bookhoard/internal/services/series_parsing.go

package services

import (
	"encoding/json"
	"regexp"
	"strconv"
	"strings"
)

// Series-metadata parsing helpers for the scanner (A2c overhaul).
//
// Sources disagree wildly on how a series and its ordinal are spelled:
// ABS sidecars write ["Name #3"] string arrays or [{series, sequence}]
// objects, Libation writes a bare string, Audible prefixes ordinals with
// "Book ", Calibre uses decimal indices. These helpers normalize all of
// them into candidates the scanner can rank and assign.

// SeriesCandidate is one parsed series membership from any source.
type SeriesCandidate struct {
	Name     string
	Sequence string  // raw sequence text ("3", "1.5", "1a", "Book 2")
	Number   float64 // leading number of Sequence (0 = none parsed)
	HasNum   bool
	FromSidecar bool
}

// Playlist markers that identify ordering constructs rather than
// bibliographic series. Deliberately explicit: this classification routes
// entries away from the series column into curated collections, so a false
// positive creates user-visible objects. Prefer misses over false hits.
var playlistMarkers = []string{
	"reading order",
	"chronological order",
	"publication order",
	"in order",
	"timeline",
}

var (
	seriesSeqSuffixRe = regexp.MustCompile(`\s+#([^#\s]+)$`)
	// Leading ordinal inside a sequence string: "3", "1.5", "Book 2",
	// "2, Dramatized Adaptation" → 2. Mirrors ABS cleanSeriesSequence.
	seriesLeadingNumRe = regexp.MustCompile(`\d+(?:\.\d+)?`)
	// "<Series Name>, Book N" (also ; – : separators), Audible/Amazon style.
	deriveSeriesRe = regexp.MustCompile(`(?i)^\s*(.+?)\s*[,;:–-]\s*book\s+(\d+(?:\.\d+)?)\s*$`)
	// Conservative "Title: <name>, Book N" split — only when the post-colon
	// text is itself a series-and-number tail.
	titleSubtitleSplitRe = regexp.MustCompile(`(?i)^(.{1,200}?)\s*:\s*(.+,\s*book\s+\d+(?:\.\d+)?)$`)
	whitespaceRe         = regexp.MustCompile(`\s+`)
)

// splitSeriesString splits "Name #1a" into name + sequence, ABS
// parseSeriesString-compatible: the sequence is anything after the last
// " #" up to end-of-string, containing no whitespace or further '#'.
func splitSeriesString(s string) (name, sequence string) {
	s = strings.TrimSpace(s)
	loc := seriesSeqSuffixRe.FindStringSubmatchIndex(s)
	if loc == nil {
		return s, ""
	}
	return strings.TrimSpace(s[:loc[0]]), s[loc[2]:loc[3]]
}

// seriesSequenceNumber extracts the ordinal from a raw sequence string.
// Returns the number, whether one was found, and whether information was
// lost in the extraction (caller should preserve the raw text, e.g. "1a").
func seriesSequenceNumber(sequence string) (num float64, found, lossy bool) {
	trimmed := strings.TrimSpace(sequence)
	if trimmed == "" {
		return 0, false, false
	}
	token := seriesLeadingNumRe.FindString(trimmed)
	if token == "" {
		return 0, false, false
	}
	num, err := strconv.ParseFloat(token, 64)
	if err != nil {
		return 0, false, false
	}
	// "1.5" tokenizes exactly (not lossy); "1a"/"Book 2" keep a raw tail.
	return num, true, trimmed != token
}

// isPlaylistSeriesName reports whether the series name is an ordering
// construct ("The Witcher (Reading Order)") rather than a bibliography.
// Match discipline: the marker must be a parenthetical qualifier or a
// trailing phrase — a series merely CONTAINING the word "timeline" mid-name
// ("The Timeline of...") is a real series, not a playlist.
func isPlaylistSeriesName(name string) bool {
	lower := strings.ToLower(strings.TrimSpace(name))
	for _, m := range playlistMarkers {
		if strings.HasSuffix(lower, m) {
			return true
		}
		if open := strings.Index(lower, "("); open >= 0 {
			if strings.Contains(lower[open:], m) {
				return true
			}
		}
	}
	return false
}

// parseSeriesCandidates normalizes the sidecar `series` field, which is
// written as an array of STRINGS ("Name #3" — ABS abmetadata), an array of
// OBJECTS ({series, sequence} — some exports), or a plain JSON string
// (Libation), into candidates.
func parseSeriesCandidates(raw json.RawMessage) []SeriesCandidate {
	trimmed := strings.TrimSpace(string(raw))
	if trimmed == "" || trimmed == "null" {
		return nil
	}
	var out []SeriesCandidate

	add := func(name, sequence string, fromSidecar bool) {
		name = strings.TrimSpace(name)
		if name == "" {
			return
		}
		num, found, _ := seriesSequenceNumber(sequence)
		out = append(out, SeriesCandidate{
			Name: name, Sequence: sequence, Number: num, HasNum: found,
			FromSidecar: fromSidecar,
		})
	}

	if strings.HasPrefix(trimmed, "[") {
		// Array of objects first ({"series": ..., "sequence": ...}).
		var objs []struct {
			Series   string `json:"series"`
			Name     string `json:"name"`
			Sequence string `json:"sequence"`
		}
		if err := json.Unmarshal(raw, &objs); err == nil && len(objs) > 0 {
			for _, o := range objs {
				name := o.Series
				if name == "" {
					name = o.Name
				}
				add(name, o.Sequence, true)
			}
			return out
		}
		// Array of strings: ABS abmetadata form "Name #3".
		var strs []string
		if err := json.Unmarshal(raw, &strs); err == nil {
			for _, s := range strs {
				name, seq := splitSeriesString(s)
				add(name, seq, true)
			}
			return out
		}
		return nil
	}

	// Plain JSON string (Libation): "Name" or "Name #3".
	var single string
	if err := json.Unmarshal(raw, &single); err == nil {
		name, seq := splitSeriesString(single)
		add(name, seq, true)
	}
	return out
}

// deriveSeriesFromText extracts "<series>, Book N" from a title/subtitle
// string (Audible/Amazon convention). Returns ok=false when the text is not
// obviously a series tail — this fallback must not guess.
func deriveSeriesFromText(text string) (name string, num float64, hasNum bool, ok bool) {
	if strings.TrimSpace(text) == "" {
		return "", 0, false, false
	}
	m := deriveSeriesRe.FindStringSubmatch(text)
	if m == nil {
		return "", 0, false, false
	}
	name = whitespaceRe.ReplaceAllString(strings.TrimSpace(m[1]), " ")
	if name == "" || len(name) > 200 || strings.HasPrefix(strings.ToLower(name), "book ") {
		return "", 0, false, false
	}
	num, err := strconv.ParseFloat(m[2], 64)
	if err != nil {
		return "", 0, false, false
	}
	return name, num, true, true
}

// splitTitleOnSubtitle splits "Title: <name>, Book N" into title +
// subtitle, but ONLY when the post-colon text is itself a series-and-number
// tail — arbitrary colons in titles are never touched.
func splitTitleOnSubtitle(folderTitle string) (title, subtitle string, split bool) {
	m := titleSubtitleSplitRe.FindStringSubmatch(strings.TrimSpace(folderTitle))
	if m == nil {
		return folderTitle, "", false
	}
	return strings.TrimSpace(m[1]), strings.TrimSpace(m[2]), true
}

// normalizeLanguageCode maps sidecar/display language names to ISO 639-1
// codes (the media_items.language convention). Values already in code form
// pass through; unknown display names are kept verbatim when they fit the
// VARCHAR(10) column, else dropped (empty) — never truncate mid-word.
func normalizeLanguageCode(v string) string {
	v = strings.TrimSpace(v)
	if v == "" {
		return ""
	}
	if code, ok := languageNameToCode[strings.ToLower(v)]; ok {
		return code
	}
	lower := strings.ToLower(v)
	if len(lower) == 2 {
		return lower // already a code (or close enough to be harmless)
	}
	if len(v) <= 10 {
		return v
	}
	return ""
}

// languageCodeToName — canonical English display name per ISO code,
// mirroring languageNameToCode (server owns display; the column stores
// ISO 639-1).
var languageCodeToName = map[string]string{
	"en": "English", "es": "Spanish", "fr": "French", "de": "German",
	"it": "Italian", "pt": "Portuguese", "nl": "Dutch", "ru": "Russian",
	"uk": "Ukrainian", "pl": "Polish", "cs": "Czech", "sk": "Slovak",
	"sv": "Swedish", "no": "Norwegian", "da": "Danish", "fi": "Finnish",
	"is": "Icelandic", "hu": "Hungarian", "ro": "Romanian", "bg": "Bulgarian",
	"el": "Greek", "tr": "Turkish", "ar": "Arabic", "he": "Hebrew",
	"fa": "Persian", "hi": "Hindi", "bn": "Bengali", "ur": "Urdu",
	"th": "Thai", "vi": "Vietnamese", "id": "Indonesian", "ms": "Malay",
	"ja": "Japanese", "ko": "Korean", "zh": "Chinese", "sw": "Swahili",
	"af": "Afrikaans", "ca": "Catalan", "hr": "Croatian", "sr": "Serbian",
	"sl": "Slovenian", "lt": "Lithuanian", "lv": "Latvian", "et": "Estonian",
	"ka": "Georgian", "hy": "Armenian", "cy": "Welsh", "ga": "Irish",
	"eu": "Basque", "gl": "Galician",
}

// LanguageDisplayName renders a stored language value for DISPLAY.
// Returns "" when the value is not a known code — callers keep the raw
// value then (legacy verbatim rows like "Pig Latin" display as
// themselves).
func LanguageDisplayName(code string) string {
	if name, ok := languageCodeToName[strings.ToLower(strings.TrimSpace(code))]; ok {
		return name
	}
	return ""
}

var languageNameToCode = map[string]string{
	"english": "en", "spanish": "es", "español": "es", "french": "fr",
	"français": "fr", "german": "de", "deutsch": "de", "italian": "it",
	"italiano": "it", "portuguese": "pt", "dutch": "nl", "russian": "ru",
	"ukrainian": "uk", "polish": "pl", "czech": "cs", "slovak": "sk",
	"swedish": "sv", "norwegian": "no", "danish": "da", "finnish": "fi",
	"icelandic": "is", "hungarian": "hu", "romanian": "ro", "bulgarian": "bg",
	"greek": "el", "turkish": "tr", "arabic": "ar", "hebrew": "he",
	"persian": "fa", "hindi": "hi", "bengali": "bn", "urdu": "ur",
	"thai": "th", "vietnamese": "vi", "indonesian": "id", "malay": "ms",
	"japanese": "ja", "korean": "ko", "chinese": "zh", "mandarin": "zh",
	"cantonese": "zh", "swahili": "sw", "afrikaans": "af", "catalan": "ca",
	"croatian": "hr", "serbian": "sr", "slovenian": "sl", "lithuanian": "lt",
	"latvian": "lv", "estonian": "et", "georgian": "ka", "armenian": "hy",
	"welsh": "cy", "irish": "ga", "basque": "eu", "galician": "gl",
}