package main

import (
	"bytes"
	"database/sql"
	"encoding/base64"
	"encoding/hex"
	"flag"
	"fmt"
	"git.gammaspectra.live/S.O.N.G/MakyuuIchaival"
	"git.gammaspectra.live/S.O.N.G/MakyuuIchaival/contentmessage"
	"git.gammaspectra.live/S.O.N.G/MakyuuIchaival/httputils"
	"git.gammaspectra.live/S.O.N.G/MakyuuIchaival/tlsutils"
	"github.com/cloudflare/circl/sign/ed25519"
	"github.com/ipfs/go-cid"
	_ "github.com/lib/pq"
	"github.com/multiformats/go-multihash"
	"log"
	"net/http"
	"net/url"
	"os"
	"path"
	"strings"
	"sync"
	"time"
)

type ContentCacheEntry struct {
	Entry      ContentEntry
	AccessTime time.Time
}

var dbHandle *sql.DB
var sha256Statement *sql.Stmt
var md5Statement *sql.Stmt
var fdlimit int

var objectCacheMutex sync.RWMutex
var objectCache = make(map[string]*ContentCacheEntry)

var trustedPublicKeys []ed25519.PublicKey

var debugOutput = false

func getFirstValidContentEntry(entries *[]ContentEntry) *ContentEntry {
	for _, entry := range *entries {
		stat, err := os.Stat(entry.Path)
		if err == nil && (entry.Size == 0 || uint64(stat.Size()) == entry.Size) { //TODO: update Size if not found
			copiedEntry := entry
			copiedEntry.Size = uint64(stat.Size())
			return &copiedEntry
		}
	}

	return nil
}

func GetMimeTypeFromExtension(ext string) string {

	if len(ext) > 0 {
		switch strings.ToLower(ext[1:]) {

		//Audio types
		case "flac":
			return "audio/flac"
		case "mp3":
			return "audio/mpeg;codecs=mp3"
		case "m4a":
			return "audio/mp4"
		case "mka":
			return "audio/x-matroska"
		case "ogg":
			return "audio/ogg"
		case "opus":
			return "audio/opus"
		case "tta":
			return "audio/tta"
		case "aac":
			return "audio/aac"
		case "alac":
			return "audio/alac"
		case "wav":
			return "audio/wav"
		case "ape":
			return "audio/ape"

		//Image types
		case "png":
			return "image/png"
		case "jfif":
			fallthrough
		case "jpeg":
			fallthrough
		case "jpg":
			return "image/jpeg"
		case "gif":
			return "image/gif"
		case "svg":
			return "image/svg+xml"
		case "tiff":
			fallthrough
		case "tif":
			return "image/tiff"
		case "webp":
			return "image/webp"
		case "bmp":
			return "image/bmp"

		//Text types
		case "txt":
			return "text/plain"
		case "log":
			return "text/x-log"
		case "accurip":
			return "text/x-accurip"
		case "cue":
			return "text/x-cue"
		case "toc":
			return "text/x-toc"

		//Text subtitles
		case "lrc":
			return "text/x-subtitle-lrc"
		case "ssa":
			return "text/x-subtitle-ssa"
		case "ass":
			return "text/x-subtitle-ass"
		case "srt":
			return "text/x-subtitle-subrip"

		//Web types
		case "js":
			return "text/javascript"
		case "wasm":
			return "application/wasm"
		case "html":
			return "text/html"
		case "css":
			return "text/css"
		case "ttf":
			return "font/ttf"
		case "otf":
			return "font/otf"
		case "woff":
			return "font/woff"
		case "woff2":
			return "font/woff2"

		}
	}

	return "application/octet-stream"
}

func handleQueryRequest(ctx *httputils.RequestContext, identifier cid.Cid, extraArguments []string) {
	cTime := time.Now()
	var cacheEntry = tryGetCacheEntryForIdentifier(identifier)

	if cacheEntry == nil {
		result := getEntriesForCID(identifier)

		entry := getFirstValidContentEntry(&result)

		if entry != nil {
			cacheEntry = getCacheEntryForContentEntry(entry, identifier)
		}
		ctx.AddTimingInformational("ec", "Content Cache MISS")
	} else {
		ctx.AddTimingInformational("ec", "Content Cache HIT")
	}
	pTime := cTime
	cTime = time.Now()
	ctx.AddTiming("e", "Content Entry", cTime.Sub(pTime))

	if cacheEntry == nil {
		var origin string

		if len(ctx.GetRequestHeader("Referer")) > 0 {
			origin = ctx.GetRequestHeader("Referer")
		} else if len(ctx.GetRequestHeader("Origin")) > 0 {
			origin = ctx.GetRequestHeader("Origin")
		} else if len(extraArguments) > 1 {
			origin = "https://" + extraArguments[1]
		}

		//Try to redirect back to origin
		if len(extraArguments) > 0 && origin != "" {
			mh, _ := multihash.Decode(identifier.Hash())
			var kind string
			if mh.Code == multihash.SHA2_256 {
				kind = "sha256"
			} else if mh.Code == multihash.MD5 {
				kind = "md5"
			}
			if kind != "" {
				ctx.DoRedirect(fmt.Sprintf("%s/%s/%s/%s", origin, kind, hex.EncodeToString(mh.Digest), strings.Join(extraArguments, "/")), http.StatusFound)
				return
			}
		}
		ctx.SetResponseCode(http.StatusNotFound)
		return
	}

	mh, _ := multihash.Decode(cacheEntry.Entry.Identifier.Hash())

	ctx.SetResponseHeader("Accept-Ranges", "bytes")
	ctx.SetResponseHeader("X-Request-CID", identifier.String())
	ctx.SetResponseHeader("ETag", fmt.Sprintf("\"%s\"", cacheEntry.Entry.Identifier.String()))
	if mh.Code == multihash.SHA2_256 {
		ctx.SetResponseHeader("Digest", fmt.Sprintf("sha-256=%s", base64.StdEncoding.EncodeToString(mh.Digest)))
	}
	ctx.SetResponseHeader("Cache-Control", "public, max-age=2592000, immutable")

	filename := path.Base(cacheEntry.Entry.Path)

	//TODO: setting to hide filename
	ctx.SetResponseHeader("Content-Disposition", fmt.Sprintf("inline; filename*=utf-8''%s", url.PathEscape(filename)))

	pTime = cTime
	cTime = time.Now()
	ctx.AddTiming("s", "Content Serve", cTime.Sub(pTime))

	mime := GetMimeTypeFromExtension(path.Ext(cacheEntry.Entry.Path))
	if len(mime) > 0 {
		ctx.SetResponseHeader("Content-Type", mime)
	}

	ctx.ServeFile(cacheEntry.Entry.Path)
}

func setOtherHeaders(ctx *httputils.RequestContext) {
	ctx.SetResponseHeader("Server", "OrbitalBeat")
	ctx.SetResponseHeader("Vary", "Content-Encoding")
	ctx.SetResponseHeader("X-Content-Type-Options", "nosniff")
	ctx.SetResponseHeader("X-Robots-Tags", "noindex, nofollow, notranslate")

	for k, v := range ctx.GetExtraHeaders() {
		ctx.SetResponseHeader(k, v)
	}
}
func setCORSHeaders(ctx *httputils.RequestContext) {
	ctx.SetResponseHeader("Access-Control-Allow-Credentials", "true")
	ctx.SetResponseHeader("Access-Control-Max-Age", "7200") //Firefox caps this to 86400, Chrome to 7200. Default is 5 seconds (!!!)
	ctx.SetResponseHeader("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS")
	ctx.SetResponseHeader("Access-Control-Allow-Headers", "DNT,ETag,Origin,Accept,Accept-Language,X-Requested-With,Range")
	ctx.SetResponseHeader("Access-Control-Allow-Origin", "*")
	ctx.SetResponseHeader("Access-Control-Expose-Headers", "*")

	//CORP, COEP, COOP
	ctx.SetResponseHeader("Cross-Origin-Embedder-Policy", "require-corp")
	ctx.SetResponseHeader("Cross-Origin-Resource-Policy", "cross-origin")
	ctx.SetResponseHeader("Cross-Origin-Opener-Policy", "unsafe-none")
}

func getCacheEntryForContentEntry(entry *ContentEntry, originalIdentifier cid.Cid) *ContentCacheEntry {

	cacheEntry := tryGetCacheEntryForIdentifier(entry.Identifier)

	if cacheEntry != nil {
		return cacheEntry
	}
	objectCacheMutex.Lock()
	defer objectCacheMutex.Unlock()

	if len(objectCache) >= fdlimit {
		//Find oldest value, remove it
		var item *ContentCacheEntry
		for _, e := range objectCache {
			if item == nil || e.AccessTime.Before(item.AccessTime) {
				item = e
			}
		}

		if item != nil {
			delete(objectCache, item.Entry.Identifier.String())
		}
	}

	c := &ContentCacheEntry{
		Entry:      *entry,
		AccessTime: time.Now(),
	}

	objectCache[entry.Identifier.String()] = c

	if originalIdentifier.String() != entry.Identifier.String() {
		objectCache[originalIdentifier.String()] = c
	}

	return c
}

func tryGetCacheEntryForIdentifier(identifier cid.Cid) *ContentCacheEntry {

	objectCacheMutex.RLock()
	defer objectCacheMutex.RUnlock()

	cacheEntry, ok := objectCache[identifier.String()]
	if ok {
		cacheEntry.AccessTime = time.Now().UTC()
		return cacheEntry
	}

	return nil
}

func IsTrustedPublicKey(key ed25519.PublicKey) bool {
	for _, k := range trustedPublicKeys {
		if bytes.Compare(k, key) == 0 {
			return true
		}
	}
	return false
}

func handle(ctx *httputils.RequestContext) {
	if len(ctx.GetRequestHeader("Host")) > 0 && ctx.GetRequestHeader("Host") == ctx.GetTLSServerName() { //Prevents rebinding / DNS stuff
		ctx.SetResponseCode(http.StatusNotFound)
		return
	}

	cTime := time.Now()
	if ctx.IsFastHttp() {
		ctx.AddTiming("c", "Connection", ctx.GetRequestTime().Sub(ctx.GetConnectionTime()))
	}
	ctx.AddTiming("r", "Request Handler", cTime.Sub(ctx.GetRequestTime()))

	if ctx.IsGet() || ctx.IsHead() {
		if debugOutput {
			log.Printf("Serve %s", ctx.GetPath())
		}
		setOtherHeaders(ctx)
		setCORSHeaders(ctx)
		pathElements := strings.Split(ctx.GetPath(), "/")
		if len(pathElements) < 2 {
			ctx.SetResponseCode(http.StatusBadRequest)
			return
		}

		messageBytes, err := MakyuuIchaival.Bech32Encoding.DecodeString(pathElements[1])
		if err != nil {
			ctx.SetResponseCode(http.StatusBadRequest)
			return
		}
		message := contentmessage.DecodeContentMessage(messageBytes)
		if message == nil {
			ctx.SetResponseCode(http.StatusBadRequest)
			return
		}

		if !IsTrustedPublicKey(message.PublicKey) {
			ctx.SetResponseCode(http.StatusForbidden)
			return
		}

		pTime := cTime
		cTime := time.Now()
		ctx.AddTiming("d", "Decode", cTime.Sub(pTime))

		result, cacheHit := message.Verify()

		pTime = cTime
		cTime = time.Now()
		if cacheHit {
			ctx.AddTimingInformational("vc", "Ed25519 Cache HIT")
		} else {
			ctx.AddTimingInformational("vc", "Ed25519 Cache MISS")
		}
		ctx.AddTiming("v", "Ed25519 Verify", cTime.Sub(pTime))

		if !result {
			ctx.SetResponseCode(http.StatusForbidden)
			return
		}

		if debugOutput {
			log.Printf("Serving CID %s", message.Identifier.String())
		}

		handleQueryRequest(ctx, message.Identifier, pathElements[2:])
	} else if ctx.IsOptions() {
		setOtherHeaders(ctx)
		setCORSHeaders(ctx)
		ctx.SetResponseCode(http.StatusNoContent)
	} else {
		ctx.SetResponseCode(http.StatusNotImplemented)
	}
}

type ContentEntry struct {
	Identifier cid.Cid
	Path       string
	Size       uint64
}

func handleQuery(rows *sql.Rows, err error) []ContentEntry {
	if err != nil {
		log.Print(err)
		return []ContentEntry{}
	}
	defer rows.Close()

	var result []ContentEntry

	for rows.Next() {
		var entry ContentEntry
		var sha256 multihash.Multihash
		var size sql.NullInt64
		err := rows.Scan(&entry.Path, &size, &sha256)
		if err != nil {
			log.Print(err)
			break
		}
		if size.Valid {
			entry.Size = uint64(size.Int64)
		}
		mh, _ := multihash.Encode(sha256, multihash.SHA2_256)
		entry.Identifier = cid.NewCidV1(cid.Raw, mh)

		result = append(result, entry)
	}

	return result
}

func getEntriesForCID(identifier cid.Cid) []ContentEntry {

	mh, _ := multihash.Decode(identifier.Hash())
	if mh.Code == multihash.SHA2_256 {
		return handleQuery(sha256Statement.Query(mh.Digest))
	} else if mh.Code == multihash.MD5 {
		return handleQuery(md5Statement.Query(mh.Digest))
	}

	return []ContentEntry{}
}

func main() {
	//TODO: OCSP
	certificatePath := flag.String("certificate", "", "Path to SSL certificate file.")
	keypairPath := flag.String("keypair", "", "Path to SSL key file.")

	pgConnStr := flag.String("connstr", "", "Postgres connection string for postgres database")

	listenAddress := flag.String("listen", ":7777", "Address/port to lisent on.")

	trustedKeys := flag.String("trusted_keys", "", "Trusted list of public keys, comma separated.")

	sniAddressOption := flag.String("sni", "", "Define SNI address if desired. Empty will serve any requests regardless.")

	fdLimitOption := flag.Int("fdlimit", 512, "Maximum number of lingering cached open files.")

	debugOption := flag.Bool("debug", false, "Output debug information.")

	http2Option := flag.Bool("http2", false, "Enable HTTP/2")

	http3Option := flag.Bool("http3", false, "Enable HTTP/3")

	signatureCacheLimitOption := flag.Int("siglimit", 4096, "Maximum number of lingering valid signature cache results.")

	flag.Parse()

	fdlimit = *fdLimitOption
	contentmessage.SetMessageCacheLimit(*signatureCacheLimitOption)

	debugOutput = *debugOption

	var err error

	for _, k := range strings.Split(*trustedKeys, ",") {
		var publicKey ed25519.PublicKey
		publicKey, err = MakyuuIchaival.Bech32Encoding.DecodeString(strings.Trim(k, " "))
		if err != nil {
			log.Fatal(err)
		}

		if len(publicKey) != ed25519.PublicKeySize {
			continue
		}
		trustedPublicKeys = append(trustedPublicKeys, publicKey)
		log.Printf("Added public key %s", strings.Trim(k, " "))
	}

	dbHandle, err = sql.Open("postgres", *pgConnStr)
	if err != nil {
		log.Fatal(err)
	}

	defer dbHandle.Close()

	sha256Statement, err = dbHandle.Prepare("SELECT path, size, sha256 FROM entries WHERE sha256 = $1;")
	if err != nil {
		log.Fatal(err)
	}
	defer sha256Statement.Close()

	md5Statement, err = dbHandle.Prepare("SELECT path, size, sha256 FROM entries WHERE md5 = $1;")
	if err != nil {
		log.Fatal(err)
	}
	defer md5Statement.Close()

	tlsConfiguration, err := tlsutils.NewTLSConfiguration(*certificatePath, *keypairPath, strings.ToLower(*sniAddressOption))
	if err != nil {
		log.Fatal(err)
	}

	server := &httputils.Server{
		ListenAddress: *listenAddress,
		TLSConfig:     tlsConfiguration,
		EnableHTTP2:   *http2Option,
		EnableHTTP3:   *http3Option,
		Handler:       handle,
		Debug:         debugOutput,
	}

	server.Serve()

}