/*
Copyright 2011 Google Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package search

import (
	"fmt"
	"http"
	"log"
	"os"
	"sort"
	"strings"
	"sync"
	"time"

	"camli/blobref"
	"camli/blobserver"
	"camli/jsonconfig"
	"camli/httputil"
)

func init() {
	blobserver.RegisterHandlerConstructor("search", newHandlerFromConfig)
}

type Handler struct {
	index Index
	owner *blobref.BlobRef
}

func newHandlerFromConfig(ld blobserver.Loader, conf jsonconfig.Obj) (http.Handler, os.Error) {
	indexPrefix := conf.RequiredString("index") // TODO: add optional help tips here?
	ownerBlobStr := conf.RequiredString("owner")
	if err := conf.Validate(); err != nil {
		return nil, err
	}

	indexHandler, err := ld.GetHandler(indexPrefix)
	if err != nil {
		return nil, fmt.Errorf("search config references unknown handler %q", indexPrefix)
	}
	indexer, ok := indexHandler.(Index)
	if !ok {
		return nil, fmt.Errorf("search config references invalid indexer %q (actually a %T)", indexPrefix, indexHandler)
	}
	ownerBlobRef := blobref.Parse(ownerBlobStr)
	if ownerBlobRef == nil {
		return nil, fmt.Errorf("search 'owner' has malformed blobref %q; expecting e.g. sha1-xxxxxxxxxxxx",
			ownerBlobStr)
	}
	return &Handler{
		index: indexer,
		owner: ownerBlobRef,
	}, nil
}


// TODO: figure out a plan for an owner having multiple active public keys, or public
// key rotation
func (h *Handler) Owner() *blobref.BlobRef {
	return h.owner
}

func (h *Handler) Index() Index {
	return h.index
}

func jsonMap() map[string]interface{} {
	return make(map[string]interface{})
}

func jsonMapList() []map[string]interface{} {
	return make([]map[string]interface{}, 0)
}

func (sh *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()
	defer httputil.ReturnJson(rw, ret)

	_ = req.Header.Get("X-PrefixHandler-PathBase")
	suffix := req.Header.Get("X-PrefixHandler-PathSuffix")

	if req.Method == "GET" {
		switch suffix {
		case "camli/search/recent":
			sh.serveRecentPermanodes(rw, req)
			return
		case "camli/search/describe":
			sh.serveDescribe(rw, req)
			return
		case "camli/search/claims":
			sh.serveClaims(rw, req)
			return
		case "camli/search/files":
			sh.serveFiles(rw, req)
			return
		case "camli/search/signerattrvalue":
			sh.serveSignerAttrValue(rw, req)
			return
		case "camli/search/signerpaths":
			sh.serveSignerPaths(rw, req)
			return
		}
	}

	// TODO: discovery for the endpoints & better error message with link to discovery info
	ret["error"] = "Unsupported search path or method"
	ret["errorType"] = "input"
}

func (sh *Handler) serveRecentPermanodes(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()
	defer httputil.ReturnJson(rw, ret)

	ch := make(chan *Result)
	errch := make(chan os.Error)
	go func() {
		errch <- sh.index.GetRecentPermanodes(ch, []*blobref.BlobRef{sh.owner}, 50)
	}()

	dr := sh.NewDescribeRequest()

	recent := jsonMapList()
	for res := range ch {
		dr.Describe(res.BlobRef, 2)
		jm := jsonMap()
		jm["blobref"] = res.BlobRef.String()
		jm["owner"] = res.Signer.String()
		t := time.SecondsToUTC(res.LastModTime)
		jm["modtime"] = t.Format(time.RFC3339)
		recent = append(recent, jm)
	}

	err := <-errch
	if err != nil {
		// TODO: return error status code
		ret["error"] = fmt.Sprintf("%v", err)
		return
	}

	ret["recent"] = recent
	dr.PopulateJSON(ret)
}

func (sh *Handler) serveClaims(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()

	pn := blobref.Parse(req.FormValue("permanode"))
	if pn == nil {
		http.Error(rw, "Missing or invalid 'permanode' param", 400)
		return
	}

	// TODO: rename GetOwnerClaims to GetClaims?
	claims, err := sh.index.GetOwnerClaims(pn, sh.owner)
	if err != nil {
		log.Printf("Error getting claims of %s: %v", pn.String(), err)
	} else {
		sort.Sort(claims)
		jclaims := jsonMapList()

		for _, claim := range claims {
			jclaim := jsonMap()
			jclaim["blobref"] = claim.BlobRef.String()
			jclaim["signer"] = claim.Signer.String()
			jclaim["permanode"] = claim.Permanode.String()
			jclaim["date"] = claim.Date.Format(time.RFC3339)
			jclaim["type"] = claim.Type
			if claim.Attr != "" {
				jclaim["attr"] = claim.Attr
			}
			if claim.Value != "" {
				jclaim["value"] = claim.Value
			}

			jclaims = append(jclaims, jclaim)
		}
		ret["claims"] = jclaims
	}

	httputil.ReturnJson(rw, ret)
}

type DescribeRequest struct {
	sh *Handler

	lk   sync.Mutex             // protects m & done
	m    map[string]interface{} // top-level response JSON, TODO: ditch this
	done map[string]bool        // blobref -> described

	wg *sync.WaitGroup // for load requests
}

func (sh *Handler) NewDescribeRequest() *DescribeRequest {
	return &DescribeRequest{
		sh: sh,
		m:  make(map[string]interface{}), // TODO: ditch this, use Go data structure until the end
		wg: new(sync.WaitGroup),
	}
}

func (dr *DescribeRequest) PopulateJSON(dest map[string]interface{}) {
	dr.wg.Wait()
	dr.lk.Lock()
	defer dr.lk.Unlock()
	for k, v := range dr.m {
		dest[k] = v
	}
}

func (dr *DescribeRequest) blobRefMap(b *blobref.BlobRef) map[string]interface{} {
	dr.lk.Lock()
	defer dr.lk.Unlock()
	bs := b.String()
	if m, ok := dr.m[bs]; ok {
		return m.(map[string]interface{})
	}
	m := jsonMap()
	dr.m[bs] = m
	return m
}

func (dr *DescribeRequest) Describe(br *blobref.BlobRef, depth int) {
	if depth <= 0 {
		return
	}
	dr.lk.Lock()
	defer dr.lk.Unlock()
	if dr.done == nil {
		dr.done = make(map[string]bool)
	}
	if dr.done[br.String()] {
		return
	}
	dr.done[br.String()] = true
	dr.wg.Add(1)
	go func() {
		defer dr.wg.Done()
		dr.describeReally(br, depth)
	}()
}

func (dr *DescribeRequest) describeReally(br *blobref.BlobRef, depth int) {
	mime, size, err := dr.sh.index.GetBlobMimeType(br)
	if err == os.ENOENT {
		return
	}
	if err != nil {
		dr.lk.Lock()
		defer dr.lk.Unlock()
		dr.m["error"] = err.String()
		return
	}
	m := dr.blobRefMap(br)
	setMimeType(m, mime)
	m["size"] = size

	switch mime {
	case "application/json; camliType=permanode":
		pm := jsonMap()
		m["permanode"] = pm
		dr.populatePermanodeFields(pm, br, dr.sh.owner, depth)
	case "application/json; camliType=file":
		fm := jsonMap()
		m["file"] = fm
		dr.populateFileFields(fm, br)
	}
}

func (sh *Handler) serveDescribe(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()
	defer httputil.ReturnJson(rw, ret)

	br := blobref.Parse(req.FormValue("blobref"))
	if br == nil {
		ret["error"] = "Missing or invalid 'blobref' param"
		ret["errorType"] = "input"
		return
	}

	dr := sh.NewDescribeRequest()
	dr.Describe(br, 4)
	dr.PopulateJSON(ret)
}

func (sh *Handler) serveFiles(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()
	defer httputil.ReturnJson(rw, ret)

	br := blobref.Parse(req.FormValue("bytesref"))
	if br == nil {
		// TODO: formalize how errors are returned And make
		// ReturnJson set the HTTP status to 400 automatically
		// in some cases, if errorType is "input"?  Document
		// this somewhere.  Are there existing JSON
		// conventions to use?
		ret["error"] = "Missing or invalid 'bytesref' param"
		ret["errorType"] = "input"
		return
	}

	files, err := sh.index.ExistingFileSchemas(br)
	if err != nil {
		ret["error"] = err.String()
		ret["errorType"] = "server"
		return
	}

	strList := []string{}
	for _, br := range files {
		strList = append(strList, br.String())
	}
	ret["files"] = strList
	return
}

func (dr *DescribeRequest) populateFileFields(fm map[string]interface{}, fbr *blobref.BlobRef) {
	fi, err := dr.sh.index.GetFileInfo(fbr)
	if err != nil {
		return
	}
	fm["size"] = fi.Size
	fm["fileName"] = fi.FileName
	fm["mimeType"] = fi.MimeType
}

// dmap may be nil, returns the jsonMap to populate into
func (dr *DescribeRequest) populatePermanodeFields(jm map[string]interface{}, pn, signer *blobref.BlobRef, depth int) {
	//log.Printf("populate permanode %s depth %d", pn, depth)
	attr := jsonMap()
	jm["attr"] = attr

	claims, err := dr.sh.index.GetOwnerClaims(pn, signer)
	if err != nil {
		log.Printf("Error getting claims of %s: %v", pn.String(), err)
		jm["error"] = fmt.Sprintf("Error getting claims of %s: %v", pn.String(), err)
		return
	}

	sort.Sort(claims)
claimLoop:
	for _, cl := range claims {
		switch cl.Type {
		case "del-attribute":
			if cl.Value == "" {
				attr[cl.Attr] = nil, false
			} else {
				sl, ok := attr[cl.Attr].([]string)
				if ok {
					filtered := make([]string, 0, len(sl))
					for _, val := range sl {
						if val != cl.Value {
							filtered = append(filtered, val)
						}
					}
					attr[cl.Attr] = filtered
				}
			}
		case "set-attribute":
			attr[cl.Attr] = nil, false
			fallthrough
		case "add-attribute":
			if cl.Value == "" {
				continue
			}
			sl, ok := attr[cl.Attr].([]string)
			if ok {
				for _, exist := range sl {
					if exist == cl.Value {
						continue claimLoop
					}
				}
			} else {
				sl = make([]string, 0, 1)
				attr[cl.Attr] = sl
			}
			attr[cl.Attr] = append(sl, cl.Value)
		}
	}

	// If the content permanode is now known, look up its type
	if content, ok := attr["camliContent"].([]string); ok && len(content) > 0 {
		cbr := blobref.Parse(content[len(content)-1])
		dr.Describe(cbr, depth-1)
	}

	// Resolve children
	if member, ok := attr["camliMember"].([]string); ok && len(member) > 0 {
		for _, member := range member {
			membr := blobref.Parse(member)
			if membr != nil {
				dr.Describe(membr, depth-1)
			}
		}
	}
}

func mustGet(req *http.Request, param string) string {
	v := req.FormValue(param)
	if v == "" {
		panic(fmt.Sprintf("missing required parameter %q", param))
	}
	return v
}

func setPanicError(m map[string]interface{}) {
	p := recover()
	if p == nil {
		return
	}
	m["error"] = p.(string)
	m["errorType"] = "input"
}

func (sh *Handler) serveSignerAttrValue(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()
	defer httputil.ReturnJson(rw, ret)
	defer setPanicError(ret)

	signer := blobref.MustParse(mustGet(req, "signer"))
	attr := mustGet(req, "attr")
	value := mustGet(req, "value")
	pn, err := sh.index.PermanodeOfSignerAttrValue(signer, attr, value)
	if err != nil {
		ret["error"] = err.String()
	} else {
		ret["permanode"] = pn.String()

		dr := sh.NewDescribeRequest()
		dr.Describe(pn, 2)
		dr.PopulateJSON(ret)
	}
}

func (sh *Handler) serveSignerPaths(rw http.ResponseWriter, req *http.Request) {
	ret := jsonMap()
	defer httputil.ReturnJson(rw, ret)
	defer setPanicError(ret)

	signer := blobref.MustParse(mustGet(req, "signer"))
	target := blobref.MustParse(mustGet(req, "target"))
	paths, err := sh.index.PathsOfSignerTarget(signer, target)
	if err != nil {
		ret["error"] = err.String()
	} else {
		jpaths := []map[string]interface{}{}
		for _, path := range paths {
			jpaths = append(jpaths, map[string]interface{}{
				"claimRef": path.Claim.String(),
				"baseRef":  path.Base.String(),
				"suffix":   path.Suffix,
			})
		}
		ret["paths"] = jpaths
		dr := sh.NewDescribeRequest()
		for _, path := range paths {
			dr.Describe(path.Base, 2)
		}
		dr.PopulateJSON(ret)
	}
}

const camliTypePrefix = "application/json; camliType="

func setMimeType(m map[string]interface{}, mime string) {
	m["type"] = mime
	if strings.HasPrefix(mime, camliTypePrefix) {
		m["camliType"] = mime[len(camliTypePrefix):]
	}
}