package checker

import (
	"encoding/json"

	"github.com/miekg/dns"
)

// ObservationKeyPTR is the observation key for the PTR checker payload.
const ObservationKeyPTR = "ptr"

// ForwardAddress records a single A/AAAA answer collected for the PTR target.
type ForwardAddress struct {
	Type    string `json:"type"` // "A" or "AAAA"
	Address string `json:"address"`
	TTL     uint32 `json:"ttl,omitempty"`
}

// PTRData is the raw observation payload persisted by the checker. It
// contains NO judgement: severity, pass/fail and derived issues are the
// responsibility of CheckRule implementations.
type PTRData struct {
	// OwnerName is the FQDN of the PTR record as declared by the service
	// (the reverse-arpa name, e.g. "4.3.2.1.in-addr.arpa.").
	OwnerName string `json:"owner_name"`

	// DeclaredTarget is the hostname the service says the PTR should point
	// to. Always fully-qualified and lowercased.
	DeclaredTarget string `json:"declared_target"`

	// DeclaredTTL is the TTL declared by the service.
	DeclaredTTL uint32 `json:"declared_ttl,omitempty"`

	// InReverseArpa reports whether OwnerName lies under in-addr.arpa or
	// ip6.arpa.
	InReverseArpa bool `json:"in_reverse_arpa"`

	// IsIPv6 reports whether OwnerName is an ip6.arpa name.
	IsIPv6 bool `json:"is_ipv6"`

	// ReverseIP is the IP address reconstructed from OwnerName (if parseable).
	ReverseIP string `json:"reverse_ip,omitempty"`

	// OwnerDecodeFailed is true when OwnerName lies under *.arpa but no IP
	// could be decoded from it (malformed labels).
	OwnerDecodeFailed bool `json:"owner_decode_failed,omitempty"`

	// ReverseZone is the apex of the reverse zone serving OwnerName (where
	// the SOA lives). Empty when it could not be located.
	ReverseZone string `json:"reverse_zone,omitempty"`

	// ReverseNS are the authoritative servers of the reverse zone.
	ReverseNS []string `json:"reverse_ns,omitempty"`

	// ZoneLookupError captures the transport/NXDOMAIN-style failure
	// encountered while walking up to find the SOA. Empty on success.
	ZoneLookupError string `json:"zone_lookup_error,omitempty"`

	// ObservedTargets lists every PTR target observed at OwnerName. In a
	// healthy setup, this has exactly one entry equal to DeclaredTarget.
	ObservedTargets []string `json:"observed_targets,omitempty"`

	// ObservedTTL is the TTL of the PTR RRset as seen from authoritative
	// servers.
	ObservedTTL uint32 `json:"observed_ttl,omitempty"`

	// QueryError captures a transport-level failure while querying the PTR
	// RRset (unreachable servers, timeouts, …). Empty on success.
	QueryError string `json:"query_error,omitempty"`

	// Rcode is the textual rcode of the PTR lookup (e.g. "NOERROR",
	// "NXDOMAIN", "SERVFAIL"); empty when not applicable.
	Rcode string `json:"rcode,omitempty"`

	// EffectiveTarget is the hostname actually examined for hygiene and
	// FCrDNS (the first observed target, or the declared one when none is
	// observed). Empty when neither is available.
	EffectiveTarget string `json:"effective_target,omitempty"`

	// TargetSyntaxValid reports whether EffectiveTarget parses as a valid
	// DNS hostname. False when EffectiveTarget is empty or malformed.
	TargetSyntaxValid bool `json:"target_syntax_valid,omitempty"`

	// TargetLooksGeneric reports whether EffectiveTarget embeds the IP or
	// matches common ISP auto-generated patterns.
	TargetLooksGeneric bool `json:"target_looks_generic,omitempty"`

	// ForwardAddresses are the A/AAAA addresses the target resolves to
	// (recursive resolution from the system resolver).
	ForwardAddresses []ForwardAddress `json:"forward_addresses,omitempty"`

	// ForwardMatch is true when ReverseIP appears among ForwardAddresses
	// (Forward-Confirmed Reverse DNS).
	ForwardMatch bool `json:"forward_match,omitempty"`

	// TargetResolves is true when the PTR target produced at least one A or
	// AAAA. Distinct from ForwardMatch: a target can resolve yet point
	// somewhere else.
	TargetResolves bool `json:"target_resolves,omitempty"`
}

// ptrService is the minimal local mirror of happyDomain's `svcs.PTR`. It
// carries a single *dns.PTR. The JSON key matches the Go struct field name
// used in happyDomain (`Record`).
type ptrService struct {
	Record *dns.PTR `json:"Record"`
}

// serviceMessage is the minimal local mirror of happyDomain's ServiceMessage
// envelope.
type serviceMessage struct {
	Type    string          `json:"_svctype"`
	Domain  string          `json:"_domain"`
	Service json.RawMessage `json:"Service"`
}