// Package dav holds the code shared between the CalDAV and CardDAV checkers:
// discovery (SRV/TXT, /.well-known), OPTIONS probing, PROPFIND helpers, and
// the HTML report CSS. The CalDAV/CardDAV-specific collect pipelines live in
// their own packages and compose these helpers.
package dav

import "time"

// Kind distinguishes the two protocol flavours. A single Kind value is carried
// end-to-end through a checker run so shared helpers can pick the right
// service names, well-known paths, and required DAV classes.
type Kind string

const (
	KindCalDAV  Kind = "caldav"
	KindCardDAV Kind = "carddav"
)

// ServiceName returns the RFC 6764 SRV service label for kind, with the
// leading "_" but without the "_tcp" suffix.
func (k Kind) ServiceName(secure bool) string {
	switch k {
	case KindCalDAV:
		if secure {
			return "_caldavs"
		}
		return "_caldav"
	case KindCardDAV:
		if secure {
			return "_carddavs"
		}
		return "_carddav"
	}
	return ""
}

// WellKnownPath returns the RFC 6764 well-known path for kind.
func (k Kind) WellKnownPath() string {
	return "/.well-known/" + string(k)
}

// RequiredCapability is the string that must appear in the DAV: response
// header for the server to qualify as a valid implementation.
func (k Kind) RequiredCapability() string {
	switch k {
	case KindCalDAV:
		return "calendar-access"
	case KindCardDAV:
		return "addressbook"
	}
	return ""
}

// Observation is the root data structure persisted by either checker. The
// CalDAV-only fields (Scheduling) are populated for KindCalDAV runs and left
// zero-valued for KindCardDAV.
type Observation struct {
	Kind           Kind              `json:"kind"`
	Domain         string            `json:"domain"`
	HasCredentials bool              `json:"has_credentials"`
	Discovery      DiscoveryResult   `json:"discovery"`
	Transport      TransportResult   `json:"transport"`
	Options        OptionsResult     `json:"options"`
	Principal      PrincipalResult   `json:"principal"`
	HomeSet        HomeSetResult     `json:"home_set"`
	Collections    CollectionsResult `json:"collections"`
	Report         ReportResult      `json:"report"`
	Scheduling     *SchedulingResult `json:"scheduling,omitempty"`
	CollectedAt    time.Time         `json:"collected_at"`
}

// SRVRecord is a flat, JSON-friendly view of a DNS SRV answer.
type SRVRecord struct {
	Target   string `json:"target"`
	Port     uint16 `json:"port"`
	Priority uint16 `json:"priority"`
	Weight   uint16 `json:"weight"`
}

// DiscoveryResult captures every signal we gathered while locating the
// service: SRV secure/plaintext, TXT path hints, well-known redirects, and
// the ultimately-resolved context URL.
type DiscoveryResult struct {
	SecureSRV      []SRVRecord `json:"secure_srv,omitempty"`
	PlaintextSRV   []SRVRecord `json:"plaintext_srv,omitempty"`
	SRVError       string      `json:"srv_error,omitempty"`
	TXTPath        string      `json:"txt_path,omitempty"`
	TXTError       string      `json:"txt_error,omitempty"`
	WellKnownURL   string      `json:"well_known_url,omitempty"`
	WellKnownCode  int         `json:"well_known_code,omitempty"`
	WellKnownChain []string    `json:"well_known_chain,omitempty"`
	WellKnownError string      `json:"well_known_error,omitempty"`
	ContextURL     string      `json:"context_url,omitempty"`
	Source         string      `json:"source,omitempty"` // "explicit", "well-known", "srv-txt"
	Error          string      `json:"error,omitempty"`
}

// TransportResult records whether the resolved context URL accepts HTTPS
// requests. TLS certificate validation is out of scope (a dedicated TLS
// checker covers it); we only report the raw transport-level error if any.
type TransportResult struct {
	Reached bool   `json:"reached"`
	Error   string `json:"error,omitempty"`
}

// OptionsResult captures the response to an OPTIONS request against the
// context URL: which DAV: classes are advertised, which HTTP methods are in
// Allow:, and which authentication schemes the server offered.
type OptionsResult struct {
	StatusCode   int      `json:"status_code"`
	DAVClasses   []string `json:"dav_classes,omitempty"`
	AllowMethods []string `json:"allow_methods,omitempty"`
	AuthSchemes  []string `json:"auth_schemes,omitempty"`
	Server       string   `json:"server,omitempty"`
	Error        string   `json:"error,omitempty"`
}

// PrincipalResult holds the `current-user-principal` URL discovered after
// authenticating. Skipped is set to true when no credentials were supplied
// (the rule surfaces this as StatusUnknown).
type PrincipalResult struct {
	Skipped bool   `json:"skipped,omitempty"`
	URL     string `json:"url,omitempty"`
	Error   string `json:"error,omitempty"`
}

// HomeSetResult holds the CalDAV `calendar-home-set` or CardDAV
// `addressbook-home-set` URL for the authenticated principal.
type HomeSetResult struct {
	Skipped bool   `json:"skipped,omitempty"`
	URL     string `json:"url,omitempty"`
	Error   string `json:"error,omitempty"`
}

// CollectionInfo describes a single discovered calendar or addressbook.
type CollectionInfo struct {
	Path                  string   `json:"path"`
	Name                  string   `json:"name,omitempty"`
	Description           string   `json:"description,omitempty"`
	MaxResourceSize       int64    `json:"max_resource_size,omitempty"`
	SupportedComponentSet []string `json:"supported_component_set,omitempty"` // CalDAV only
	SupportedAddressData  []string `json:"supported_address_data,omitempty"`  // CardDAV only
}

// CollectionsResult is the enumerated content of the home-set.
type CollectionsResult struct {
	Skipped bool             `json:"skipped,omitempty"`
	Items   []CollectionInfo `json:"items,omitempty"`
	Error   string           `json:"error,omitempty"`
}

// ReportResult is the outcome of a minimal REPORT probe against the first
// collection found (empty calendar-query/addressbook-query).
type ReportResult struct {
	Skipped   bool   `json:"skipped,omitempty"`
	QueryOK   bool   `json:"query_ok,omitempty"`
	ProbePath string `json:"probe_path,omitempty"`
	Error     string `json:"error,omitempty"`
}

// SchedulingResult is CalDAV-only: presence of inbox/outbox when the server
// advertises the `calendar-schedule` capability.
type SchedulingResult struct {
	Advertised bool   `json:"advertised"`
	InboxURL   string `json:"inbox_url,omitempty"`
	OutboxURL  string `json:"outbox_url,omitempty"`
	Error      string `json:"error,omitempty"`
}