package perf

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

func TestPercentiles(t *testing.T) {
	ds := []float64{10, 20, 30, 40, 50, 60, 70, 80, 90, 100}
	p50, p90, p99, mx := percentiles(ds)
	if p50 != 50 {
		t.Errorf("p50 = %v, want 50", p50)
	}
	if p90 != 90 {
		t.Errorf("p90 = %v, want 90", p90)
	}
	if p99 != 100 {
		t.Errorf("p99 = %v, want 100", p99)
	}
	if mx != 100 {
		t.Errorf("max = %v, want 100", mx)
	}
	// Empty input is a no-op.
	if _, _, _, m := percentiles(nil); m != 0 {
		t.Errorf("empty max = %v, want 0", m)
	}
}

func TestDisabledIsNoOp(t *testing.T) {
	p := New(false, t.TempDir(), "x.csv")
	p.Record(Ctx{Page: "editor"})
	if p.enabled {
		t.Fatalf("disabled profiler reported enabled")
	}
	if p.seq != 0 || len(p.buf) != 0 {
		t.Errorf("disabled profiler recorded: seq=%d buf=%d", p.seq, len(p.buf))
	}
}

func TestRecordFlushAndStop(t *testing.T) {
	dir := t.TempDir()
	p := New(true, dir, "logic_frames.csv")
	if p == nil || p.file == nil {
		t.Fatalf("expected an open output file, got %+v", p)
	}
	for i := 0; i < 5; i++ {
		p.Record(Ctx{Page: "editor", ScrollDP: float32(i * 10), MaxScrollDP: 1000, TotalLines: 42, VisStart: i, VisEnd: i + 100})
	}
	// Force a flush regardless of the 2s timer.
	p.lastFlush = time.Time{}
	p.Record(Ctx{Page: "editor", ScrollDP: 50})
	p.Stop()

	out := filepath.Join(dir, "logic_frames.csv")
	b, err := os.ReadFile(out)
	if err != nil {
		t.Fatalf("read csv: %v", err)
	}
	lines := strings.Split(strings.TrimSpace(string(b)), "\n")
	if len(lines) != 6 {
		t.Fatalf("want 6 CSV rows, got %d:\n%s", len(lines), b)
	}
	// First row is seq 1, editor page.
	if !strings.HasPrefix(lines[0], "1,") || !strings.Contains(lines[0], "editor") {
		t.Errorf("unexpected first row: %s", lines[0])
	}
	// Last row should have TotalLines 42 (from the 5th record) and the 6th (Stop flush).
	if !strings.Contains(lines[4], "42") {
		t.Errorf("row 5 missing TotalLines=42: %s", lines[4])
	}
}