package librarydiff

import (
	"strings"
	"testing"
)

func rows(t *testing.T, body string) []map[string]any {
	t.Helper()
	parsed, err := ReadDocuments(strings.NewReader(body))
	if err != nil {
		t.Fatalf("ReadDocuments: %v", err)
	}
	return parsed
}

func TestCompareUsesStableIdentityAndIgnoresVolatileColumns(t *testing.T) {
	base := rows(t, `[
		{"id":"doc-a","title":"机械臂报警","content":"正文一","updated_at":"2026-10-01T00:00:00Z"},
		{"id":"doc-b","title":"示教器","content":"正文二","updated_at":"2026-10-01T00:00:00Z"},
		{"id":"doc-c","title":"将删除","content":"正文三"}
	]`)
	target := rows(t, `[
		{"id":"doc-a","title":"机械臂报警","content":"正文一","updated_at":"2026-10-28T00:00:00Z"},
		{"id":"doc-b","title":"示教器","content":"正文二（已更新）","updated_at":"2026-10-01T00:00:00Z"},
		{"id":"doc-d","title":"新增文档","content":"正文四"}
	]`)
	result, err := Compare(base, target)
	if err != nil {
		t.Fatalf("Compare: %v", err)
	}
	// doc-a 只有 updated_at 变了：不算更新。
	if len(result.Added) != 1 || result.Added[0].ID != "doc-d" {
		t.Fatalf("added = %+v, want doc-d", result.Added)
	}
	if len(result.Updated) != 1 || result.Updated[0].ID != "doc-b" {
		t.Fatalf("updated = %+v, want doc-b", result.Updated)
	}
	if len(result.Removed) != 1 || result.Removed[0].ID != "doc-c" {
		t.Fatalf("removed = %+v, want doc-c", result.Removed)
	}
	if result.BaseCount != 3 || result.TargetCount != 3 {
		t.Fatalf("counts = %d/%d, want 3/3", result.BaseCount, result.TargetCount)
	}
}

func TestCompareTreatsTitleChangeAsUpdate(t *testing.T) {
	base := rows(t, `[{"id":"doc-a","title":"旧标题","content":"正文"}]`)
	target := rows(t, `[{"id":"doc-a","title":"新标题","content":"正文"}]`)
	result, err := Compare(base, target)
	if err != nil {
		t.Fatalf("Compare: %v", err)
	}
	if len(result.Updated) != 1 || result.Updated[0].Title != "新标题" {
		t.Fatalf("title change must count as update: %+v", result.Updated)
	}
}

func TestCompareRejectsDuplicateIDs(t *testing.T) {
	base := rows(t, `[{"id":"doc-a","title":"x"}]`)
	dup := rows(t, `[{"id":"doc-a","title":"x"},{"id":"doc-a","title":"y"}]`)
	if _, err := Compare(base, dup); err == nil {
		t.Fatal("duplicate knowledge IDs must be rejected, not silently collapsed")
	}
}

func TestCompareEmptyBaseMarksEverythingAdded(t *testing.T) {
	result, err := Compare(nil, rows(t, `[{"id":"doc-a","title":"x"}]`))
	if err != nil {
		t.Fatalf("Compare: %v", err)
	}
	if len(result.Added) != 1 || len(result.Removed) != 0 {
		t.Fatalf("empty base must be all added: %+v", result)
	}
}

func TestReadDocumentsRejectsNonArray(t *testing.T) {
	if _, err := ReadDocuments(strings.NewReader(`{"id":"x"}`)); err == nil {
		t.Fatal("object payload must be rejected")
	}
}