package main

import (
    "fmt"
    fb "github.com/huandu/facebook"
)

func main() {
    res, _ := fb.Get("/538744468", fb.Params{
        "fields": "username",
        "access_token": "a-valid-access-token",
    })
    fmt.Println("here is my facebook username:", res["username"])
}

// Decode "username" to a go string.
var username string
res.DecodeField("username", &username)
fmt.Println("alternative way to get username:", username)

// It's also possible to decode the whole result into a predefined struct.
type User struct {
    Username string
}

var user User
res.Decode(&user)
fmt.Println("print username in struct:", user.Username)

res, err := fb.Get("/me/feed", fb.Params{
     "access_token": "a-valid-access-token",
})

if err != nil {
    // err can be an facebook API error.
    // if so, the Error struct contains error details.
    if e, ok := err.(*Error); ok {
        fmt.Logf("facebook error. [message:%v] [type:%v] [code:%v] [subcode:%v]",
            e.Message, e.Type, e.Code, e.ErrorSubcode)
        return
    }

    return
}

// read my last feed.
fmt.Println("my latest feed story is:", res.Get("data.0.story"))

res, _ := fb.Get("/search", fb.Params{
        "access_token": "a-valid-access-token",
        "type":         "page",
        "q":            "nightlife,singapore",
    })

var items []fb.Result

err := res.DecodeField("data", &items)

if err != nil {
    fmt.Logf("An error has happened %v", err)
    return
}

for _, item := range items {
    fmt.Println(item["id"])
}

// create a global App var to hold app id and secret.
var globalApp = fb.New("your-app-id", "your-app-secret")

// facebook asks for a valid redirect uri when parsing signed request.
// it's a new enforced policy starting in late 2013.
globalApp.RedirectUri = "http://your.site/canvas/url/"

// here comes a client with a facebook signed request string in query string.
// creates a new session with signed request.
session, _ := globalApp.SessionFromSignedRequest(signedRequest)

// if there is another way to get decoded access token,
// creates a session directly with the token.
session := globalApp.Session(token)

// validate access token. err is nil if token is valid.
err := session.Validate()

// use session to send api request with access token.
res, _ := session.Get("/me/feed", nil)

res, _ := session.Get("/me/home", nil)

// create a paging structure.
paging, _ := res.Paging(session)

// get current results.
results := paging.Data()

// get next page.
noMore, err := paging.Next()
results = paging.Data()

type Data struct {
    FooBar string  // "FooBar" maps to "foo_bar" in JSON automatically in this case.
}

// define a facebook feed object.
type FacebookFeed struct {
    Id          string `facebook:",required"`             // this field must exist in response.
                                                          // mind the "," before "required".
    Story       string
    FeedFrom    *FacebookFeedFrom `facebook:"from"`       // use customized field name "from"
    CreatedTime string `facebook:"created_time,required"` // both customized field name and "required" flag.
}

type FacebookFeedFrom struct {
    Name, Id string
}

// create a feed object direct from graph api result.
var feed FacebookFeed
res, _ := session.Get("/me/feed", nil)
res.DecodeField("data.0", &feed) // read latest feed

params1 := Params{
    "method": fb.GET,
    "relative_url": "me",
}
params2 := Params{
    "method": fb.GET,
    "relative_url": uint64(100002828925788),
}
results, err := fb.BatchApi(your_access_token, params1, params2)

if err != nil {
    // check error...
    return
}

// batchResult1 and batchResult2 are response for params1 and params2.
batchResult1, _ := results[0].Batch()
batchResult2, _ := results[1].Batch()

// Use parsed result.
var id string
res := batchResult1.Result
res.DecodeField("id", &id)

// Use response header.
contentType := batchResult1.Header.Get("Content-Type")

results, _ := fb.FQL("SELECT username FROM page WHERE page_id = 20531316728")
fmt.Println(results[0]["username"]) // print "facebook"

// most FQL query requires access token. create session to hold access token.
session := &fb.Session{}
session.SetAccessToken("A-VALID-ACCESS-TOKEN")
results, _ := session.FQL("SELECT username FROM page WHERE page_id = 20531316728")
fmt.Println(results[0]["username"]) // print "facebook"

res, _ := fb.MultiFQL(Params{
    "query1": "SELECT username FROM page WHERE page_id = 20531316728",
    "query2": "SELECT uid FROM user WHERE uid = 538744468",
})
var query1, query2 []Result

// get response for query1 and query2.
res.DecodeField("query1", &query1)
res.DecodeField("query2", &query2)

// most FQL query requires access token. create session to hold access token.
session := &fb.Session{}
session.SetAccessToken("A-VALID-ACCESS-TOKEN")
res, _ := session.MultiFQL(Params{
    "query1": "...",
    "query2": "...",
})

// same as the sample without access token...

import (
    "appengine"
    "appengine/urlfetch"
)

// suppose it's the appengine context initialized somewhere.
var context appengine.Context

// default Session object uses http.DefaultClient which is not allowed to use
// in appengine. one has to create a Session and assign it a special client.
seesion := globalApp.Session("a-access-token")
session.HttpClient = urlfetch.Client(context)

// now, session uses appengine http client now.
res, err := session.Get("/me", nil)

// this package uses default version which is controlled by facebook app setting.
// change following global variable to specific a global default version.
fb.Version = "v2.0"

// starting with graph api v2.0, it's not allowed to get user information without access token.
fb.Api("huan.du", GET, nil)

// it's possible to specify version per session.
session := &fb.Session{}
session.Version = "v2.0" // overwrite global default.

globalApp := fb.New("your-app-id", "your-app-secret")

// enable "appsecret_proof" for all sessions created by this app.
globalApp.EnableAppsecretProof = true

// all calls in this session are secured.
session := globalApp.Session("a-valid-access-token")
session.Get("/me", nil)

// it's also possible to enable/disable this feature per session.
session.EnableAppsecretProof(false)

fb.Debug = fb.DEBUG_ALL

res, _ := fb.Get("/me", fb.Params{"access_token": "xxx"})
debugInfo := res.DebugInfo()

fmt.Println("http headers:", debugInfo.Header)
fmt.Println("facebook api version:", debugInfo.FacebookApiVersion)