// Cthulhu screen reader.
// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.

package app

import (
	"context"
	"log/slog"

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

func processInputEvents(
	ctx context.Context,
	logger *slog.Logger,
	speech speechEnqueuer,
	listener InputListener,
	echoSettings input.EchoSettings,
	live *liveSettings,
	commands commandListener,
	ocrSessions ...*ocrSession,
) {
	echo := newKeyEchoPolicy(echoSettings)
	var lastOverflow uint64
	for {
		select {
		case <-ctx.Done():
			return
		case event, ok := <-listener.Events():
			if !ok {
				return
			}
			if guarded, ok := speech.(gatedSpeech); ok && guarded.gate.Locked() {
				echo.Reset()
				continue
			}
			if modal, ok := commands.(interface{ InternalUIEchoActive() bool }); ok && modal.InternalUIEchoActive() {
				echo.Reset()
				continue
			}
			if learner, ok := commands.(interface{ LearnModeEchoActive() bool }); ok && learner.LearnModeEchoActive() {
				echo.Reset()
				continue
			}
			if overflow := listener.Overflow(); overflow > lastOverflow {
				logger.Warn("X11 event queue overflow", "dropped_events", overflow-lastOverflow)
				lastOverflow = overflow
				echo.Reset()
			}
			if len(ocrSessions) > 0 {
				ocrSessions[0].Input(event)
			}
			if input.ShouldInterruptSpeech(event) {
				if interrupt, ok := speech.(interface{ InterruptForInput(input.Event) bool }); ok {
					if !interrupt.InterruptForInput(event) {
						continue
					}
				} else if interrupt, ok := speech.(interface{ InterruptForUser() }); ok {
					interrupt.InterruptForUser()
				} else {
					speech.Interrupt()
				}
				logger.Debug("queued speech interrupted by key press", "input_timestamp", event.Timestamp,
					"input_keycode", event.Keycode, "input_repeat", event.Repeat)
			}
			custom := false
			if live != nil {
				settings := live.Load()
				echo.settings = inputEchoSettingsFromConfig(settings)
				custom = customEcho(settings, "key")
			}
			if text := echo.Text(event); text != "" {
				speech.Enqueue(speechRequest{Text: text, Role: "key", Cause: "key-echo", CustomEcho: custom})
				logger.Debug("queued non-printable key echo", "kind", event.Kind)
			}
		}
	}
}

type keyEchoPolicy struct {
	settings         input.EchoSettings
	cthulhuModifiers map[string]struct{}
	heldCthulhuKeys  [256]bool
}

func newKeyEchoPolicy(settings input.EchoSettings) *keyEchoPolicy {
	modifiers := make(map[string]struct{}, len(settings.CthulhuModifierKeys))
	for _, name := range settings.CthulhuModifierKeys {
		modifiers[name] = struct{}{}
	}
	return &keyEchoPolicy{settings: settings, cthulhuModifiers: modifiers}
}

func (policy *keyEchoPolicy) Text(event input.Event) string {
	if _, isCthulhuModifier := policy.cthulhuModifiers[event.Name]; isCthulhuModifier {
		policy.heldCthulhuKeys[event.Keycode] = event.Pressed
		return ""
	}
	for _, held := range policy.heldCthulhuKeys {
		if held {
			return ""
		}
	}
	return input.EchoText(event, policy.settings)
}

func (policy *keyEchoPolicy) Reset() {
	clear(policy.heldCthulhuKeys[:])
}