package app

import (
	"fmt"
	"log"
	"os"
	"regexp"
	"strings"
	"time"
)

// ---------------------------------------------------------------------
// autoloop
// ---------------------------------------------------------------------

// EN: Long-running VPN autoloop worker that keeps the tunnel connected,
// EN: updates login/license state, enforces policy route defaults, and emits events.
// RU: Долгоживущий воркер VPN autoloop, который поддерживает соединение,
// RU: обновляет login/license state, чинит policy route и публикует события.

func runAutoloop(iface, table string, mtu int, stateDirPath, defaultLoc string) {
	locFile := stateDirPath + "/adguard-location.txt"
	logFile := stateDirPath + "/adguard-autoloop.log"
	loginStateFile := stateDirPath + "/adguard-login.json"
	licenseTTL := 3600 * time.Second
	statusTimeout := 8 * time.Second
	connectTimeout := 25 * time.Second
	disconnectTimeout := 8 * time.Second
	licenseTimeout := 10 * time.Second
	lastLicense := time.Time{}

	_ = os.MkdirAll(stateDirPath, 0o755)

	log.Printf("autoloop: start iface=%s table=%s mtu=%d", iface, table, mtu)

	logLine := func(msg string) {
		line := fmt.Sprintf("%s autoloop: %s\n", time.Now().Format(time.RFC3339), msg)
		f, err := os.OpenFile(logFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
		if err == nil {
			defer f.Close()
			_, _ = f.WriteString(line)
		}
		fmt.Print(line)
	}

	writeLoginState := func(state, email, msg string) {
		ts := time.Now().Format(time.RFC3339)
		payload := fmt.Sprintf(`{"ts":"%s","state":"%s","email":"%s","msg":"%s"}`, ts, escapeJSON(state), escapeJSON(email), escapeJSON(msg))
		_ = os.WriteFile(loginStateFile, []byte(payload), 0o644)
	}

	getLocation := func() string {
		if data, err := os.ReadFile(locFile); err == nil {
			for _, ln := range strings.Split(string(data), "\n") {
				t := strings.TrimSpace(ln)
				if t != "" && !strings.HasPrefix(t, "#") {
					return t
				}
			}
		}
		return defaultLoc
	}

	isConnected := func(out string) bool {
		low := strings.ToLower(out)
		return strings.Contains(low, "vpn is connected") ||
			strings.Contains(low, "connected to") ||
			strings.Contains(low, "after connect: connected")
	}

	fixPolicy := func() {
		_, stderr, _, err := runCommandTimeout(5*time.Second,
			"ip", "-4", "route", "replace",
			"default", "dev", iface,
			"table", table,
			"mtu", fmt.Sprintf("%d", mtu),
		)
		if err != nil {
			logLine("route: FAILED to set default dev " + iface +
				" table " + table + ": " + stderr)
		} else {
			logLine("route: default dev " + iface + " table " + table +
				" mtu " + fmt.Sprintf("%d", mtu) + " OK")
		}
	}
	var emailRe = regexp.MustCompile(`[A-Za-z0-9._%+\-]+@[A-Za-z0-9.\-]+`)
	parseEmail := func(text string) string {
		return emailRe.FindString(text)
	}

	isLoginRequired := func(t string) bool {
		low := strings.ToLower(t)
		return strings.Contains(low, "please log in") ||
			strings.Contains(low, "not logged in") ||
			strings.Contains(low, "login required") ||
			strings.Contains(low, "sign in")
	}

	updateLoginStateFromText := func(text string) {
		if isLoginRequired(text) {
			writeLoginState("no_login", "", "NOT LOGGED IN")
			logLine("login: NO (detected from output)")
			return
		}
		if em := parseEmail(text); em != "" {
			writeLoginState("ok", em, "logged in")
			logLine("login: OK email=" + em)
			return
		}
		low := strings.ToLower(text)
		if strings.Contains(low, "not logged in") ||
			strings.Contains(low, "expired") ||
			strings.Contains(low, "no active license") {
			writeLoginState("no_login", "", "NOT LOGGED IN (license)")
			logLine("login: NO (license says not logged in)")
			return
		}

		if strings.Contains(low, "license") &&
			(strings.Contains(low, "active") || strings.Contains(low, "valid")) {
			writeLoginState("ok", "", "logged in (license ok)")
			logLine("login: OK (license ok, email not found)")
			return
		}
	}

	updateLicense := func() {
		now := time.Now()
		if !lastLicense.IsZero() && now.Sub(lastLicense) < licenseTTL {
			return
		}
		lastLicense = now
		out, _, _, _ := runCommandTimeout(licenseTimeout, adgvpnCLI, "license")
		out = stripANSI(out)
		updateLoginStateFromText(out)
	}

	writeLoginState("unknown", "", "not checked yet")
	updateLicense()

	for {
		statusOut, _, exitCode, err := runCommandTimeout(statusTimeout, adgvpnCLI, "status")
		statusOut = stripANSI(statusOut)
		if err != nil {
			logLine(fmt.Sprintf("status: ERROR exit=%d err=%v raw=%q", exitCode, err, statusOut))
		}
		if isConnected(statusOut) {
			logLine("status: CONNECTED; raw: " + statusOut)
			fixPolicy()
			updateLicense()
			events.push("autoloop_status_changed", map[string]string{
				"status_word": "CONNECTED",
				"raw_text":    statusOut,
			})
			time.Sleep(20 * time.Second)
			continue
		}

		logLine("status: DISCONNECTED; raw: " + statusOut)
		events.push("autoloop_status_changed", map[string]string{
			"status_word": "DISCONNECTED",
			"raw_text":    statusOut,
		})
		updateLoginStateFromText(statusOut)

		loc := getLocation()
		logLine("reconnecting to " + loc)

		_, _, _, _ = runCommandTimeout(disconnectTimeout, adgvpnCLI, "disconnect")
		connectOut, _, _, _ := runCommandTimeout(connectTimeout, adgvpnCLI, "connect", "-l", loc, "--log-to-file")
		connectOut = stripANSI(connectOut)
		logLine("connect raw: " + connectOut)
		updateLoginStateFromText(connectOut)

		statusAfter, _, _, _ := runCommandTimeout(statusTimeout, adgvpnCLI, "status")
		statusAfter = stripANSI(statusAfter)
		if isConnected(statusAfter) {
			logLine("after connect: CONNECTED; raw: " + statusAfter)
			fixPolicy()
			updateLicense()
			events.push("autoloop_status_changed", map[string]string{
				"status_word": "CONNECTED",
				"raw_text":    statusAfter,
			})
			time.Sleep(20 * time.Second)
			continue
		}

		logLine("after connect: STILL DISCONNECTED; raw: " + statusAfter)
		time.Sleep(10 * time.Second)
	}
}

// ---------------------------------------------------------------------
// autoloop helpers
// ---------------------------------------------------------------------

func escapeJSON(s string) string {
	s = strings.ReplaceAll(s, `\`, `\\`)
	s = strings.ReplaceAll(s, `"`, `\\"`)
	s = strings.ReplaceAll(s, "\n", "\\n")
	s = strings.ReplaceAll(s, "\r", "")
	return s
}