// Package checker implements a TLS checker for happyDomain. See README for
// the payload shape and consumer contract.
package checker

import "time"

// ObservationKeyTLSProbes is the observation key this checker writes.
const ObservationKeyTLSProbes = "tls_probes"

// Option ids on CheckerOptions.
const (
	OptionEndpoints      = "endpoints"
	OptionProbeTimeoutMs = "probeTimeoutMs"
)

// Defaults shared between the definition's Default field and the runtime
// fallback when probeTimeoutMs is unset or invalid.
const (
	DefaultProbeTimeoutMs = 10000
	// MaxConcurrentProbes caps parallel probes per collect run to avoid
	// exhausting file descriptors on domains with many endpoints.
	MaxConcurrentProbes = 32
)

// Severity values used in Issue.Severity (lowercase, ascii).
const (
	SeverityCrit = "crit"
	SeverityWarn = "warn"
	SeverityInfo = "info"
)

// TLSData is the full collected payload written under ObservationKeyTLSProbes.
type TLSData struct {
	Probes      map[string]TLSProbe `json:"probes"`
	CollectedAt time.Time           `json:"collected_at"`
}

// TLSProbe captures the outcome of probing a single endpoint. Field names
// mirror what consumers already parse (checker-xmpp's tlsProbeView).
type TLSProbe struct {
	Host          string    `json:"host"`
	Port          uint16    `json:"port"`
	Endpoint      string    `json:"endpoint"`
	Type          string    `json:"type"`
	SNI           string    `json:"sni,omitempty"`
	TLSVersion    string    `json:"tls_version,omitempty"`
	CipherSuite   string    `json:"cipher_suite,omitempty"`
	HostnameMatch *bool     `json:"hostname_match,omitempty"`
	ChainValid    *bool     `json:"chain_valid,omitempty"`
	NotAfter      time.Time `json:"not_after,omitempty"`
	Issuer        string    `json:"issuer,omitempty"`
	// IssuerDN is the leaf's issuer as an RFC 2253 DN string, suitable for
	// matching the CCADB CAA Identifiers CSV "Subject" column when the AKI
	// lookup misses.
	IssuerDN string `json:"issuer_dn,omitempty"`
	// IssuerAKI is the uppercase hex of the leaf's Authority Key Identifier
	// extension (i.e. the issuer cert's SKI). This is the primary lookup key
	// into the CCADB CAA Identifiers CSV ("Subject Key Identifier (Hex)").
	IssuerAKI string   `json:"issuer_aki,omitempty"`
	Subject   string   `json:"subject,omitempty"`
	DNSNames  []string `json:"dns_names,omitempty"`
	// Chain carries one entry per certificate presented by the server
	// (leaf first, then intermediates in order). Each entry precomputes
	// the four TLSA selector×matching_type hashes plus the raw DER so
	// DANE consumers can match without re-handshaking or re-parsing.
	Chain     []CertInfo `json:"chain,omitempty"`
	ElapsedMS int64      `json:"elapsed_ms,omitempty"`
	Error     string     `json:"error,omitempty"`
	Issues    []Issue    `json:"issues,omitempty"`
}

// CertInfo describes one certificate in the presented chain together with
// pre-hashed forms suitable for DANE/TLSA matching (RFC 6698 §2.1).
//
// Hex fields are lowercase, matching the representation emitted by
// miekg/dns for TLSA RR Certificate fields.
type CertInfo struct {
	// DERBase64 is the standard base64 encoding of the certificate's DER
	// form. Carried so consumers can do matching-type 0 (Full) without
	// requiring a precomputed "full" hash and for fallback inspection.
	DERBase64 string `json:"der_base64,omitempty"`

	// Subject / Issuer are short human-readable DNs for the HTML report.
	Subject string `json:"subject,omitempty"`
	Issuer  string `json:"issuer,omitempty"`

	// NotAfter is the certificate's expiry. Carried so editors can show
	// "expires on …" without re-parsing the DER.
	NotAfter time.Time `json:"not_after,omitempty"`

	// Selector 0 = full certificate.
	CertSHA256 string `json:"cert_sha256,omitempty"`
	CertSHA512 string `json:"cert_sha512,omitempty"`

	// Selector 1 = SubjectPublicKeyInfo.
	SPKISHA256 string `json:"spki_sha256,omitempty"`
	SPKISHA512 string `json:"spki_sha512,omitempty"`

	// SPKIDERBase64 lets consumers handle (selector=1, matching=0) without
	// re-parsing the certificate.
	SPKIDERBase64 string `json:"spki_der_base64,omitempty"`
}

// Issue is a single TLS finding surfaced to the consumer.
type Issue struct {
	Code     string `json:"code"`
	Severity string `json:"severity"`
	Message  string `json:"message,omitempty"`
	Fix      string `json:"fix,omitempty"`
}