package niri

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strconv"

	"git.tordarus.net/tordarus/slices"
	"github.com/adrg/xdg"
)

var niriSocketFilenameFormat = "niri.wayland-%d.%d.sock"
var niriSocketFilenamePattern = regexp.MustCompile(`^niri\.wayland-(\d+?)\.(\d+?)\.sock$`)

type Client struct {
	display int
	pid     int
}

var ErrClientNotFound = errors.New("client not found")

func GetClientByPID(pid int) (*Client, error) {
	clients, err := GetAllClients()
	if err != nil {
		return nil, err
	}

	for _, c := range clients {
		if c.pid == pid {
			return c, nil
		}
	}

	return nil, ErrClientNotFound
}

func GetClientByDisplay(display int) (*Client, error) {
	clients, err := GetAllClients()
	if err != nil {
		return nil, err
	}

	for _, c := range clients {
		if c.display == display {
			return c, nil
		}
	}

	return nil, ErrClientNotFound
}

func GetDefaultClient() (*Client, error) {
	if niriSocket, ok := os.LookupEnv("NIRI_SOCKET"); ok {
		return GetClientBySocketPath(niriSocket)
	}

	if display, ok := os.LookupEnv("WAYLAND_DISPLAY"); ok {
		displayInt, err := strconv.Atoi(display)
		if err != nil {
			return nil, err
		}

		return GetClientByDisplay(displayInt)
	}

	return nil, ErrClientNotFound
}

func GetAllClients() ([]*Client, error) {
	runtimeDir := xdg.RuntimeDir

	entries, err := os.ReadDir(runtimeDir)
	if err != nil {
		return nil, err
	}

	return slices.Filter(slices.Map(entries, parseEntryAsClient), notNull), nil
}

func GetClientBySocketPath(socketPath string) (*Client, error) {
	baseName := filepath.Base(socketPath)

	matches := niriSocketFilenamePattern.FindStringSubmatch(baseName)
	if matches == nil {
		return nil, errors.New("invalid niri socket path")
	}

	display, err := strconv.Atoi(matches[1])
	if err != nil {
		return nil, err
	}

	pid, err := strconv.Atoi(matches[2])
	if err != nil {
		return nil, err
	}

	return &Client{
		display: display,
		pid:     pid,
	}, nil
}

func (c Client) GetSocketPath() string {
	return filepath.Join(xdg.RuntimeDir, fmt.Sprintf(niriSocketFilenameFormat, c.display, c.pid))
}