package api

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

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

func typesHandler(res http.ResponseWriter, req *http.Request) {
	var types = []string{}
	for t := range item.Types {
		types = append(types, string(t))
	}

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

	sendData(res, j, http.StatusOK)
}

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

	if _, ok := item.Types[t]; !ok {
		res.WriteHeader(http.StatusNotFound)
		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, j, http.StatusOK)
}

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

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

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

	defer push(res, pt, post)

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

	sendData(res, j, http.StatusOK)
}

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

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

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

	sendData(res, j, http.StatusOK)
}

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
}

func push(res http.ResponseWriter, pt func() interface{}, data []byte) {
	// Push(target string, opts *PushOptions) error
	if pusher, ok := res.(http.Pusher); ok {
		if p, ok := pt().(item.Pushable); ok {
			// get fields to pull values from data
			fields := p.Push()

			// parse values from data to push
			values := gjson.GetManyBytes(data, fields...)

			// push all values from Pushable items' fields
			for i := range values {
				val := values[i]
				val.ForEach(func(k, v gjson.Result) bool {
					err := pusher.Push(v.String(), nil)
					if err != nil {
						log.Println("Error during Push of value:", v.String())
					}

					return true
				})
			}
		}
	}

}

// sendData() should be used any time you want to communicate
// data back to a foreign client
func sendData(res http.ResponseWriter, data []byte, code int) {
	res.Header().Set("Access-Control-Allow-Headers", "Accept, Authorization, Content-Type")
	res.Header().Set("Access-Control-Allow-Origin", "*")
	res.Header().Set("Content-Type", "application/json")
	res.WriteHeader(code)
	_, 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
}

// CORS wraps a HandleFunc 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) {
		if req.Method == http.MethodOptions {
			sendPreflight(res)
			return
		}

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

// Record wraps a HandleFunc 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)
	})
}