academy-chauffeurs - calendar.go

  package main
  
  import (
  	"bytes"
  	"compress/gzip"
  	"database/sql"
  	"net/http"
  	"strconv"
  	"strings"
  	"time"
  
  	"vimagination.zapto.org/ics"
  )
  
  func (c *Calls) calendar(w http.ResponseWriter, r *http.Request) {
  	c.mu.Lock()
  	cal, err := c.makeCalendar()
  	c.mu.Unlock()
  	if err != nil {
  		http.Error(w, err.Error(), http.StatusInternalServerError)
  		return
  	}
  	var buf bytes.Buffer
  	err = ics.Encode(&buf, cal)
  	if err != nil {
  		http.Error(w, err.Error(), http.StatusInternalServerError)
  		return
  	}
  	for _, e := range strings.Split(r.Header.Get("Accept-Encoding"), ",") {
  		if strings.TrimSpace(e) == "gzip" {
  			w.Header().Set("Content-Encoding", "gzip")
  			var b bytes.Buffer
  			g := gzip.NewWriter(&b)
  			buf.WriteTo(g)
  			g.Close()
  			buf = b
  			break
  		}
  	}
  	w.Header().Add("Content-Length", strconv.Itoa(buf.Len()))
  	w.Header().Add("Content-Type", "text/v-calendar; charset=utf-8")
  	w.Header().Add("Content-Disposition", "attachment; filename=calendar.ics")
  	buf.WriteTo(w)
  }
  
  func (c *Calls) makeCalendar() (*ics.Calendar, error) {
  	var alarmTime int
  	if err := c.statements[AlarmTime].QueryRow().Scan(&alarmTime); err != nil {
  		return nil, err
  	}
  	var (
  		a   ics.AlarmDisplay
  		cal ics.Calendar
  	)
  	if alarmTime < 0 {
  		a.Trigger.Duration = &ics.Duration{Negative: true, Minutes: uint(-alarmTime)}
  	} else {
  		a.Trigger.Duration = &ics.Duration{Minutes: uint(alarmTime)}
  	}
  	alarm := []ics.Alarm{{AlarmType: &a}}
  	cal.ProductID = "Academy Chauffeurs 1.1"
  	cal.Version = "2.0"
  	n := now()
  	rows, err := c.statements[CalendarData].Query((n - 3600*24*30*6) * 1000)
  	if err != nil {
  		return nil, err
  	}
  	defer rows.Close()
  	cal.Event = make([]ics.Event, 0, 1024)
  	for rows.Next() {
  		var (
  			id, start, end, created, updated                                           int64
  			from, to, client, company, driverStr, phoneNumber, note, other, flightTime string
  			driver                                                                     sql.NullString
  		)
  		err := rows.Scan(&id, &start, &end, &from, &to, &created, &updated, &note, &other, &driver, &client, &company, &phoneNumber, &flightTime)
  		if err != nil {
  			return nil, err
  		}
  		client2 := client
  		if other != "" {
  			client2 += " + " + other
  		}
  		from = strings.Replace(from, "\n", " ", -1)
  		to = strings.Replace(to, "\n", " ", -1)
  		if driver.Valid {
  			driverStr = driver.String
  		} else {
  			driverStr = "Unassigned"
  		}
  		var ev ics.Event
  		ev.UID = ics.PropUID(time.Unix(created, 0).In(time.UTC).Format("20060102T150405Z") + "-" + pad(strconv.FormatUint(uint64(id), 36)) + "@academy-chauffeurs.co.uk")
  		ev.DateTimeStamp.Time = time.Unix(created, 0).In(time.UTC)
  		ev.LastModified = &ics.PropLastModified{Time: time.Unix(updated, 0).In(time.UTC)}
  		startD := time.Unix(start/1000, start%1000).In(time.UTC)
  		y, m, d := startD.Date()
  		h, mi, s := startD.Clock()
  		ev.DateTimeStart = &ics.PropDateTimeStart{DateTime: &ics.DateTime{Time: time.Date(y, m, d, h, mi, s, 0, time.Local)}}
  		var days, hours uint
  		mins := uint(time.Unix(end/1000, end%1000).In(time.UTC).Sub(startD).Minutes())
  		for mins > 60*24 {
  			days++
  			mins -= 60 * 24
  		}
  		for mins > 60 {
  			hours++
  			mins -= 60
  		}
  		ev.Duration = &ics.PropDuration{Days: days, Hours: hours, Minutes: mins}
  		ev.Location = &ics.PropLocation{Text: ics.Text(from)}
  		var ft string
  		if flightTime != "" {
  			ft = "\n" + flightTime
  		}
  		ev.Description = &ics.PropDescription{Text: ics.Text(driverStr + " - " + client2 + " (" + company + ") - " + from + " -> " + to + " - " + phoneNumber + ft + "\n" + note)}
  		ev.Summary = &ics.PropSummary{Text: ics.Text(driverStr + " - " + client + " (" + company + ")")}
  		ev.Alarm = alarm
  		ev.Contact = []ics.PropContact{{Text: ics.Text(client + ", " + company + " - " + phoneNumber)}}
  		ev.Comment = []ics.PropComment{{Text: ics.Text(note)}}
  		cal.Event = append(cal.Event, ev)
  	}
  	return &cal, nil
  }
  
  const padLength = 20
  
  func pad(s string) string {
  	t := bytes.Repeat([]byte{'0'}, padLength)
  	copy(t[padLength-len(s):], s)
  	return string(t)
  }