// Copyright (c) 2026, Pim van Pelt <pim@ipng.ch>

package config

import (
	"testing"
	"time"
)

const validConfig = `
maglev:
  healthchecker:
    transition-history: 5
    netns: dataplane
  healthchecks:
    http-check:
      type: http
      port: 80
      probe-ipv4-src: 10.0.0.1
      params:
        path: /healthz
        host: example.com
        response-code: "200"
      interval: 2s
      timeout: 3s
      rise: 2
      fall: 3
    icmp-check:
      type: icmp
      probe-ipv6-src: 2001:db8:1::1
      interval: 1s
      timeout: 3s
      fall: 5
  backends:
    be-v4:
      address: 192.0.2.10
      healthcheck: http-check
    be-v6a:
      address: 2001:db8:2::1
      healthcheck: icmp-check
    be-v6b:
      address: 2001:db8:2::2
      healthcheck: icmp-check
      weight: 50
      enabled: true
  frontends:
    web4:
      description: "IPv4 VIP"
      address: 192.0.2.1
      protocol: tcp
      port: 80
      backends: [be-v4]
    web6:
      description: "IPv6 VIP"
      address: 2001:db8::1
      protocol: tcp
      port: 443
      backends: [be-v6a, be-v6b]
`

func TestValidConfig(t *testing.T) {
	cfg, err := parse([]byte(validConfig))
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if cfg.HealthChecker.Netns != "dataplane" {
		t.Errorf("healthchecker.netns: got %q, want dataplane", cfg.HealthChecker.Netns)
	}
	if cfg.HealthChecker.TransitionHistory != 5 {
		t.Errorf("transition-history: got %d, want 5", cfg.HealthChecker.TransitionHistory)
	}
	if len(cfg.Frontends) != 2 {
		t.Fatalf("frontends: got %d, want 2", len(cfg.Frontends))
	}

	hc := cfg.HealthChecks["http-check"]
	if hc.Type != "http" {
		t.Errorf("http-check type: got %q, want http", hc.Type)
	}
	if hc.Fall != 3 || hc.Rise != 2 {
		t.Errorf("http-check fall/rise: got %d/%d, want 3/2", hc.Fall, hc.Rise)
	}
	if hc.ProbeIPv4Src.String() != "10.0.0.1" {
		t.Errorf("http-check probe-ipv4-src: got %s, want 10.0.0.1", hc.ProbeIPv4Src)
	}
	if hc.HTTP == nil {
		t.Fatal("http-check HTTP params should not be nil")
	}
	if hc.HTTP.Path != "/healthz" {
		t.Errorf("http-check path: got %q, want /healthz", hc.HTTP.Path)
	}
	if hc.HTTP.Host != "example.com" {
		t.Errorf("http-check host: got %q, want example.com", hc.HTTP.Host)
	}
	if hc.HTTP.ResponseCodeMin != 200 || hc.HTTP.ResponseCodeMax != 200 {
		t.Errorf("http-check response-code: got %d-%d, want 200-200",
			hc.HTTP.ResponseCodeMin, hc.HTTP.ResponseCodeMax)
	}

	icmp := cfg.HealthChecks["icmp-check"]
	if icmp.Fall != 5 {
		t.Errorf("icmp-check fall: got %d, want 5", icmp.Fall)
	}
	if icmp.ProbeIPv6Src.String() != "2001:db8:1::1" {
		t.Errorf("icmp-check probe-ipv6-src: got %s, want 2001:db8:1::1", icmp.ProbeIPv6Src)
	}

	// Backend defaults and explicit fields.
	beV4 := cfg.Backends["be-v4"]
	if beV4.Address.String() != "192.0.2.10" {
		t.Errorf("be-v4 address: got %s", beV4.Address)
	}
	if beV4.HealthCheck != "http-check" {
		t.Errorf("be-v4 healthcheck: got %q", beV4.HealthCheck)
	}
	if !beV4.Enabled {
		t.Error("be-v4 enabled: want true (default)")
	}
	if beV4.Weight != 100 {
		t.Errorf("be-v4 weight: got %d, want 100 (default)", beV4.Weight)
	}

	beV6b := cfg.Backends["be-v6b"]
	if beV6b.Weight != 50 {
		t.Errorf("be-v6b weight: got %d, want 50", beV6b.Weight)
	}

	// Frontend references.
	web4 := cfg.Frontends["web4"]
	if len(web4.Backends) != 1 || web4.Backends[0] != "be-v4" {
		t.Errorf("web4 backends: got %v", web4.Backends)
	}
	web6 := cfg.Frontends["web6"]
	if len(web6.Backends) != 2 {
		t.Errorf("web6 backends: got %d, want 2", len(web6.Backends))
	}
}

func TestDefaults(t *testing.T) {
	raw := `
maglev:
  healthchecks:
    icmp:
      type: icmp
      interval: 1s
      timeout: 2s
  backends:
    be:
      address: 10.0.0.2
      healthcheck: icmp
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`
	cfg, err := parse([]byte(raw))
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if cfg.HealthChecker.Netns != "" {
		t.Errorf("default netns: got %q, want empty", cfg.HealthChecker.Netns)
	}
	if cfg.HealthChecker.TransitionHistory != 5 {
		t.Errorf("default transition-history: got %d, want 5", cfg.HealthChecker.TransitionHistory)
	}
	hc := cfg.HealthChecks["icmp"]
	if hc.Rise != 2 || hc.Fall != 3 {
		t.Errorf("defaults rise/fall: got %d/%d, want 2/3", hc.Rise, hc.Fall)
	}
	be := cfg.Backends["be"]
	if !be.Enabled || be.Weight != 100 {
		t.Errorf("backend defaults: enabled=%v weight=%d", be.Enabled, be.Weight)
	}
}

func TestBackendNoHealthcheck(t *testing.T) {
	// A backend with no healthcheck reference is valid; probe is skipped.
	raw := `
maglev:
  healthchecks: {}
  backends:
    be:
      address: 10.0.0.2
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`
	cfg, err := parse([]byte(raw))
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if cfg.Backends["be"].HealthCheck != "" {
		t.Error("expected empty healthcheck")
	}
}

func TestOptionalIntervals(t *testing.T) {
	raw := `
maglev:
  healthchecks:
    icmp:
      type: icmp
      interval: 2s
      fast-interval: 500ms
      down-interval: 30s
      timeout: 1s
  backends:
    be:
      address: 10.0.0.2
      healthcheck: icmp
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`
	cfg, err := parse([]byte(raw))
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	hc := cfg.HealthChecks["icmp"]
	if hc.Interval != 2*time.Second {
		t.Errorf("interval: got %v, want 2s", hc.Interval)
	}
	if hc.FastInterval != 500*time.Millisecond {
		t.Errorf("fast-interval: got %v, want 500ms", hc.FastInterval)
	}
	if hc.DownInterval != 30*time.Second {
		t.Errorf("down-interval: got %v, want 30s", hc.DownInterval)
	}
}

func TestValidationErrors(t *testing.T) {
	base := func(hcExtra, beExtra, feExtra string) string {
		return `
maglev:
  healthchecks:
    c:
      type: icmp
      interval: 1s
      timeout: 2s
` + hcExtra + `
  backends:
    be:
      address: 10.0.0.2
      healthcheck: c
` + beExtra + `
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
` + feExtra
	}

	tests := []struct {
		name   string
		yaml   string
		errSub string
	}{
		{
			name:   "wrong family probe-ipv4-src",
			yaml:   base("      probe-ipv4-src: 2001:db8::1\n", "", ""),
			errSub: "probe-ipv4-src",
		},
		{
			name: "mixed backend address families in frontend",
			yaml: `
maglev:
  healthchecks:
    c:
      type: icmp
      interval: 1s
      timeout: 2s
  backends:
    v4: {address: 10.0.0.2, healthcheck: c}
    v6: {address: 2001:db8::1, healthcheck: c}
  frontends:
    v:
      address: 192.0.2.1
      backends: [v4, v6]
`,
			errSub: "address family",
		},
		{
			name:   "port without protocol",
			yaml:   base("", "", "      port: 80\n"),
			errSub: "port requires protocol",
		},
		{
			name: "protocol without port",
			yaml: `
maglev:
  healthchecks:
    c:
      type: icmp
      interval: 1s
      timeout: 2s
  backends:
    be: {address: 10.0.0.2, healthcheck: c}
  frontends:
    v:
      address: 192.0.2.1
      protocol: tcp
      backends: [be]
`,
			errSub: "requires port",
		},
		{
			name: "invalid healthcheck type",
			yaml: `
maglev:
  healthchecks:
    c:
      type: dns
      interval: 1s
      timeout: 2s
  backends:
    be: {address: 10.0.0.2, healthcheck: c}
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`,
			errSub: "type must be",
		},
		{
			name: "http missing path",
			yaml: `
maglev:
  healthchecks:
    c:
      type: http
      port: 80
      interval: 1s
      timeout: 2s
  backends:
    be: {address: 10.0.0.2, healthcheck: c}
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`,
			errSub: "params.path",
		},
		{
			name:   "negative interval",
			yaml:   base("", "", ""),
			errSub: "",
		},
		{
			name: "undefined healthcheck reference",
			yaml: `
maglev:
  healthchecks: {}
  backends:
    be: {address: 10.0.0.2, healthcheck: missing}
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`,
			errSub: "not defined",
		},
		{
			name: "undefined backend reference in frontend",
			yaml: `
maglev:
  healthchecks:
    c:
      type: icmp
      interval: 1s
      timeout: 2s
  backends: {}
  frontends:
    v:
      address: 192.0.2.1
      backends: [missing]
`,
			errSub: "not defined",
		},
		{
			name:   "weight out of range",
			yaml:   base("", "      weight: 150\n", ""),
			errSub: "out of range",
		},
		{
			name:   "fall zero becomes default",
			yaml:   base("      fall: 0\n", "", ""),
			errSub: "",
		},
		{
			name: "tcp missing port",
			yaml: `
maglev:
  healthchecks:
    c:
      type: tcp
      interval: 1s
      timeout: 2s
  backends:
    be: {address: 10.0.0.2, healthcheck: c}
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`,
			errSub: "requires port",
		},
		{
			name: "http missing port",
			yaml: `
maglev:
  healthchecks:
    c:
      type: http
      interval: 1s
      timeout: 2s
      params:
        path: /
  backends:
    be: {address: 10.0.0.2, healthcheck: c}
  frontends:
    v:
      address: 192.0.2.1
      backends: [be]
`,
			errSub: "requires port",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			_, err := parse([]byte(tt.yaml))
			if tt.errSub == "" {
				if err != nil {
					t.Fatalf("expected no error, got: %v", err)
				}
				return
			}
			if err == nil {
				t.Fatalf("expected error containing %q, got nil", tt.errSub)
			}
			if !contains(err.Error(), tt.errSub) {
				t.Errorf("error %q does not contain %q", err.Error(), tt.errSub)
			}
		})
	}
}

func contains(s, sub string) bool {
	return len(s) >= len(sub) && (s == sub || len(sub) == 0 ||
		func() bool {
			for i := 0; i <= len(s)-len(sub); i++ {
				if s[i:i+len(sub)] == sub {
					return true
				}
			}
			return false
		}())
}