package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	homelabv1 "pwa-homelab-mon/gen/homelab/v1"
	"pwa-homelab-mon/gen/homelab/v1/homelabv1connect"
)

// --- config ---

type Item struct {
	Name     string   `yaml:"name"`
	Script   string   `yaml:"script"`
	Refresh  int      `yaml:"refresh"`   // monitor: seconds
	Args     int      `yaml:"args"`      // exec: arg count
	ArgTypes []string `yaml:"arg_types"` // exec: text | number per arg
}

type Monitor struct {
	Name    string `yaml:"name"`
	Script  string `yaml:"script"`
	Refresh int    `yaml:"refresh"` // seconds
}

type Link struct {
	Name string `yaml:"name"`
	URL  string `yaml:"url"`
}

// --- service ---

type server struct {
	cfg      *Config
	exec     map[string]*Item // by item name, read-only after start
	monVals  sync.Map         // monitor item name -> *monData (last parsed output)
	docsDir  string
	srvDir   string               // dir with *.service units (~/srv on the box)
	probeErr sync.Map             // probe key -> last logged error; poll errors log once per change, not every 3s tick
	mockSvcs []*homelabv1.Service // MOCK=1: static fixtures, buttons mutate them; nil = real probes
}

const execTimeout = 10 * time.Second

// monData — распарсенный вывод скрипта-монитора: первая строка — процент,
// остальные — строки key=value для подписей в карточке.
type monData struct {
	percentage int32 // -1 = скрипт не дал процент
	stats      []*homelabv1.Stat
}

func parseMonitor(out string) *monData {
	d := &monData{percentage: -1}
	lines := strings.Split(strings.TrimSpace(out), "\n")
	if lines[0] == "" {
		return d
	}
	if n, err := strconv.Atoi(strings.TrimSpace(lines[0])); err == nil {
		d.percentage = int32(n)
	}
	for _, l := range lines[1:] {
		if k, v, ok := strings.Cut(strings.TrimSpace(l), "="); ok {
			d.stats = append(d.stats, &homelabv1.Stat{Name: strings.TrimSpace(k), Value: strings.TrimSpace(v)})
		}
	}
	return d
}

func runScript(script string, args ...string) (string, error) {
	ctx, cancel := context.WithTimeout(context.Background(), execTimeout)
	defer cancel()
	out, err := exec.CommandContext(ctx, script, args...).CombinedOutput()
	if err != nil {
		return "", fmt.Errorf("%v: %s", err, out)
	}
	return string(out), nil
}

func (s *server) startMonitors() {
	for i := range s.cfg.Monitor {
		sc := &s.cfg.Monitor[i]
		log.Printf("monitor started: %s (%s) every %ds", sc.Name, sc.Script, sc.Refresh)
		go func(sc *Monitor) {
			for {
				out, err := runScript(sc.Script)
				if err != nil {
					log.Printf("monitor %s: %v", sc.Name, err)
					out = "-\nerror=" + err.Error()
				}
				d := parseMonitor(out)
				log.Printf("monitor %s -> %d%% (%d stats)", sc.Name, d.percentage, len(d.stats))
				s.monVals.Store(sc.Name, d)
				time.Sleep(time.Duration(sc.Refresh) * time.Second)
			}
		}(sc)
	}
}

// --- main ---

func main() {
	cfgPath := os.Getenv("CONFIG")
	if cfgPath == "" {
		cfgPath = "config.yaml"
	}
	cfg, err := loadConfig(cfgPath)
	if err != nil {
		fmt.Fprintln(os.Stderr, "config:", err)
		os.Exit(1)
	}

	docsDir := "docs"
	if err := os.MkdirAll(docsDir, 0o755); err != nil {
		fmt.Fprintln(os.Stderr, "docs:", err)
		os.Exit(1)
	}

	svc := &server{cfg: cfg, exec: map[string]*Item{}, docsDir: docsDir, srvDir: srvDir()}
	if os.Getenv("MOCK") != "" {
		svc.mockSvcs = mockServices()
		log.Print("MOCK mode: services are fixtures, buttons mutate them")
	}
	for i := range cfg.Exec {
		svc.exec[cfg.Exec[i].Name] = &cfg.Exec[i]
	}
	svc.startMonitors()

	log.Printf("config %s: %d links, %d monitors, %d exec; units from %s", cfgPath, len(cfg.Links), len(cfg.Monitor), len(cfg.Exec), svc.srvDir)

	e := echo.New()
	e.HideBanner = true
	// HTTP request log, except the ListContent heartbeat (every 3s per client — pure noise).
	e.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
		Skipper: func(c echo.Context) bool {
			return c.Request().URL.Path == "/homelab.v1.HomelabService/ListContent"
		},
	}))

	// ConnectRPC handler on the mux (matches /homelab.v1.HomelabService/<Method>).
	mux := http.NewServeMux()
	mux.Handle(homelabv1connect.NewHomelabServiceHandler(svc))
	e.Any("/homelab.v1.HomelabService/*", echo.WrapHandler(mux))

	// sw.js and index.html must never be cached: stale index = stale asset references = iOS never updates.
	e.Use(func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) error {
			p := c.Request().URL.Path
			if p == "/sw.js" || p == "/manifest.webmanifest" || p == "/index.html" || p == "/" {
				c.Response().Header().Set("Cache-Control", "no-cache")
			}
			return next(c)
		}
	})

	// Static PWA from dist/ (built by make web); HTML5 mode falls back to index.html for SPA routes.
	e.Use(middleware.StaticWithConfig(middleware.StaticConfig{
		Root:  "dist",
		HTML5: true,
	}))

	e.Logger.Fatal(e.Start(port()))
}

func port() string {
	if p := os.Getenv("PORT"); p != "" {
		return ":" + p
	}
	return ":8080"
}

// srvDir: units live in ~/srv on the box, which is outside WorkingDirectory, so it is not repo-relative
// (unlike dist/ and docs/). SRV_DIR overrides it for dev/tests.
func srvDir() string {
	if d := os.Getenv("SRV_DIR"); d != "" {
		return d
	}
	home, err := os.UserHomeDir()
	if err != nil {
		return "srv"
	}
	return filepath.Join(home, "srv")
}