package versions

import (
	"context"
	"fmt"
	"math"
	"testing"

	"github.com/buger/jsonparser"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/thrasher-corp/gocryptotrader/common"
	v0 "github.com/thrasher-corp/gocryptotrader/config/versions/v0"
	v1 "github.com/thrasher-corp/gocryptotrader/config/versions/v1"
	v2 "github.com/thrasher-corp/gocryptotrader/config/versions/v2"
)

func TestDeploy(t *testing.T) {
	t.Parallel()
	m := manager{}
	_, err := m.Deploy(context.Background(), []byte(``), UseLatestVersion)
	assert.ErrorIs(t, err, errNoVersions)

	m.registerVersion(1, &TestVersion1{})
	_, err = m.Deploy(context.Background(), []byte(``), UseLatestVersion)
	require.ErrorIs(t, err, errVersionIncompatible)

	m = manager{}

	m.registerVersion(0, &v0.Version{})
	m.registerVersion(1, &v1.Version{})
	_, err = m.Deploy(context.Background(), []byte(`not an object`), UseLatestVersion)
	require.ErrorIs(t, err, jsonparser.KeyPathNotFoundError, "Must throw the correct error trying to add version to bad json")
	require.ErrorIs(t, err, common.ErrSettingField, "Must throw the correct error trying to add version to bad json")
	require.ErrorContains(t, err, "version", "Must throw the correct error trying to add version to bad json")

	_, err = m.Deploy(context.Background(), []byte(`{"version":"not an int"}`), UseLatestVersion)
	require.ErrorIs(t, err, common.ErrGettingField, "Must throw the correct error trying to get version from bad json")

	_, err = m.Deploy(context.Background(), []byte(`{"version":65535}`), UseLatestVersion)
	require.ErrorIs(t, err, errConfigVersionMax, "Must throw the correct error when version is too high")

	_, err = m.Deploy(context.Background(), []byte(`{"version":-1}`), UseLatestVersion)
	require.ErrorIs(t, err, errConfigVersionNegative, "Must throw the correct error when version is negative")

	in := []byte(`{"version":0,"exchanges":[{"name":"Juan"}]}`)
	j, err := m.Deploy(context.Background(), in, UseLatestVersion)
	require.NoError(t, err)
	assert.Contains(t, string(j), `"version": 1`)

	j2, err := m.Deploy(context.Background(), j, UseLatestVersion)
	require.NoError(t, err, "Deploy the same version again must not error")
	require.Equal(t, string(j2), string(j), "Deploy the same version again must not change config")

	_, err = m.Deploy(context.Background(), j, 2)
	assert.ErrorIs(t, err, errTargetVersion, "Downgrade to a unregistered version should not be allowed")

	m.versions = append(m.versions, &TestVersion2{ConfigErr: true, ExchErr: false})
	_, err = m.Deploy(context.Background(), j, UseLatestVersion)
	require.ErrorIs(t, err, errUpgrade)

	m.versions[len(m.versions)-1] = &TestVersion2{ConfigErr: false, ExchErr: true}
	_, err = m.Deploy(context.Background(), in, UseLatestVersion)
	require.Implements(t, (*ExchangeVersion)(nil), m.versions[1])
	require.ErrorIs(t, err, errUpgrade)
	require.ErrorContains(t, err, "for `Juan`")

	j2, err = m.Deploy(context.Background(), j, 0)
	require.NoError(t, err)
	assert.Contains(t, string(j2), `"version": 0`, "Explicit downgrade should work correctly")

	m.versions = m.versions[:1]
	_, err = m.Deploy(context.Background(), j, UseLatestVersion)
	assert.ErrorIs(t, err, errConfigVersionUnavail, "Config version ahead of latest version should error")
}

// TestExchangeDeploy exercises exchangeDeploy
// There are a number of error paths we can't currently cover without exposing unacceptable risks to the hot-paths as well
func TestExchangeDeploy(t *testing.T) {
	t.Parallel()
	m := manager{}
	_, err := m.Deploy(context.Background(), []byte(``), UseLatestVersion)
	assert.ErrorIs(t, err, errNoVersions)

	v := &TestVersion2{}
	in := []byte(`{"version":0,"exchanges":[{}]}`)
	_, err = exchangeDeploy(context.Background(), v, ExchangeVersion.UpgradeExchange, in)
	require.ErrorIs(t, err, errModifyingExchange)
	require.ErrorIs(t, err, common.ErrGettingField)
	require.ErrorIs(t, err, jsonparser.KeyPathNotFoundError)
	require.ErrorContains(t, err, "`name`")
	require.ErrorContains(t, err, "[0]")

	in = []byte(`{"version":0,"exchanges":[{"name":"Juan"},{"name":"Megashaft"}]}`)
	_, err = exchangeDeploy(context.Background(), v, ExchangeVersion.UpgradeExchange, in)
	require.NoError(t, err)
}

func TestRegisterVersion(t *testing.T) {
	t.Parallel()
	m := manager{}

	m.registerVersion(0, &v0.Version{})
	assert.NotEmpty(t, m.versions)

	m.registerVersion(2, &TestVersion2{})
	require.Equal(t, 3, len(m.versions), "Must allocate a space for missing version 1")
	require.NotNil(t, m.versions[2], "Must put Version 2 in the correct slot")
	require.Nil(t, m.versions[1], "Must leave Version 1 alone")

	m.registerVersion(1, &TestVersion1{})
	require.Equal(t, 3, len(m.versions), "Must leave len alone when registering out-of-sequence")
	require.NotNil(t, m.versions[1], "Must put Version 1 in the correct slot")

	assert.PanicsWithError(t, fmt.Sprintf("%s: %d", errAlreadyRegistered, 2), func() {
		m.registerVersion(2, &TestVersion2{})
	}, "registeringVersion must panic registering an existing version")
}

func TestLatest(t *testing.T) {
	t.Parallel()
	m := manager{}
	_, err := m.latest()
	require.ErrorIs(t, err, errNoVersions)

	m.registerVersion(0, &v0.Version{})
	m.registerVersion(1, &v1.Version{})
	v, err := m.latest()
	require.NoError(t, err)
	assert.Equal(t, uint16(1), v)

	m.registerVersion(2, &v2.Version{})
	v, err = m.latest()
	require.NoError(t, err)
	assert.Equal(t, uint16(2), v)
}

func TestVersion(t *testing.T) {
	t.Parallel()
	m := manager{}
	m.registerVersion(0, &v0.Version{})
	l, err := m.latest()
	require.NoError(t, err, "latest must not error")
	assert.Nil(t, m.Version(l-1))
	assert.NotNil(t, m.Version(l))
	assert.Nil(t, m.Version(math.MaxUint16))
}