package main

import (
	"concord.hectabit.org/Hectabit/burgerbackup/lib/common"
	"errors"
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/spf13/viper"
	"golang.org/x/crypto/argon2"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"os"
	"strconv"
	"time"
)

func main() {
	if _, err := os.Stat("config.ini"); err == nil {
		log.Println("[INFO] Config loaded at", time.Now().Unix())
	} else if os.IsNotExist(err) {
		log.Fatalln("[FATAL] config.ini does not exist")
	} else {
		log.Fatalln("[FATAL] File is in quantum uncertainty:", err)
	}

	viper.SetConfigName("config")
	viper.AddConfigPath("./")
	viper.AutomaticEnv()

	err := viper.ReadInConfig()
	if err != nil {
		log.Fatalln("[FATAL] Error in config file at", strconv.FormatInt(time.Now().Unix(), 10)+":", err)
	}

	backupKey := viper.GetString("BACKUP_KEY")
	cryptoKey := viper.GetString("CRYPTO_KEY")
	port := viper.GetInt("PORT")
	host := viper.GetString("HOST")
	backupFolder := viper.GetString("BACKUP_FOLDER")

	if host == "" {
		log.Fatalln("[FATAL] HOST is not set")
	}

	if port == 0 {
		log.Fatalln("[FATAL] PORT is not set")
	}

	if backupKey == "" {
		log.Fatalln("[FATAL] BACKUP_KEY is not set")
	} else if backupKey == "supersecretkey" {
		log.Println("[WARN] SECRET_KEY is set to a default value. Please set it to another value.")
	}

	if cryptoKey == "" {
		log.Fatalln("[FATAL] CRYPTO_KEY is not set")
	} else if cryptoKey == "supersecretkey" {
		log.Println("[WARN] SECRET_KEY is set to a default value. If it is also set to this on the client, please set both to another value.")
	}

	if _, err := os.Stat(backupFolder); os.IsNotExist(err) {
		log.Println("[INFO] Backup folder does not exist, creating")
		if err := os.Mkdir(backupFolder, 0755); err != nil {
			log.Fatalln("[FATAL] Could not create backup folder:", err)
		}
	}

	gin.SetMode(gin.ReleaseMode)
	router := gin.Default()

	router.Use(func(c *gin.Context) {
		c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
		c.Writer.Header().Set("Access-Control-Allow-Headers", "*, Authorization")
		c.Writer.Header().Set("Access-Control-Allow-Methods", "*")

		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(200)
			return
		}

		c.Next()
	})

	router.POST("/api/backup", func(c *gin.Context) {
		clientBackupKey := c.GetHeader("Authorization")
		if clientBackupKey == "" {
			c.JSON(400, gin.H{"error": "BackupKey not found", "goErr": "backupKey not found"})
			return
		}

		var authenticated bool
		authenticated, err = common.VerifyHash(clientBackupKey, backupKey)
		if err != nil {
			c.JSON(500, gin.H{"error": "Something went wrong on our end. Please report this bug at https://centrifuge.hectabit.org/hectabit/burgerbackup and refer to the documentation for more info. Your error code is: UNKNOWN-API-BACKUP-VERIFYERR", "goErr": err.Error()})
			log.Println("[ERROR] Error in /api/backup hash verify:", err)
			return
		}

		if authenticated {
			file, err := c.FormFile("file")
			if err != nil {
				if errors.Is(err, http.ErrMissingFile) {
					c.JSON(400, gin.H{"error": "No file uploaded", "goErr": err.Error()})
				} else {
					c.JSON(500, gin.H{"error": "Something went wrong on our end. Please report this bug at https://centrifuge.hectabit.org/hectabit/burgerbackup and refer to the documentation for more info. Your error code is: UNKNOWN-API-BACKUP-FILEERR", "goErr": err.Error()})
					log.Println("[ERROR] Error in /api/backup file upload:", err)
				}
				return
			}
			fileName := "database_" + strconv.FormatInt(time.Now().Unix(), 10) + ".db"
			encryptedFile, err := file.Open()
			if err != nil {
				c.JSON(422, gin.H{"error": "Could not open file", "goErr": err.Error()})
			}
			defer func(encryptedFile multipart.File) {
				err := encryptedFile.Close()
				if err != nil {
					c.JSON(500, gin.H{"error": "Something went wrong on our end. Please report this bug at https://centrifuge.hectabit.org/hectabit/burgerbackup and refer to the documentation for more info. Your error code is: UNKNOWN-API-BACKUP-FILEDEFERERR", "goErr": err.Error()})
					log.Println("[ERROR] Error in /api/backup file defer:", err)
					return
				}
			}(encryptedFile)

			encryptedData, err := io.ReadAll(encryptedFile)
			if err != nil {
				c.JSON(500, gin.H{"error": "Something went wrong on our end. Please report this bug at https://centrifuge.hectabit.org/hectabit/burgerbackup and refer to the documentation for more info. Your error code is: UNKNOWN-API-BACKUP-FILECONTENTERR", "goErr": err.Error()})
				log.Println("[ERROR] Error in /api/backup file read:", err)
				return
			}

			cryptoKeyHashed := argon2.IDKey([]byte(cryptoKey), []byte("burgerbackup"), 1, 64*1024, 4, 32)
			decryptedData, err := common.DecryptAES(cryptoKeyHashed, encryptedData)
			if err != nil {
				c.JSON(500, gin.H{"error": "Something went wrong on our end. Please report this bug at https://centrifuge.hectabit.org/hectabit/burgerbackup and refer to the documentation for more info. Your error code is: UNKNOWN-API-BACKUP-DECRYPTERR", "goErr": err.Error()})
				log.Println("[ERROR] Error in /api/backup file decrypt:", err)
				return
			}

			filePath := backupFolder + "/" + fileName
			if err := os.WriteFile(filePath, decryptedData, 0644); err != nil {
				c.JSON(500, gin.H{"error": "Something went wrong on our end. Please report this bug at https://centrifuge.hectabit.org/hectabit/burgerbackup and refer to the documentation for more info. Your error code is: UNKNOWN-API-BACKUP-WRITEERR", "goErr": err.Error()})
				log.Println("[ERROR] Error in /api/backup file write:", err)
				return
			}

			fmt.Println("[INFO] Received and decrypted backup from", c.ClientIP())
			c.JSON(200, gin.H{"success": "true", "timeTaken": time.Now().Unix(), "goErr": ""})
		} else {
			c.JSON(401, gin.H{"error": "Incorrect backup key", "goErr": "incorrect backup key"})
		}
	})

	log.Println("[INFO] Server started at", time.Now().Unix())
	log.Println("[INFO] Welcome to Burgerbackup! Today we are running on IP " + host + " on port " + strconv.Itoa(port) + ".")
	err = router.Run(host + ":" + strconv.Itoa(port))
	if err != nil {
		log.Fatalln("[FATAL] Server failed to begin operations at", time.Now().Unix(), err)
	}
}