/******************************************************************************
 * A Discord API for Golang.
 * See discord.go for more information.
 *
 * This file contains functions for interacting with the Discord HTTP REST API
 * at the lowest level.
 */

package discordgo

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"time"
)

// Constants of known Discord API Endpoints
// Please let me know if you know of any others.
const (
	// Base URLS
	DISCORD  = "http://discordapp.com"
	API      = DISCORD + "/api"
	SERVERS  = API + "/guilds"
	CHANNELS = API + "/channels"
	USERS    = API + "/users"
	LOGIN    = API + "/auth/login"
	LOGOUT   = API + "/auth/logout"
	GATEWAY  = API + "/gateway"

	// Constants not implemented below yet. TODO tracker :)
	REGISTER        = API + "/auth/register"
	INVITE          = API + "/invite"
	TRACK           = API + "/track"
	SSO             = API + "/sso"
	VERIFY          = API + "/auth/verify"
	VERIFY_RESEND   = API + "/auth/verify/resend"
	FORGOT_PASSWORD = API + "/auth/forgot"
	RESET_PASSWORD  = API + "/auth/reset"
	REGIONS         = API + "/voice/regions"
	ICE             = API + "/voice/ice"
	REPORT          = API + "/report"
	INTEGRATIONS    = API + "/integrations"
	// Authenticated User Info
	AU             = USERS + "/@me"
	AU_DEVICES     = AU + "/devices"
	AU_SETTINGS    = AU + "/settings"
	AU_CONNECTIONS = AU + "/connections"
	AU_CHANNELS    = AU + "/channels"
	AU_SERVERS     = AU + "/guilds"

	// Need a way to handle these here so the variables can be inserted.
	// Maybe defined as functions?
	/*
		INTEGRATIONS_JOIN: integrationId => `/integrations/${integrationId}/join`,
		AVATAR: (userId, hash) => `/users/${userId}/avatars/${hash}.jpg`,
		MESSAGES: channelId => `/channels/${channelId}/messages`,
		INSTANT_INVITES: channelId => `/channels/${channelId}/invites`,
		TYPING: channelId => `/channels/${channelId}/typing`,
		CHANNEL_PERMISSIONS: channelId => `/channels/${channelId}/permissions`,
		TUTORIAL: `/tutorial`,
		TUTORIAL_INDICATORS: `/tutorial/indicators`,
		USER_CHANNELS: userId => `/users/${userId}/channels`,
		GUILD_CHANNELS: guildId => `/guilds/${guildId}/channels`,
		GUILD_MEMBERS: guildId => `/guilds/${guildId}/members`,
		GUILD_INTEGRATIONS: guildId => `/guilds/${guildId}/integrations`,
		GUILD_BANS: guildId => `/guilds/${guildId}/bans`,
		GUILD_ROLES: guildId => `/guilds/${guildId}/roles`,
		GUILD_INSTANT_INVITES: guildId => `/guilds/${guildId}/invites`,
		GUILD_EMBED: guildId => `/guilds/${guildId}/embed`,
		GUILD_PRUNE: guildId => `/guilds/${guildId}/prune`,
		GUILD_ICON: (guildId, hash) => `/guilds/${guildId}/icons/${hash}.jpg`,
	*/

)

// Request makes a (GET/POST/?) Requests to Discord REST API.
// All the other functions in this file use this function.
func (s *Session) Request(method, urlStr, body string) (response []byte, err error) {

	if s.Debug {
		fmt.Println("REQUEST  :: " + method + " " + urlStr + "\n" + body)
	}

	req, err := http.NewRequest(method, urlStr, bytes.NewBuffer([]byte(body)))
	if err != nil {
		return
	}

	// Not used on initial login..
	if s.Token != "" {
		req.Header.Set("authorization", s.Token)
	}

	req.Header.Set("Content-Type", "application/json")
	client := &http.Client{Timeout: (20 * time.Second)}

	resp, err := client.Do(req)
	if err != nil {
		return
	}

	response, err = ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}
	resp.Body.Close()

	if resp.StatusCode != 204 && resp.StatusCode != 200 {
		err = errors.New(fmt.Sprintf("StatusCode: %d, %s", resp.StatusCode, string(response)))
		return
	}

	if s.Debug {
		var prettyJSON bytes.Buffer
		error := json.Indent(&prettyJSON, response, "", "\t")
		if error != nil {
			fmt.Print("JSON parse error: ", error)
			return
		}
		fmt.Println("RESPONSE ::\n" + string(prettyJSON.Bytes()))
	}
	return
}

// Login asks the Discord server for an authentication token
func (s *Session) Login(email string, password string) (token string, err error) {

	response, err := s.Request("POST", LOGIN, fmt.Sprintf(`{"email":"%s", "password":"%s"}`, email, password))

	var temp map[string]interface{}
	err = json.Unmarshal(response, &temp)
	token = temp["token"].(string)

	return
}

// Returns the user details of the given userId
// session : An active session connection to Discord
// user    : A user Id or name
func (s *Session) Users(userId string) (user User, err error) {

	body, err := s.Request("GET", fmt.Sprintf("%s/%s", USERS, userId), ``)
	err = json.Unmarshal(body, &user)
	return
}

// USERS could pull users channels, servers, settings and so forth too?
// you know, pull all the data for the user.  update the user strut
// to house that data.  Seems reasonable.

// PrivateChannels returns an array of Channel structures for all private
// channels for a user
func (s *Session) PrivateChannels(userId string) (channels []Channel, err error) {

	body, err := s.Request("GET", fmt.Sprintf("%s/%s/channels", USERS, userId), ``)
	err = json.Unmarshal(body, &channels)

	return
}

// Guilds returns an array of Guild structures for all servers for a user
func (s *Session) Guilds(userId string) (servers []Guild, err error) {

	body, err := s.Request("GET", fmt.Sprintf("%s/%s/guilds", USERS, userId), ``)
	err = json.Unmarshal(body, &servers)

	return
}

// add one to get specific server by ID, or enhance the above with an ID field.
// GET http://discordapp.com/api/guilds/ID#

// Members returns an array of Member structures for all members of a given
// server.
func (s *Session) Members(serverId int) (members []Member, err error) {

	body, err := s.Request("GET", fmt.Sprintf("%s/%d/members", SERVERS, serverId), ``)
	err = json.Unmarshal(body, &members)

	return
}

// Channels returns an array of Channel structures for all channels of a given
// server.
func (s *Session) Channels(serverId int) (channels []Channel, err error) {

	body, err := s.Request("GET", fmt.Sprintf("%s/%d/channels", SERVERS, serverId), ``)
	err = json.Unmarshal(body, &channels)

	return
}

// update above or add a way to get channel by ID.  ChannelByName could be handy
// too you know.
// http://discordapp.com/api/channels/ID#

// Messages returns an array of Message structures for messaages within a given
// channel.  limit, beforeId, and afterId can be used to control what messages
// are returned.
func (s *Session) Messages(channelId int, limit int, beforeId int, afterId int) (messages []Message, err error) {

	var urlStr string

	if limit > 0 {
		urlStr = fmt.Sprintf("%s/%d/messages?limit=%d", CHANNELS, channelId, limit)
	}

	if afterId > 0 {
		if urlStr != "" {
			urlStr = urlStr + fmt.Sprintf("&after=%d", afterId)
		} else {
			urlStr = fmt.Sprintf("%s/%d/messages?after=%d", CHANNELS, channelId, afterId)
		}
	}

	if beforeId > 0 {
		if urlStr != "" {
			urlStr = urlStr + fmt.Sprintf("&before=%d", beforeId)
		} else {
			urlStr = fmt.Sprintf("%s/%d/messages?after=%d", CHANNELS, channelId, beforeId)
		}
	}

	if urlStr == "" {
		urlStr = fmt.Sprintf("%s/%d/messages", CHANNELS, channelId)
	}

	body, err := s.Request("GET", urlStr, ``)
	err = json.Unmarshal(body, &messages)

	return
}

// SendMessage sends a message to the given channel.
func (s *Session) SendMessage(channelId int, content string) (message Message, err error) {

	var urlStr string = fmt.Sprintf("%s/%d/messages", CHANNELS, channelId)
	response, err := s.Request("POST", urlStr, fmt.Sprintf(`{"content":"%s"}`, content))
	err = json.Unmarshal(response, &message)

	return
}

// Returns the a websocket Gateway address
// session : An active session connection to Discord
func (s *Session) Gateway() (gateway string, err error) {

	response, err := s.Request("GET", GATEWAY, ``)

	var temp map[string]interface{}
	err = json.Unmarshal(response, &temp)
	gateway = temp["url"].(string)
	return
}

// Close ends a session and logs out from the Discord REST API.
// This does not seem to actually invalidate the token.  So you can still
// make API calls even after a Logout.  So, it seems almost pointless to
// even use.
func (s *Session) Logout() (err error) {

	_, err = s.Request("POST", LOGOUT, fmt.Sprintf(`{"token": "%s"}`, s.Token))

	return
}