package services

import "strings"

// Genre model v2 (faceted-navigation plan, Batch B): the `genre` column
// holds ONLY top-level shelves; every more specific candidate is a tag
// mapped to its parent shelf. User rule: *a subgenre is not a genre, it's
// a tag*.
//
// Sources arrive as comma-blobs ("Epic, Action & Adventure, Military,
// Sword & Sorcery" — one Audible genre string), media-format noise
// ("Audiobook"), maximally generic tags ("Fiction"), or library-type
// words ("Manga", "Comics" — ComicInfo files that describe the TYPE,
// not a shelf). Deterministic ranked rule set — no network, no guessing:
//
//  1. split candidate strings on , ; /
//  2. alias-map variants to canonical forms (shelf or subgenre)
//  3. discard demoted tokens (formats/editions/type-words) — never win
//  4. pick: first DIRECT shelf (source order) > first MAPPED subgenre
//     shelf > Fiction/Nonfiction floor > "" (unknown-only: tags carry it)
//  5. every candidate (split parts included) still lands in tags
//
// "adventure" and "action & adventure" are BOTH shelves — provider data
// (Audible/Calibre) uses both, and the user-verified traces pin them:
// {Pirates} → adventure (mapped), Malazan blob → action & adventure
// (direct beats mapped). Merging them is deferred aliasing work.
var genreShelves = map[string]bool{
	// Fiction side
	"fiction": true, "action & adventure": true, "adventure": true,
	"fantasy": true, "science fiction": true, "horror": true,
	"mystery": true, "thriller": true, "romance": true,
	"historical fiction": true, "western": true, "war & military": true,
	"young adult": true, "middle grade": true, "children's": true,
	"classics": true, "humor": true, "poetry": true, "short stories": true,
	// Nonfiction side
	"nonfiction": true, "biography & memoir": true, "history": true,
	"science": true, "true crime": true, "self-help": true,
	"philosophy": true, "business": true,
}

// genreFloors are shelves that only win when NO other shelf candidate
// exists (direct or mapped) — maximally generic positions. {Fiction,
// Epic Fantasy} → fantasy, {Fiction} alone → fiction.
func isGenreFloor(lower string) bool {
	return lower == "fiction" || lower == "nonfiction"
}

// genreSubgenreShelf maps subgenre candidates (lowercase) to their parent
// shelf. Anything here is a TAG by definition; its shelf wins the genre
// column only when no direct shelf hit exists.
var genreSubgenreShelf = map[string]string{
	// Fantasy subgenres
	"epic fantasy": "fantasy", "sword & sorcery": "fantasy",
	"dark fantasy": "fantasy", "urban fantasy": "fantasy",
	"paranormal": "fantasy", "high fantasy": "fantasy",
	"fairy tales": "fantasy", "mythology": "fantasy",
	"folklore": "fantasy", "litrpg": "fantasy",
	"progression fantasy": "fantasy",
	// Science fiction subgenres
	"space opera": "science fiction", "cyberpunk": "science fiction",
	"military science fiction": "science fiction", "dystopian": "science fiction",
	"post-apocalyptic": "science fiction", "apocalyptic": "science fiction",
	"time travel": "science fiction", "alternate history": "science fiction",
	"first contact": "science fiction", "steampunk": "science fiction",
	// Romance subgenres
	"contemporary romance": "romance", "historical romance": "romance",
	"paranormal romance": "romance",
	// Mystery subgenres
	"cozy mystery": "mystery", "crime": "mystery",
	"police procedural": "mystery", "noir": "mystery", "hardboiled": "mystery",
	// Thriller subgenres
	"suspense": "thriller", "espionage": "thriller",
	// Horror subgenres
	"gothic": "horror", "supernatural": "horror",
	// Fiction-side themes
	"literary fiction": "fiction", "coming of age": "fiction",
	"satire": "fiction", "anthology": "fiction", "alternate world": "fiction",
	// War & Military subgenres
	"military": "war & military", "war": "war & military",
	// Adventure subgenres
	"pirates": "adventure",
	// Biography & Memoir subgenres
	"biography": "biography & memoir", "autobiography": "biography & memoir",
	"memoir": "biography & memoir",
	// Remaining nonfiction topics → the nonfiction umbrella shelf
	"psychology": "nonfiction", "economics": "nonfiction",
	"politics": "nonfiction", "religion": "nonfiction",
	"spirituality": "nonfiction", "travel": "nonfiction",
	"cooking": "nonfiction", "food": "nonfiction",
	"health": "nonfiction", "fitness": "nonfiction",
	"sports": "nonfiction", "music": "nonfiction",
	"art": "nonfiction", "photography": "nonfiction",
	"education": "nonfiction", "reference": "nonfiction",
	"legal": "nonfiction", "medical": "nonfiction",
}

// genreAliases maps provider variants to a canonical shelf OR subgenre
// form (which the maps above then resolve).
var genreAliases = map[string]string{
	"sci-fi": "science fiction", "scifi": "science fiction",
	"sf": "science fiction", "sff": "science fiction",
	"sci fi": "science fiction", "sci_fi": "science fiction",
	"speculative fiction": "science fiction",
	"detectives":          "mystery", "detective": "mystery",
	"whodunnit": "mystery", "whodunit": "mystery",
	"adventure fiction":    "action & adventure",
	"action and adventure": "action & adventure",
	"ya":                   "young adult", "mg": "middle grade",
	"coming-of-age":    "coming of age",
	"histfiction":      "historical fiction",
	"epic":             "epic fantasy",
	"military scifi":   "military science fiction",
	"military sf":      "military science fiction",
	"post apocalyptic": "post-apocalyptic",
	"self help":        "self-help",
}

// genreDemoted never wins the genre column — media formats, editions,
// and library-TYPE words (ComicInfo genre="Manga" describes the type,
// not a shelf; shelves apply uniformly across all library types). They
// still pass through to tags.
var genreDemoted = map[string]bool{
	"audiobook": true, "unabridged": true, "abridged": true,
	"dramatization": true, "dramatized": true, "audio drama": true,
	"manga": true, "comics": true, "graphic novel": true,
	"graphic novels": true,
}

// splitGenreCandidates splits compound genre strings ("Epic, Action &
// Adventure" — one Audible blob) into individual candidates.
func splitGenreCandidates(genres []string) []string {
	var out []string
	for _, g := range genres {
		for _, part := range strings.Split(g, ",") {
			for _, p := range strings.Split(part, ";") {
				for _, piece := range strings.Split(p, "/") {
					t := strings.TrimSpace(piece)
					if t != "" {
						out = append(out, t)
					}
				}
			}
		}
	}
	return out
}

// normalizeGenreCandidate lowercases, trims, and alias-resolves one
// candidate; "" means noise (empty input).
func normalizeGenreCandidate(c string) string {
	lower := strings.ToLower(strings.TrimSpace(c))
	if lower == "" {
		return ""
	}
	if a, ok := genreAliases[lower]; ok {
		return a
	}
	return lower
}

// pickSmartGenre chooses the SHELF for the genre column from candidate
// strings (genre model v2). Returns the winner ("" when no shelf is
// known — unknown-only input stays tag-only) and the full candidate
// list for the tags array.
func pickSmartGenre(genres []string) (genre string, all []string) {
	all = splitGenreCandidates(genres)
	direct := "" // first non-floor shelf, source order
	mapped := "" // first subgenre-resolved shelf, source order
	floor := ""  // fiction / nonfiction, source order
	for _, c := range all {
		lower := normalizeGenreCandidate(c)
		if lower == "" || genreDemoted[lower] {
			continue
		}
		switch {
		case genreShelves[lower]:
			if isGenreFloor(lower) {
				if floor == "" {
					floor = lower
				}
			} else if direct == "" {
				direct = lower
			}
		case genreSubgenreShelf[lower] != "":
			if mapped == "" {
				mapped = genreSubgenreShelf[lower]
			}
		}
		// Unknown candidates are tags-only — never guess a shelf.
	}
	if direct != "" {
		return direct, all
	}
	if mapped != "" {
		return mapped, all
	}
	return floor, all
}