package main

import (
	"bufio"
	"bytes"
	"crypto/sha256"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"sync"

	"github.com/bmatcuk/doublestar/v4"
)

var Error *log.Logger
var Warning *log.Logger

func init() {
	log.SetFlags(log.Lmicroseconds | log.Lshortfile)
	logFile, err := os.OpenFile("updater.log", os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
	if err != nil {
		log.Fatalf("error opening log file: %v", err)
	}
	Error = log.New(io.MultiWriter(os.Stderr, logFile),
		fmt.Sprintf("%sERROR:%s ", "\033[0;101m", "\033[0m"),
		log.Lmicroseconds|log.Lshortfile)
	Warning = log.New(io.MultiWriter(os.Stdout, logFile),
		fmt.Sprintf("%sWarning:%s ", "\033[0;93m", "\033[0m"),
		log.Lmicroseconds|log.Lshortfile)
}

const remoteUrl = "https://git.site.quack-lab.dev/dave/barotrauma-gamefiles/raw/branch/cooked/Content"

func main() {
	nodl := flag.Bool("nodl", false, "nodl")
	hashfile := flag.String("hashfile", "hashes.txt", "hashfile")
	hash := flag.Bool("hash", false, "hash")
	root := flag.String("root", ".", "root")
	flag.Parse()

	cwd, err := os.Getwd()
	if err != nil {
		Error.Printf("error getting cwd: %v", err)
		return
	}
	log.Printf("cwd: %s", cwd)
	log.Printf("root: %s", *root)

	*root = filepath.Join(cwd, *root, "Content")
	log.Printf("root: %s", *root)

	*hashfile = filepath.Join(*root, *hashfile)
	hashes, err := LoadLocalHashes(*hashfile)
	if err != nil {
		Error.Printf("error loading hashes: %v", err)
		return
	}
	log.Printf("loaded hashes")

	remoteHashes, err := LoadRemoteHashes(remoteUrl + "/hashes.txt")
	if err != nil {
		Error.Printf("error loading remote hashes: %v", err)
		return
	}
	log.Printf("loaded remote hashes")

	files, err := doublestar.Glob(os.DirFS(*root), "**/*.xml")
	if err != nil {
		Error.Printf("error globbing files: %v", err)
		return
	}

	var wg sync.WaitGroup
	for _, file := range files {
		wg.Add(1)
		go func(file string) {
			defer wg.Done()
			file = strings.ReplaceAll(file, "\\", "/")
			path := filepath.Join(*root, file)
			path = strings.ReplaceAll(path, "\\", "/")
			hash, err := GetLocalHash(path)
			if err != nil {
				Error.Printf("error getting hash: %v", err)
				return
			}
			relativepath, err := filepath.Rel(*root, path)
			if err != nil {
				Error.Printf("error getting relative path: %v", err)
				return
			}
			relativepath = strings.ReplaceAll(relativepath, "\\", "/")
			hashes.Store(relativepath, hash)
		}(file)
	}
	wg.Wait()

	if *hash {
		err = SaveLocalHashes(*hashfile, hashes)
		if err != nil {
			Error.Printf("error saving hashes: %v", err)
			return
		}
		log.Printf("saved hashes")
		return
	}

	mismatched := 0
	checked := 0
	toDownload := []string{}
	remoteHashes.Range(func(key, value interface{}) bool {
		localhash, ok := hashes.Load(key)
		if !ok {
			Warning.Printf("local hash not found: %s", key)
			mismatched++
			toDownload = append(toDownload, key.(string))
			return true
		}
		if localhash != value {
			Warning.Printf("hash mismatch: %s", key)
			mismatched++
			toDownload = append(toDownload, key.(string))
		}
		checked++
		return true
	})
	log.Printf("Hashes checked: %d, mismatched: %d", checked, mismatched)

	if mismatched > 0 {
		log.Printf("Downloading %d files", len(toDownload))
		wg := sync.WaitGroup{}
		for _, file := range toDownload {
			wg.Add(1)
			go func(file string) {
				defer wg.Done()
				file = strings.ReplaceAll(file, "\\", "/")
				path := filepath.Join(*root, file)
				log.Printf("Downloading %s", file)
				if *nodl {
					log.Printf("Skipping download for %s", file)
					return
				}
				err := UpdateLocalFile(path, remoteUrl+"/"+file)
				if err != nil {
					Error.Printf("error updating local file: %v", err)
				}
				newhash, err := GetLocalHash(path)
				if err != nil {
					Error.Printf("error getting local hash: %v", err)
					return
				}
				hashes.Store(file, newhash)
			}(file)
		}
		wg.Wait()
	}
	// We want to update the newly downloaded files, if any
	err = SaveLocalHashes(*hashfile, hashes)
	if err != nil {
		Error.Printf("error saving hashes: %v", err)
	}
}

func GetLocalHash(path string) (string, error) {
	hash := sha256.New()

	file, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer file.Close()

	io.Copy(hash, file)
	return fmt.Sprintf("%x", hash.Sum(nil)), nil
}

func LoadLocalHashes(path string) (*sync.Map, error) {
	hashes := &sync.Map{}

	file, err := os.Open(path)
	if err != nil {
		if os.IsNotExist(err) {
			Warning.Printf("hashes file not found: %s", path)
			return hashes, nil
		}
		return nil, err
	}
	defer file.Close()

	count := 0
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		// Hopefully none of the files have spaces in the name.................
		line := scanner.Text()
		parts := strings.Split(line, " ")
		if len(parts) != 2 {
			Warning.Printf("invalid line: %s", line)
			continue
		}
		hashes.Store(parts[0], parts[1])
		count++
	}
	log.Printf("loaded %d local hashes", count)

	return hashes, nil
}

type FileHash struct {
	Path string
	Hash string
}

func SaveLocalHashes(path string, hashes *sync.Map) error {
	file, err := os.Create(path)
	if err != nil {
		return err
	}
	defer file.Close()

	hashesarr := []FileHash{}
	hashes.Range(func(key, value interface{}) bool {
		hashesarr = append(hashesarr, FileHash{
			Path: key.(string),
			Hash: value.(string),
		})
		return true
	})

	slices.SortFunc(hashesarr, func(a, b FileHash) int {
		return strings.Compare(a.Path, b.Path)
	})

	// We are sorting this shit so that our resulting hashes file is consistent
	for _, hash := range hashesarr {
		file.WriteString(fmt.Sprintf("%s %s\n", hash.Path, hash.Hash))
	}

	return nil
}

func LoadRemoteHashes(url string) (*sync.Map, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	count := 0
	hashes := &sync.Map{}
	scanner := bufio.NewScanner(bytes.NewReader(body))
	for scanner.Scan() {
		line := scanner.Text()
		parts := strings.Split(line, " ")
		if len(parts) != 2 {
			return nil, fmt.Errorf("invalid line: %s", line)
		}
		count++
		hashes.Store(parts[0], parts[1])
	}
	log.Printf("loaded %d remote hashes", count)

	return hashes, nil
}

func UpdateLocalFile(path string, remoteUrl string) error {
	resp, err := http.Get(remoteUrl)
	if err != nil {
		return err
	}
	if resp.StatusCode != 200 {
		return fmt.Errorf("failed downloading %s on url %q: %d", path, remoteUrl, resp.StatusCode)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("failed reading body for %s on url %q: %v", path, remoteUrl, err)
	}

	err = os.WriteFile(path, body, 0644)
	if err != nil {
		return fmt.Errorf("failed writing file for %s on url %q: %v", path, remoteUrl, err)
	}

	return nil
}