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

package app

import (
	"bufio"
	"context"
	"encoding/json"
	"io"
	"log/slog"
	"os"
	"os/exec"
	"sync"
	"time"

	"git.stormux.org/storm/cthulhu/internal/platform/session"
	"git.stormux.org/storm/cthulhu/internal/speechhistoryui"
)

const speechHistoryWindowTitle = "Speech History - Cthulhu"

type speechHistoryWindows struct {
	logger  *slog.Logger
	history *speechHistory
	speech  speechEnqueuer
	gate    *focusGate
	open    chan struct{}
	refresh chan struct{}
	toggle  chan struct{}
	done    chan struct{}
	cancel  context.CancelFunc
	once    sync.Once
}

func newSpeechHistoryWindows(logger *slog.Logger, history *speechHistory, speech speechEnqueuer, gate *focusGate) *speechHistoryWindows {
	return &speechHistoryWindows{logger: logger, history: history, speech: speech, gate: gate,
		open: make(chan struct{}, 1), refresh: make(chan struct{}, 1), toggle: make(chan struct{}, 1), done: make(chan struct{})}
}
func (w *speechHistoryWindows) Refresh() {
	select {
	case w.refresh <- struct{}{}:
	default:
	}
}
func (w *speechHistoryWindows) Open() {
	select {
	case w.open <- struct{}{}:
	default:
	}
}
func (w *speechHistoryWindows) ToggleMonitor() {
	select {
	case w.toggle <- struct{}{}:
	default:
	}
}
func (w *speechHistoryWindows) Start(ctx context.Context) error {
	ctx, w.cancel = context.WithCancel(ctx)
	go w.run(ctx)
	return nil
}
func (w *speechHistoryWindows) Stop(ctx context.Context) error {
	w.once.Do(func() {
		if w.cancel != nil {
			w.cancel()
		}
	})
	select {
	case <-w.done:
		return nil
	case <-ctx.Done():
		return ctx.Err()
	}
}
func (w *speechHistoryWindows) announce(text string) {
	if w.gate != nil && (w.gate.Locked() || w.gate.Suspended()) {
		return
	}
	w.speech.Enqueue(speechRequest{Text: text, Role: "system", Cause: "speech-history"})
}
func (w *speechHistoryWindows) run(ctx context.Context) {
	defer close(w.done)
	var historyUpdates, monitorUpdates chan speechhistoryui.Message
	var historyDone, monitorDone chan struct{}
	var stopHistory, stopMonitor context.CancelFunc
	defer func() {
		if stopHistory != nil {
			stopHistory()
		}
		if stopMonitor != nil {
			stopMonitor()
		}
		if historyDone != nil {
			<-historyDone
		}
		if monitorDone != nil {
			<-monitorDone
		}
		w.history.setPaused(false)
		w.history.setMonitor(nil)
	}()
	for {
		select {
		case <-ctx.Done():
			return
		case <-w.open:
			if historyUpdates != nil {
				select {
				case historyUpdates <- speechhistoryui.Message{Present: true}:
				default:
				}
				continue
			}
			childCtx, cancel := context.WithCancel(ctx)
			stopHistory = cancel
			historyUpdates = make(chan speechhistoryui.Message, 4)
			historyDone = make(chan struct{})
			w.history.setPaused(true)
			go func() {
				defer close(historyDone)
				if err := w.window(childCtx, "history", historyUpdates, nil); err != nil && childCtx.Err() == nil {
					w.logger.Error("speech history window", "error", err)
				}
			}()
		case <-w.refresh:
			if historyUpdates != nil {
				update := speechhistoryui.Message{Items: append([]string{}, w.history.snapshot()...)}
				select {
				case historyUpdates <- update:
				case <-ctx.Done():
					return
				}
			}
		case <-historyDone:
			historyUpdates, historyDone = nil, nil
			stopHistory = nil
			w.history.setPaused(false)
		case <-w.toggle:
			if monitorUpdates != nil {
				stopMonitor()
				w.announce("Speech monitor disabled.")
				continue
			}
			childCtx, cancel := context.WithCancel(ctx)
			stopMonitor = cancel
			monitorUpdates = make(chan speechhistoryui.Message, 128)
			monitorDone = make(chan struct{})
			stream := make(chan string, 128)
			w.history.setMonitor(stream)
			go func() {
				defer close(monitorDone)
				if err := w.window(childCtx, "monitor", monitorUpdates, stream); err != nil && childCtx.Err() == nil {
					w.logger.Error("speech monitor window", "error", err)
				}
			}()
			w.announce("Speech monitor enabled.")
		case <-monitorDone:
			monitorUpdates, monitorDone = nil, nil
			stopMonitor = nil
			w.history.setMonitor(nil)
		}
	}
}

func (w *speechHistoryWindows) window(ctx context.Context, mode string, updates <-chan speechhistoryui.Message, stream <-chan string) error {
	executable, err := os.Executable()
	if err != nil {
		return err
	}
	childCtx, stop := context.WithCancel(ctx)
	defer stop()
	command := exec.CommandContext(childCtx, executable, "--speech-history-ui")
	command.Env = session.GTKEnvironment()
	command.WaitDelay = time.Second
	in, err := command.StdinPipe()
	if err != nil {
		return err
	}
	out, err := command.StdoutPipe()
	if err != nil {
		in.Close()
		return err
	}
	command.Stderr = os.Stderr
	if err := command.Start(); err != nil {
		in.Close()
		out.Close()
		return err
	}
	defer func() { stop(); in.Close(); out.Close(); _ = command.Wait() }()
	encoder := json.NewEncoder(in)
	initial := speechhistoryui.Message{Mode: mode}
	if mode == "history" {
		initial.Items = append([]string{}, w.history.snapshot()...)
	}
	if err := encoder.Encode(initial); err != nil {
		return err
	}
	requests := make(chan speechhistoryui.Request, 1)
	readDone := make(chan error, 1)
	go func() {
		scanner := bufio.NewScanner(out)
		scanner.Buffer(make([]byte, 4096), 1024*1024)
		for scanner.Scan() {
			var request speechhistoryui.Request
			if err := json.Unmarshal(scanner.Bytes(), &request); err != nil {
				readDone <- err
				return
			}
			select {
			case requests <- request:
			case <-childCtx.Done():
				return
			}
		}
		readDone <- scanner.Err()
	}()
	for {
		select {
		case <-ctx.Done():
			return ctx.Err()
		case err := <-readDone:
			if err == nil || err == io.EOF {
				return nil
			}
			return err
		case update := <-updates:
			if err := encoder.Encode(update); err != nil {
				return err
			}
		case text := <-stream:
			if text != "" {
				if err := encoder.Encode(speechhistoryui.Message{Append: text}); err != nil {
					return err
				}
			}
		case request := <-requests:
			switch request.Action {
			case "copy":
				w.announce("Copied to clipboard.")
			case "empty":
				w.announce("No speech history item selected.")
			case "remove":
				if request.Selection == "" {
					w.announce("No speech history item selected.")
					break
				}
				if w.history.remove(request.Selection) {
					w.announce("Removed from history.")
				} else {
					w.announce("Item not found in history.")
				}
				if err := encoder.Encode(speechhistoryui.Message{Items: append([]string{}, w.history.snapshot()...), Selected: 0}); err != nil {
					return err
				}
			}
		}
	}
}