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

package app

import (
	"context"
	"errors"
	"sync"
	"time"

	"git.stormux.org/storm/cthulhu/internal/config"
	"git.stormux.org/storm/cthulhu/internal/speech"
)

// remoteSpeechVoice owns a separate SSIP speaking/control pair. Its cancellation
// cannot target local speech, echo or status. This is a backend prerequisite,
// not a Remote lease authorizer or a production mailbox owner.
type remoteSpeechVoice struct {
	client       *speech.Client
	ctx          context.Context
	cancel       context.CancelFunc
	once         sync.Once
	closed       chan struct{}
	closeErr     error
	render       sync.Mutex // One typed assembly, including metadata I/O.
	request      sync.Mutex
	renderCancel context.CancelFunc // Protected by request; never backend I/O.
}

// open_remote_voice is called only by an output worker, never an input callback.
// Acquisition neither changes the local configuration nor opens a serial device.
// There is at most one handle; a replacement requires its predecessor to close.
// ctx bounds acquisition only. A future lease owner must Close on revocation.
func (speaker *configuredSpeaker) open_remote_voice(ctx context.Context) (*remoteSpeechVoice, error) {
	if !speaker.update.TryLock() {
		return nil, errors.New("speech configuration is busy")
	}
	defer speaker.update.Unlock()
	if err := ctx.Err(); err != nil {
		return nil, err
	}
	speaker.mu.RLock()
	_, software := speaker.active.(*echoSpeaker)
	closed, previous := speaker.closed, speaker.remote
	settings := speechSettingsFromConfig(speaker.settings)
	speaker.mu.RUnlock()
	if closed || !software {
		return nil, errors.New("isolated Remote speech requires a connected software backend")
	}
	if previous != nil {
		select {
		case <-previous.closed:
		default:
			return nil, errors.New("Remote speech voice is already owned")
		}
	}
	client := speech.NewWithSettings(speaker.socket, settings)
	if err := client.Connect(ctx); err != nil {
		return nil, err
	}
	if err := client.SetBackgroundPriority(ctx); err != nil {
		_ = client.Close(context.Background())
		return nil, err
	}
	if err := ctx.Err(); err != nil {
		_ = client.Close(context.Background())
		return nil, err
	}
	lifetime, cancel := context.WithCancel(context.Background())
	voice := &remoteSpeechVoice{client: client, ctx: lifetime, cancel: cancel, closed: make(chan struct{})}
	speaker.mu.Lock()
	speaker.remote = voice
	speaker.mu.Unlock()
	return voice, nil
}

// A successful configuration commit retires the old remote voice. A failed
// preparation must leave it usable. Handles never silently adopt new settings.
func (speaker *configuredSpeaker) retire_remote_voice(settings config.Settings) {
	speaker.mu.Lock()
	speaker.settings = settings
	remote := speaker.remote
	speaker.mu.Unlock()
	if remote != nil {
		cleanup, cancel := context.WithTimeout(context.Background(), 2*time.Second)
		defer cancel()
		// The local configuration has committed; cleanup cannot undo that commit.
		_ = remote.Close(cleanup)
	}
}

// SpeakAndWait retains ownership through the backend's END/CANCEL notification.
// Both caller cancellation and configuration retirement cancel only this client.
// This plain-text primitive deliberately does not interpret relay metadata.
func (voice *remoteSpeechVoice) SpeakAndWait(ctx context.Context, text string, began func()) error {
	if err := voice.ctx.Err(); err != nil {
		return err
	}
	request, cancel := context.WithCancel(voice.ctx)
	stop := context.AfterFunc(ctx, cancel)
	defer func() { stop(); cancel() }()
	if err := ctx.Err(); err != nil {
		return err
	}
	return voice.client.SpeakAndWait(request, text, began)
}

func (voice *remoteSpeechVoice) Cancel(ctx context.Context) error {
	voice.request.Lock()
	cancel := voice.renderCancel
	if cancel != nil {
		cancel()
	}
	voice.request.Unlock()
	if cancel != nil {
		// Typed cancellation retires the whole assembly even while it is
		// preparing metadata and has no SSIP message to cancel yet.
		return nil
	}
	if voice.ctx.Err() != nil {
		return nil
	}
	return voice.client.Cancel(ctx)
}

func (voice *remoteSpeechVoice) Close(ctx context.Context) error {
	voice.once.Do(func() {
		voice.cancel()
		voice.closeErr = errors.Join(voice.client.Cancel(ctx), voice.client.Close(ctx))
		close(voice.closed)
	})
	return voice.closeErr
}