package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net/http"
	"strings"
)

type DispatchFunction func([]string, []byte) (interface{}, error)

var apiRoutes = map[string]*(map[string]DispatchFunction){
	"version": &ApiVersionRouting,
	"themes":  &ApiThemesRouting,
	"teams":   &ApiTeamsRouting,
}

type apiRouting struct{}

func ApiHandler() http.Handler {
	return apiRouting{}
}

func (a apiRouting) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Printf("Handling %s request from %s: %s [%s]\n", r.Method, r.RemoteAddr, r.URL.Path, r.UserAgent())

	// Extract URL arguments
	var sURL = strings.Split(r.URL.Path, "/")[1:]
	if len(sURL) > 1 && sURL[len(sURL)-1] == "" {
		// Remove trailing /
		sURL = sURL[:len(sURL)-1]
	}

	w.Header().Set("Content-Type", "application/json")

	var ret interface{}
	var err error = nil

	// Read the body
	if r.ContentLength < 0 || r.ContentLength > 6553600 {
		http.Error(w, fmt.Sprintf("{errmsg:\"Request too large or request size unknown\"}", err), http.StatusRequestEntityTooLarge)
		return
	}
	var body []byte
	if r.ContentLength > 0 {
		tmp := make([]byte, 1024)
		for {
			n, err := r.Body.Read(tmp)
			for j := 0; j < n; j++ {
				body = append(body, tmp[j])
			}
			if err != nil || n <= 0 {
				break
			}
		}
	}

	// Route request
	if len(sURL) > 0 {
		if h, ok := apiRoutes[sURL[0]]; ok {
			if f, ok := (*h)[r.Method]; ok {
				ret, err = f(sURL[1:], body)
			} else {
				err = errors.New(fmt.Sprintf("Invalid action (%s) provided for %s.", r.Method, sURL[0]))
			}
		}
	} else {
		err = errors.New("No action provided.")
	}

	// Format response
	resStatus := http.StatusOK
	if err != nil {
		ret = map[string]string{"errmsg": err.Error()}
		resStatus = http.StatusBadRequest
		log.Println(r.RemoteAddr, resStatus, err.Error())
	}

	if ret == nil {
		ret = map[string]string{"errmsg": "Page not found"}
		resStatus = http.StatusNotFound
	}

	if str, found := ret.(string); found {
		w.WriteHeader(resStatus)
		io.WriteString(w, str)
	} else if j, err := json.Marshal(ret); err != nil {
		http.Error(w, fmt.Sprintf("{\"errmsg\":\"%q\"}", err), http.StatusInternalServerError)
	} else {
		w.WriteHeader(resStatus)
		w.Write(j)
	}
}