package membank

import (
	"strings"
	"testing"

	"textmachine/backend/internal/store"
)

// TestTermWindowGapsSeesTheHoleTheLoaderCannot pins backlog row 490: the loader refuses two rows that
// OVERLAP and says nothing about two that leave a chapter between them.
func TestTermWindowGapsSeesTheHoleTheLoaderCannot(t *testing.T) {
	rows := []store.GlossaryEntry{
		// THE HOLE: chapter 4 belongs to neither window.
		{Src: "古月", Dst: "Гуюэ", SinceCh: 1, UntilCh: 3, Status: "approved"},
		{Src: "古月", Dst: "клан Гу Юэ", SinceCh: 5, UntilCh: 0, Status: "approved"},
		// CONTIGUOUS: a handover, not a hole — the commonest legitimate shape and the one a noisy check
		// would report on every spoiler boundary in the book.
		{Src: "方源", Dst: "Фан Юань", SinceCh: 1, UntilCh: 10, Status: "approved"},
		{Src: "方源", Dst: "Демон", SinceCh: 11, UntilCh: 0, Status: "approved"},
		// ONE ROW, open-ended: nothing to compare.
		{Src: "元石", Dst: "юаньши", SinceCh: 0, UntilCh: 0, Status: "draft"},
		// TWO SENSES of one surface: two laws by design (the A3 disambiguator is part of the uniqueness
		// key), so their windows must NOT be measured against each other.
		{Src: "青茅", Sense: "гора", Dst: "Цинмао", SinceCh: 1, UntilCh: 3, Status: "approved"},
		{Src: "青茅", Sense: "трава", Dst: "синяя осока", SinceCh: 40, UntilCh: 0, Status: "approved"},
	}
	got := TermWindowGaps(rows)
	if len(got) != 1 {
		t.Fatalf("reported %d gap(s), want exactly the one real hole: %v", len(got), got)
	}
	for _, want := range []string{`"古月"`, "chapters 4–4", "window ends at 3", "next starts at 5"} {
		if !strings.Contains(got[0], want) {
			t.Errorf("the message must name the chapters the owner has to look at; %q is missing from:\n  %s", want, got[0])
		}
	}
	// The control that makes the «exactly one» readable: this function can see MORE than one, so the count
	// above is a measurement of the fixture rather than a ceiling of the function.
	wider := append([]store.GlossaryEntry(nil), rows...)
	wider = append(wider,
		store.GlossaryEntry{Src: "蛊师", Dst: "гу-мастер", SinceCh: 1, UntilCh: 2, Status: "approved"},
		store.GlossaryEntry{Src: "蛊师", Dst: "мастер Гу", SinceCh: 9, UntilCh: 0, Status: "approved"})
	if n := len(TermWindowGaps(wider)); n != 2 {
		t.Fatalf("control: a second genuine hole produced %d report(s), want 2 — the function reports at most one and the assertion above measured that, not the data", n)
	}
}