package chunk

import (
	"reflect"
	"strings"
	"testing"

	"textmachine/backend/internal/lang"
)

// chunker_manifest_test.go: the seam SplitChunksWithChapters adds for the persisted manifest (backlog
// row 100). Two properties matter and neither is obvious from the signature: the split itself must not
// have changed, and the chapter texts returned must be index-aligned to the chapter NUMBERS the split
// emitted — a chapter that consumes no number must not consume a slot either, or every chapter after the
// first empty one is identified by its neighbour's text.

var manifestSeg = SegBudget{DraftBudgetOut: 1797, EditCeilingOut: 3200, FertCJK: 1.1978, FertOther: 0.3852}

func TestSplitChunksWithChaptersLeavesTheSplitUnchanged(t *testing.T) {
	chapters := []string{
		"Первая глава книги.",
		"   \n\t  ", // whitespace-only: consumes NO chapter number
		"Вторая глава книги.",
		"",
		strings.Repeat("Длинный абзац для нарезки. ", 200),
	}
	want := SplitChunks(chapters, manifestSeg, nil, nil)
	got, kept, _ := SplitChunksWithChapters(chapters, manifestSeg, nil, nil)
	if !reflect.DeepEqual(got, want) {
		t.Fatal("SplitChunksWithChapters must produce the SAME cut as SplitChunks — the chunk boundaries decide what goes on the wire")
	}
	if len(kept) != 3 {
		t.Fatalf("three chapters yield text, so three consume a number; got %d: %q", len(kept), kept)
	}
	// Index alignment: kept[n-1] must be the text of chapter n as the chunker numbered it.
	if kept[0] != chapters[0] || kept[1] != chapters[2] || kept[2] != chapters[4] {
		t.Fatalf("kept texts are not aligned to the emitted chapter numbers: %q", kept)
	}
	// …and every emitted chapter number has a slot.
	highest := 0
	for _, c := range got {
		if c.Chapter > highest {
			highest = c.Chapter
		}
	}
	if highest != len(kept) {
		t.Fatalf("the split emitted chapters up to %d but returned %d chapter texts", highest, len(kept))
	}
}

// TestSplitChunksWithChaptersReturnsPreStripText: the text handed back is the chapter AS INGESTED, with
// its source header still in it. That is what makes an identity built on it survive a heading-rule edit —
// the rule changes what is STRIPPED and what title is rendered, not what ingest produced. Asserted with a
// rule ON and OFF over the same chapter, so the invariance is measured rather than assumed.
func TestSplitChunksWithChaptersReturnsPreStripText(t *testing.T) {
	chapters := []string{"第一节：подзаголовок\nтело главы"}
	rule := &lang.ChapterRule{Structure: lang.NewSourceStructure("第", "节"), Template: "Глава {n}"}

	withRule, keptWith, _ := SplitChunksWithChapters(chapters, manifestSeg, rule, nil)
	withoutRule, keptWithout, _ := SplitChunksWithChapters(chapters, manifestSeg, nil, nil)
	if len(withRule) == 0 || len(withoutRule) == 0 {
		t.Fatalf("fixture drifted: %d/%d chunks", len(withRule), len(withoutRule))
	}
	if withRule[0].Heading != "Глава 1" || strings.Contains(withRule[0].Text, "第一节") {
		t.Fatalf("precondition: the rule must render a title and strip the marker, got heading=%q text=%q", withRule[0].Heading, withRule[0].Text)
	}
	if keptWith[0] != chapters[0] || keptWithout[0] != chapters[0] {
		t.Fatalf("the chapter text must be returned AS INGESTED under both rules, got %q / %q", keptWith[0], keptWithout[0])
	}
}