// Copyright 2020 Nick White.
// Use of this source code is governed by the GPLv3
// license that can be found in the LICENSE file.

// bbcschedule lists a day schedule from a BBC radio station (which
// can be in the past, present or future), including IDs that work
// with get_iplayer.
//
// This uses the BBC's broadcasts/schedules api, which is roughly
// documented at https://rms.api.bbc.co.uk/docs and
// https://rms.api.bbc.co.uk/docs/swagger.json
//
// An alternative to these APIs would be doing what get_iplayer does
// in get_links_schedule_mojo and get_links_schedule_json and
// extracting the contents of the <script type="application/ld+json">
// with "@graph" from an HTML page like
// https://www.bbc.co.uk/schedules/p00fzl7j/2020/11/14
// But who wants to parse HTML if it can be avoided, eh?
package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"strings"
	"time"
)

const usage = `Usage: bbcschedule [-station stationname] [-date yyyy-mm-dd] [-v]

Lists the schedule for a BBC radio station.
`

const urlBase = "https://rms.api.bbc.co.uk/v2/broadcasts/schedules/%s/%s"

// Broadcasts holds the parts of the JSON response that we care about.
// It is intended to be filled by json.Unmarshal.
type Broadcasts struct {
	Data []struct {
		Urn string
		Start string
		Duration int
		Titles struct {
			Primary string
		}
		Synopses struct {
			Short string
			Medium string
			Long string
		}
	}
}

// fmtDate just reformats an RFC3339 date into a "Kitchen" style time.
func fmtDate(d string) string {
	t, err := time.Parse(time.RFC3339, d)
	if err != nil {
		return d
	}
	return t.Local().Format(time.Kitchen)
}

// idFromUrn gets the ID from an iPlayer URN. This is the appropriate
// ID to give to get_iplayer, so it's what we use.
func idFromUrn(u string) string {
	s := strings.Split(u, ":")
	if len(s) != 5 {
		return u
	}
	return s[4]
}

func main() {
	station := flag.String("station", "bbc_radio_fourfm", "Radio station name (called 'service id' by BBC)")
	date := flag.String("date", time.Now().Format("2006-01-02"), "Date of schedule")
	verbose := flag.Bool("v", false, "Verbose - use long descriptions for programmes")

	flag.Usage = func() {
		fmt.Fprintf(flag.CommandLine.Output(), usage)
		flag.PrintDefaults()
	}
	flag.Parse()

	if flag.NArg() > 0 {
		flag.Usage()
		return
	}

	url := fmt.Sprintf(urlBase, *station, *date)
	resp, err := http.Get(url)
	if err != nil {
		log.Fatalf("Error getting url %s: %v\n", url, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		log.Fatalf("Error getting url %s, HTTP status code: %d\n", url, resp.StatusCode)
	}

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Fatalf("Error reading response for %s: %v\n", url, err)
	}

	var r Broadcasts
	err = json.Unmarshal(b, &r)
	if err != nil {
		log.Fatalf("Error unmarshalling json for %s: %v\n", url, err)
	}

	var longest int
	for _, v := range r.Data {
		l := len(v.Titles.Primary)
		if l > longest {
			longest = l
		}
	}
	for _, v := range r.Data {
		fmtString := fmt.Sprintf("%%7s | %%-%ds | %%3d minutes | %%s | %%s\n", longest)
		var synopsis string
		if *verbose && len(v.Synopses.Long) > 0 {
			synopsis = v.Synopses.Long
		} else if *verbose && len(v.Synopses.Medium) > 0 {
			synopsis = v.Synopses.Medium
		} else {
			synopsis = v.Synopses.Short
		}
		fmt.Printf(fmtString, fmtDate(v.Start), v.Titles.Primary, v.Duration / 60, idFromUrn(v.Urn), synopsis)
	}
}