package checker

import (
	"encoding/json"

	"github.com/miekg/dns"
)

// ObservationKeyDelegation is the observation key for delegation data.
const ObservationKeyDelegation = "delegation"

// Severity classifies a finding emitted by the delegation checker.
type Severity string

const (
	SeverityInfo Severity = "info"
	SeverityWarn Severity = "warn"
	SeverityCrit Severity = "crit"
)

// DelegationFinding describes a single observation produced while running
// the delegation testsuite.
type DelegationFinding struct {
	// Code is a stable machine-readable identifier (e.g. "delegation_ns_mismatch").
	Code string `json:"code"`

	// Severity grades the finding.
	Severity Severity `json:"severity"`

	// Message is a human-readable explanation.
	Message string `json:"message"`

	// Server is the DNS server that exhibited the finding (parent or child),
	// when applicable. Empty for findings tied to the service definition itself.
	Server string `json:"server,omitempty"`
}

// DelegationData is the observation payload stored by the checker. It carries
// every finding emitted by the testsuite plus the raw observed state from the
// parent and from each delegated server.
type DelegationData struct {
	// DelegatedFQDN is the FQDN of the delegated zone (subdomain + parent).
	DelegatedFQDN string `json:"delegated_fqdn"`

	// ParentZone is the FQDN of the parent zone that delegates DelegatedFQDN.
	ParentZone string `json:"parent_zone"`

	// ParentNS lists the parent zone's authoritative servers that were
	// queried (FQDNs of NS records).
	ParentNS []string `json:"parent_ns,omitempty"`

	// AdvertisedNS holds the NS RRset returned by the parent for the
	// delegated FQDN, normalized as lowercase FQDNs.
	AdvertisedNS []string `json:"advertised_ns,omitempty"`

	// AdvertisedGlue maps an in-bailiwick NS hostname to the glue addresses
	// returned by the parent for that name.
	AdvertisedGlue map[string][]string `json:"advertised_glue,omitempty"`

	// ParentDS lists the DS records returned by the parent for the
	// delegated FQDN, in their textual presentation form.
	ParentDS []string `json:"parent_ds,omitempty"`

	// ChildSerials maps an NS hostname to the SOA serial it returns for
	// the delegated FQDN.
	ChildSerials map[string]uint32 `json:"child_serials,omitempty"`

	// Findings is the list of issues / observations produced by the run.
	Findings []DelegationFinding `json:"findings"`
}

// delegationService is the minimal local mirror of happyDomain's
// `services/abstract.Delegation` type. It is duplicated on purpose so that
// this checker does not have to import the (heavy) happyDomain server module
// just to decode the service payload. github.com/miekg/dns marshals
// dns.NS / dns.DS to JSON in the same shape happyDomain uses.
type delegationService struct {
	NameServers []*dns.NS `json:"ns"`
	DS          []*dns.DS `json:"ds"`
}

// serviceMessage is the minimal local mirror of happyDomain's ServiceMessage
// envelope. We only need the embedded service JSON; the rest of the meta
// fields are ignored.
type serviceMessage struct {
	Type    string          `json:"_svctype"`
	Domain  string          `json:"_domain"`
	Service json.RawMessage `json:"Service"`
}