package handlers

import (
	"context"
	"errors"
	"io"

	"git.defalsify.org/vise.git/engine"
	"git.defalsify.org/vise.git/resource"
	"git.defalsify.org/vise.git/persist"
	"git.defalsify.org/vise.git/logging"

	"git.grassecon.net/urdt/ussd/internal/storage"
)

var (
	logg = logging.NewVanilla().WithDomain("handlers")
)

var (
	ErrInvalidRequest = errors.New("invalid request for context")
	ErrSessionMissing = errors.New("missing session")
	ErrInvalidInput = errors.New("invalid input")
	ErrStorage = errors.New("storage retrieval fail")
	ErrEngineType = errors.New("incompatible engine")
	ErrEngineInit = errors.New("engine init fail")
	ErrEngineExec = errors.New("engine exec fail")
)

type RequestSession struct {
	Ctx context.Context
	Config engine.Config
	Engine engine.Engine
	Input []byte
	Storage storage.Storage
	Writer io.Writer
	Continue bool
}

type engineMaker func(cfg engine.Config, rs resource.Resource, pr *persist.Persister) engine.Engine

// TODO: seems like can remove this.
type RequestParser interface {
	GetSessionId(rq any) (string, error)
	GetInput(rq any) ([]byte, error)
}

type RequestHandler interface {
	GetConfig() engine.Config
	GetRequestParser() RequestParser
	GetEngine(cfg engine.Config, rs resource.Resource, pe *persist.Persister) engine.Engine 
	Process(rs RequestSession) (RequestSession, error)
	Output(rs RequestSession) (RequestSession, error)
	AtOutput(rs RequestSession) (RequestSession, error)
	Reset(rs RequestSession) (RequestSession, error)
	Shutdown()
}