package integration

import (
	"context"
	"crypto/md5"
	"errors"
	"fmt"
	"os"
	"time"

	"code.icb4dc0.de/buildr/wasi-module-sdk-go/mem"

	"github.com/google/uuid"
	"github.com/tetratelabs/wazero"
	"github.com/tetratelabs/wazero/api"
	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
	"golang.org/x/exp/slog"

	sdk "code.icb4dc0.de/buildr/wasi-module-sdk-go"
	rpcv1 "code.icb4dc0.de/buildr/wasi-module-sdk-go/protocol/generated/rpc/v1"
)

func StateKey(cat sdk.Category, modName, key string) string {
	h := md5.New()
	_, _ = h.Write([]byte(cat.String()))
	_, _ = h.Write([]byte(modName))
	_, _ = h.Write([]byte(key))

	return string(h.Sum(nil))
}

type TestSpec struct {
	ModuleCategory sdk.Category
	ModuleType     string
	ModuleName     string
	RawTaskSpec    []byte
}

type HostOption func(h *Host)

func WithState(key string, value []byte) HostOption {
	return func(h *Host) {
		h.state[key] = value
	}
}

func NewHost(logger *slog.Logger, opts ...HostOption) *Host {
	h := &Host{
		Logger: logger,
		state:  make(map[string][]byte),
	}

	for i := range opts {
		opts[i](h)
	}

	return h
}

type Host struct {
	memMgr *memoryManager
	state  map[string][]byte
	Logger *slog.Logger
}

func (h *Host) Run(ctx context.Context, wasiPayload []byte, spec TestSpec) (err error) {
	runtimeConfig := wazero.NewRuntimeConfig().
		WithCloseOnContextDone(true)

	r := wazero.NewRuntimeWithConfig(ctx, runtimeConfig)
	defer func() {
		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
		defer cancel()
		err = errors.Join(err, r.Close(ctx))
	}()

	_, err = r.NewHostModuleBuilder("buildr").
		NewFunctionBuilder().WithFunc(h.log).Export("log_msg").
		NewFunctionBuilder().WithFunc(h.getState).Export("get_state").
		NewFunctionBuilder().WithFunc(h.setState).Export("set_state").
		Instantiate(ctx)

	if err != nil {
		return err
	}

	closer, err := wasi_snapshot_preview1.Instantiate(ctx, r)
	if err != nil {
		return err
	}

	defer func() {
		err = errors.Join(err, closer.Close(context.Background()))
	}()

	config := wazero.NewFSConfig().
		WithDirMount(".", "/work")

	moduleConfig := wazero.NewModuleConfig().
		WithStdout(os.Stdout).
		WithStderr(os.Stderr).
		WithFSConfig(config)

	mod, err := r.InstantiateWithConfig(ctx, wasiPayload, moduleConfig)
	if err != nil {
		return err
	}

	h.memMgr = newMemoryManager(mod)

	inv, err := h.getInventory(ctx, mod)
	if err != nil {
		return err
	}

	for _, ref := range inv {
		fmt.Printf("%s/%s/n", ref.Category, ref.Type)
	}

	startTask := &rpcv1.StartTaskRequest{
		Reference: &rpcv1.TaskReference{
			Id: uuid.NewString(),
			Module: &rpcv1.ModuleReference{
				ModuleCategory: spec.ModuleCategory.String(),
				ModuleType:     spec.ModuleType,
			},
			Name: spec.ModuleName,
		},
		Buildr: &rpcv1.Buildr{
			Repo: &rpcv1.Buildr_Repo{
				Root: "/work",
			},
		},
		RawTask: spec.RawTaskSpec,
	}

	data, err := startTask.MarshalVT()
	if err != nil {
		return err
	}

	run := mod.ExportedFunction("run")

	defer func() {
		err = errors.Join(err, h.memMgr.Close())
	}()

	err = h.memMgr.WithMem(ctx, uint64(len(data)), func(ptr uint64) error {
		if !mod.Memory().Write(uint32(ptr), data) {
			return errors.New("failed to write to memory")
		}

		_, err = run.Call(ctx, ptr, uint64(len(data)))

		return err
	})

	return err
}

func (h *Host) getInventory(ctx context.Context, mod api.Module) (refs []sdk.Reference, err error) {
	result, err := mod.ExportedFunction("inventory").Call(ctx)
	if err != nil {
		return nil, err
	}

	ptr, size := mem.UnifiedPtrToSizePtr(result[0])
	if ptr == 0 {
		return nil, errors.New("failed to get inventory - 0 pointer")
	}

	defer func() {
		err = errors.Join(err, h.memMgr.Deallocate(ctx, uint64(ptr)))
	}()

	data, ok := mod.Memory().Read(ptr, size)
	if !ok {
		return nil, errors.New("failed to get inventory")
	}

	var inventory rpcv1.PluginInventory
	if err = inventory.UnmarshalVT(data); err != nil {
		return nil, err
	}

	refs = make([]sdk.Reference, 0, len(inventory.Modules))
	for _, m := range inventory.Modules {
		refs = append(refs, sdk.Reference{
			Category: sdk.Category(m.GetModuleCategory()),
			Type:     m.GetModuleType(),
		})
	}

	return refs, nil
}

func (h *Host) getState(ctx context.Context, m api.Module, offset, byteCount uint32) uint64 {
	if h.state == nil {
		h.state = make(map[string][]byte)
	}

	buf, ok := m.Memory().Read(offset, byteCount)
	if !ok {
		return 0
	}

	getStateReq := new(rpcv1.GetStateRequest)
	if err := getStateReq.UnmarshalVT(buf); err != nil {
		h.Logger.Error("failed to unmarshal getStateRequest", slog.String("err", err.Error()))
		return 0
	}

	resp := new(rpcv1.GetStateResponse)
	resp.Data, _ = h.state[string(getStateReq.Key)]

	if ptr, err := h.memMgr.WriteMessage(ctx, m, resp); err != nil {
		h.Logger.Error("Failed to write message", slog.String("err", err.Error()))
		return 0
	} else {
		return ptr
	}
}

func (h *Host) setState(ctx context.Context, m api.Module, offset, byteCount uint32) (result uint64) {
	if h.state == nil {
		h.state = make(map[string][]byte)
	}

	buf, ok := m.Memory().Read(offset, byteCount)
	if !ok {
		return 0
	}

	setState := new(rpcv1.SetState)
	if err := setState.UnmarshalVT(buf); err != nil {
		h.Logger.Error("failed to unmarshal SetState", slog.String("err", err.Error()))
		return 0
	}

	var resp rpcv1.Result
	if len(setState.Key) < 1 {
		resp.Error = "key might not be empty"
	} else {
		h.state[string(setState.Key)] = setState.Data
		resp.Success = true
	}

	if ptr, err := h.memMgr.WriteMessage(ctx, m, &resp); err != nil {
		h.Logger.Error("Failed to write message", slog.String("err", err.Error()))
		return 0
	} else {
		return ptr
	}
}

func (h *Host) log(ctx context.Context, m api.Module, offset, byteCount uint32) {
	buf, ok := m.Memory().Read(offset, byteCount)
	if !ok {
		return
	}

	taskLog := new(rpcv1.TaskLog)
	if err := taskLog.UnmarshalVT(buf); err != nil {
		h.Logger.Warn("failed to unmarshal task log", slog.String("err", err.Error()))
		return
	}

	rec := slog.NewRecord(time.UnixMicro(taskLog.Time), slog.Level(taskLog.Level), taskLog.Message, 0)

	for i := range taskLog.Attributes {
		attr := taskLog.Attributes[i]
		rec.AddAttrs(slog.String(attr.Key, attr.Value))
	}

	_ = h.Logger.Handler().Handle(ctx, rec)
}