package client

import (
	"context"
	"crypto/ecdsa"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/refs"
	rpcapi "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/client"
	v2session "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/signature"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
)

// PrmSessionCreate groups parameters of SessionCreate operation.
type PrmSessionCreate struct {
	prmCommonMeta

	exp uint64

	keySet bool
	key    ecdsa.PrivateKey
}

// SetExp sets number of the last NepFS epoch in the lifetime of the session after which it will be expired.
func (x *PrmSessionCreate) SetExp(exp uint64) {
	x.exp = exp
}

// UseKey specifies private key to sign the requests and compute token owner.
// If key is not provided, then Client default key is used.
func (x *PrmSessionCreate) UseKey(key ecdsa.PrivateKey) {
	x.keySet = true
	x.key = key
}

func (x *PrmSessionCreate) buildRequest(c *Client) (*v2session.CreateRequest, error) {
	ownerKey := c.prm.key.PublicKey
	if x.keySet {
		ownerKey = x.key.PublicKey
	}
	var ownerID user.ID
	user.IDFromKey(&ownerID, ownerKey)

	var ownerIDV2 refs.OwnerID
	ownerID.WriteToV2(&ownerIDV2)

	reqBody := new(v2session.CreateRequestBody)
	reqBody.SetOwnerID(&ownerIDV2)
	reqBody.SetExpiration(x.exp)

	var meta v2session.RequestMetaHeader
	writeXHeadersToMeta(x.xHeaders, &meta)

	var req v2session.CreateRequest
	req.SetBody(reqBody)
	c.prepareRequest(&req, &meta)
	return &req, nil
}

// ResSessionCreate groups resulting values of SessionCreate operation.
type ResSessionCreate struct {
	statusRes

	id []byte

	sessionKey []byte
}

// ID returns identifier of the opened session in a binary FrostFS API protocol format.
//
// Client doesn't retain value so modification is safe.
func (x ResSessionCreate) ID() []byte {
	return x.id
}

// PublicKey returns public key of the opened session in a binary FrostFS API protocol format.
func (x ResSessionCreate) PublicKey() []byte {
	return x.sessionKey
}

// SessionCreate opens a session with the node server on the remote endpoint.
// The session lifetime coincides with the server lifetime. Results can be written
// to session token which can be later attached to the requests.
//
// Exactly one return value is non-nil. By default, server status is returned in res structure.
// Any client's internal or transport errors are returned as `error`.
// If PrmInit.ResolveFrostFSFailures has been called, unsuccessful
// FrostFS status codes are returned as `error`, otherwise, are included
// in the returned result structure.
//
// Returns an error if parameters are set incorrectly (see PrmSessionCreate docs).
// Context is required and must not be nil. It is used for network communication.
//
// Return statuses:
//   - global (see Client docs).
func (c *Client) SessionCreate(ctx context.Context, prm PrmSessionCreate) (*ResSessionCreate, error) {
	req, err := prm.buildRequest(c)
	if err != nil {
		return nil, err
	}

	if err := signature.SignServiceMessage(&c.prm.key, req); err != nil {
		return nil, fmt.Errorf("sign request: %w", err)
	}

	resp, err := rpcapi.CreateSession(&c.c, req, client.WithContext(ctx))
	if err != nil {
		return nil, err
	}

	var res ResSessionCreate
	res.st, err = c.processResponse(resp)
	if err != nil || !apistatus.IsSuccessful(res.st) {
		return &res, err
	}

	body := resp.GetBody()
	res.id = body.GetID()
	res.sessionKey = body.GetSessionKey()
	return &res, nil
}