package main

import (
	"math"
	"os"
	"testing"
)

func approx(a, b float64) bool { return math.Abs(a-b) < 0.01 }

func TestParseLoadAvg(t *testing.T) {
	got := parseLoadAvg([]byte("0.42 0.31 0.19 1/234 5678\n"))
	if !approx(got, 0.42) {
		t.Fatalf("load = %v, want 0.42", got)
	}
	if v := parseLoadAvg([]byte("")); v != 0 {
		t.Fatalf("empty load = %v, want 0", v)
	}
}

func TestParseCPUStat(t *testing.T) {
	total, idle, ok := parseCPUStat([]byte("cpu  100 0 50 800 50 0 0 0 0 0\ncpu0 1 2 3 4\n"))
	if !ok {
		t.Fatal("parseCPUStat not ok")
	}
	// total = 100+0+50+800+50 = 1000; idle = idle(800)+iowait(50) = 850.
	if total != 1000 || idle != 850 {
		t.Fatalf("total=%d idle=%d, want 1000/850", total, idle)
	}
}

func TestCPUBusyPct(t *testing.T) {
	// From (total 1000, idle 850) to (total 1100, idle 900): dTotal=100, dIdle=50
	// → busy = 50/100 = 50%.
	if got := cpuBusyPct(1000, 850, 1100, 900); !approx(got, 50) {
		t.Fatalf("busy = %v, want 50", got)
	}
	// No forward progress → 0 (guards a counter reset / same sample).
	if got := cpuBusyPct(1000, 850, 1000, 850); got != 0 {
		t.Fatalf("no-delta busy = %v, want 0", got)
	}
	// idle jumping more than total is clamped, never negative.
	if got := cpuBusyPct(1000, 850, 1100, 1000); got != 0 {
		t.Fatalf("clamped busy = %v, want 0", got)
	}
}

func TestParseMemUsedPct(t *testing.T) {
	// total 1000, available 250 → used 75%.
	mem := []byte("MemTotal:       1000 kB\nMemFree:  100 kB\nMemAvailable:    250 kB\n")
	if got := parseMemUsedPct(mem); !approx(got, 75) {
		t.Fatalf("mem used = %v, want 75", got)
	}
	if got := parseMemUsedPct([]byte("garbage")); got != 0 {
		t.Fatalf("garbage mem = %v, want 0", got)
	}
}

func TestParseHandle(t *testing.T) {
	for _, tc := range []struct {
		in   string
		want uint32
		bad  bool
	}{
		{"0x81000100", 0x81000100, false},
		{"81000100", 0x81000100, false},
		{"0X01800100", 0x01800100, false},
		{"nope", 0, true},
	} {
		h, err := parseHandle(tc.in)
		if tc.bad {
			if err == nil {
				t.Errorf("parseHandle(%q) = %#x, want error", tc.in, uint32(h))
			}
			continue
		}
		if err != nil || uint32(h) != tc.want {
			t.Errorf("parseHandle(%q) = %#x, %v; want %#x", tc.in, uint32(h), err, tc.want)
		}
	}
}

func TestHostOf(t *testing.T) {
	for _, tc := range []struct{ in, want string }{
		{"diskless-server.bitasylum.org:9600", "diskless-server.bitasylum.org"},
		{"host", "host"},
		{"[2001:db8::1]:9600", "2001:db8::1"},
	} {
		if got := hostOf(tc.in); got != tc.want {
			t.Errorf("hostOf(%q) = %q, want %q", tc.in, got, tc.want)
		}
	}
}

func TestReadKioskURL(t *testing.T) {
	dir := t.TempDir()
	f := dir + "/kiosk.env"
	if err := os.WriteFile(f, []byte("# comment\nKIOSK_URL=\"http://boot.fleet.lab/kiosk/\"\nOTHER=x\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	if got := readKioskURL(f); got != "http://boot.fleet.lab/kiosk/" {
		t.Fatalf("kiosk url = %q", got)
	}
	if got := readKioskURL(dir + "/missing"); got != "" {
		t.Fatalf("missing kiosk env = %q, want empty", got)
	}
}