package app

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"os"
	"time"
)

// ---------------------------------------------------------------------
// status file watcher
// ---------------------------------------------------------------------

func watchStatusFile(ctx context.Context, every time.Duration) {
	var last [32]byte
	have := false
	for {
		select {
		case <-ctx.Done():
			return
		case <-time.After(every):
		}

		data, err := os.ReadFile(statusFilePath)
		if err != nil {
			continue
		}
		h := sha256.Sum256(data)
		if have && h == last {
			continue
		}
		last = h
		have = true

		var st Status
		if err := json.Unmarshal(data, &st); err != nil {
			events.push("status_error", map[string]any{"error": err.Error()})
			continue
		}
		events.push("status_changed", st)
	}
}

// ---------------------------------------------------------------------
// login file watcher
// ---------------------------------------------------------------------

func watchLoginFile(ctx context.Context, every time.Duration) {
	var last [32]byte
	have := false
	for {
		select {
		case <-ctx.Done():
			return
		case <-time.After(every):
		}

		data, err := os.ReadFile(loginStatePath)
		if err != nil {
			continue
		}
		h := sha256.Sum256(data)
		if have && h == last {
			continue
		}
		last = h
		have = true

		var st VPNLoginState
		if err := json.Unmarshal(data, &st); err != nil {
			events.push("login_state_error", map[string]any{"error": err.Error()})
			continue
		}
		events.push("login_state_changed", st)
	}
}

// ---------------------------------------------------------------------
// generic file watcher
// ---------------------------------------------------------------------

func watchFileChange(ctx context.Context, path string, kind string, mode string, every time.Duration) {
	var lastMod time.Time
	var lastSize int64 = -1
	for {
		select {
		case <-ctx.Done():
			return
		case <-time.After(every):
		}

		info, err := os.Stat(path)
		if err != nil {
			continue
		}
		if info.ModTime() == lastMod && info.Size() == lastSize {
			continue
		}
		lastMod = info.ModTime()
		lastSize = info.Size()
		events.push(kind, map[string]any{
			"path":  path,
			"mode":  mode,
			"size":  info.Size(),
			"mtime": info.ModTime().UTC().Format(time.RFC3339Nano),
		})
	}
}