penguin/golifehk

datasources/mtr/bus/busschedule.go

raw · 3559 bytes

package bus

import (
    "fmt"
    "bytes"
    "encoding/json"
    "io"
    "log"
    "net/http"
    "path/filepath"
    "time"

    "github.com/tgckpg/golifehk/utils"
)

type Location struct {
    latitude float32
    longitude float32
}

type Bus struct {
    ETA int `json:"arrivalTimeInSecond,string"`
    ETAText string `json:"arrivalTimeText"`
    BusId string `json:"busId"`
    BusLocation Location `json:"busLocation"`
    ETD string `json:"departureTimeInSecond"`
    ETDText string `json:"departureTimeText"`
    Delayed string `json:"isDelayed"`
    Scheduled string `json:"isScheduled"`
    LineRef string `json:"lineRef"`
}

type BusStopBuses struct {
    Buses [] Bus `json:"bus"`
    BusStopId string `json:"busStopId"`
    Suspended string `json:"isSuspended"`
}

type ScheduleStatusTime struct {
    time.Time
}

type BusSchedule struct {
    RefreshTime int `json:"appRefreshTimeInSecond,string"`
    BusStops [] BusStopBuses `json:"busStop"`
    StatusTime ScheduleStatusTime `json:"routeStatusTime"`
    RemarksTitle string `json:"routeStatusRemarkTitle"`
    // 0   = OK
    // 100 = Rate limit ( Unconfirmed. Not in spec )
    Status int `json:"status,string"`
}

func (t *ScheduleStatusTime) UnmarshalJSON(b []byte) (err error) {
    date, err := time.Parse(`"2006\/01\/02 15:04"`, string(b))
    if err != nil {
        return err
    }
    t.Time = date
    return
}

func getSchedule( lang string, routeName string ) ( *BusSchedule, error ) {

    CACHE_PATH := filepath.Join(
        utils.WORKDIR,
        "mtr_bsch" + "-" + lang + "-" + routeName + ".json",
    )

    postLang := "en"
    if lang == "zh-Hant" {
        postLang = "zh"
    }

    QUERY_FUNC := func() ( io.ReadCloser, error ) {
        // Query Remote
        values := map[string]string { "language": postLang, "routeName": routeName }
        jsonValue, _ := json.Marshal(values)
        resp, err := http.Post(
            "https://rt.data.gov.hk/v1/transport/mtr/bus/getSchedule",
            "application/json",
            bytes.NewBuffer( jsonValue ),
        )

        if err != nil {
            return nil, err
        }

        return resp.Body, nil
    }

    cs, err := utils.CacheStreamEx( CACHE_PATH, QUERY_FUNC )
    if err != nil {
        return nil, err
    }

    oldSch := BusSchedule{
        Status: -1,
    }

    if cs.Local != nil {
        err = json.Unmarshal( cs.Local.Bytes(), &oldSch )
        if err != nil {
            return nil, err
        }
    }

    newSch := BusSchedule{
        Status: -1,
    }

    for i := 0; i < 3; i ++ {

        if cs.Remote != nil {
            err = json.Unmarshal( cs.Remote.Bytes(), &newSch )
            if err != nil {
                return nil, err
            }
        }

        if newSch.Status == 0 {
            cs.Commit()
            return &newSch, nil
        }

        if oldSch.Status == 0 && cs.NotExpired( 60 ) {
            log.Printf( "Using cache: %s", CACHE_PATH )
            return &oldSch, nil
        }

        if oldSch.StatusTime.Time == newSch.StatusTime.Time {
            log.Printf( "Using cache: %s", CACHE_PATH )
            return &oldSch, nil
        }

        // First time + try again i times
        err = cs.Reload()
        log.Printf( "Reloading (%d): %s", i, CACHE_PATH )
        if err != nil {
            err = fmt.Errorf( "Error retrieving data: %s", err )
            return nil, err
        }
    }

    if newSch.Status != 0 {
        err = fmt.Errorf( "%s (%d)", newSch.RemarksTitle, newSch.Status )
    }

    return &newSch, err
}