFile, Paths: []string{"/etc/sysctl.d/*.conf"}, Glob: true, Reload: "sysctl --system"},
	{ID: "chrony", Kind: KindFile, Paths: []string{"/etc/chrony/chrony.conf", "/etc/chrony/sources.d/*.sources"}, Glob: true,
		Reload: "systemctl restart chrony"},
	{ID: "multipath", Kind: KindFile, Paths: []string{"/etc/multipath.conf"}, Reload: "multipathd reconfigure"},
	{ID: "wwids", Kind: KindFile, Paths: []string{"/etc/multipath/wwids"}, Additive: true, Reload: "multipathd reconfigure"},
	{ID: "dns", Kind: KindDNS},
	// interfaces.d/sdn is generated by the SDN of PVE: never replicated
	{ID: "interfaces-d", Kind: KindFile, Paths: []string{"/etc/network/interfaces.d/*"}, Exclude: []string{"/etc/network/interfaces.d/sdn"},
		Glob: true, Reload: "ifreload -a", Network: true},
	{ID: "network", Kind: KindNetwork, Network: true},
}

// ItemByID returns an item of the catalog.
func ItemByID(id string) (Item, error) {
	for _, it := range Items {
		if it.ID == id {
			return it, nil
		}
	}
	return Item{}, fmt.Errorf("unknown item %q", id)
}

func itemRank(id string) int {
	for i, it := range Items {
		if it.ID == id {
			return i
		}
	}
	return len(Items)
}

// Policy of a field of an API item (network, dns).
type Policy string

const (
	Sync     Policy = "sync"     // copied from the master
	Ignore   Policy = "ignore"   // never written
	Override Policy = "override" // only written from the target mapping
)

// defaultPolicy: the addresses and gateways are those of each node; they are
// only written from the mapping of a target.
func defaultPolicy(item, field string) Policy {
	if item == "network" {
		switch field {
		case "cidr", "cidr6", "gateway", "gateway6":
			return Override
		}
	}
	return Sync
}

// DefaultPolicies lists the fields whose default is not "sync", for the UI.
var DefaultPolicies = map[string]map[string]Policy{
	"network": {"cidr": Override, "cidr6": Override, "gateway": Override, "gateway6": Override},
}