package api

import (
	"bytes"
	"compress/gzip"
	"encoding/json"
	"log"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	"github.com/ponzu-cms/ponzu/system/api/analytics"
	"github.com/ponzu-cms/ponzu/system/db"
	"github.com/ponzu-cms/ponzu/system/item"
)

// deprecating from API, but going to provide code here in case someone wants it
func typesHandler(res http.ResponseWriter, req *http.Request) {
	var types = []string{}
	for t, fn := range item.Types {
		if !hide(fn(), res, req) {
			types = append(types, t)
		}
	}

	j, err := toJSON(types)
	if err != nil {
		res.WriteHeader(http.StatusInternalServerError)
		return
	}

	sendData(res, req, j)
}

func contentsHandler(res http.ResponseWriter, req *http.Request) {
	q := req.URL.Query()
	t := q.Get("type")
	if t == "" {
		res.WriteHeader(http.StatusBadRequest)
		return
	}

	it, ok := item.Types[t]
	if !ok {
		res.WriteHeader(http.StatusNotFound)
		return
	}

	if hide(it(), res, req) {
		return
	}

	count, err := strconv.Atoi(q.Get("count")) // int: determines number of posts to return (10 default, -1 is all)
	if err != nil {
		if q.Get("count") == "" {
			count = 10
		} else {
			res.WriteHeader(http.StatusInternalServerError)
			return
		}
	}

	offset, err := strconv.Atoi(q.Get("offset")) // int: multiplier of count for pagination (0 default)
	if err != nil {
		if q.Get("offset") == "" {
			offset = 0
		} else {
			res.WriteHeader(http.StatusInternalServerError)
			return
		}
	}

	order := strings.ToLower(q.Get("order")) // string: sort order of posts by timestamp ASC / DESC (DESC default)
	if order != "asc" {
		order = "desc"
	}

	opts := db.QueryOptions{
		Count:  count,
		Offset: offset,
		Order:  order,
	}

	_, bb := db.Query(t+"__sorted", opts)
	var result = []json.RawMessage{}
	for i := range bb {
		result = append(result, bb[i])
	}

	j, err := fmtJSON(result...)
	if err != nil {
		res.WriteHeader(http.StatusInternalServerError)
		return
	}

	sendData(res, req, j)
}

func contentHandler(res http.ResponseWriter, req *http.Request) {
	q := req.URL.Query()
	id := q.Get("id")
	t := q.Get("type")
	slug := q.Get("slug")

	if slug != "" {
		contentHandlerBySlug(res, req)
		return
	}

	if t == "" || id == "" {
		res.WriteHeader(http.StatusBadRequest)
		return
	}

	pt, ok := item.Types[t]
	if !ok {
		res.WriteHeader(http.StatusNotFound)
		return
	}

	if hide(pt(), res, req) {
		return
	}

	post, err := db.Content(t + ":" + id)
	if err != nil {
		res.WriteHeader(http.StatusInternalServerError)
		return
	}

	push(res, req, pt, post)

	j, err := fmtJSON(json.RawMessage(post))
	if err != nil {
		res.WriteHeader(http.StatusInternalServerError)
		return
	}

	sendData(res, req, j)
}

func contentHandlerBySlug(res http.ResponseWriter, req *http.Request) {
	slug := req.URL.Query().Get("slug")

	if slug == "" {
		res.WriteHeader(http.StatusBadRequest)
		return
	}

	// lookup type:id by slug key in __contentIndex
	t, post, err := db.ContentBySlug(slug)
	if err != nil {
		log.Println("Error finding content by slug:", slug, err)
		res.WriteHeader(http.StatusInternalServerError)
		return
	}

	it, ok := item.Types[t]
	if !ok {
		res.WriteHeader(http.StatusBadRequest)
		return
	}

	if hide(it(), res, req) {
		return
	}

	push(res, req, it, post)

	j, err := fmtJSON(json.RawMessage(post))
	if err != nil {
		res.WriteHeader(http.StatusInternalServerError)
		return
	}

	sendData(res, req, j)
}

func hide(it interface{}, res http.ResponseWriter, req *http.Request) bool {
	// check if should be hidden
	if h, ok := it.(item.Hideable); ok {
		err := h.Hide(res, req)
		if err == item.ErrAllowHiddenItem {
			return false
		}

		if err != nil {
			res.WriteHeader(http.StatusInternalServerError)
			return true
		}

		res.WriteHeader(http.StatusNotFound)
		return true
	}

	return false
}

func fmtJSON(data ...json.RawMessage) ([]byte, error) {
	var msg = []json.RawMessage{}
	for _, d := range data {
		msg = append(msg, d)
	}

	resp := map[string][]json.RawMessage{
		"data": msg,
	}

	var buf = &bytes.Buffer{}
	enc := json.NewEncoder(buf)
	err := enc.Encode(resp)
	if err != nil {
		log.Println("Failed to encode data to JSON:", err)
		return nil, err
	}

	return buf.Bytes(), nil
}

func toJSON(data []string) ([]byte, error) {
	var buf = &bytes.Buffer{}
	enc := json.NewEncoder(buf)
	resp := map[string][]string{
		"data": data,
	}

	err := enc.Encode(resp)
	if err != nil {
		log.Println("Failed to encode data to JSON:", err)
		return nil, err
	}

	return buf.Bytes(), nil
}

// sendData should be used any time you want to communicate
// data back to a foreign client
func sendData(res http.ResponseWriter, req *http.Request, data []byte) {
	res.Header().Set("Content-Type", "application/json")
	res.Header().Set("Vary", "Accept-Encoding")

	_, err := res.Write(data)
	if err != nil {
		log.Println("Error writing to response in sendData")
	}
}

// sendPreflight is used to respond to a cross-origin "OPTIONS" request
func sendPreflight(res http.ResponseWriter) {
	res.Header().Set("Access-Control-Allow-Headers", "Accept, Authorization, Content-Type")
	res.Header().Set("Access-Control-Allow-Origin", "*")
	res.WriteHeader(200)
	return
}

func responseWithCORS(res http.ResponseWriter, req *http.Request) (http.ResponseWriter, bool) {
	if db.ConfigCache("cors_disabled").(bool) == true {
		// check origin matches config domain
		domain := db.ConfigCache("domain").(string)
		origin := req.Header.Get("Origin")
		u, err := url.Parse(origin)
		if err != nil {
			log.Println("Error parsing URL from request Origin header:", origin)
			return res, false
		}

		// hack to get dev environments to bypass cors since u.Host (below) will
		// be empty, based on Go's url.Parse function
		if domain == "localhost" {
			domain = ""
		}
		origin = u.Host

		// currently, this will check for exact match. will need feedback to
		// determine if subdomains should be allowed or allow multiple domains
		// in config
		if origin == domain {
			// apply limited CORS headers and return
			res.Header().Set("Access-Control-Allow-Headers", "Accept, Authorization, Content-Type")
			res.Header().Set("Access-Control-Allow-Origin", domain)
			return res, true
		}

		// disallow request
		res.WriteHeader(http.StatusForbidden)
		return res, false
	}

	// apply full CORS headers and return
	res.Header().Set("Access-Control-Allow-Headers", "Accept, Authorization, Content-Type")
	res.Header().Set("Access-Control-Allow-Origin", "*")

	return res, true
}

// CORS wraps a HandlerFunc to respond to OPTIONS requests properly
func CORS(next http.HandlerFunc) http.HandlerFunc {
	return db.CacheControl(http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
		res, cors := responseWithCORS(res, req)
		if !cors {
			return
		}

		if req.Method == http.MethodOptions {
			sendPreflight(res)
			return
		}

		next.ServeHTTP(res, req)
	}))
}

// Record wraps a HandlerFunc to record API requests for analytical purposes
func Record(next http.HandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
		go analytics.Record(req)

		next.ServeHTTP(res, req)
	})
}

// Gzip wraps a HandlerFunc to compress responses when possible
func Gzip(next http.HandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
		if db.ConfigCache("gzip_disabled").(bool) == true {
			next.ServeHTTP(res, req)
			return
		}

		// check if req header content-encoding supports gzip
		if strings.Contains(req.Header.Get("Accept-Encoding"), "gzip") {
			// gzip response data
			res.Header().Set("Content-Encoding", "gzip")
			var gzres gzipResponseWriter
			if pusher, ok := res.(http.Pusher); ok {
				gzres = gzipResponseWriter{res, pusher, gzip.NewWriter(res)}
			} else {
				gzres = gzipResponseWriter{res, nil, gzip.NewWriter(res)}
			}

			next.ServeHTTP(gzres, req)
			return
		}

		next.ServeHTTP(res, req)
	})
}

type gzipResponseWriter struct {
	http.ResponseWriter
	pusher http.Pusher

	gw *gzip.Writer
}

func (gzw gzipResponseWriter) Write(p []byte) (int, error) {
	defer gzw.gw.Close()
	return gzw.gw.Write(p)
}

func (gzw gzipResponseWriter) Push(target string, opts *http.PushOptions) error {
	if opts == nil {
		opts = &http.PushOptions{
			Header: make(http.Header),
		}
	}

	opts.Header.Set("Accept-Encoding", "gzip")

	return gzw.pusher.Push(target, opts)
}