package pipeline

import (
	"encoding/json"
	"fmt"
	"os"
	"sort"
	"strings"
	"unicode"

	"gopkg.in/yaml.v3"

	"textmachine/backend/internal/store"
)

// memseed.go: the DETERMINISTIC seeding of the glossary from its two milestone inputs —
// a manual seed file (curated approved/draft terms) and the captured ruby readings
// (classified into auto candidates). No LLM (autopopulation/adjudication are a later
// milestone). The output is a []store.GlossaryEntry that seedGlossary REPLACES into the
// book (idempotent full-replace: same inputs → same rows, an edit converges every column).

// --- manual seed file (YAML) ----------------------------------------------------

type seedFile struct {
	Terms []seedTerm `yaml:"terms"`
}

type seedTerm struct {
	Src                 string      `yaml:"src"`
	Dst                 string      `yaml:"dst"`
	Type                string      `yaml:"type"`
	Sense               string      `yaml:"sense"`
	Gender              string      `yaml:"gender"`
	Speech              string      `yaml:"speech"`
	Decl                *seedDecl   `yaml:"decl"`
	TranslitPolicy      string      `yaml:"translit_policy"`
	FirstPerson         string      `yaml:"first_person"`
	NicknameTranslation string      `yaml:"nickname_translation"`
	SinceCh             int         `yaml:"since_ch"`
	UntilCh             int         `yaml:"until_ch"`
	Status              string      `yaml:"status"`
	AllowShort          bool        `yaml:"allow_short"`
	Note                string      `yaml:"note"`
	Aliases             []seedAlias `yaml:"aliases"`
}

type seedDecl struct {
	Invariant bool     `yaml:"invariant"`
	Forms     []string `yaml:"forms"`
}

type seedAlias struct {
	Alias string `yaml:"alias"`
	Type  string `yaml:"type"`
}

// loadGlossarySeed parses a glossary seed YAML into store entries. A manual seed is
// curated, so an empty status defaults to "approved" (the author downgrades explicitly
// with status: draft|auto). Validation is fail-loud: a term without src, or with an
// unknown status, is a config error (a silently-dropped term is exactly the A-class
// hole this bank exists to close).
func loadGlossarySeed(path string) ([]store.GlossaryEntry, error) {
	raw, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("pipeline: read glossary seed %s: %w", path, err)
	}
	var sf seedFile
	if err := yaml.Unmarshal(raw, &sf); err != nil {
		return nil, fmt.Errorf("pipeline: parse glossary seed %s: %w", path, err)
	}
	var out []store.GlossaryEntry
	var problems []string
	termKeys := map[[4]string]bool{} // (src,sense,since,until) → detect a duplicate term key
	for i, t := range sf.Terms {
		if strings.TrimSpace(t.Src) == "" {
			problems = append(problems, fmt.Sprintf("term %d: src is required", i))
			continue
		}
		// A duplicate (src, sense, window) would crash ReplaceGlossary on the store's
		// UNIQUE constraint mid-run (aborting the whole book) — catch it here as a clear
		// config error instead (self-review #5, sibling of the alias case below).
		tk := [4]string{t.Src, t.Sense, fmt.Sprint(t.SinceCh), fmt.Sprint(t.UntilCh)}
		if termKeys[tk] {
			problems = append(problems, fmt.Sprintf("term %q: duplicate (src, sense=%q, since_ch=%d, until_ch=%d) — a term may appear once per spoiler window", t.Src, t.Sense, t.SinceCh, t.UntilCh))
			continue
		}
		termKeys[tk] = true
		status := t.Status
		if status == "" {
			status = "approved"
		}
		switch status {
		case "auto", "draft", "approved":
		default:
			problems = append(problems, fmt.Sprintf("term %q: status must be auto|draft|approved, got %q", t.Src, status))
			continue
		}
		// An approved OR draft term with no dst is silently inert (not matchable — it renders
		// nothing) yet reads as an intended rendering: fail loud (external-review minor #5).
		// Only status=auto (a raw candidate — e.g. a ruby reading awaiting a dst) may be empty.
		if (status == "approved" || status == "draft") && strings.TrimSpace(t.Dst) == "" {
			problems = append(problems, fmt.Sprintf("term %q: a %s term must have a non-empty dst (an empty one is silently inert; only status=auto may lack a dst)", t.Src, status))
			continue
		}
		decl := ""
		if t.Decl != nil {
			b, mErr := json.Marshal(declInfo{Invariant: t.Decl.Invariant, Forms: t.Decl.Forms})
			if mErr != nil {
				return nil, mErr
			}
			decl = string(b)
		}
		e := store.GlossaryEntry{
			BookID: "", Src: t.Src, Dst: t.Dst, Type: t.Type, Sense: t.Sense,
			Gender: t.Gender, Speech: t.Speech, Decl: decl,
			TranslitPolicy: t.TranslitPolicy, FirstPerson: t.FirstPerson,
			NicknameTranslation: t.NicknameTranslation,
			SinceCh:             t.SinceCh, UntilCh: t.UntilCh, Status: status,
			AllowShort: t.AllowShort, Source: "seed", Note: t.Note,
		}
		// Dedup aliases within a term by surface (keep the first type). A repeated alias
		// surface — a copy-paste, or the same name annotated with two types — would
		// otherwise crash ReplaceGlossary on UNIQUE(book_id,term_id,alias) and abort the
		// whole book run (self-review #5). Deduping is the forgiving fix: the surface is
		// what matters for matching, and a redundant alias is a harmless authoring slip.
		seenAlias := map[string]bool{}
		for _, a := range t.Aliases {
			if strings.TrimSpace(a.Alias) == "" {
				problems = append(problems, fmt.Sprintf("term %q: an alias is empty", t.Src))
				continue
			}
			if seenAlias[a.Alias] {
				continue
			}
			seenAlias[a.Alias] = true
			e.Aliases = append(e.Aliases, store.GlossaryAlias{Alias: a.Alias, AliasType: a.Type})
		}
		out = append(out, e)
	}
	// Overlapping spoiler windows for the SAME (src,sense) with DIFFERENT dst inject two
	// contradictory renderings at a chapter in the overlap — silently (external-review
	// minor #4). Fail loud. UNIQUE(src,sense,window) already blocks identical windows, so
	// this catches the partial-overlap case. Iterate `out` in order (deterministic message).
	for i := range out {
		for j := 0; j < i; j++ {
			a, b := out[i], out[j]
			if a.Src == b.Src && a.Sense == b.Sense && a.Dst != b.Dst && windowsOverlap(a.SinceCh, a.UntilCh, b.SinceCh, b.UntilCh) {
				problems = append(problems, fmt.Sprintf("term %q (sense %q): spoiler windows [%d,%d] and [%d,%d] overlap with different dst (%q vs %q) — a term has ONE rendering per chapter",
					a.Src, a.Sense, b.SinceCh, b.UntilCh, a.SinceCh, a.UntilCh, b.Dst, a.Dst))
			}
		}
	}
	if len(problems) > 0 {
		return nil, fmt.Errorf("glossary seed %s:\n  - %s", path, strings.Join(problems, "\n  - "))
	}
	return out, nil
}

// windowsOverlap reports whether two spoiler windows share any chapter. since_ch 0 means
// "from chapter 1"; until_ch 0 means "no end".
func windowsOverlap(since1, until1, since2, until2 int) bool {
	const inf = 1 << 62
	s1, s2 := since1, since2
	if s1 == 0 {
		s1 = 1
	}
	if s2 == 0 {
		s2 = 1
	}
	u1, u2 := until1, until2
	if u1 == 0 {
		u1 = inf
	}
	if u2 == 0 {
		u2 = inf
	}
	lo, hi := s1, u1
	if s2 > lo {
		lo = s2
	}
	if u2 < hi {
		hi = u2
	}
	return lo <= hi
}

// --- ruby → auto candidates -----------------------------------------------------

// rubyToCandidates classifies the captured ruby readings into auto glossary candidates
// (registry §Ruby-seed / §8). One candidate per BASE (the dominant reading by occurrence,
// ties broken lexically) so variant readings never collide on UNIQUE(src,sense,window)
// — the (base,reading) source of truth stays in ruby_readings. A base already covered by
// the manual seed is skipped (the curated entry wins). Every candidate is status=auto
// with NO dst: the reading is the Polivanov bridge (B6, Phase 2), not a dst — so nothing
// is auto-injected, and a human/batch-judge promotes it (never a blind name-lock, which
// would be a mistranslation). The ruby_class is a deterministic HINT for that promotion.
func rubyToCandidates(readings []store.RubyReading, manualSrcs map[string]bool) []store.GlossaryEntry {
	// Group by base → the dominant (base,reading).
	type best struct {
		reading string
		occ     int
		firstCh int
	}
	byBase := map[string]best{}
	order := []string{}
	for _, rr := range readings {
		if manualSrcs[rr.Base] {
			continue // the curated seed already owns this src
		}
		cur, ok := byBase[rr.Base]
		if !ok {
			byBase[rr.Base] = best{rr.Reading, rr.Occurrences, rr.FirstChapter}
			order = append(order, rr.Base)
			continue
		}
		// Dominant reading: higher occurrences wins; tie → lexically smaller reading.
		if rr.Occurrences > cur.occ || (rr.Occurrences == cur.occ && rr.Reading < cur.reading) {
			cur.reading, cur.occ = rr.Reading, rr.Occurrences
		}
		if rr.FirstChapter < cur.firstCh { // earliest appearance across readings
			cur.firstCh = rr.FirstChapter
		}
		byBase[rr.Base] = cur
	}
	sort.Strings(order) // deterministic output regardless of input order
	var out []store.GlossaryEntry
	for _, base := range order {
		b := byBase[base]
		class := classifyRubyReading(base, b.reading)
		typ := ""
		if class == rubyClassName {
			typ = "name"
		}
		out = append(out, store.GlossaryEntry{
			Src: base, Dst: "", Type: typ, Status: "auto", Source: "ruby",
			RubyReading: b.reading, RubyClass: class, SinceCh: b.firstCh,
			Confidence: b.occ,
			Note:       "ruby auto-candidate (" + class + "); reading is the Polivanov bridge, not a dst — promote before use",
		})
	}
	return out
}

// ruby classifier classes (deterministic HINTS for human promotion).
const (
	rubyClassName      = "name_candidate" // all-Han base + all-kana reading: the furigana-name SHAPE
	rubyClassGloss     = "gloss_candidate" // reading carries Han: likely an author double-reading → footnote, NOT a lock
	rubyClassAmbiguous = "ambiguous"       // anything else → flag to a human
)

// classifyRubyReading is the deterministic clear-case rule (§8). It NEVER auto-locks:
// the all-Han+all-kana shape is a name-lock CANDIDATE (it could still be a double-reading
// like 強敵→とも "friend", indistinguishable without a yomi dictionary — Phase 2), so it is
// flagged for human confirmation, not locked. A reading that carries kanji is a clear
// author's double-reading/gloss → a footnote candidate. Over-flagging is safe; a blind
// lock is a mistranslation. Pure and deterministic.
func classifyRubyReading(base, reading string) string {
	if runesAnyHan(reading) {
		return rubyClassGloss // the "reading" is itself a word (semantic gloss / double-reading)
	}
	if runesAllHan(base) && runesAllKana(reading) {
		return rubyClassName
	}
	return rubyClassAmbiguous
}

func runesAllHan(s string) bool {
	if s == "" {
		return false
	}
	for _, r := range s {
		if !unicode.Is(unicode.Han, r) {
			return false
		}
	}
	return true
}

func runesAnyHan(s string) bool {
	for _, r := range s {
		if unicode.Is(unicode.Han, r) {
			return true
		}
	}
	return false
}

func runesAllKana(s string) bool {
	if s == "" {
		return false
	}
	for _, r := range s {
		if r == 'ー' || r == '・' { // prolonged-sound mark, middle dot — allowed within kana readings
			continue
		}
		if !unicode.Is(unicode.Hiragana, r) && !unicode.Is(unicode.Katakana, r) {
			return false
		}
	}
	return true
}