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

package app

import (
	"errors"
	"slices"

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

func (owner *tentacleLifecycle) ensureManager() error {
	if owner.manager != nil {
		return nil
	}
	if owner.runtime.input == nil {
		return errors.New("native bindings are unavailable")
	}
	var err error
	owner.manager, err = owner.runtime.makeManager()
	return err
}

func (owner *tentacleLifecycle) revoke(id string) {
	if session := owner.sessions[id]; session != nil {
		session.Disable()
		owner.runtime.output.RetireRevoked()
	}
}

func (owner *tentacleLifecycle) replyStartup(id string, err error) {
	startup, exists := owner.startups[id]
	if !exists {
		return
	}
	delete(owner.startups, id)
	startup.stop()
	if err == nil {
		if startup.previous != nil {
			previous := *startup.previous
			// Starting the replacement already waited for the old session.
			owner.removedPackages[previous.PackageDirectory] = tentacleRetiredPackage{entry: previous}
		}
		err = startup.saveError
	}
	owner.setSnapshot()
	startup.call.result <- err
}

func (owner *tentacleLifecycle) failStartup(id, message string) {
	owner.problems[id] = message
	startup, exists := owner.startups[id]
	if !exists {
		return
	}
	owner.revoke(id)
	if owner.current != nil && owner.current.TentacleID() == id {
		owner.current, owner.ready = nil, nil
	}
	delete(owner.pending, id)
	next := tentacle.CloneEntries(owner.entries)
	for index := range next {
		if next[index].ID == id {
			if startup.previous != nil {
				next[index] = *startup.previous
			} else {
				next[index].Enabled = false
			}
		}
	}
	err := owner.runtime.registry.Save(next)
	if err == nil || errors.Is(err, tentacle.ErrRegistrySync) {
		if startup.previous != nil {
			failed := slices.IndexFunc(owner.entries, func(entry tentacle.Entry) bool { return entry.ID == id })
			if failed >= 0 {
				entry := owner.entries[failed]
				owner.removedPackages[entry.PackageDirectory] = tentacleRetiredPackage{entry: entry, session: owner.sessions[id]}
			}
			owner.runtime.mutex.Lock()
			disabled := owner.runtime.disabled
			owner.runtime.mutex.Unlock()
			owner.pending[id] = startup.previous.Enabled && !disabled && owner.ctx.Err() == nil
			message += " The previous package was restored."
		}
		owner.entries = next
	}
	if err != nil {
		message += " The recovery state could not be saved durably: " + err.Error()
	}
	owner.replyStartup(id, errors.New(message))
}

func (owner *tentacleLifecycle) cancelStartups() {
	for id := range owner.startups {
		owner.failStartup(id, "Tentacle startup was cancelled before activation.")
	}
}

func (owner *tentacleLifecycle) startPending() {
	for _, entry := range owner.entries {
		if !owner.pending[entry.ID] || owner.sessions[entry.ID] != nil {
			continue
		}
		owner.pending[entry.ID] = false
		err := owner.ensureManager()
		var session *tentacle.Session
		if err == nil {
			session, err = owner.manager.Start(owner.ctx, entry.Spec())
		}
		if err != nil {
			owner.failStartup(entry.ID, "Tentacle could not start; check resource containment and its program, then enable it again.")
			owner.runtime.logger.Warn("start configured tentacle", "tentacle", entry.ID, "error", err)
			owner.runtime.report("A tentacle could not start.")
			owner.notify()
			break
		}
		owner.sessions[entry.ID] = session
		owner.runtime.mutex.Lock()
		owner.runtime.sessions = append(owner.runtime.sessions, session)
		if owner.runtime.disabled {
			session.Disable()
		}
		owner.runtime.mutex.Unlock()
		owner.current, owner.ready = session, session.Ready()
		done := make(chan struct{})
		// Prune joined watcher handles so retries never accumulate history.
		owner.watchers = slices.DeleteFunc(owner.watchers, func(done <-chan struct{}) bool {
			select {
			case <-done:
				return true
			default:
				return false
			}
		})
		owner.watchers = append(owner.watchers, done)
		speechDone := owner.runtime.start_remote_speech(owner.ctx, session)
		keysDone := owner.runtime.start_remote_keyboard(owner.ctx, session)
		captureDone := owner.runtime.start_remote_capture(owner.ctx, session)
		brailleDone := owner.runtime.start_remote_braille(owner.ctx, session)
		go func() {
			defer close(done)
			defer func() { <-speechDone; <-keysDone; <-captureDone; <-brailleDone }()
			select {
			case <-session.Revoked():
			case <-owner.ctx.Done():
			}
			owner.runtime.output.RetireRevoked()
			owner.runtime.signal_extensions()
			owner.notify()
			<-session.Done()
			owner.notify()
		}()
		break
	}
}

func (owner *tentacleLifecycle) activateReady() error {
	session := owner.current
	owner.current, owner.ready = nil, nil
	if state, _ := session.Status(); state != tentacle.Ready {
		owner.failStartup(session.TentacleID(), "Tentacle failed during startup; check its program and resource limits, then enable it again.")
		return nil
	}
	if startup, exists := owner.startups[session.TentacleID()]; exists && startup.call.ctx.Err() != nil {
		owner.failStartup(session.TentacleID(), "Tentacle startup was cancelled before activation.")
		return nil
	}
	candidate := append(slices.Clone(owner.active), session)
	if err := owner.runtime.bind(owner.ctx, candidate); err != nil {
		session.Disable()
		owner.runtime.logger.Warn("configured tentacle bindings rejected", "tentacle", session.TentacleID(), "error", err)
		owner.runtime.report("A tentacle could not acquire its keyboard shortcuts.")
		owner.failStartup(session.TentacleID(), "Tentacle could not acquire its keyboard shortcuts; enable it again after resolving the conflict.")
		return nil
	}
	// Native binding setup can wait for held keys. Cancellation during
	// that wait must roll back the new grabs before reporting failure.
	activationError := owner.ctx.Err()
	if startup, exists := owner.startups[session.TentacleID()]; exists && activationError == nil {
		activationError = startup.call.ctx.Err()
	}
	if activationError == nil {
		activationError = session.Activate()
	}
	if activationError != nil {
		session.Disable()
		if err := owner.runtime.bind(owner.ctx, owner.active); err != nil && owner.ctx.Err() == nil {
			select {
			case owner.runtime.failures <- err:
			default:
			}
			return err
		}
		owner.failStartup(session.TentacleID(), "Tentacle stopped before activation; enable it again to retry.")
		return nil
	}
	owner.active = candidate
	delete(owner.problems, session.TentacleID())
	owner.runtime.publishCommands(owner.active)
	owner.replyStartup(session.TentacleID(), nil)
	owner.runtime.logger.Info("configured tentacle active", "tentacle", session.TentacleID(), "session", session.Identity())
	return nil
}