package main

import (
	"bufio"
	"bytes"
	"encoding/hex"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"runtime"
	"strconv"
	"strings"
)

func intEnvConfig(i *int, name string) {
	if env, err := strconv.Atoi(os.Getenv(name)); err == nil {
		*i = env
	}
}

func megaIntEnvConfig(f *int, name string) {
	if env, err := strconv.ParseFloat(os.Getenv(name), 64); err == nil {
		*f = int(env * 1000000)
	}
}

func strEnvConfig(s *string, name string) {
	if env := os.Getenv(name); len(env) > 0 {
		*s = env
	}
}

func boolEnvConfig(b *bool, name string) {
	*b = false
	if env, err := strconv.ParseBool(os.Getenv(name)); err == nil {
		*b = env
	}
}

func hexEnvConfig(b *[]byte, name string) {
	var err error

	if env := os.Getenv(name); len(env) > 0 {
		if *b, err = hex.DecodeString(env); err != nil {
			log.Fatalf("%s expected to be hex-encoded string\n", name)
		}
	}
}

func hexFileConfig(b *[]byte, filepath string) {
	if len(filepath) == 0 {
		return
	}

	f, err := os.Open(filepath)
	if err != nil {
		log.Fatalf("Can't open file %s\n", filepath)
	}

	src, err := ioutil.ReadAll(f)
	if err != nil {
		log.Fatalln(err)
	}

	src = bytes.TrimSpace(src)

	dst := make([]byte, hex.DecodedLen(len(src)))
	n, err := hex.Decode(dst, src)
	if err != nil {
		log.Fatalf("%s expected to contain hex-encoded string\n", filepath)
	}

	*b = dst[:n]
}

func presetEnvConfig(p presets, name string) {
	if env := os.Getenv(name); len(env) > 0 {
		presetStrings := strings.Split(env, ",")

		for _, presetStr := range presetStrings {
			parsePreset(p, presetStr)
		}
	}
}

func presetFileConfig(p presets, filepath string) {
	if len(filepath) == 0 {
		return
	}

	f, err := os.Open(filepath)
	if err != nil {
		log.Fatalf("Can't open file %s\n", filepath)
	}

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		parsePreset(p, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		log.Fatalf("Failed to read presets file: %s", err)
	}
}

type config struct {
	Bind            string
	ReadTimeout     int
	WaitTimeout     int
	WriteTimeout    int
	DownloadTimeout int
	Concurrency     int
	MaxClients      int
	TTL             int

	MaxSrcDimension  int
	MaxSrcResolution int

	JpegProgressive bool
	PngInterlaced   bool
	Quality         int
	GZipCompression int

	EnableWebpDetection bool
	EnforceWebp         bool

	Key           []byte
	Salt          []byte
	AllowInsecure bool

	Secret string

	AllowOrigin string

	IgnoreSslVerification bool

	LocalFileSystemRoot string

	ETagEnabled bool

	BaseURL string

	Presets presets
}

var conf = config{
	Bind:                  ":8080",
	ReadTimeout:           10,
	WriteTimeout:          10,
	DownloadTimeout:       5,
	Concurrency:           runtime.NumCPU() * 2,
	TTL:                   3600,
	IgnoreSslVerification: false,
	MaxSrcDimension:       8192,
	MaxSrcResolution:      16800000,
	AllowInsecure:         false,
	Quality:               80,
	GZipCompression:       5,
	ETagEnabled:           false,
}

func init() {
	keyPath := flag.String("keypath", "", "path of the file with hex-encoded key")
	saltPath := flag.String("saltpath", "", "path of the file with hex-encoded salt")
	presetsPath := flag.String("presets", "", "path of the file with presets")
	showVersion := flag.Bool("v", false, "show version")
	flag.Parse()

	if *showVersion {
		fmt.Println(version)
		os.Exit(0)
	}

	if port := os.Getenv("PORT"); len(port) > 0 {
		conf.Bind = fmt.Sprintf(":%s", port)
	}

	strEnvConfig(&conf.Bind, "IMGPROXY_BIND")
	intEnvConfig(&conf.ReadTimeout, "IMGPROXY_READ_TIMEOUT")
	intEnvConfig(&conf.WriteTimeout, "IMGPROXY_WRITE_TIMEOUT")
	intEnvConfig(&conf.DownloadTimeout, "IMGPROXY_DOWNLOAD_TIMEOUT")
	intEnvConfig(&conf.Concurrency, "IMGPROXY_CONCURRENCY")
	intEnvConfig(&conf.MaxClients, "IMGPROXY_MAX_CLIENTS")

	intEnvConfig(&conf.TTL, "IMGPROXY_TTL")

	intEnvConfig(&conf.MaxSrcDimension, "IMGPROXY_MAX_SRC_DIMENSION")
	megaIntEnvConfig(&conf.MaxSrcResolution, "IMGPROXY_MAX_SRC_RESOLUTION")

	boolEnvConfig(&conf.JpegProgressive, "IMGPROXY_JPEG_PROGRESSIVE")
	boolEnvConfig(&conf.PngInterlaced, "IMGPROXY_PNG_INTERLACED")
	intEnvConfig(&conf.Quality, "IMGPROXY_QUALITY")
	intEnvConfig(&conf.GZipCompression, "IMGPROXY_GZIP_COMPRESSION")

	boolEnvConfig(&conf.EnableWebpDetection, "IMGPROXY_ENABLE_WEBP_DETECTION")
	boolEnvConfig(&conf.EnforceWebp, "IMGPROXY_ENFORCE_WEBP")

	hexEnvConfig(&conf.Key, "IMGPROXY_KEY")
	hexEnvConfig(&conf.Salt, "IMGPROXY_SALT")

	hexFileConfig(&conf.Key, *keyPath)
	hexFileConfig(&conf.Salt, *saltPath)

	strEnvConfig(&conf.Secret, "IMGPROXY_SECRET")

	strEnvConfig(&conf.AllowOrigin, "IMGPROXY_ALLOW_ORIGIN")

	boolEnvConfig(&conf.IgnoreSslVerification, "IMGPROXY_IGNORE_SSL_VERIFICATION")

	strEnvConfig(&conf.LocalFileSystemRoot, "IMGPROXY_LOCAL_FILESYSTEM_ROOT")

	boolEnvConfig(&conf.ETagEnabled, "IMGPROXY_USE_ETAG")

	strEnvConfig(&conf.BaseURL, "IMGPROXY_BASE_URL")

	conf.Presets = make(presets)
	presetEnvConfig(conf.Presets, "IMGPROXY_PRESETS")
	presetFileConfig(conf.Presets, *presetsPath)

	if len(conf.Key) == 0 {
		warning("Key is not defined, so signature checking is disabled")
		conf.AllowInsecure = true
	}
	if len(conf.Salt) == 0 {
		warning("Salt is not defined, so signature checking is disabled")
		conf.AllowInsecure = true
	}

	if len(conf.Bind) == 0 {
		log.Fatalln("Bind address is not defined")
	}

	if conf.ReadTimeout <= 0 {
		log.Fatalf("Read timeout should be greater than 0, now - %d\n", conf.ReadTimeout)
	}

	if conf.WriteTimeout <= 0 {
		log.Fatalf("Write timeout should be greater than 0, now - %d\n", conf.WriteTimeout)
	}

	if conf.DownloadTimeout <= 0 {
		log.Fatalf("Download timeout should be greater than 0, now - %d\n", conf.DownloadTimeout)
	}

	if conf.Concurrency <= 0 {
		log.Fatalf("Concurrency should be greater than 0, now - %d\n", conf.Concurrency)
	}

	if conf.MaxClients <= 0 {
		conf.MaxClients = conf.Concurrency * 10
	}

	if conf.TTL <= 0 {
		log.Fatalf("TTL should be greater than 0, now - %d\n", conf.TTL)
	}

	if conf.MaxSrcDimension <= 0 {
		log.Fatalf("Max src dimension should be greater than 0, now - %d\n", conf.MaxSrcDimension)
	}

	if conf.MaxSrcResolution <= 0 {
		log.Fatalf("Max src resolution should be greater than 0, now - %d\n", conf.MaxSrcResolution)
	}

	if conf.Quality <= 0 {
		log.Fatalf("Quality should be greater than 0, now - %d\n", conf.Quality)
	} else if conf.Quality > 100 {
		log.Fatalf("Quality can't be greater than 100, now - %d\n", conf.Quality)
	}

	if conf.GZipCompression < 0 {
		log.Fatalf("GZip compression should be greater than or quual to 0, now - %d\n", conf.GZipCompression)
	} else if conf.GZipCompression > 9 {
		log.Fatalf("GZip compression can't be greater than 9, now - %d\n", conf.GZipCompression)
	}

	if conf.IgnoreSslVerification {
		warning("Ignoring SSL verification is very unsafe")
	}

	if conf.LocalFileSystemRoot != "" {
		stat, err := os.Stat(conf.LocalFileSystemRoot)
		if err != nil {
			log.Fatalf("Cannot use local directory: %s", err)
		} else {
			if !stat.IsDir() {
				log.Fatalf("Cannot use local directory: not a directory")
			}
		}
		if conf.LocalFileSystemRoot == "/" {
			log.Print("Exposing root via IMGPROXY_LOCAL_FILESYSTEM_ROOT is unsafe")
		}
	}

	checkPresets(conf.Presets)

	initVips()
	initDownloading()
}