package pipeline

import (
	"strings"
	"testing"

	"textmachine/backend/internal/chunk"
	"textmachine/backend/internal/config"
)

// banknote_test.go pins the WS4 §4(д) parser invariants (byte-faithful port of exp16 banknote.py).
// The 95-line corpus pin (0 parse_fail / 0 truncated over 14 saved raw outputs) is the domain of the
// $0 reference eval/design11/ws4_banknote_verify.py; these unit tests cover the parser CONTRACT.

// attestedIn is the test double for the src rule: the surfaces the "book" contains. The production
// predicate is bankSrcAttested over bankSourceIndex; both answer the same question over the same
// normalization, and TestBankSourceIndexParity pins that they agree.
func attestedIn(source string) func(string) bool {
	r := &Runner{bankSrc: newBankSourceIndex([]chunk.Chunk{{Text: source}})}
	return r.bankSrcAttested("")
}

// srcAll is the corpus every legacy parser test above was written against.
const srcAll = "方源\n蛊师\n青茅山\n古月\n蛊\n龙公\nRoseanne\n"

func TestSplitBanknoteNoSeparatorIsAllClean(t *testing.T) {
	out := "Судзуки шёл по коридору.  \n"
	clean, block, _ := splitBanknote(out)
	if clean != "Судзуки шёл по коридору." || block != "" {
		t.Fatalf("no-SEP: clean=%q block=%q, want the whole right-trimmed output and empty block", clean, block)
	}
}

func TestSplitBanknoteSlicesBlock(t *testing.T) {
	out := "Перевод... последнее предложение.\n\n" + bankSeparator + "\n方源\tФан Юань\tname\n蛊师\tгу-мастер\ttitle"
	clean, block, _ := splitBanknote(out)
	if !strings.HasSuffix(clean, "последнее предложение.") {
		t.Fatalf("clean tail wrong: %q", clean)
	}
	if strings.Contains(clean, bankSeparator) || strings.Contains(clean, "方源") {
		t.Fatalf("the banknote block leaked into the clean translation: %q", clean)
	}
	ents, flags := parseBanknote(block, attestedIn(srcAll))
	if len(ents) != 2 || flags.ParseFail || flags.Truncated || flags.NLines != 2 {
		t.Fatalf("parse = %+v flags=%+v, want 2 clean entries", ents, flags)
	}
	if ents[0].Src != "方源" || ents[0].Dst != "Фан Юань" || ents[0].Type != "name" {
		t.Fatalf("entry[0] = %+v", ents[0])
	}
	if ents[1].Type != "title" {
		t.Fatalf("entry[1] type = %q, want title", ents[1].Type)
	}
}

func TestParseBanknoteTolerantFieldSplit(t *testing.T) {
	// tab, ≥2 spaces, and pipe are all accepted delimiters (a model that emits spaces instead of a
	// real TAB still parses). type falls back to "term" when absent or unknown.
	block := "方源\tФан Юань\tname\n蛊师  гу-мастер  title\n青茅山 | гора Цинмао | place\n古月\tГу Юэ"
	ents, flags := parseBanknote(block, attestedIn(srcAll))
	if flags.ParseFail {
		t.Fatalf("tolerant split should not fail: %+v", flags)
	}
	if len(ents) != 4 {
		t.Fatalf("want 4 entries across tab/space/pipe delimiters, got %d: %+v", len(ents), ents)
	}
	if ents[3].Type != "term" { // no type field → default term
		t.Fatalf("missing type must default to term, got %q", ents[3].Type)
	}
}

// TestParseBanknoteSrcMustBeAttested replaces the old "src must contain a Han ideograph" pin (backlog 19,
// D39.53 default). Two things changed in ONE rule: a non-ideographic src is no longer malformed by
// construction (the channel was DEAD on every non-CJK source — 5/6 of the bank's candidates), and a src
// the book does not contain is now malformed even when it looks Chinese (the old rule accepted invented
// surfaces, which then reached the owner's sign map).
func TestParseBanknoteSrcMustBeAttested(t *testing.T) {
	src := "方源 шёл по тропе. Roseanne ждала у Silversaint, рядом стоял San Michon.\nリン сказала: идём.\n"
	block := strings.Join([]string{
		"方源\tФан Юань\tname",
		"Roseanne\tРозанна\tname", // latin src, attested → ACCEPTED (was: parse_fail)
		"Silversaint\tСеребряный святой\ttitle",
		"San Michon\tСан-Мишон\tplace", // multi-word latin src
		"リン\tРин\tname",                // kana src
	}, "\n")
	ents, flags := parseBanknote(block, attestedIn(src))
	if flags.ParseFail {
		t.Fatalf("every src here is in the source; none may be a parse fail: %+v", flags)
	}
	if len(ents) != 5 {
		t.Fatalf("want all 5 attested lines, got %d: %+v", len(ents), ents)
	}
	// The other half of the rule: a plausible, well-formed, Han-bearing line the book never contains.
	invented := "天魔宗\tСекта Небесного Демона\tplace"
	ents, flags = parseBanknote(invented, attestedIn(src))
	if !flags.ParseFail || len(ents) != 0 {
		t.Fatalf("an invented src must be a parse fail and yield nothing, got %+v %+v", ents, flags)
	}
	// And the empty src can never be attested.
	if attestedIn(src)("") || attestedIn(src)("   ") {
		t.Fatal("an empty src must never count as attested")
	}
}

// TestParseBanknoteRecoversColumnOrder pins the cold-run finding that the attested rule also SOLVES: a
// model that writes the pair in the other order (target first) used to lose the whole block. The order is
// decided by which side the book attests, so the recovery is pair-blind and never guesses.
func TestParseBanknoteRecoversColumnOrder(t *testing.T) {
	src := "学堂家老在花海。San Michon стоял рядом."
	block := strings.Join([]string{
		"старейшина школы\t学堂家老\ttitle", // reversed by the model
		"花海\tМоре цветов\tplace",        // declared order
		"выдумка\tтоже выдумка\tterm",   // neither side attested → still a parse fail
	}, "\n")
	ents, flags := parseBanknote(block, attestedIn(src))
	if !flags.ParseFail {
		t.Fatalf("the unattested line must still fail: %+v", flags)
	}
	if len(ents) != 2 {
		t.Fatalf("want the reversed line recovered and the normal one kept, got %+v", ents)
	}
	if ents[0].Src != "学堂家老" || ents[0].Dst != "старейшина школы" {
		t.Fatalf("reversed line not normalized to (source, target): %+v", ents[0])
	}
	if ents[1].Src != "花海" || ents[1].Dst != "Море цветов" {
		t.Fatalf("declared order must be preserved: %+v", ents[1])
	}
	// Ambiguity is resolved by the DECLARED order, never by a guess: when the book attests both fields
	// (a source that quotes the target language, or a same-script pair), the model's order stands.
	both := "San Michon\tСан-Мишон\tplace"
	ents, flags = parseBanknote(both, attestedIn(src+" Сан-Мишон"))
	if flags.ParseFail || len(ents) != 1 || ents[0].Src != "San Michon" {
		t.Fatalf("both-attested must keep the declared order, got %+v %+v", ents, flags)
	}
}

// TestBankSourceIndexParity pins the property that lets the live path check the CHUNK first: a chunk hit
// implies a book hit, so the fast path can never accept a line the book-wide rule would reject (and the
// re-fold path, which passes no chunk, reaches the same verdict).
func TestBankSourceIndexParity(t *testing.T) {
	chunks := []chunk.Chunk{{Chapter: 1, ChunkIdx: 0, Text: "方源 вышел из дома."}, {Chapter: 1, ChunkIdx: 1, Text: "古月赤城 ждал во дворе."}}
	r := &Runner{bankSrc: newBankSourceIndex(chunks)}
	for _, c := range chunks {
		chunkPred, bookPred := r.bankSrcAttested(c.Text), r.bankSrcAttested("")
		for _, probe := range []string{"方源", "古月赤城", "天魔宗", "вышел", ""} {
			if chunkPred(probe) && !bookPred(probe) {
				t.Fatalf("chunk %d accepted %q that the book-wide rule rejects — the fast path is not a subset", c.ChunkIdx, probe)
			}
		}
	}
	// A term attested in ANOTHER chunk is accepted through the book fallback, not silently dropped.
	if !r.bankSrcAttested(chunks[0].Text)("古月赤城") {
		t.Fatal("a surface attested elsewhere in the book must pass the fallback")
	}
	// The boundary guard: the join must not let a key straddle two chunks.
	if r.bankSrcAttested("")("дома.古月赤城") {
		t.Fatal("a key spanning a chunk boundary must not count as attested")
	}
}

// TestParseBanknoteShortLastLineIsAParseFail: the parser's truncation TOLERANCE is gone with the fix-pack,
// and this pins what replaced it. A short last line reaches this parser only under finish=stop — a complete
// generation that simply emitted a broken line — and that is a parse fail, not a tolerated cut. The
// truncation FACT now lives where it is actually known, one level up, off the finish reason
// (TestBanknoteTruncatedIsReachable).
func TestParseBanknoteShortLastLineIsAParseFail(t *testing.T) {
	block := "方源\tФан Юань\tname\n蛊" // last line has no dst
	ents, flags := parseBanknote(block, attestedIn(srcAll))
	if flags.Truncated || !flags.ParseFail || len(ents) != 1 {
		t.Fatalf("a complete generation's short line is a parse_fail, got %+v %+v", ents, flags)
	}
}

func TestParseBanknoteEmptyBlock(t *testing.T) {
	ents, flags := parseBanknote("", attestedIn(srcAll))
	if len(ents) != 0 || flags.ParseFail || flags.Truncated || flags.NLines != 0 {
		t.Fatalf("empty block must yield no entries and clean flags, got %+v %+v", ents, flags)
	}
}

func TestBankSeparatorIsNotANoteWord(t *testing.T) {
	// The separator must not be a trailing-note word the sanitizer reserves (§B3-1) — the two
	// channels must never collide.
	for _, note := range []string{"Примечание", "Сноска", "Комментарий", "Note", "TN"} {
		if strings.Contains(bankSeparator, note) {
			t.Fatalf("separator %q collides with the reserved note-word %q", bankSeparator, note)
		}
	}
	if !strings.HasPrefix(bankSeparator, "⟦") {
		t.Fatalf("separator lost its unusual delimiter: %q", bankSeparator)
	}
}

// --- pack-20 (D39.42 п.4): the channel is a property of the TEXT, not of a config key ----------------

// TestBanknoteSliceIsUnconditional pins the fix for S5, the phase-1 BLOCKER. The slice used to be gated
// on gates.banknote.enabled, and that key is in no shipping config — so the literal reading of "move the
// block into translator.md" would have sent the raw ⟦TM-BANK-v1⟧ table into the draft, the editor and the
// EXPORT with nothing to catch it (the output sanitizer is final-stage-only). Slicing on the text itself
// removes the failure mode; a draft with no separator still takes the byte-identical early return.
func TestBanknoteSliceIsUnconditional(t *testing.T) {
	r := &Runner{Pipeline: &config.Pipeline{}} // gate OFF (zero value)
	const clean = "Тихое утро в библиотеке."
	const bankTestSource = "龙公 сидел в библиотеке."
	raw := clean + "\n" + bankSeparator + "\n龙公\tЛун Гун\tname"

	got, stripped, flags, entries := r.applyBanknoteWithEntries(roleTranslator, raw, "stop", bankTestSource)
	if got != clean || stripped != clean {
		t.Fatalf("the block must be sliced even with the gate off, got %q / %q", got, stripped)
	}
	if len(entries) != 1 || flags.NLines != 1 {
		t.Fatalf("the WHAT must still be read (parsing is free), got %+v / %+v", entries, flags)
	}
	// The byte-identical path: no separator → the raw text back, no derived export.
	if g, s, f, e := r.applyBanknoteWithEntries(roleTranslator, clean, "stop", bankTestSource); g != clean || s != "" || f != (bankFlags{}) || e != nil {
		t.Fatalf("a draft with no separator must take the unchanged path, got %q/%q/%+v/%+v", g, s, f, e)
	}
	// The editor never emits banknotes — its output is never touched.
	if g, s, _, _ := r.applyBanknoteWithEntries(roleEditor, raw, "stop", bankTestSource); g != raw || s != "" {
		t.Fatalf("the editor's output must not be sliced, got %q/%q", g, s)
	}
}

// TestBanknoteMalformedSeparatorIsCaught pins S12 — the very case §B3-1 was written for and the code
// never covered. A model that TRIES to open the channel and mistypes the marker used to have its table
// read as prose: it travelled into the editor and the export while banknote_parse_fail stayed 0.
func TestBanknoteMalformedSeparatorIsCaught(t *testing.T) {
	r := &Runner{Pipeline: &config.Pipeline{}}
	const clean = "Тихое утро в библиотеке."
	const bankTestSource = "龙公 сидел в библиотеке."
	for _, broken := range []string{
		"⟦TM-BANK-v2⟧",   // a version the parser does not know
		"[TM-BANK-v1]",   // the wrong brackets
		"⟦ TM-BANK-v1 ⟧", // stray spaces
	} {
		raw := clean + "\n" + broken + "\n龙公\tЛун Гун\tname"
		got, stripped, flags, entries := r.applyBanknoteWithEntries(roleTranslator, raw, "stop", bankTestSource)
		if strings.Contains(got, "龙公") || strings.Contains(got, "TM-BANK") {
			t.Fatalf("%s: the malformed block must still be cut off the draft, got %q", broken, got)
		}
		if got != clean || stripped != clean {
			t.Fatalf("%s: the cleaned draft must be the translation, got %q", broken, got)
		}
		if !flags.ParseFail {
			t.Fatalf("%s: a malformed separator must be flagged, got %+v", broken, flags)
		}
		if len(entries) != 0 {
			t.Fatalf("%s: a block we could not open is not evidence, got %+v", broken, entries)
		}
	}
	// A translation that merely mentions nothing of the sort is untouched — no false positives.
	if got, _, flags, _ := r.applyBanknoteWithEntries(roleTranslator, clean, "stop", bankTestSource); got != clean || flags.ParseFail {
		t.Fatalf("ordinary prose must not trip the malformed-separator check: %q / %+v", got, flags)
	}
}

// TestBankTokenBudgetIsDerived pins the D39.41 acceptance finding: the reservation must be COMPUTED from
// the line format under the engine's own estimator, not a round literal. The old `bankMaxLines * 12` was
// 144 against a measured worst block of 142.6–147.2 — at best exactly the need, at worst already negative.
func TestBankTokenBudgetIsDerived(t *testing.T) {
	// A worst-case block: bankMaxLines full lines plus the separator.
	var b strings.Builder
	b.WriteString(bankSeparator + "\n")
	for i := 0; i < bankMaxLines; i++ {
		b.WriteString(strings.Repeat("蛊", 8) + "\t" + strings.Repeat("я", 40) + "\tnickname\n")
	}
	need := EstimateTokens(b.String())
	if bankTokenBudget < need {
		t.Fatalf("the reservation (%d) must cover a worst-case block (%d est-tokens) — a budget that is exactly the need truncates the channel on the densest chapters", bankTokenBudget, need)
	}
	// …and it must not be absurdly generous either: an unused ceiling is cheap, but the number should
	// still be recognisable as this block's cost.
	if bankTokenBudget > 2*need {
		t.Fatalf("the reservation (%d) is more than twice the worst case (%d) — that is a guess again, not a derivation", bankTokenBudget, need)
	}
	if bankMaxLines <= 12 {
		t.Fatalf("the line cap was raised on the mini-run measurement (2 of 9 blocks pressed against 12), got %d", bankMaxLines)
	}
}

// TestParseBanknoteRejoinsASplitRendering is backlog row 129. The field splitter tolerates a run of ≥2
// spaces because models substitute spaces for tabs — and that same tolerance splits INSIDE a rendering the
// moment a model writes «Фан␣␣Юань». Taking parts[1] alone banked the half-name and pushed the tail into
// the type column, where it failed the closed vocabulary and silently became "term": a mangled surface on
// the owner's sign map with parse_fail still reading 0. The terminologist's parser was fixed for exactly
// this; the banknote's was not.
func TestParseBanknoteRejoinsASplitRendering(t *testing.T) {
	attested := attestedIn(srcAll)
	// BOTH shapes: with the type column present, and as a bare two-column line.
	entries, flags := parseBanknote("方源\tФан  Юань\tname\n蛊师\tмастер  гу", attested)
	if flags.ParseFail {
		t.Fatalf("neither line is malformed: %+v", flags)
	}
	if len(entries) != 2 {
		t.Fatalf("want both lines, got %+v", entries)
	}
	if entries[0].Dst != "Фан Юань" || entries[0].Type != "name" {
		t.Fatalf("a split rendering must be re-joined and the type column still read: %+v", entries[0])
	}
	if entries[1].Dst != "мастер гу" || entries[1].Type != "term" {
		t.Fatalf("with no type column the whole tail is the rendering: %+v", entries[1])
	}
	// THE SPACE-RUN PATH is the only one where the re-join can be observed at all: on a TAB line the
	// rendering is one column, so join(fields[1:]) and fields[1] are the same string and the re-join could be
	// reverted with every test still green. Here they differ, and «Фан» alone is what used to be banked.
	spaced, sflags := parseBanknote("方源  Фан  Юань  name", attested)
	if sflags.ParseFail || len(spaced) != 1 || spaced[0].Dst != "Фан Юань" || spaced[0].Type != "name" {
		t.Fatalf("a space-delimited line must re-join its rendering: %+v %+v", spaced, sflags)
	}
	if two, _ := parseBanknote("蛊师  мастер  гу", attested); len(two) != 1 || two[0].Dst != "мастер гу" {
		t.Fatalf("and so must a space-delimited line with no type column: %+v", two)
	}
	// The recognised shapes are unchanged: a real three-field line is still src/dst/type.
	plain, _ := parseBanknote("青茅山\tгора Цинмао\tplace", attested)
	if len(plain) != 1 || plain[0].Dst != "гора Цинмао" || plain[0].Type != "place" {
		t.Fatalf("the ordinary three-field line must be untouched: %+v", plain)
	}
	// A TAB-delimited third column outside the type vocabulary is a benign unknown TYPE, exactly as it was
	// before the fix-pack — NOT a piece of the rendering. Guessing it into the rendering is what the first cut
	// of this fix did, and it corrupted four terms and dropped two on the frozen coldrun-a reference.
	odd, _ := parseBanknote("古月\tклан  Гуюэ\tсемья", attested)
	if len(odd) != 1 || odd[0].Dst != "клан Гуюэ" || odd[0].Type != "term" {
		t.Fatalf("an unknown TYPE column must be discarded, not glued onto the rendering: %+v", odd)
	}
	// And the column-order recovery still works, including over a rendering the model spaced out.
	rev, _ := parseBanknote("Фан  Юань\t方源\tname", attested)
	if len(rev) != 1 || rev[0].Src != "方源" || rev[0].Dst != "Фан Юань" {
		t.Fatalf("a reversed line must still be recovered: %+v", rev)
	}
}

// TestParseBanknoteReadsDeclaredColumnsPositionally is the pin the frozen reference bought. A tab or a pipe
// is a delimiter the model CHOSE — it cannot occur inside a rendering — so such a line has declared its own
// columns and is read by position, as it was before the fix-pack. Only a line delimited by a run of spaces
// is ambiguous, and only there may the type be guessed from the closed vocabulary.
//
// Measured cost of getting this wrong: replaying 56 real banknote blocks of ~/books/gu-zhenren/coldrun-a
// through the first cut of the fix gave −6 lines against HEAD and +0 — four renderings corrupted by a glued
// type word (clan/event/proverb/onomatopoeia — 1.25% of the reference carries a type outside the
// vocabulary) and two lines dropped outright, with banknote_parse_fail unchanged in every one of them.
func TestParseBanknoteReadsDeclaredColumnsPositionally(t *testing.T) {
	attested := attestedIn(srcAll)
	for _, tc := range []struct{ line, src, dst, typ string }{
		// An unknown third column: discarded as an unknown type, never glued (the four corrupted terms).
		{"古月\tГу Юэ\tclan", "古月", "Гу Юэ", "term"},
		{"方源|Фан Юань|proverb", "方源", "Фан Юань", "term"},
		// The same line REVERSED: the src is still found by attestation, and the unknown type still discarded.
		// The first cut looked for the src in the last field, found «clan», and dropped the line (the two lost).
		{"Гу Юэ\t古月\tclan", "古月", "Гу Юэ", "term"},
		// A known type column is read as a type, in both orders.
		{"青茅山\tгора Цинмао\tplace", "青茅山", "гора Цинмао", "place"},
		// And a rendering the model spaced out inside a REAL column arrives whole and clean.
		{"方源\tФан  Юань\tname", "方源", "Фан Юань", "name"},
	} {
		got, flags := parseBanknote(tc.line, attested)
		if len(got) != 1 {
			t.Fatalf("%q: want one entry, got %+v (parse_fail=%v)", tc.line, got, flags.ParseFail)
		}
		if got[0].Src != tc.src || got[0].Dst != tc.dst || got[0].Type != tc.typ {
			t.Fatalf("%q: got %+v, want src=%q dst=%q type=%q", tc.line, got[0], tc.src, tc.dst, tc.typ)
		}
	}
}

// TestBanknoteTruncatedIsReachable closes the hygiene finding beside row 129: banknote_truncated was
// derived inside the parser from an argument the only production caller pinned to false, so the column was
// structurally 0 while its comment claimed otherwise. The refusal itself is the signal — a block present
// under a non-stop finish was cut by generation length — and reading it off the finish reason changes
// nothing about the ratified stop-only gate: still no candidates, still no telemetry lines.
func TestBanknoteTruncatedIsReachable(t *testing.T) {
	r := &Runner{bankSrc: newBankSourceIndex([]chunk.Chunk{{Text: srcAll}})}
	raw := "Незаконченный перевод\n" + bankSeparator + "\n方源\tФан"
	_, _, flags, entries := r.applyBanknoteWithEntries(roleTranslator, raw, "length", srcAll)
	if !flags.Truncated {
		t.Fatalf("a block under a non-stop finish IS the truncation the column was meant to record: %+v", flags)
	}
	if len(entries) != 0 || flags.NLines != 0 {
		t.Fatalf("the stop-only gate still accepts nothing: %+v / %+v", entries, flags)
	}
	// A complete generation is unaffected.
	_, _, ok, got := r.applyBanknoteWithEntries(roleTranslator, raw, "stop", srcAll)
	if ok.Truncated || len(got) != 1 {
		t.Fatalf("a complete generation is not truncated and its block is parsed: %+v / %+v", ok, got)
	}
}