package isphere

import (
	"bufio"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

func LoadEncryptedPacketLogSourceFromFile(path string) (EncryptedPacketLogSource, error) {
	trimmedPath := strings.TrimSpace(path)
	if trimmedPath == "" {
		return EncryptedPacketLogSource{}, fmt.Errorf("packet log file path is empty")
	}

	lines, err := readEncryptedPacketLogLinesFromFile(trimmedPath)
	if err != nil {
		return EncryptedPacketLogSource{}, err
	}
	return EncryptedPacketLogSource{Lines: lines}, nil
}

func LoadEncryptedPacketLogSourceFromDirectory(path string) (EncryptedPacketLogSource, error) {
	trimmedPath := strings.TrimSpace(path)
	if trimmedPath == "" {
		return EncryptedPacketLogSource{}, fmt.Errorf("packet log directory path is empty")
	}
	info, err := os.Stat(trimmedPath)
	if err != nil {
		return EncryptedPacketLogSource{}, fmt.Errorf("stat packet log directory %q: %w", trimmedPath, err)
	}
	if !info.IsDir() {
		return EncryptedPacketLogSource{}, fmt.Errorf("packet log directory %q is not a directory", trimmedPath)
	}

	paths := []string{}
	if err := filepath.WalkDir(trimmedPath, func(path string, entry fs.DirEntry, walkErr error) error {
		if walkErr != nil {
			return walkErr
		}
		if entry.IsDir() {
			return nil
		}
		ext := strings.ToLower(filepath.Ext(entry.Name()))
		if ext == ".log" || ext == ".txt" {
			paths = append(paths, path)
		}
		return nil
	}); err != nil {
		return EncryptedPacketLogSource{}, fmt.Errorf("walk packet log directory %q: %w", trimmedPath, err)
	}
	sort.Strings(paths)

	lines := []string{}
	for _, path := range paths {
		fileLines, err := readEncryptedPacketLogLinesFromFile(path)
		if err != nil {
			return EncryptedPacketLogSource{}, err
		}
		lines = append(lines, fileLines...)
	}
	return EncryptedPacketLogSource{Lines: lines}, nil
}

func readEncryptedPacketLogLinesFromFile(path string) ([]string, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, fmt.Errorf("open packet log file %q: %w", path, err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	scanner.Buffer(make([]byte, 64*1024), 16*1024*1024)
	lines := []string{}
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" {
			continue
		}
		lines = append(lines, line)
	}
	if err := scanner.Err(); err != nil {
		return nil, fmt.Errorf("read packet log file %q: %w", path, err)
	}
	return lines, nil
}