package config_test

import (
	"bytes"
	"encoding/json"
	"log/slog"
	"maps"
	"net/netip"
	"slices"
	"strings"
	"testing"
	"time"

	"sneak.berlin/go/smallwebwaf/internal/config"
)

// The settings, by name.
const (
	listenAddr              = "SWWAF_LISTEN_ADDR"
	upstreamURL             = "SWWAF_UPSTREAM_URL"
	trustedProxies          = "SWWAF_TRUSTED_PROXIES"
	clientRequestTimeout    = "SWWAF_CLIENT_REQUEST_TIMEOUT"
	clientResponseTimeout   = "SWWAF_CLIENT_RESPONSE_TIMEOUT"
	upstreamRequestTimeout  = "SWWAF_UPSTREAM_REQUEST_TIMEOUT"
	upstreamResponseTimeout = "SWWAF_UPSTREAM_RESPONSE_TIMEOUT"
	requestMaxBytes         = "SWWAF_REQUEST_MAX_BYTES"
	responseMaxBytes        = "SWWAF_RESPONSE_MAX_BYTES"
)

// off switches a timeout or a size limit off.
const off = "off"

// environment is a set of environment variables, for FromEnvironment.
type environment map[string]string

// lookupEnv reads one of the variables, as os.LookupEnv does.
func (e environment) lookupEnv(name string) (string, bool) {
	value, ok := e[name]

	return value, ok
}

// fromEnvironment reads the settings from env, which must be valid.
func fromEnvironment(t *testing.T, env environment) *config.Config {
	t.Helper()

	cfg, err := config.FromEnvironment(env.lookupEnv)
	if err != nil {
		t.Fatalf("settings %v: %v", env, err)
	}

	return cfg
}

func TestDefaults(t *testing.T) {
	t.Parallel()

	cfg := fromEnvironment(t, environment{})

	wantSettings(t, cfg, config.Config{
		ListenAddr:              ":8080",
		ClientRequestTimeout:    time.Minute,
		ClientResponseTimeout:   30 * time.Minute,
		UpstreamRequestTimeout:  time.Minute,
		UpstreamResponseTimeout: 30 * time.Minute,
		RequestMaxBytes:         100 << 20,
		ResponseMaxBytes:        5 << 30,
	})

	if cfg.UpstreamURL.String() != "http://127.0.0.1:8081" {
		t.Errorf("%s is %s", upstreamURL, cfg.UpstreamURL)
	}

	wantNetblocks(t, cfg.TrustedProxies,
		"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16")
}

func TestValuesAsSet(t *testing.T) {
	t.Parallel()

	cfg := fromEnvironment(t, environment{
		listenAddr:              "127.0.0.1:9000",
		upstreamURL:             "https://app.internal:8443/",
		trustedProxies:          " 192.0.2.1, 10.1.2.3/8 ,2001:db8::/32",
		clientRequestTimeout:    "90s",
		clientResponseTimeout:   "7d",
		upstreamRequestTimeout:  "1h30m",
		upstreamResponseTimeout: off,
		requestMaxBytes:         "512K",
		responseMaxBytes:        "1234",
	})

	wantSettings(t, cfg, config.Config{
		ListenAddr:              "127.0.0.1:9000",
		ClientRequestTimeout:    90 * time.Second,
		ClientResponseTimeout:   7 * 24 * time.Hour,
		UpstreamRequestTimeout:  90 * time.Minute,
		UpstreamResponseTimeout: 0,
		RequestMaxBytes:         512 << 10,
		ResponseMaxBytes:        1234,
	})

	if cfg.UpstreamURL.String() != "https://app.internal:8443/" {
		t.Errorf("%s is %s", upstreamURL, cfg.UpstreamURL)
	}

	wantNetblocks(t, cfg.TrustedProxies, "192.0.2.1/32", "10.0.0.0/8", "2001:db8::/32")
}

func TestSizesAndOff(t *testing.T) {
	t.Parallel()

	cfg := fromEnvironment(t, environment{
		requestMaxBytes:      "3G",
		responseMaxBytes:     off,
		clientRequestTimeout: off,
	})

	if cfg.RequestMaxBytes != 3<<30 || cfg.ResponseMaxBytes != 0 ||
		cfg.ClientRequestTimeout != 0 {
		t.Errorf("3G, off and off read as %d, %d and %s",
			cfg.RequestMaxBytes, cfg.ResponseMaxBytes, cfg.ClientRequestTimeout)
	}
}

func TestTrustedProxiesSetButEmptyTrustNothing(t *testing.T) {
	t.Parallel()

	cfg := fromEnvironment(t, environment{trustedProxies: ""})
	if len(cfg.TrustedProxies) != 0 {
		t.Errorf("trusted proxies %v, want none", cfg.TrustedProxies)
	}
}

func TestInvalidValueStopsTheStart(t *testing.T) {
	t.Parallel()

	for _, tc := range []struct{ name, value string }{
		{listenAddr, "8080"},
		{listenAddr, ":http"},
		{listenAddr, ":65536"},
		{upstreamURL, "127.0.0.1:8081"},
		{upstreamURL, "ftp://127.0.0.1:8081"},
		{upstreamURL, "http://"},
		{upstreamURL, "http://127.0.0.1:8081/app"},
		{upstreamURL, "http://127.0.0.1:8081/?a=1"},
		{upstreamURL, "http://user:secret@127.0.0.1:8081"},
		{trustedProxies, "10.0.0.0/33"},
		{trustedProxies, "traefik"},
		{trustedProxies, "10.0.0.0/8,,192.168.0.0/16"},
		{trustedProxies, "fe80::1%eth0"},
		{clientRequestTimeout, "60"},
		{clientRequestTimeout, ""},
		{clientResponseTimeout, "1y"},
		{upstreamRequestTimeout, "-1s"},
		{upstreamResponseTimeout, "0s"},
		{upstreamResponseTimeout, "1.5d"},
		{requestMaxBytes, "100MB"},
		{requestMaxBytes, "100m"},
		{requestMaxBytes, "1.5M"},
		{responseMaxBytes, "0"},
		{responseMaxBytes, "-5"},
		{responseMaxBytes, "99999999999G"},
	} {
		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
			t.Parallel()

			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
			if err == nil {
				t.Fatalf("%s=%q was accepted", tc.name, tc.value)
			}

			if !strings.HasPrefix(err.Error(), tc.name+": ") {
				t.Errorf("error %q does not name %s", err, tc.name)
			}
		})
	}
}

func TestLogsEachSettingWithItsValue(t *testing.T) {
	t.Parallel()

	cfg := fromEnvironment(t, environment{clientRequestTimeout: "45s"})

	var out bytes.Buffer

	slog.New(slog.NewJSONHandler(&out, nil)).Info("starting", "settings", cfg)

	var line struct {
		Settings map[string]string `json:"settings"`
	}

	err := json.Unmarshal(out.Bytes(), &line)
	if err != nil {
		t.Fatalf("decode %s: %v", out.Bytes(), err)
	}

	want := map[string]string{
		listenAddr:              ":8080",
		upstreamURL:             "http://127.0.0.1:8081",
		trustedProxies:          "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16",
		clientRequestTimeout:    "45s",
		clientResponseTimeout:   "30m",
		upstreamRequestTimeout:  "60s",
		upstreamResponseTimeout: "30m",
		requestMaxBytes:         "100M",
		responseMaxBytes:        "5G",
	}
	if !maps.Equal(line.Settings, want) {
		t.Errorf("logged settings\n%v\nwant\n%v", line.Settings, want)
	}
}

// wantSettings checks the settings that are plain values.
func wantSettings(t *testing.T, got *config.Config, want config.Config) {
	t.Helper()

	if got.ListenAddr != want.ListenAddr ||
		got.ClientRequestTimeout != want.ClientRequestTimeout ||
		got.ClientResponseTimeout != want.ClientResponseTimeout ||
		got.UpstreamRequestTimeout != want.UpstreamRequestTimeout ||
		got.UpstreamResponseTimeout != want.UpstreamResponseTimeout ||
		got.RequestMaxBytes != want.RequestMaxBytes ||
		got.ResponseMaxBytes != want.ResponseMaxBytes {
		t.Errorf("settings\n%+v\nwant\n%+v", got, want)
	}
}

// wantNetblocks checks a list of netblocks.
func wantNetblocks(t *testing.T, got []netip.Prefix, want ...string) {
	t.Helper()

	gotText := make([]string, 0, len(got))
	for _, netblock := range got {
		gotText = append(gotText, netblock.String())
	}

	if !slices.Equal(gotText, want) {
		t.Errorf("netblocks %v, want %v", gotText, want)
	}
}