package network

import (
	"context"
	"errors"
	"fmt"
	"io/fs"
	"isle/bootstrap"
	"isle/daemon/children"
	"isle/daemon/daecommon"
	"isle/nebula"
	"isle/toolkit"
	"os"
	"path/filepath"
	"testing"
	"time"

	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

type loaderHarness struct {
	ctx            context.Context
	logger         *mlog.Logger
	envBinDirPath  string
	stateDirPath   string
	runtimeDirPath string
	constructors   *mockConstructors

	loader Loader
}

func newLoaderHarness(t *testing.T) *loaderHarness {
	t.Parallel()

	var (
		ctx           = context.Background()
		logger        = toolkit.NewTestLogger(t)
		rootDir       = toolkit.TempDir(t)
		envBinDir, _  = rootDir.MkChildDir("bin", false)
		stateDir, _   = rootDir.MkChildDir("state", false)
		runtimeDir, _ = rootDir.MkChildDir("runtime", false)
		constructors  = newMockConstructors(t)
		now           = time.Date(2024, 12, 17, 16, 15, 14, 0, time.UTC)
	)

	loader, err := NewLoader(
		ctx, logger, envBinDir.Path, &LoaderOpts{
			EnvVars: daecommon.EnvVars{
				StateDir:   stateDir,
				RuntimeDir: runtimeDir,
			},
			constructors: constructors,
			nowFunc:      func() time.Time { return now },
		},
	)
	require.NoError(t, err)

	return &loaderHarness{
		ctx,
		logger,
		envBinDir.Path,
		stateDir.Path,
		runtimeDir.Path,
		constructors,
		loader,
	}
}

func (h *loaderHarness) networkStateDirPath(networkID string) string {
	return filepath.Join(h.stateDirPath, "networks", networkID)
}

func (h *loaderHarness) networkRuntimeDirPath(networkID string) string {
	return filepath.Join(h.runtimeDirPath, "networks", networkID)
}

func (h *loaderHarness) join(
	t *testing.T, creationParams bootstrap.CreationParams,
) *MockNetwork {
	var (
		joiningBootstrap = JoiningBootstrap{
			Bootstrap: bootstrap.Bootstrap{
				NetworkCreationParams: creationParams,
			},
		}
		networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
		networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
		network               = NewMockNetwork(t)
	)

	h.constructors.
		On(
			"join",
			toolkit.MockArg[context.Context](),
			toolkit.MockArg[*mlog.Logger](),
			h.envBinDirPath,
			toolkit.MockArg[*children.NebulaDeviceNamer](),
			joiningBootstrap,
			toolkit.Dir{Path: networkStateDirPath},
			toolkit.Dir{Path: networkRuntimeDirPath},
			(*Opts)(nil),
		).
		Return(network, nil).
		Once()

	got, err := h.loader.Join(
		h.ctx,
		h.logger,
		joiningBootstrap,
		nil,
	)

	require.NoError(t, err)
	require.Equal(t, got, network)

	require.NoError(t, writeBootstrapToStateDir(
		networkStateDirPath, joiningBootstrap.Bootstrap,
	))

	return network
}

func (h *loaderHarness) assertDirExists(
	t *testing.T, exists bool, path string,
) {
	stat, err := os.Stat(path)
	if exists {
		assert.NoError(t, err)
		assert.Equal(t, os.ModeDir, stat.Mode().Type())
	} else {
		assert.ErrorIs(t, err, fs.ErrNotExist)
	}
}

func TestLoader_Loadable(t *testing.T) {
	allCreationParams := []bootstrap.CreationParams{
		bootstrap.NewCreationParams("AAA", "a.com"),
		bootstrap.NewCreationParams("BBB", "b.com"),
	}

	t.Run("empty", func(t *testing.T) {
		h := newLoaderHarness(t)
		got, err := h.loader.Loadable(h.ctx)
		assert.NoError(t, err)
		assert.Empty(t, got)
	})

	t.Run("single", func(t *testing.T) {
		h := newLoaderHarness(t)
		h.join(t, allCreationParams[0])
		got, err := h.loader.Loadable(h.ctx)
		assert.NoError(t, err)
		assert.Equal(t, allCreationParams[:1], got)
	})

	t.Run("multiple", func(t *testing.T) {
		h := newLoaderHarness(t)
		h.join(t, allCreationParams[0])
		h.join(t, allCreationParams[1])
		got, err := h.loader.Loadable(h.ctx)
		assert.NoError(t, err)
		assert.ElementsMatch(t, allCreationParams, got)
	})

	t.Run("after Leave", func(t *testing.T) {
		h := newLoaderHarness(t)
		h.join(t, allCreationParams[0])
		h.join(t, allCreationParams[1])
		assert.NoError(t, h.loader.Leave(h.ctx, allCreationParams[1]))
		got, err := h.loader.Loadable(h.ctx)
		assert.NoError(t, err)
		assert.Equal(t, allCreationParams[:1], got)
	})
}

func TestLoader_Load(t *testing.T) {
	var (
		creationParams = bootstrap.NewCreationParams("AAA", "a.com")
	)

	t.Run("success", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
			network               = h.join(t, creationParams)
		)

		h.constructors.
			On(
				"load",
				toolkit.MockArg[context.Context](),
				toolkit.MockArg[*mlog.Logger](),
				h.envBinDirPath,
				toolkit.MockArg[*children.NebulaDeviceNamer](),
				toolkit.Dir{Path: networkStateDirPath},
				toolkit.Dir{Path: networkRuntimeDirPath},
				(*Opts)(nil),
			).
			Return(network, nil).
			Once()

		got, err := h.loader.Load(
			h.ctx,
			h.logger,
			creationParams,
			nil,
		)

		assert.NoError(t, err)
		assert.Equal(t, network, got)
	})

	t.Run("error/not yet joined", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
		)

		_, err := h.loader.Load(
			h.ctx,
			h.logger,
			creationParams,
			nil,
		)

		assert.ErrorContains(t, err, "not yet joined")
		h.assertDirExists(t, false, networkStateDirPath)
		h.assertDirExists(t, false, networkRuntimeDirPath)
	})
}

func TestLoader_Join(t *testing.T) {
	var (
		creationParams   = bootstrap.NewCreationParams("AAA", "a.com")
		joiningBootstrap = JoiningBootstrap{
			Bootstrap: bootstrap.Bootstrap{
				NetworkCreationParams: creationParams,
			},
		}
		network = NewMockNetwork(t)
	)

	t.Run("success", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
		)

		h.constructors.
			On(
				"join",
				toolkit.MockArg[context.Context](),
				toolkit.MockArg[*mlog.Logger](),
				h.envBinDirPath,
				toolkit.MockArg[*children.NebulaDeviceNamer](),
				joiningBootstrap,
				toolkit.Dir{Path: networkStateDirPath},
				toolkit.Dir{Path: networkRuntimeDirPath},
				(*Opts)(nil),
			).
			Return(network, nil).
			Once()

		got, err := h.loader.Join(
			h.ctx,
			h.logger,
			joiningBootstrap,
			nil,
		)

		assert.NoError(t, err)
		assert.Equal(t, network, got)
		h.assertDirExists(t, true, networkStateDirPath)
		h.assertDirExists(t, true, networkRuntimeDirPath)
	})

	t.Run("error/constructor", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
			wantErr               = errors.New("some error")
		)

		h.constructors.
			On(
				"join",
				toolkit.MockArg[context.Context](),
				toolkit.MockArg[*mlog.Logger](),
				h.envBinDirPath,
				toolkit.MockArg[*children.NebulaDeviceNamer](),
				joiningBootstrap,
				toolkit.Dir{Path: networkStateDirPath},
				toolkit.Dir{Path: networkRuntimeDirPath},
				(*Opts)(nil),
			).
			Return(nil, wantErr).
			Once()

		_, err := h.loader.Join(
			h.ctx,
			h.logger,
			joiningBootstrap,
			nil,
		)

		assert.ErrorIs(t, err, wantErr)
		h.assertDirExists(t, false, networkStateDirPath)
		h.assertDirExists(t, false, networkRuntimeDirPath)
	})
}

func TestLoader_Create(t *testing.T) {
	var (
		creationParams = bootstrap.NewCreationParams("AAA", "a.com")
		ipNet          = nebula.MustParseIPNet(t, "172.16.0.0/24")
		hostName       = nebula.HostName("foo")
		network        = NewMockNetwork(t)
	)

	t.Run("success", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
		)

		h.constructors.
			On(
				"create",
				toolkit.MockArg[context.Context](),
				toolkit.MockArg[*mlog.Logger](),
				h.envBinDirPath,
				toolkit.MockArg[*children.NebulaDeviceNamer](),
				toolkit.Dir{Path: networkStateDirPath},
				toolkit.Dir{Path: networkRuntimeDirPath},
				creationParams,
				ipNet,
				hostName,
				(*Opts)(nil),
			).
			Return(network, nil).
			Once()

		got, err := h.loader.Create(
			h.ctx,
			h.logger,
			creationParams,
			ipNet,
			hostName,
			nil,
		)

		assert.NoError(t, err)
		assert.Equal(t, network, got)
		h.assertDirExists(t, true, networkStateDirPath)
		h.assertDirExists(t, true, networkRuntimeDirPath)
	})

	t.Run("error", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
			wantErr               = errors.New("some error")
		)

		h.constructors.
			On(
				"create",
				toolkit.MockArg[context.Context](),
				toolkit.MockArg[*mlog.Logger](),
				h.envBinDirPath,
				toolkit.MockArg[*children.NebulaDeviceNamer](),
				toolkit.Dir{Path: networkStateDirPath},
				toolkit.Dir{Path: networkRuntimeDirPath},
				creationParams,
				ipNet,
				hostName,
				(*Opts)(nil),
			).
			Return(nil, wantErr).
			Once()

		_, err := h.loader.Create(
			h.ctx,
			h.logger,
			creationParams,
			ipNet,
			hostName,
			nil,
		)

		assert.ErrorIs(t, err, wantErr)
		h.assertDirExists(t, false, networkStateDirPath)
		h.assertDirExists(t, false, networkRuntimeDirPath)
	})
}

func TestLoader_Leave(t *testing.T) {
	var (
		creationParams = bootstrap.NewCreationParams("AAA", "a.com")
	)

	t.Run("success", func(t *testing.T) {
		var (
			h                     = newLoaderHarness(t)
			networkStateDirPath   = h.networkStateDirPath(creationParams.ID)
			networkRuntimeDirPath = h.networkRuntimeDirPath(creationParams.ID)
		)

		h.join(t, creationParams)

		assert.NoError(t, h.loader.Leave(h.ctx, creationParams))
		h.assertDirExists(t, false, networkStateDirPath)
		h.assertDirExists(t, false, networkRuntimeDirPath)

		wantStateDirRenamedTo := h.networkStateDirPath(fmt.Sprintf(
			".%s.20241217-161514.bak",
			creationParams.ID,
		))
		t.Logf("wantStateDirRenamedTo:%q", wantStateDirRenamedTo)
		h.assertDirExists(t, true, wantStateDirRenamedTo)

		// Make sure the data inside the state directory was actually preserved.
		bootstrap, err := loadBootstrapFromStateDir(wantStateDirRenamedTo)
		assert.NoError(t, err)
		assert.Equal(t, creationParams, bootstrap.NetworkCreationParams)
	})
}