nzb

type File struct {
	Index   int // position in NZB.Files
	Poster  string
	Date    time.Time
	Subject string
	Groups  []string
	// Segments sorted by Number, de-duplicated: the first occurrence of a
	// number wins, later message-IDs for it become its Alternates.
	Segments []Segment

	// Name is the file name derived from the subject (may be obfuscated).
	Name string
	// Obfuscated reports that Name looks random (hashes, missing extension),
	// so it says nothing about the content.
	Obfuscated bool
	// Info classifies Name.
	Info FileInfo
	// SubjectIndex / SubjectCount are the "[03/50]" file counter in the
	// subject, 0 when absent. Useful to order obfuscated volumes.
	SubjectIndex int
	SubjectCount int
	// ExpectedSegments is the "(1/N)" segment count in the subject, or 0.
	ExpectedSegments int
	// Duplicates counts repeated segment numbers folded into an earlier
	// segment (as Alternates when the message-ID differs).
	Duplicates int
}

type FileInfo struct {
	Kind Kind
	// Ext is the lower-cased extension of the content: "mkv" for
	// "movie.mkv" and for "movie.mkv.001"; "rar" / "7z" for archives.
	Ext string
	// Volume is the 0-based position of an archive volume in its set
	// (.rar=0, .r00=1, .part01.rar=0, .7z.001=0, .001=0). -1 otherwise.
	Volume int
	// SetName is the lower-cased name shared by every volume of a set, so
	// volumes group by (Kind, SetName). For other files it is the
	// lower-cased name without extension.
	SetName string
	// NewStyle is true for .partNN.rar naming, false for .rar/.rNN.
	NewStyle bool
	// Sample and Extra flag short clips that are not the feature.
	Sample bool
	Extra  bool
}

type Kind int

type NZB struct {
	// Meta holds <head><meta type="..."> values by lower-cased type.
	Meta map[string][]string
	// Files in document order. Files without any valid segment are dropped.
	Files []*File
}

type Segment struct {
	Number    int    // 1-based part number
	Bytes     int64  // article size as listed in the NZB (encoded, approximate)
	MessageID string // without angle brackets
	// Alternates are message-IDs of reposts ("fills") of this same part,
	// in NZB order, to try when MessageID is missing everywhere. A repost
	// carries the same yEnc part, so its bytes must land on the same range.
	Alternates []string
}

type Set struct {
	Kind Kind
	// Name is the lower-cased set name shared by the volumes
	// ("movie.2024" for movie.2024.part01.rar, "movie.mkv" for movie.mkv.001).
	Name string
	// NewStyle is true for .partNN.rar sets.
	NewStyle bool
	// Volumes in order; gaps are listed in Missing. The files' Info is left
	// untouched (a part00/.000 set keeps numbering from -1), so grouping the
	// same files again gives the same result and concurrent callers do not
	// write shared files.
	Volumes []*File
	// Missing lists absent 0-based volume numbers below the highest present.
	Missing []int
	// Duplicates are reposted volumes that lost to a larger copy.
	Duplicates []*File
}