// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package tentacle

import (
	"context"
	"encoding/json"

	"git.stormux.org/storm/cthulhu/internal/tentaclewire"
)

// RemoteBrailleDelivery is admitted Braille work for the reader's owner.
// The owner must recheck Context and RemoteContext(braille-stream) and its own
// display policy before any effect. Role is the lease's core-assigned role.
type RemoteBrailleDelivery struct {
	Context  context.Context
	Lease    tentaclewire.RemoteLease
	Role     string
	Sequence uint64
	Braille  tentaclewire.RemoteBraille
}

// EnableRemoteBraille attaches one reader-owned Braille mailbox. It performs
// no display setup and grants no authority.
func (session *Session) EnableRemoteBraille() <-chan RemoteBrailleDelivery {
	session.mutex.Lock()
	defer session.mutex.Unlock()
	if session.remoteBraille == nil {
		session.remoteBraille = make(chan RemoteBrailleDelivery, tentaclewire.RemoteBrailleQueueSize)
	}
	return session.remoteBraille
}

func (session *Session) remote_braille_locked(params json.RawMessage) (any, *RPCError) {
	var request tentaclewire.RemoteBrailleRequest
	if decode_strict(params, &request) != nil {
		return nil, &RPCError{Code: -32602, Message: "Invalid session parameters"}
	}
	lease := tentaclewire.RemoteLease{Lease: request.Lease, Epoch: request.Epoch}
	access := session.remote_access_locked(lease, "braille-stream")
	if access == nil || request.Sequence <= access.sequence || !tentaclewire.ValidRemoteBrailleFor(access.role, true, request.Braille) {
		return nil, &RPCError{Code: -32001, Message: "Session permission denied"}
	}
	if session.remoteBraille == nil {
		return nil, &RPCError{Code: -32601, Message: "Remote Braille owner unavailable"}
	}
	access.sequence = request.Sequence
	select {
	case session.remoteBraille <- RemoteBrailleDelivery{Context: access.ctx, Lease: lease, Role: access.role, Sequence: request.Sequence, Braille: request.Braille}:
		return struct{}{}, nil
	default:
		session.revoke_remote_locked("local", true)
		return nil, &RPCError{Code: -32002, Message: "Remote Braille queue full"}
	}
}

// PublishRemoteBraille sends one Braille operation to the child. The owner
// supplies only rendered cells (controlled), local geometry or local display
// gestures (controller); never text, routing identities or native handles.
func (session *Session) PublishRemoteBraille(lease tentaclewire.RemoteLease, value tentaclewire.RemoteBraille) error {
	session.mutex.Lock()
	defer session.mutex.Unlock()
	access := session.remote_access_locked(lease, "braille-stream")
	if access == nil || !tentaclewire.ValidRemoteBrailleFor(access.role, false, value) {
		return ErrPermission
	}
	value.Cells = append([]int(nil), value.Cells...)
	if len(value.Cells) == 0 {
		value.Cells = nil
	}
	event := tentaclewire.SessionEvent{Kind: "remote.braille", Lease: lease.Lease, Epoch: lease.Epoch, Braille: &value}
	if !session.remote_event_locked(&event) {
		session.fail_locked(ErrLimit)
		return ErrLimit
	}
	return nil
}