/*
Copyright © 2023 Philipp Wolfer <phw@uploadedlobster.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
package listenbrainz

import (
	"fmt"
	"sort"
	"time"

	"github.com/spf13/viper"
	"go.uploadedlobster.com/scotty/models"
)

type ListenBrainzApiBackend struct {
	client        Client
	username      string
	existingMbids map[string]bool
}

func (b *ListenBrainzApiBackend) Name() string { return "listenbrainz" }

func (b *ListenBrainzApiBackend) FromConfig(config *viper.Viper) models.Backend {
	b.client = NewClient(config.GetString("token"))
	b.client.MaxResults = MaxItemsPerGet
	b.username = config.GetString("username")
	return b
}

func (b *ListenBrainzApiBackend) StartImport() error  { return nil }
func (b *ListenBrainzApiBackend) FinishImport() error { return nil }

func (b *ListenBrainzApiBackend) ExportListens(oldestTimestamp time.Time, results chan models.ListensResult, progress chan models.Progress) {
	startTime := time.Now()
	maxTime := startTime
	minTime := time.Unix(0, 0)

	totalDuration := startTime.Sub(oldestTimestamp)

	defer close(results)
	defer close(progress)

	// FIXME: Optimize by fetching the listens in reverse listen time order
	listens := make(models.ListensList, 0, 2*MaxItemsPerGet)
	p := models.Progress{Total: int64(totalDuration.Seconds())}

out:
	for {
		result, err := b.client.GetListens(b.username, maxTime, minTime)
		if err != nil {
			progress <- p.Complete()
			results <- models.ListensResult{Error: err}
			return
		}

		count := len(result.Payload.Listens)
		if count == 0 {
			break
		}

		// Set maxTime to the oldest returned listen
		maxTime = time.Unix(result.Payload.Listens[count-1].ListenedAt, 0)
		remainingTime := maxTime.Sub(oldestTimestamp)

		for _, listen := range result.Payload.Listens {
			if listen.ListenedAt > oldestTimestamp.Unix() {
				listens = append(listens, listen.ToListen())
			} else {
				// result contains listens older then oldestTimestamp,
				// we can stop requesting more
				p.Total = int64(startTime.Sub(time.Unix(listen.ListenedAt, 0)).Seconds())
				break out
			}
		}

		p.Elapsed = int64(totalDuration.Seconds() - remainingTime.Seconds())
		progress <- p
	}

	sort.Sort(listens)
	progress <- p.Complete()
	results <- models.ListensResult{Listens: listens, OldestTimestamp: oldestTimestamp}
}

func (b *ListenBrainzApiBackend) ExportLoves(oldestTimestamp time.Time, results chan models.LovesResult, progress chan models.Progress) {
	offset := 0
	defer close(results)
	defer close(progress)
	loves := make(models.LovesList, 0, 2*MaxItemsPerGet)
	p := models.Progress{}

out:
	for {
		result, err := b.client.GetFeedback(b.username, 1, offset)
		if err != nil {
			results <- models.LovesResult{Error: err}
			return
		}

		count := len(result.Feedback)
		if count == 0 {
			break out
		}

		for _, feedback := range result.Feedback {
			love := feedback.ToLove()
			if love.Created.Unix() > oldestTimestamp.Unix() {
				loves = append(loves, love)
				p.Elapsed += 1
				progress <- p
			} else {
				break out
			}
		}

		p.Total = int64(result.TotalCount)
		p.Elapsed += int64(count)

		offset += MaxItemsPerGet
	}

	sort.Sort(loves)
	progress <- p.Complete()
	results <- models.LovesResult{Loves: loves}
}

func (b *ListenBrainzApiBackend) ImportLoves(export models.LovesResult, importResult models.ImportResult, progress chan models.Progress) (models.ImportResult, error) {
	if len(b.existingMbids) == 0 {
		existingLovesChan := make(chan models.LovesResult)
		go b.ExportLoves(time.Unix(0, 0), existingLovesChan, progress)
		existingLoves := <-existingLovesChan
		if existingLoves.Error != nil {
			return importResult, existingLoves.Error
		}

		// TODO: Store MBIDs directly
		b.existingMbids = make(map[string]bool, len(existingLoves.Loves))
		for _, love := range existingLoves.Loves {
			b.existingMbids[string(love.RecordingMbid)] = true
		}
	}

	for _, love := range export.Loves {
		recordingMbid := string(love.RecordingMbid)

		if recordingMbid == "" {
			lookup, err := b.client.Lookup(love.TrackName, love.ArtistName())
			if err == nil {
				recordingMbid = lookup.RecordingMbid
			}
		}

		if recordingMbid != "" {
			ok := false
			errMsg := ""
			if b.existingMbids[recordingMbid] {
				ok = true
			} else {
				resp, err := b.client.SendFeedback(Feedback{
					RecordingMbid: recordingMbid,
					Score:         1,
				})
				ok = err == nil && resp.Status == "ok"
				if err != nil {
					errMsg = err.Error()
				}
			}

			if ok {
				importResult.UpdateTimestamp(love.Created)
				importResult.ImportCount += 1
			} else {
				msg := fmt.Sprintf("Failed import of \"%s\" by %s: %v",
					love.TrackName, love.ArtistName(), errMsg)
				importResult.ImportErrors = append(importResult.ImportErrors, msg)
			}
		}

		progress <- models.Progress{}.FromImportResult(importResult)
	}

	return importResult, nil
}

func (lbListen Listen) ToListen() models.Listen {
	track := lbListen.TrackMetadata
	listen := models.Listen{
		ListenedAt: time.Unix(lbListen.ListenedAt, 0),
		UserName:   lbListen.UserName,
		Track: models.Track{
			TrackName:        track.TrackName,
			ReleaseName:      track.ReleaseName,
			ArtistNames:      []string{track.ArtistName},
			Duration:         track.Duration(),
			TrackNumber:      track.TrackNumber(),
			RecordingMbid:    models.MBID(track.RecordingMbid()),
			ReleaseMbid:      models.MBID(track.ReleaseMbid()),
			ReleaseGroupMbid: models.MBID(track.ReleaseGroupMbid()),
			Isrc:             track.Isrc(),
			AdditionalInfo:   track.AdditionalInfo,
		},
	}
	return listen
}

func (f Feedback) ToLove() models.Love {
	track := f.TrackMetadata
	recordingMbid := models.MBID(f.RecordingMbid)
	love := models.Love{
		UserName:      f.UserName,
		RecordingMbid: recordingMbid,
		Created:       time.Unix(f.Created, 0),
		Track: models.Track{
			RecordingMbid: recordingMbid,
		},
	}

	if track != nil {
		love.Track.TrackName = track.TrackName
		love.Track.ReleaseName = track.ReleaseName
		love.ArtistNames = []string{track.ArtistName}
		love.ReleaseMbid = models.MBID(track.MbidMapping.ReleaseMbid)
		love.ArtistMbids = make([]models.MBID, 0, len(track.MbidMapping.ArtistMbids))

		if track.MbidMapping != nil {
			for _, artistMbid := range track.MbidMapping.ArtistMbids {
				love.Track.ArtistMbids = append(love.Track.ArtistMbids, models.MBID(artistMbid))
			}
		}
	}

	return love
}