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package main

import (
	"crypto/ed25519"
	"encoding/base64"
	"fmt"
	"io"
	"log"
	"net/http"
	"sort"
	"strings"
)

// Try to peer with another server
func addPeer(peer string) error {
	peerHash := sha256sum(peer)
	// Check if already peered
	mu.Lock()
	_, ok := hashToDomain[peerHash]
	mu.Unlock()
	if ok {
		return nil
	}
	mu.Lock()
	hashToDomain[peerHash] = peer
	mu.Unlock()

	// Try request to peer
	log.Printf("%s trying to peer with %s", me, peer)
	resp, err := http.Get(peer + "/peer?peer=" + me)
	if err != nil {
		// Request failed, delete peer
		mu.Lock()
		delete(hashToDomain, peerHash)
		mu.Unlock()
		return err
	}

	log.Printf("%s successfully peered with %s", me, peer)
	mu.Lock()
	i := sort.SearchStrings(peerHashes, peerHash)
	peerHashes = append(peerHashes, "")
	copy(peerHashes[i+1:], peerHashes[i:])
	peerHashes[i] = peerHash
	myPos = sort.SearchStrings(peerHashes, me)
	mu.Unlock()
	// Read response body
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	// Try adding all peers of this peer
	newPeers := strings.Split(string(body), "\n")
	for _, newPeer := range newPeers[:len(newPeers)-1] {
		go addPeer(newPeer)
	}
	return nil
}

// Handle incoming peer requests
func peerHandler(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()
	peer := r.Form.Get("peer")
	if peer == "" {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	for _, p := range hashToDomain {
		fmt.Fprintf(w, "%s\n", p)
	}
	go addPeer(peer)
}

// Handle DHT requests
func dhtHandler(w http.ResponseWriter, r *http.Request) {
	key := r.URL.String()[5:]
	keyHash := sha256sum(key)
	pubKey := asPubKey(key)
	fmt.Println(key, keyHash, pubKey)
	mu.Lock()
	keyPos := sort.SearchStrings(peerHashes, keyHash)
	if keyPos < myPos {
		keyPos += len(peerHashes)
	}
	mu.Unlock()
	if r.Method == "GET" {
		if keyPos - myPos < 5 {
			mu.Lock()
			if val, ok := kvstore[key]; ok {
				w.Write([]byte(val))
			} else {
				w.WriteHeader(http.StatusNotFound)
			}
			mu.Unlock()
		} else {
			for i := 0; i < 5 && i < len(peerHashes); i++ {
				j := hashToDomain[peerHashes[(keyPos+i)%len(peerHashes)]]
				go func() string {
					resp, err := http.Get(j + r.URL.String())
					if err != nil {
						return ""
					}
					b, err := io.ReadAll(resp.Body)
					if err != nil {
						return ""
					}
					return string(b)
				}()

			}


		}
	} else if r.Method == "PUT" {
		// Read request body
		b, err := io.ReadAll(r.Body)
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		// Extract signature
		valSplit := strings.Split(string(b), "\n")
		sig := valSplit[len(valSplit)-1]
		// Verify signature
		if !ed25519.Verify(pubKey, b[:len(b)-len(sig)-1], []byte(sig)) {
			w.WriteHeader(http.StatusUnauthorized)
			return
		}
		if keyPos - myPos < 5 {
			mu.Lock()
			kvstore[key] = string(b[:len(b)-len(sig)-1])
			mu.Unlock()
		} else {

		}
	} else {
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}