package main

import (
	"strings"
	"testing"
)

func TestTopNBasic(t *testing.T) {
	logs := strings.Join([]string{
		"t GET /a 200 1ms",
		"t GET /b 200 1ms",
		"t GET /a 200 1ms",
		"t GET /c 200 1ms",
		"t GET /a 200 1ms",
		"t GET /b 200 1ms",
	}, "\n")

	got, err := TopN(strings.NewReader(logs), 2)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(got) != 2 {
		t.Fatalf("want 2 results, got %d: %v", len(got), got)
	}
	if got[0].Endpoint != "/a" || got[0].Count != 3 {
		t.Errorf("want /a x3 first, got %+v", got[0])
	}
	if got[1].Endpoint != "/b" || got[1].Count != 2 {
		t.Errorf("want /b x2 second, got %+v", got[1])
	}
}

func TestMalformedLinesSkipped(t *testing.T) {
	logs := "t GET /a 200 1ms\n\ngarbage\nonly two\nt GET /a 200 1ms\n"
	got, err := TopN(strings.NewReader(logs), 5)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(got) != 1 || got[0].Count != 2 {
		t.Fatalf("malformed lines mishandled: %v", got)
	}
}

func TestNLargerThanDistinct(t *testing.T) {
	got, err := TopN(strings.NewReader("t GET /a 200 1ms"), 10)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(got) != 1 {
		t.Fatalf("want 1 result, got %d", len(got))
	}
}

func TestLongLines(t *testing.T) {
	// A single line > 64KB (bufio.Scanner default max token size).
	long := "t GET /huge?q=" + strings.Repeat("x", 80*1024) + " 200 1ms"
	logs := long + "\nt GET /small 200 1ms\nt GET /small 200 1ms\n"
	got, err := TopN(strings.NewReader(logs), 1)
	if err != nil {
		t.Fatalf("long line broke the scanner: %v (raise Scanner.Buffer)", err)
	}
	if len(got) == 0 || got[0].Endpoint != "/small" {
		t.Fatalf("want /small on top, got %v", got)
	}
}