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

package app

import (
	"context"
	"errors"
	"fmt"

	"git.stormux.org/storm/cthulhu/internal/atspi"
	"git.stormux.org/storm/cthulhu/internal/config"
	"git.stormux.org/storm/cthulhu/internal/input"
	"git.stormux.org/storm/cthulhu/internal/messaging"
)

type messageCopyRequest struct {
	ctx    context.Context
	serial uint64
	text   string
}

type messageCopyResult struct {
	messageCopyRequest
	err error
}

// messagingController belongs to the accessibility event loop. Histories survive
// focus changes, retire with their native window/transcript, and clear on lock.
// Its one clipboard worker has a bounded queue and never performs native queries.
type messagingController struct {
	history messaging.History
	speech  speechEnqueuer
	braille interface {
		Flash(string, config.BrailleOptions) bool
	}
	live         *liveSettings
	gate         *focusGate
	ctx          context.Context
	cancelWorker context.CancelFunc
	cancelCopy   context.CancelFunc
	serial       uint64
	requests     chan messageCopyRequest
	results      chan messageCopyResult
	done         chan struct{}
}

func newMessagingController(ctx context.Context, speech speechEnqueuer, gate *focusGate, live *liveSettings, write func(context.Context, string) error) *messagingController {
	ctx, cancelWorker := context.WithCancel(ctx)
	controller := &messagingController{ctx: ctx, cancelWorker: cancelWorker, speech: speech, gate: gate, live: live,
		requests: make(chan messageCopyRequest, 1), results: make(chan messageCopyResult, 1), done: make(chan struct{})}
	go func() {
		defer close(controller.done)
		for {
			select {
			case <-ctx.Done():
				return
			case request := <-controller.requests:
				if request.ctx.Err() != nil || gate.Locked() {
					continue
				}
				err := write(request.ctx, request.text)
				if errors.Is(request.ctx.Err(), context.Canceled) {
					continue
				}
				select {
				case controller.results <- messageCopyResult{request, err}:
				case <-ctx.Done():
					return
				}
			}
		}
	}()
	return controller
}

func (controller *messagingController) handle(event atspi.Event) bool {
	if controller == nil {
		return false
	}
	if event.Type == atspi.WindowDestroyedEvent || event.Type == atspi.DefunctStateEvent && event.Detail1 != 0 {
		id := event.Source.ID()
		if event.Type == atspi.WindowDestroyedEvent && event.Window.Valid() {
			id = event.Window
		}
		controller.history.Retire(id.BusName, id.Path)
	}
	message := event.ChatMessage
	if message == nil || event.Type != atspi.TextInsertedEvent || event.Source.ApplicationProcess != "pidgin" ||
		event.Source.Defunct || event.Source.Role != "text" ||
		message.Provider != event.Source.BusName || message.Conversation != event.Source.Path ||
		!event.Source.ID().Valid() || event.Window != atspi.NewObjectID(message.Provider, message.Window) {
		return false
	}
	if !controller.gate.Locked() && controller.history.Add(*message) {
		stored, _ := controller.history.Previous(message.Provider, 0)
		controller.present(stored.Text, true)
	}
	return true
}

func (controller *messagingController) present(text string, background bool) {
	if controller.gate.Locked() {
		return
	}
	if controller.braille != nil {
		options := config.DefaultSettings().Braille
		if controller.live != nil {
			options = controller.live.Load().Braille
		}
		controller.braille.Flash(text, options)
	}
	// The controller owns the flash; avoid a duplicate system-message flash.
	controller.speech.Enqueue(speechRequest{Text: text, Role: "notification", Cause: "chat-message", BypassFocusGate: background})
}

func (controller *messagingController) review(command input.Command, current atspi.Snapshot) {
	index, copyMessage, ok := input.MessageCommandIndex(command)
	if !ok || controller.gate.Locked() || controller.gate.Suspended() || current.ApplicationProcess != "pidgin" {
		return
	}
	message, exists := controller.history.Previous(current.BusName, index)
	if !exists {
		return
	} // Legacy leaves empty history slots silent.
	if !copyMessage {
		controller.present(message.Text, false)
		return
	}
	controller.cancelCopyRequest()
	copyCtx, cancel := context.WithTimeout(controller.ctx, clipboardReadTimeout)
	controller.cancelCopy = cancel
	request := messageCopyRequest{ctx: copyCtx, serial: controller.serial, text: message.Text}
	// Only the event loop produces requests. Replace an obsolete queued copy
	// rather than dropping the newest command while the worker cancels a write.
	select {
	case <-controller.requests:
	default:
	}
	select {
	case controller.requests <- request:
	default:
		cancel()
	}
}

func (controller *messagingController) copied(result messageCopyResult) {
	if result.serial != controller.serial || errors.Is(result.ctx.Err(), context.Canceled) || controller.gate.Locked() || controller.gate.Suspended() {
		return
	}
	text := fmt.Sprintf("Copied %s to clipboard.", result.text)
	if result.err != nil {
		text = "Error accessing clipboard"
	}
	controller.present(text, false)
	controller.cancelCopyRequest()
}

func (controller *messagingController) cancelCopyRequest() {
	controller.serial++
	if controller.cancelCopy != nil {
		controller.cancelCopy()
		controller.cancelCopy = nil
	}
}

func (controller *messagingController) reset() {
	controller.cancelCopyRequest()
	controller.history.Reset()
}

func (controller *messagingController) stop() {
	controller.reset()
	controller.cancelWorker()
	<-controller.done
}