package api

import (
	"bufio"
	"fmt"
	"io"
	"math/big"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"

	"github.com/ethereum/go-ethereum/swarm/storage"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/chequebook"
	"github.com/ethereum/go-ethereum/common/registrar"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/logger"
	"github.com/ethereum/go-ethereum/logger/glog"
)

var (
	hashMatcher      = regexp.MustCompile("^[0-9A-Fa-f]{64}")
	slashes          = regexp.MustCompile("/+")
	domainAndVersion = regexp.MustCompile("[@:;,]+")
)

/*
Api implements webserver/file system related content storage and retrieval
on top of the dpa
it is the public interface of the dpa which is included in the ethereum stack
*/
type Api struct {
	dpa       *storage.DPA
	registrar registrar.VersionedRegistrar
	conf      *Config
}

//the api constructor initialises
func NewApi(dpa *storage.DPA, registrar registrar.VersionedRegistrar, conf *Config) (self *Api) {
	return &Api{dpa, registrar, conf}
}

// this should move over to chequebook ipc api
func (self *Api) Issue(beneficiary common.Address, amount *big.Int) (cheque *chequebook.Cheque, err error) {
	return self.conf.Swap.Chequebook().Issue(beneficiary, amount)
}

func (self *Api) Cash(cheque *chequebook.Cheque) (txhash string, err error) {
	return self.conf.Swap.Chequebook().Cash(cheque)
}

func (self *Api) Deposit(amount *big.Int) (txhash string, err error) {
	return self.conf.Swap.Chequebook().Deposit(amount)
}

// serialisable info about swarm
type Info struct {
	*Config
	*chequebook.Params
}

func (self *Api) Info() *Info {

	return &Info{
		Config: self.conf,
		Params: chequebook.ContractParams,
	}

}

// Get uses iterative manifest retrieval and prefix matching
// to resolve path to content using dpa retrieve
func (self *Api) Get(bzzpath string) (content []byte, mimeType string, status int, size int, err error) {
	var reader storage.SectionReader
	reader, mimeType, status, err = self.getPath("/" + bzzpath)
	if err != nil {
		return
	}
	content = make([]byte, reader.Size())
	size, err = reader.Read(content)
	if err == io.EOF {
		err = nil
	}
	return
}

// Put provides singleton manifest creation and optional name registration
// on top of dpa store
func (self *Api) Put(content, contentType string) (string, error) {
	sr := io.NewSectionReader(strings.NewReader(content), 0, int64(len(content)))
	wg := &sync.WaitGroup{}
	key, err := self.dpa.Store(sr, wg)
	if err != nil {
		return "", err
	}
	manifest := fmt.Sprintf(`{"entries":[{"hash":"%v","contentType":"%s"}]}`, key, contentType)
	sr = io.NewSectionReader(strings.NewReader(manifest), 0, int64(len(manifest)))
	key, err = self.dpa.Store(sr, wg)
	if err != nil {
		return "", err
	}
	wg.Wait()
	return key.String(), nil
}

func (self *Api) Modify(rootHash, path, contentHash, contentType string) (newRootHash string, err error) {
	root := common.Hex2Bytes(rootHash)
	trie, err := loadManifest(self.dpa, root)
	if err != nil {
		return
	}

	if contentHash != "" {
		entry := &manifestTrieEntry{
			Path:        path,
			Hash:        contentHash,
			ContentType: contentType,
		}
		trie.addEntry(entry)
	} else {
		trie.deleteEntry(path)
	}

	err = trie.recalcAndStore()
	if err != nil {
		return
	}
	return trie.hash.String(), nil
}

const maxParallelFiles = 5

// Download replicates the manifest path structure on the local filesystem
// under localpath
func (self *Api) Download(bzzpath, localpath string) (err error) {
	lpath, err := filepath.Abs(filepath.Clean(localpath))
	if err != nil {
		return
	}
	err = os.MkdirAll(lpath, os.ModePerm)
	if err != nil {
		return
	}

	parts := slashes.Split(bzzpath, 3)
	if len(parts) < 2 {
		return fmt.Errorf("Invalid bzz path")
	}
	hostPort := parts[1]
	var path string
	if len(parts) > 2 {
		path = regularSlashes(parts[2]) + "/"
	}
	glog.V(logger.Debug).Infof("[BZZ] Swarm: host: '%s', path '%s' requested.", hostPort, path)

	//resolving host and port
	var key storage.Key
	key, err = self.Resolve(hostPort)
	if err != nil {
		err = errResolve(err)
		glog.V(logger.Debug).Infof("[BZZ] Swarm: error : %v", err)
		return
	}

	trie, err := loadManifest(self.dpa, key)
	if err != nil {
		glog.V(logger.Debug).Infof("[BZZ] Swarm: loadManifestTrie error: %v", err)
		return
	}

	type downloadListEntry struct {
		key  storage.Key
		path string
	}

	var list []*downloadListEntry
	var mde, mderr error

	prevPath := lpath
	err = trie.listWithPrefix(path, func(entry *manifestTrieEntry, suffix string) { // TODO: paralellize
		key := common.Hex2Bytes(entry.Hash)
		path := lpath + "/" + suffix
		dir := filepath.Dir(path)
		if dir != prevPath {
			mde = os.MkdirAll(dir, os.ModePerm)
			if mde != nil {
				mderr = mde
			}
			prevPath = dir
		}
		if (mde == nil) && (path != dir+"/") {
			list = append(list, &downloadListEntry{key: key, path: path})
		}
	})
	if err == nil {
		err = mderr
	}

	cnt := len(list)
	errors := make([]error, cnt)
	done := make(chan bool, maxParallelFiles)
	dcnt := 0

	for i, entry := range list {
		if i >= dcnt+maxParallelFiles {
			<-done
			dcnt++
		}
		go func(i int, entry *downloadListEntry, done chan bool) {
			f, err := os.Create(entry.path) // TODO: path separators
			if err == nil {
				reader := self.dpa.Retrieve(entry.key)
				writer := bufio.NewWriter(f)
				_, err = io.CopyN(writer, reader, reader.Size()) // TODO: handle errors
				err2 := writer.Flush()
				if err == nil {
					err = err2
				}
				err2 = f.Close()
				if err == nil {
					err = err2
				}
			}

			errors[i] = err
			done <- true
		}(i, entry, done)
	}
	for dcnt < cnt {
		<-done
		dcnt++
	}

	if err != nil {
		return
	}
	for i, _ := range list {
		if errors[i] != nil {
			return errors[i]
		}
	}
	return
}

// Upload replicates a local directory as a manifest file and uploads it
// using dpa store
// TODO: localpath should point to a manifest
func (self *Api) Upload(lpath, index string) (string, error) {
	var list []*manifestTrieEntry
	localpath, err := filepath.Abs(filepath.Clean(lpath))
	if err != nil {
		return "", err
	}

	f, err := os.Open(localpath)
	if err != nil {
		return "", err
	}
	stat, err := f.Stat()
	if err != nil {
		return "", err
	}

	var start int
	if stat.IsDir() {
		start = len(localpath)
		glog.V(logger.Debug).Infof("[BZZ] uploading '%s'", localpath)
		err = filepath.Walk(localpath, func(path string, info os.FileInfo, err error) error {
			if (err == nil) && !info.IsDir() {
				//fmt.Printf("lp %s  path %s\n", localpath, path)
				if len(path) <= start {
					return fmt.Errorf("Path is too short")
				}
				if path[:start] != localpath {
					return fmt.Errorf("Path prefix of '%s' does not match localpath '%s'", path, localpath)
				}
				entry := &manifestTrieEntry{
					Path: path,
				}
				list = append(list, entry)
			}
			return err
		})
		if err != nil {
			return "", err
		}
	} else {
		dir := filepath.Dir(localpath)
		start = len(dir)
		if len(localpath) <= start {
			return "", fmt.Errorf("Path is too short")
		}
		if localpath[:start] != dir {
			return "", fmt.Errorf("Path prefix of '%s' does not match dir '%s'", localpath, dir)
		}
		entry := &manifestTrieEntry{
			Path: localpath,
		}
		list = append(list, entry)
	}

	cnt := len(list)
	errors := make([]error, cnt)
	done := make(chan bool, maxParallelFiles)
	dcnt := 0

	for i, entry := range list {
		if i >= dcnt+maxParallelFiles {
			<-done
			dcnt++
		}
		go func(i int, entry *manifestTrieEntry, done chan bool) {
			f, err := os.Open(entry.Path)
			if err == nil {
				stat, _ := f.Stat()
				sr := io.NewSectionReader(f, 0, stat.Size())
				wg := &sync.WaitGroup{}
				var hash storage.Key
				hash, err = self.dpa.Store(sr, wg)
				if hash != nil {
					list[i].Hash = hash.String()
				}
				wg.Wait()
				if err == nil {
					first512 := make([]byte, 512)
					fread, _ := sr.ReadAt(first512, 0)
					if fread > 0 {
						mimeType := http.DetectContentType(first512[:fread])
						if filepath.Ext(entry.Path) == ".css" {
							mimeType = "text/css"
						}
						list[i].ContentType = mimeType
						//fmt.Printf("%v %v %v\n", entry.Path, mimeType, filepath.Ext(entry.Path))
					}
				}
				f.Close()
			}
			errors[i] = err
			done <- true
		}(i, entry, done)
	}
	for dcnt < cnt {
		<-done
		dcnt++
	}

	trie := &manifestTrie{
		dpa: self.dpa,
	}
	for i, entry := range list {
		if errors[i] != nil {
			return "", errors[i]
		}
		entry.Path = regularSlashes(entry.Path[start:])
		if entry.Path == index {
			ientry := &manifestTrieEntry{
				Path:        "",
				Hash:        entry.Hash,
				ContentType: entry.ContentType,
			}
			trie.addEntry(ientry)
		}
		trie.addEntry(entry)
	}

	err2 := trie.recalcAndStore()
	var hs string
	if err2 == nil {
		hs = trie.hash.String()
	}
	return hs, err2
}

func (self *Api) Register(sender common.Address, domain string, hash common.Hash) (err error) {
	domainhash := common.BytesToHash(crypto.Sha3([]byte(domain)))

	if self.registrar != nil {
		glog.V(logger.Debug).Infof("[BZZ] Swarm: host '%s' (hash: '%v') to be registered as '%v'", domain, domainhash.Hex(), hash.Hex())
		_, err = self.registrar.Registry().SetHashToHash(sender, domainhash, hash)
	} else {
		err = fmt.Errorf("no registry: %v", err)
	}
	return
}

type errResolve error

func (self *Api) Resolve(hostPort string) (contentHash storage.Key, err error) {
	host := hostPort
	if hashMatcher.MatchString(host) {
		contentHash = storage.Key(common.Hex2Bytes(host))
		glog.V(logger.Debug).Infof("[BZZ] Swarm: host is a contentHash: '%v'", contentHash)
	} else {
		if self.registrar != nil {
			var hash common.Hash
			var version *big.Int
			parts := domainAndVersion.Split(host, 3)
			if len(parts) > 1 && parts[1] != "" {
				host = parts[0]
				version = common.Big(parts[1])
			}
			hostHash := crypto.Sha3Hash([]byte(host))
			hash, err = self.registrar.Resolver(version).HashToHash(hostHash)
			if err != nil {
				err = fmt.Errorf("unable to resolve '%s': %v", hostPort, err)
			}
			contentHash = storage.Key(hash.Bytes())
			glog.V(logger.Debug).Infof("[BZZ] Swarm: resolve host '%s' to contentHash: '%v'", hostPort, contentHash)
		} else {
			err = fmt.Errorf("no resolver '%s': %v", hostPort, err)
		}
	}
	return
}

func (self *Api) getPath(uri string) (reader storage.SectionReader, mimeType string, status int, err error) {
	parts := slashes.Split(uri, 3)
	hostPort := parts[1]
	var path string
	if len(parts) > 2 {
		path = parts[2]
	}
	glog.V(logger.Debug).Infof("[BZZ] Swarm: host: '%s', path '%s' requested.", hostPort, path)

	//resolving host and port
	var key storage.Key
	key, err = self.Resolve(hostPort)
	if err != nil {
		err = errResolve(err)
		glog.V(logger.Debug).Infof("[BZZ] Swarm: error : %v", err)
		return
	}

	trie, err := loadManifest(self.dpa, key)
	if err != nil {
		glog.V(logger.Debug).Infof("[BZZ] Swarm: loadManifestTrie error: %v", err)
		return
	}

	glog.V(logger.Debug).Infof("[BZZ] Swarm: getEntry(%s)", path)
	entry, _ := trie.getEntry(path)
	if entry != nil {
		key = common.Hex2Bytes(entry.Hash)
		status = entry.Status
		mimeType = entry.ContentType
		glog.V(logger.Debug).Infof("[BZZ] Swarm: content lookup key: '%v' (%v)", key, mimeType)
		reader = self.dpa.Retrieve(key)
	} else {
		err = fmt.Errorf("manifest entry for '%s' not found", path)
		glog.V(logger.Debug).Infof("[BZZ] Swarm: %v", err)
	}
	return
}