// A facebook graph api client in go.
// https://github.com/huandu/facebook/
//
// Copyright 2012 - 2015, Huan Du
// Licensed under the MIT license
// https://github.com/huandu/facebook/blob/master/LICENSE

// This is a Go library fully supports Facebook Graph API (both 1.0 and 2.x) with
// file upload, batch request, FQL and multi-FQL. It can be used in Google App Engine.
//
// Library design is highly influenced by facebook official PHP/JS SDK.
// If you have experience with PHP/JS SDK, you may feel quite familiar with it.
//
// Go to project home page to see samples. Link: https://github.com/huandu/facebook
//
// This library doesn't implement any deprecated old RESTful API. And it won't.
package facebook

import (
	"net/http"
)

var (
	// Default facebook api version.
	// It can be any valid version string (e.g. "v2.3") or empty.
	//
	// See https://developers.facebook.com/docs/apps/versions for details.
	Version string

	// Set app level debug mode.
	// After setting DebugMode, all newly created session will use the mode
	// to communicate with graph API.
	//
	// See https://developers.facebook.com/docs/graph-api/using-graph-api/v2.3#debugging
	Debug DebugMode
)

// Makes a facebook graph api call with default session.
//
// Method can be GET, POST, DELETE or PUT.
//
// Params represents query strings in this call.
// Keys and values in params will be encoded for URL automatically. So there is
// no need to encode keys or values in params manually. Params can be nil.
//
// If you want to get
//     https://graph.facebook.com/huandu?fields=name,username
// Api should be called as following
//     Api("/huandu", GET, Params{"fields": "name,username"})
// or in a simplified way
//     Get("/huandu", Params{"fields": "name,username"})
//
// Api is a wrapper of Session.Api(). It's designed for graph api that doesn't require
// app id, app secret and access token. It can be called in multiple goroutines.
//
// If app id, app secret or access token is required in graph api, caller should
// create a new facebook session through App instance instead.
func Api(path string, method Method, params Params) (Result, error) {
	return defaultSession.Api(path, method, params)
}

// Get is a short hand of Api(path, GET, params).
func Get(path string, params Params) (Result, error) {
	return Api(path, GET, params)
}

// Post is a short hand of Api(path, POST, params).
func Post(path string, params Params) (Result, error) {
	return Api(path, POST, params)
}

// Delete is a short hand of Api(path, DELETE, params).
func Delete(path string, params Params) (Result, error) {
	return Api(path, DELETE, params)
}

// Put is a short hand of Api(path, PUT, params).
func Put(path string, params Params) (Result, error) {
	return Api(path, PUT, params)
}

// Makes a batch facebook graph api call with default session.
//
// BatchApi supports most kinds of batch calls defines in facebook batch api document,
// except uploading binary data. Use Batch to do so.
//
// Note: API response is stored in "body" field of a Result.
//     results, _ := BatchApi(accessToken, Params{...}, Params{...})
//
//     // Use first batch api response.
//     var res1 *BatchResult
//     var err error
//     res1, err = results[0].Batch()
//
//     if err != nil {
//         // this is not a valid batch api response.
//     }
//
//     // Use BatchResult#Result to get response body content as Result.
//     res := res1.Result
//
// Facebook document: https://developers.facebook.com/docs/graph-api/making-multiple-requests
func BatchApi(accessToken string, params ...Params) ([]Result, error) {
	return Batch(Params{"access_token": accessToken}, params...)
}

// Makes a batch facebook graph api call with default session.
// Batch is designed for more advanced usage including uploading binary files.
//
// An uploading files sample
//     // equivalent to following curl command (borrowed from facebook docs)
//     //     curl \
//     //         -F 'access_token=…' \
//     //         -F 'batch=[{"method":"POST","relative_url":"me/photos","body":"message=My cat photo","attached_files":"file1"},{"method":"POST","relative_url":"me/photos","body":"message=My dog photo","attached_files":"file2"},]' \
//     //         -F 'file1=@cat.gif' \
//     //         -F 'file2=@dog.jpg' \
//     //         https://graph.facebook.com
//     Batch(Params{
//         "access_token": "the-access-token",
//         "file1": File("cat.gif"),
//         "file2": File("dog.jpg"),
//     }, Params{
//         "method": "POST",
//         "relative_url": "me/photos",
//         "body": "message=My cat photo",
//         "attached_files": "file1",
//     }, Params{
//         "method": "POST",
//         "relative_url": "me/photos",
//         "body": "message=My dog photo",
//         "attached_files": "file2",
//     })
//
// Facebook document: https://developers.facebook.com/docs/graph-api/making-multiple-requests
func Batch(batchParams Params, params ...Params) ([]Result, error) {
	return defaultSession.Batch(batchParams, params...)
}

// Makes a FQL query with default session.
// Returns a slice of Result. If there is no query result, the result is nil.
//
// FQL can only make query without "access_token". For query requiring "access_token", create
// Session and call its FQL method.
//
// Facebook document: https://developers.facebook.com/docs/technical-guides/fql#query
func FQL(query string) ([]Result, error) {
	return defaultSession.FQL(query)
}

// Makes a multi FQL query with default session.
// Returns a parsed Result. The key is the multi query key, and the value is the query result.
//
// MultiFQL can only make query without "access_token". For query requiring "access_token", create
// Session and call its MultiFQL method.
//
// See Session.MultiFQL document for samples.
//
// Facebook document: https://developers.facebook.com/docs/technical-guides/fql#multi
func MultiFQL(queries Params) (Result, error) {
	return defaultSession.MultiFQL(queries)
}

// Makes an arbitrary HTTP request with default session.
// It expects server responses a facebook Graph API response.
//     request, _ := http.NewRequest("https://graph.facebook.com/538744468", "GET", nil)
//     res, err := Request(request)
//     fmt.Println(res["gender"])  // get "male"
func Request(request *http.Request) (Result, error) {
	return defaultSession.Request(request)
}

// DefaultHttpClient returns the http client for default session.
func DefaultHttpClient() HttpClient {
	return defaultSession.HttpClient
}

// SetHttpClient updates the http client of default session.
func SetHttpClient(client HttpClient) {
	defaultSession.HttpClient = client
}