package storage

import (
	"fmt"

	"galaxy/model/client"
	"galaxy/model/order"
	"galaxy/model/report"
	"galaxy/util"
)

type Storage interface {
	UIStorage
	Exists(string) (bool, error)
	ReadFile(string) ([]byte, error)
	WriteFile(string, []byte) error
}

// UIStorage manages Client's data local storing and retrieval.
// It performs all I/O operations asynchronously to avoid UI main thread blocking.
type UIStorage interface {
	// StateExists check asynchronously for previously saved [model.State] exists on the filesystem.
	// Passed callback func will will accept false and non-nil error in case of I/O or decoding errors occuried,
	// otherwise bool parameter will indicate existence of previously stores state
	StateExists(func(bool, error))

	// LoadState loads Client's [model.State] from filesystem data asynchronously.
	// Passed callback func will accept non-nil error in case of I/O or decoding errors occuried,
	// otherwise callback func accepts loaded [model.State].
	LoadState(func(client.State, error))

	// SaveState stores Client's state at the filesystem asynchronously.
	// I/O or encoding error may occur, it that case callback func will be called with non-nil error.
	SaveState(client.State, func(error))

	// LoadReport loads a [report.Report] for a given [model.GameID] and turn number from filesystem asynchronously.
	// Passed callback func will will accept non-nil error in case of I/O or decoding errors occuried,
	// otherwise callback func accepts loaded [report.Report].
	LoadReport(client.GameID, uint, func(report.Report, error))

	// PutReport stores given [report.Report] for a given [model.GameID] and turn number at the filesystem asynchronously.
	// I/O or encoding error may occur, it that case callback func will be called with non-nil error.
	PutReport(client.GameID, uint, report.Report, func(error))

	// LoadOrder loads a [order.Order] for a given [model.GameID] and turn number from filesystem asynchronously.
	// Passed callback func will will accept non-nil error in case of I/O or decoding errors occuried,
	// otherwise callback func accepts loaded [order.Order].
	LoadOrder(client.GameID, uint, func(order.Order, error))

	// PutOrder stores given [order.Order] for a given [model.GameID] and turn number at the filesystem asynchronously.
	// I/O or encoding error may occur, it that case callback func will be called with non-nil error.
	PutOrder(client.GameID, uint, order.Order, func(error))
}

type storage struct {
	path string
}

func NewStorage(path string) (*storage, error) {
	if ok, err := util.PathExists(path, true); err != nil {
		return nil, fmt.Errorf("new storage: check path %q exists: %w", path, err)
	} else if !ok {
		return nil, fmt.Errorf("new storage: path %q does not exists", path)
	}
	if ok, err := util.Writable(path); err != nil {
		return nil, fmt.Errorf("new storage: check path %q writable: %w", path, err)
	} else if !ok {
		return nil, fmt.Errorf("new storage: path %q is not writable", path)
	}
	s := &storage{
		path: path,
	}
	return s, nil
}