package frostfs

import (
	"context"
	"errors"
	"fmt"
	"io"
	"strings"

	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/internal/handler"
	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/utils"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

// FrostFS represents virtual connection to the FrostFS network.
// It is used to provide an interface to dependent packages
// which work with FrostFS.
type FrostFS struct {
	pool *pool.Pool
}

// NewFrostFS creates new FrostFS using provided pool.Pool.
func NewFrostFS(p *pool.Pool) *FrostFS {
	return &FrostFS{
		pool: p,
	}
}

// Container implements frostfs.FrostFS interface method.
func (x *FrostFS) Container(ctx context.Context, layerPrm handler.PrmContainer) (*container.Container, error) {
	prm := pool.PrmContainerGet{
		ContainerID: layerPrm.ContainerID,
	}

	res, err := x.pool.GetContainer(ctx, prm)
	if err != nil {
		return nil, handleObjectError("read container via connection pool", err)
	}

	return &res, nil
}

// CreateObject implements frostfs.FrostFS interface method.
func (x *FrostFS) CreateObject(ctx context.Context, prm handler.PrmObjectCreate) (oid.ID, error) {
	var prmPut pool.PrmObjectPut
	prmPut.SetHeader(*prm.Object)
	prmPut.SetPayload(prm.Payload)
	prmPut.SetClientCut(prm.ClientCut)
	prmPut.WithoutHomomorphicHash(prm.WithoutHomomorphicHash)
	prmPut.SetBufferMaxSize(prm.BufferMaxSize)

	if prm.BearerToken != nil {
		prmPut.UseBearer(*prm.BearerToken)
	}

	res, err := x.pool.PutObject(ctx, prmPut)
	return res.ObjectID, handleObjectError("save object via connection pool", err)
}

// wraps io.ReadCloser and transforms Read errors related to access violation
// to frostfs.ErrAccessDenied.
type payloadReader struct {
	io.ReadCloser
}

func (x payloadReader) Read(p []byte) (int, error) {
	n, err := x.ReadCloser.Read(p)
	if err != nil && errors.Is(err, io.EOF) {
		return n, err
	}
	return n, handleObjectError("read payload", err)
}

// ReadObject implements frostfs.FrostFS interface method.
func (x *FrostFS) ReadObject(ctx context.Context, prm handler.PrmObjectRead) (*handler.ObjectPart, error) {
	var prmGet pool.PrmObjectGet
	prmGet.SetAddress(prm.Address)

	if prm.BearerToken != nil {
		prmGet.UseBearer(*prm.BearerToken)
	}

	// The code below must be reworked. It was copied from frostfs-s3-gw
	// to create similar mocks for unit and fuzzing tests.
	//
	// However, this code was changed due to specific of expected responses
	// from HTTP gateway. HTTP Gateway requires two types of responses:
	// * payload as io.Reader + HEAD request
	// * only payload as io.Reader
	// Therefore all unused params were deleted and code was simplified.

	if prm.PayloadRange[0]+prm.PayloadRange[1] == 0 {
		res, err := x.pool.GetObject(ctx, prmGet)
		if err != nil {
			return nil, handleObjectError("init full payload range reading via connection pool", err)
		}

		return &handler.ObjectPart{
			Payload: res.Payload,
			Head:    &res.Header,
		}, nil
	}

	var prmRange pool.PrmObjectRange
	prmRange.SetAddress(prm.Address)
	prmRange.SetOffset(prm.PayloadRange[0])
	prmRange.SetLength(prm.PayloadRange[1])

	if prm.BearerToken != nil {
		prmRange.UseBearer(*prm.BearerToken)
	}

	res, err := x.pool.ObjectRange(ctx, prmRange)
	if err != nil {
		return nil, handleObjectError("init payload range reading via connection pool", err)
	}

	return &handler.ObjectPart{
		Payload: payloadReader{&res},
	}, nil
}

// SearchObjects implements frostfs.FrostFS interface method.
func (x *FrostFS) SearchObjects(ctx context.Context, prm handler.PrmObjectSearch) (handler.ResObjectSearch, error) {
	var prmSearch pool.PrmObjectSearch
	prmSearch.SetContainerID(prm.Container)
	prmSearch.SetFilters(prm.Filters)

	if prm.BearerToken != nil {
		prmSearch.UseBearer(*prm.BearerToken)
	}

	res, err := x.pool.SearchObjects(ctx, prmSearch)
	if err != nil {
		return nil, handleObjectError("init object search via connection pool", err)
	}

	return &res, nil
}

// GetEpochDurations implements frostfs.FrostFS interface method.
func (x *FrostFS) GetEpochDurations(ctx context.Context) (*utils.EpochDurations, error) {
	networkInfo, err := x.pool.NetworkInfo(ctx)
	if err != nil {
		return nil, err
	}

	res := &utils.EpochDurations{
		CurrentEpoch:  networkInfo.CurrentEpoch(),
		MsPerBlock:    networkInfo.MsPerBlock(),
		BlockPerEpoch: networkInfo.EpochDuration(),
	}

	if res.BlockPerEpoch == 0 {
		return nil, fmt.Errorf("EpochDuration is empty")
	}
	return res, nil
}

// ResolverFrostFS represents virtual connection to the FrostFS network.
// It implements resolver.FrostFS.
type ResolverFrostFS struct {
	pool *pool.Pool
}

// NewResolverFrostFS creates new ResolverFrostFS using provided pool.Pool.
func NewResolverFrostFS(p *pool.Pool) *ResolverFrostFS {
	return &ResolverFrostFS{pool: p}
}

// SystemDNS implements resolver.FrostFS interface method.
func (x *ResolverFrostFS) SystemDNS(ctx context.Context) (string, error) {
	networkInfo, err := x.pool.NetworkInfo(ctx)
	if err != nil {
		return "", handleObjectError("read network info via client", err)
	}

	domain := networkInfo.RawNetworkParameter("SystemDNS")
	if domain == nil {
		return "", errors.New("system DNS parameter not found or empty")
	}

	return string(domain), nil
}

func handleObjectError(msg string, err error) error {
	if err == nil {
		return nil
	}

	if reason, ok := IsErrObjectAccessDenied(err); ok {
		return fmt.Errorf("%s: %w: %s", msg, handler.ErrAccessDenied, reason)
	}

	if IsTimeoutError(err) {
		return fmt.Errorf("%s: %w: %s", msg, handler.ErrGatewayTimeout, err.Error())
	}

	return fmt.Errorf("%s: %w", msg, err)
}

func UnwrapErr(err error) error {
	unwrappedErr := errors.Unwrap(err)
	for unwrappedErr != nil {
		err = unwrappedErr
		unwrappedErr = errors.Unwrap(err)
	}

	return err
}

func IsErrObjectAccessDenied(err error) (string, bool) {
	err = UnwrapErr(err)
	switch err := err.(type) {
	default:
		return "", false
	case *apistatus.ObjectAccessDenied:
		return err.Reason(), true
	}
}

func IsTimeoutError(err error) bool {
	if strings.Contains(err.Error(), "timeout") ||
		errors.Is(err, context.DeadlineExceeded) {
		return true
	}

	return status.Code(UnwrapErr(err)) == codes.DeadlineExceeded
}