package main

import (
	"context"
	"errors"
	"fmt"
	_ "image/jpeg"
	_ "image/png"
	"log"
	"log/slog"
	"os"
	"os/signal"
	"slices"
	"strconv"
	"strings"
	"time"
	"unicode"

	"github.com/spf13/pflag"
	_ "golang.org/x/image/webp"
	"golang.org/x/sys/unix"

	"git.sr.ht/~guacamolie/faxmachine/config"
	"git.sr.ht/~guacamolie/faxmachine/escpos"
	"git.sr.ht/~guacamolie/faxmachine/escpos/protocol"
	"git.sr.ht/~guacamolie/faxmachine/keyboard"
	"git.sr.ht/~guacamolie/faxmachine/matrix"
	"git.sr.ht/~guacamolie/faxmachine/ntfy"
	"git.sr.ht/~guacamolie/faxmachine/printjob"
)

func main() {
	configPath := pflag.String("config", "", "Use alternative config file location")
	pflag.Parse()

	matrixSlogHandler := matrix.NewSlogHandler(nil)

	logger := slog.New(slogMultiHandler{
		slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
			Level: slog.LevelDebug,
		}),
		matrixSlogHandler,
	})

	conf := config.Load(*configPath)

	logger.Info("program init",
		slog.Group("conf",
			slog.Group("devices",
				slog.String("printer", conf.Devices.Printer),
				slog.String("keyboard", conf.Devices.Keyboard),
			),
			slog.Group("ntfy",
				slog.String("host", conf.Ntfy.Host),
			),
			slog.Group("matrix",
				slog.String("user", conf.Matrix.UserID),
				slog.String("admin_room", conf.Matrix.AdminRoom),
			),
		),
	)

	var kb *keyboard.Keyboard
	if conf.Devices.Keyboard != "" {
		var err error
		kb, err = keyboard.Open(conf.Devices.Keyboard)
		if err != nil {
			log.Fatalf("failed to open keyboard: %v", err)
		}
	}

	ntfyInstance := ntfy.NewInstance(conf.Ntfy, logger.WithGroup("ntfy"))
	matrixInstance, err := matrix.NewBot(context.Background(),
		conf.Matrix, logger.WithGroup("matrix"))
	if err != nil {
		log.Fatalf("failed to connect to Matrix: %v", err)
	}

	matrixSlogHandler.Attach(matrixInstance)

	daemon := &printDaemon{
		lp:       conf.Devices.Printer,
		ntfy:     ntfyInstance,
		matrix:   matrixInstance,
		keyboard: kb,
	}

	daemon.run(context.Background())
}

type printDaemon struct {
	lp       string
	ntfy     *ntfy.Instance
	matrix   *matrix.Bot
	keyboard *keyboard.Keyboard

	history []printjob.Job
}

func (d *printDaemon) run(ctx context.Context) {
	queue := make(chan printjob.Job, 10)
	inputCh := make(chan keyboard.KeyPress)

	if err := d.ntfy.Subscribe(ctx, queue); err != nil {
		log.Fatalf("failed to subscribe to ntfy: %v\n", err)
	}
	d.matrix.Subscribe(ctx, queue)

	if d.keyboard != nil {
		d.keyboard.Listen(ctx, inputCh)
	}

	sighubCh := make(chan os.Signal, 1)
	signal.Notify(sighubCh, unix.SIGHUP)

	for {
		if err := d.handlePrintJobs(ctx, queue, inputCh); err != nil {
			log.Println(err)
		}

		log.Println("waiting for SIGHUB to retry...")
		<-sighubCh
	}
}

func (d *printDaemon) handlePrintJobs(ctx context.Context,
	queue <-chan printjob.Job, inputCh <-chan keyboard.KeyPress) error {

	defer d.matrix.BecomeUnavailable(ctx)

	p, err := escpos.StartUSBPrinter(d.lp, protocol.TMT88IV, escpos.FlagNone)
	if err != nil {
		return fmt.Errorf("failed to connect to printer: %w", err)
	}
	defer p.Close()

	d.matrix.BecomeOnline(ctx)

	if err := p.EnableASB(protocol.ASBReportAll); err != nil {
		return fmt.Errorf("failed to enable ASB: %w", err)
	}

	disconnected := make(chan bool, 1)
	go func() {
		for status := range p.ASBStatus() {
			log.Printf("received ASB status: %#v\n", status)
		}
		disconnected <- true
	}()

	for {
		select {
		case job := <-queue:
			if err := p.SetPrintSpeed(5); err != nil {
				return fmt.Errorf("failed to set print speed: %w", err)
			}

			if err := handleJob(ctx, p, job); err != nil {
				var ioerr *escpos.IOError
				if errors.As(err, &ioerr) {
					return fmt.Errorf("fatal print failure: %v", err)
				}
				log.Printf("print failure: %v", err)
			}

			d.history = append(d.history, job)
			if len(d.history) > 100 {
				d.history = d.history[1:]
			}

		case inputEvent := <-inputCh:
			if name, ok := inputEvent.Sym.Name(); !ok || name != "r" {
				continue
			}

			if err := p.SetPrintSpeed(0); err != nil {
				return fmt.Errorf("failed to set print speed: %w", err)
			}

			handleInteractiveReply(ctx, p, d.history, inputCh)

		case <-disconnected:
			return fmt.Errorf("printer disconnected")
		}
	}
}

func handleInteractiveReply(ctx context.Context,
	p *escpos.Printer, history []printjob.Job,
	inputCh <-chan keyboard.KeyPress) {
	fmt.Fprintf(p, "CHOOSE MESSAGE FOR REPLY:\n")

	replyOptions := []printjob.JobReplyer{}
	for i := len(history) - 1; i >= 0; i-- {
		if job, ok := history[i].(printjob.JobReplyer); ok {
			replyOptions = append(replyOptions, job)
		}
		if len(replyOptions) >= 9 {
			break
		}
	}

	for i := len(replyOptions) - 1; i >= 0; i-- {
		option := replyOptions[i]

		description := option.Description()
		description = strings.ReplaceAll(description, "\r", "")
		description = strings.ReplaceAll(description, "\n", " ")

		fmt.Fprintf(p, "\n")
		fmt.Fprintf(p, " %d. \"%.36s\"\n", i+1, description)
		fmt.Fprintf(p, "     sent %s ago by %s\n",
			time.Since(option.Time()).Round(time.Second),
			option.Sender())
	}

	scrollUp(p)

	var chosenJob printjob.JobReplyer
	for inputEvent := range inputCh {
		if name, ok := inputEvent.Sym.Name(); ok && name == "Escape" {
			fmt.Fprintf(p, "REPLY ABORTED\n\n\n")
			p.CutPaper()
			return
		}

		num, err := strconv.Atoi(inputEvent.Char)
		if err != nil {
			continue
		}
		if num-1 >= len(replyOptions) {
			continue
		}

		fmt.Fprintf(p, "REPLYING TO MESSAGE %d\n\n", num)
		chosenJob = replyOptions[num-1]
		break
	}

	fmt.Fprintf(p, "ENTER REPLY:\n")
	scrollUp(p)

	var buffer textBuffer

	for inputEvent := range inputCh {
		mods := inputEvent.ShortcutMods
		key, _ := inputEvent.Sym.Name()

		if mods == 0 && key == "Escape" {
			fmt.Fprintf(p, "REPLY ABORTED\n\n\n")
			p.CutPaper()
			return
		}

		if mods == 0 && key == "Return" {
			break
		}

		switch {
		case mods == 0 && key == "Tab":
			fmt.Fprintf(p, "%s\n", buffer.preview())
			scrollUp(p)

		case mods == 0 && key == "Delete":
			buffer.reset()

		case mods == 0 && key == "BackSpace":
			buffer.backspace()

		case mods == 0 && key == "Left":
			buffer.moveCursor(-1)

		case mods == 0 && key == "Right":
			buffer.moveCursor(+1)

		case mods == keyboard.Control && key == "w":
			buffer.removeWord()

		case mods == 0 && inputEvent.Char != "":
			buffer.typeChar(inputEvent.Char)
		}
	}

	if err := chosenJob.Reply(ctx, buffer.String()); err != nil {
		fmt.Fprintf(p, "failed to reply: %v\n\n\n", err)
		p.CutPaper()
		return
	}

	fmt.Fprintf(p, "REPLY SENT\n\n\n")
	p.CutPaper()
}

type textBuffer struct {
	// We store each entered key seperately here. This allows us to the same
	// amount of text that was entered when pressing backspace. It's a bit of a
	// hack, but it means I don't have to figure out the (complex) rules as to
	// what exactly should happen when you press backspace.
	buffer []string
	cursor int
}

func (tb *textBuffer) reset() {
	*tb = textBuffer{}
}

func (tb *textBuffer) typeChar(c string) {
	tb.buffer = slices.Insert(tb.buffer, tb.cursor, c)
	tb.cursor++
}

func (tb *textBuffer) backspace() {
	if tb.cursor > 0 {
		tb.buffer = slices.Delete(tb.buffer, tb.cursor-1, tb.cursor)
		tb.cursor--
	}
}

// removeWord implements deletion of a word using the conventional
// "unix-word-rubout" method. It first deletes spaces until it can find a
// non-space character, and then deletes non-space characters until it reaches
// a space again.
func (tb *textBuffer) removeWord() {
	hasSpace := func(s string) bool {
		return strings.IndexFunc(s, unicode.IsSpace) != -1
	}

	for tb.cursor > 0 {
		if hasSpace(tb.buffer[tb.cursor-1]) {
			tb.backspace()
		} else {
			break
		}
	}

	for tb.cursor > 0 {
		if !hasSpace(tb.buffer[tb.cursor-1]) {
			tb.backspace()
		} else {
			break
		}
	}
}

func (tb *textBuffer) moveCursor(movement int) {
	tb.cursor = max(min(tb.cursor+movement, len(tb.buffer)), 0)
}

func (tb *textBuffer) preview() string {
	var builder strings.Builder

	for _, s := range tb.buffer[:tb.cursor] {
		builder.WriteString(s)
	}
	builder.WriteString("▒")
	for _, s := range tb.buffer[tb.cursor:] {
		builder.WriteString(s)
	}

	return builder.String()
}

func (tb *textBuffer) String() string {
	var builder strings.Builder

	for _, s := range tb.buffer {
		builder.WriteString(s)
	}

	return builder.String()
}

func scrollUp(p *escpos.Printer) {
	fmt.Fprintf(p, "\n\n\n\n\n\n\n\n")
}

func handleJob(ctx context.Context, p *escpos.Printer, job printjob.Job) (err error) {
	defer func() {
		if err == nil {
			job.OnPrinted(ctx)
		} else {
			job.OnShredded(ctx, err)
		}
	}()

	if err := job.Print(ctx, p); err != nil {
		return err
	}

	fmt.Fprint(p, "\n\n\n")

	if err := p.CutPaper(); err != nil {
		return fmt.Errorf("failed to cut paper: %w", err)
	}

	if err := p.Wait(); err != nil {
		return fmt.Errorf("failed to print: %w", err)
	}

	return nil
}