package notify

import (
	itransfer "b612.me/notify/internal/transfer"
	"errors"
)

type transferControlRuntimeAccessor interface {
	getTransferRuntime() *transferRuntime
}

func transferControlRuntimeFromClient(c Client) *transferRuntime {
	if c == nil {
		return nil
	}
	accessor, ok := any(c).(transferControlRuntimeAccessor)
	if !ok {
		return nil
	}
	return accessor.getTransferRuntime()
}

func transferControlRuntimeFromServer(s Server) *transferRuntime {
	if s == nil {
		return nil
	}
	accessor, ok := any(s).(transferControlRuntimeAccessor)
	if !ok {
		return nil
	}
	return accessor.getTransferRuntime()
}

func transferControlPrepareBegin(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, publicScope string, transportGeneration uint64, req TransferBeginRequest) {
	if runtime == nil || req.TransferID == "" {
		return
	}
	runtime.ensureTransferDescriptor(direction, runtimeScope, publicScope, transportGeneration, itransfer.Descriptor{
		ID:       req.TransferID,
		Channel:  itransfer.Channel(req.Channel),
		Size:     req.Size,
		Checksum: req.Checksum,
		Metadata: itransfer.Metadata(cloneTransferMetadata(req.Metadata)),
	})
	runtime.recordStage(direction, runtimeScope, req.TransferID, "begin")
}

func transferControlFinishBegin(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, transferID string, resp TransferBeginResponse, err error) {
	if runtime == nil {
		return
	}
	transferID = transferControlTransferID(transferID, resp.TransferID)
	if transferID == "" {
		return
	}
	if err != nil {
		runtime.recordFailureStage(direction, runtimeScope, transferID, "begin")
		runtime.fail(direction, runtimeScope, transferID, err)
		return
	}
	runtime.resume(direction, runtimeScope, transferID, transferControlOffset(resp.NextOffset))
}

func transferControlPrepareResume(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, publicScope string, transportGeneration uint64, req TransferResumeRequest) {
	if runtime == nil || req.TransferID == "" {
		return
	}
	runtime.ensureTransferDescriptor(direction, runtimeScope, publicScope, transportGeneration, itransfer.Descriptor{
		ID:      req.TransferID,
		Channel: itransfer.DataChannel,
	})
	runtime.recordStage(direction, runtimeScope, req.TransferID, "resume")
}

func transferControlFinishResume(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, transferID string, resp TransferResumeResponse, err error) {
	if runtime == nil {
		return
	}
	transferID = transferControlTransferID(transferID, resp.TransferID)
	if transferID == "" {
		return
	}
	if err != nil {
		runtime.recordFailureStage(direction, runtimeScope, transferID, "resume")
		runtime.fail(direction, runtimeScope, transferID, err)
		return
	}
	runtime.resume(direction, runtimeScope, transferID, transferControlOffset(resp.NextOffset))
}

func transferControlPrepareCommit(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, publicScope string, transportGeneration uint64, req TransferCommitRequest) {
	if runtime == nil || req.TransferID == "" {
		return
	}
	runtime.ensureTransferDescriptor(direction, runtimeScope, publicScope, transportGeneration, itransfer.Descriptor{
		ID:       req.TransferID,
		Channel:  itransfer.DataChannel,
		Size:     req.Size,
		Checksum: req.Checksum,
	})
	runtime.recordStage(direction, runtimeScope, req.TransferID, "commit")
	if direction == fileTransferDirectionSend {
		runtime.beginCommit(direction, runtimeScope, req.TransferID)
	}
}

func transferControlFinishCommit(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, transferID string, resp TransferCommitResponse, err error) {
	if runtime == nil {
		return
	}
	transferID = transferControlTransferID(transferID, resp.TransferID)
	if transferID == "" {
		return
	}
	if err != nil {
		runtime.recordFailureStage(direction, runtimeScope, transferID, "commit")
		runtime.fail(direction, runtimeScope, transferID, err)
		return
	}
	if direction == fileTransferDirectionReceive {
		runtime.beginVerify(direction, runtimeScope, transferID)
	}
	runtime.complete(direction, runtimeScope, transferID)
}

func transferControlPrepareAbort(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, publicScope string, transportGeneration uint64, req TransferAbortRequest) {
	if runtime == nil || req.TransferID == "" {
		return
	}
	stage := transferControlAbortStage(req.Stage)
	runtime.ensureTransferDescriptor(direction, runtimeScope, publicScope, transportGeneration, itransfer.Descriptor{
		ID:      req.TransferID,
		Channel: itransfer.DataChannel,
	})
	runtime.recordStage(direction, runtimeScope, req.TransferID, stage)
	runtime.recordFailureStage(direction, runtimeScope, req.TransferID, stage)
	runtime.abort(direction, runtimeScope, req.TransferID, transferControlAbortError(req.Error))
}

func transferControlFinishAbort(runtime *transferRuntime, direction fileTransferDirection, runtimeScope string, transferID string, req TransferAbortRequest, resp TransferAbortResponse, err error) {
	if runtime == nil {
		return
	}
	transferID = transferControlTransferID(transferID, resp.TransferID)
	if transferID == "" {
		return
	}
	if err == nil {
		return
	}
	stage := transferControlAbortStage(req.Stage)
	runtime.recordStage(direction, runtimeScope, transferID, stage)
	runtime.recordFailureStage(direction, runtimeScope, transferID, stage)
	runtime.abort(direction, runtimeScope, transferID, err)
}

func transferControlAbortStage(stage string) string {
	if stage == "" {
		return "abort"
	}
	return stage
}

func transferControlAbortError(message string) error {
	if message == "" {
		return nil
	}
	return errors.New(message)
}

func transferControlTransferID(primary string, fallback string) string {
	if primary != "" {
		return primary
	}
	return fallback
}

func transferControlOffset(offset int64) int64 {
	if offset < 0 {
		return 0
	}
	return offset
}