package checker

import (
	"encoding/json"

	"github.com/miekg/dns"
)

const ObservationKeyAlias = "alias"

type AliasKind string

const (
	KindCNAME  AliasKind = "CNAME"
	KindDNAME  AliasKind = "DNAME"
	KindALIAS  AliasKind = "ALIAS" // provider-flattened apex alias, no real RR on the wire
	KindTarget AliasKind = "TARGET"
)

type ChainHop struct {
	Owner       string    `json:"owner"`
	Kind        AliasKind `json:"kind"`
	Target      string    `json:"target,omitempty"`
	TTL         uint32    `json:"ttl,omitempty"`
	Server      string    `json:"server,omitempty"`
	Synthesized bool      `json:"synthesized,omitempty"` // CNAME synthesized from DNAME
}

type CoexistingRRset struct {
	Type string `json:"type"`
	TTL  uint32 `json:"ttl,omitempty"`
}

type TerminationReason string

const (
	TermOK       TerminationReason = "ok"
	TermLoop     TerminationReason = "loop"
	TermTooLong  TerminationReason = "too_long"
	TermQueryErr TerminationReason = "query_error"
	TermRcode    TerminationReason = "rcode"
)

// ChainTermination is always populated after a walk; rules key off Reason.
type ChainTermination struct {
	Reason  TerminationReason `json:"reason"`
	Subject string            `json:"subject,omitempty"`
	Detail  string            `json:"detail,omitempty"`
	Rcode   string            `json:"rcode,omitempty"` // only with TermRcode
}

// AliasData carries raw facts only; judgement is delegated to the rules.
type AliasData struct {
	Owner string `json:"owner"`

	// Apex is empty iff the apex lookup failed; ApexLookupError explains why.
	Apex            string   `json:"apex,omitempty"`
	ApexLookupError string   `json:"apex_lookup_error,omitempty"`
	AuthServers     []string `json:"auth_servers,omitempty"`

	Chain           []ChainHop       `json:"chain,omitempty"`
	ChainTerminated ChainTermination `json:"chain_terminated"`

	// FinalTarget is the last name in the chain, equal to Owner when there is
	// no indirection.
	FinalTarget string   `json:"final_target,omitempty"`
	FinalA      []string `json:"final_a,omitempty"`
	FinalAAAA   []string `json:"final_aaaa,omitempty"`
	FinalRcode  string   `json:"final_rcode,omitempty"`

	// Coexisting is populated only when Owner has a CNAME.
	Coexisting []CoexistingRRset `json:"coexisting,omitempty"`

	OwnerIsApex   bool `json:"owner_is_apex,omitempty"`
	OwnerHasCNAME bool `json:"owner_has_cname,omitempty"`

	// Apex* fields are populated only when OwnerIsApex.
	ApexHasA       bool `json:"apex_has_a,omitempty"`
	ApexHasAAAA    bool `json:"apex_has_aaaa,omitempty"`
	ApexHasCNAME   bool `json:"apex_has_cname,omitempty"`
	ApexFlattening bool `json:"apex_flattening,omitempty"`

	ZoneSigned bool `json:"zone_signed,omitempty"`
	// CNAMESigCheckDone gates CNAMESigned: a false here means we never probed
	// (zone unsigned or no CNAME), so CNAMESigned must not be interpreted.
	CNAMESigCheckDone bool `json:"cname_sig_check_done,omitempty"`
	CNAMESigned       bool `json:"cname_signed,omitempty"`

	DNAMESubstitutions []ChainHop `json:"dname_substitutions,omitempty"`
}

// cnameService mirrors happyDomain's svcs.CNAME / svcs.SpecialCNAME wire shape.
type cnameService struct {
	Record *dns.CNAME `json:"cname"`
}

// serviceMessage mirrors happyDomain's ServiceMessage envelope.
type serviceMessage struct {
	Type    string          `json:"_svctype"`
	Domain  string          `json:"_domain"`
	Service json.RawMessage `json:"Service"`
}