package geoip

import (
	"errors"
	"net/netip"
	"os"
	"testing"

	"github.com/oschwald/geoip2-golang/v2"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

const countryFixturePath = "test-data/test-data/GeoIP2-Country-Test.mmdb"

type fakeReader struct {
	countryFunc func(netip.Addr) (*geoip2.Country, error)
	closeFunc   func() error
}

func (f fakeReader) Country(addr netip.Addr) (*geoip2.Country, error) {
	if f.countryFunc == nil {
		return nil, nil
	}

	return f.countryFunc(addr)
}

func (f fakeReader) Close() error {
	if f.closeFunc == nil {
		return nil
	}

	return f.closeFunc()
}

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

	tests := []struct {
		name string
		path string
	}{
		{name: "empty", path: ""},
		{name: "whitespace", path: "   \t\n"},
	}

	for _, tt := range tests {
		tt := tt
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			resolver, err := Open(tt.path)
			require.Error(t, err)
			assert.Nil(t, resolver)
			assert.Contains(t, err.Error(), "database path must not be empty")
		})
	}
}

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

	resolver, err := Open("test-data/test-data/does-not-exist.mmdb")
	require.Error(t, err)
	assert.Nil(t, resolver)
	assert.Contains(t, err.Error(), `open geoip database "test-data/test-data/does-not-exist.mmdb"`)
}

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

	tests := []struct {
		name   string
		lookup func(*Resolver) (string, error)
		want   string
	}{
		{
			name: "addr lookup",
			lookup: func(resolver *Resolver) (string, error) {
				return resolver.Country(netip.MustParseAddr("81.2.69.160"))
			},
			want: "GB",
		},
		{
			name: "string lookup",
			lookup: func(resolver *Resolver) (string, error) {
				return resolver.CountryString(" 81.2.69.160 ")
			},
			want: "GB",
		},
	}

	for _, tt := range tests {
		tt := tt
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			resolver := openFixtureResolver(t)

			got, err := tt.lookup(resolver)
			require.NoError(t, err)
			assert.Equal(t, tt.want, got)
		})
	}
}

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

	requireFixtureDatabase(t)

	resolver, err := NewGeoIP(countryFixturePath)
	require.NoError(t, err)
	t.Cleanup(func() {
		require.NoError(t, resolver.Close())
	})

	got, err := resolver.CountryString("81.2.69.160")
	require.NoError(t, err)
	assert.Equal(t, "GB", got)
}

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

	resolver := openFixtureResolver(t)

	_, err := resolver.Country(netip.MustParseAddr("192.168.1.1"))
	require.Error(t, err)
	assert.ErrorIs(t, err, ErrCountryNotFound)
}

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

	resolver := openFixtureResolver(t)

	require.NoError(t, resolver.Close())
	require.NoError(t, resolver.Close())
}

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

	var resolver *Resolver
	require.NoError(t, resolver.Close())
}

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

	resolver := openFixtureResolver(t)
	require.NoError(t, resolver.Close())

	_, err := resolver.Country(netip.MustParseAddr("81.2.69.160"))
	require.Error(t, err)
	assert.ErrorIs(t, err, ErrClosed)
}

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

	resolver := newResolver(fakeReader{})

	_, err := resolver.Country(netip.Addr{})
	require.Error(t, err)
	assert.ErrorIs(t, err, ErrInvalidAddress)
}

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

	tests := []string{
		"",
		"not-an-ip",
		"999.0.0.1",
	}

	for _, raw := range tests {
		raw := raw
		t.Run(raw, func(t *testing.T) {
			t.Parallel()

			resolver := newResolver(fakeReader{})

			_, err := resolver.CountryString(raw)
			require.Error(t, err)
			assert.ErrorIs(t, err, ErrInvalidAddress)
		})
	}
}

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

	lookupErr := errors.New("lookup failed")
	resolver := newResolver(fakeReader{
		countryFunc: func(netip.Addr) (*geoip2.Country, error) {
			return nil, lookupErr
		},
	})

	_, err := resolver.Country(netip.MustParseAddr("203.0.113.10"))
	require.Error(t, err)
	assert.ErrorIs(t, err, lookupErr)
	assert.Contains(t, err.Error(), "lookup country for 203.0.113.10")
}

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

	resolver := newResolver(fakeReader{
		countryFunc: func(netip.Addr) (*geoip2.Country, error) {
			return &geoip2.Country{
				Continent: geoip2.Continent{Code: "EU"},
			}, nil
		},
	})

	_, err := resolver.Country(netip.MustParseAddr("203.0.113.10"))
	require.Error(t, err)
	assert.ErrorIs(t, err, ErrCountryNotFound)
}

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

	resolver := newResolver(fakeReader{
		countryFunc: func(netip.Addr) (*geoip2.Country, error) {
			return &geoip2.Country{
				Country: geoip2.CountryRecord{ISOCode: "gb"},
			}, nil
		},
	})

	got, err := resolver.Country(netip.MustParseAddr("203.0.113.10"))
	require.NoError(t, err)
	assert.Equal(t, "GB", got)
}

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

	tests := []struct {
		name string
		code string
	}{
		{name: "digit", code: "G1"},
		{name: "too long", code: "USA"},
		{name: "non ascii", code: "éé"},
	}

	for _, tt := range tests {
		tt := tt
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			resolver := newResolver(fakeReader{
				countryFunc: func(netip.Addr) (*geoip2.Country, error) {
					return &geoip2.Country{
						Country: geoip2.CountryRecord{ISOCode: tt.code},
					}, nil
				},
			})

			_, err := resolver.Country(netip.MustParseAddr("203.0.113.10"))
			require.Error(t, err)
			assert.NotErrorIs(t, err, ErrCountryNotFound)
			assert.Contains(t, err.Error(), "invalid ISO 3166-1 alpha-2 code")
		})
	}
}

func openFixtureResolver(t *testing.T) *Resolver {
	t.Helper()

	requireFixtureDatabase(t)

	resolver, err := Open(countryFixturePath)
	require.NoError(t, err)

	t.Cleanup(func() {
		require.NoError(t, resolver.Close())
	})

	return resolver
}

func requireFixtureDatabase(t *testing.T) {
	t.Helper()

	_, err := os.Stat(countryFixturePath)
	require.NoErrorf(
		t,
		err,
		"fixture database %q is unavailable; run `git submodule update --init --recursive` before running tests",
		countryFixturePath,
	)
}