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

This file is part of Scotty.

Scotty is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later version.

Scotty is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
Scotty. If not, see <https://www.gnu.org/licenses/>.
*/
package scrobblerlog

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strings"
	"time"

	"go.uploadedlobster.com/scotty/internal/config"
	"go.uploadedlobster.com/scotty/internal/i18n"
	"go.uploadedlobster.com/scotty/internal/models"
	"go.uploadedlobster.com/scotty/pkg/scrobblerlog"
)

type ScrobblerLogBackend struct {
	filePath       string
	includeSkipped bool
	append         bool
	file           *os.File
	timezone       *time.Location
	log            scrobblerlog.ScrobblerLog
}

func (b *ScrobblerLogBackend) Name() string { return "scrobbler-log" }

func (b *ScrobblerLogBackend) Options() []models.BackendOption {
	return []models.BackendOption{{
		Name:  "file-path",
		Label: i18n.Tr("File path"),
		Type:  models.String,
	}, {
		Name:  "include-skipped",
		Label: i18n.Tr("Include skipped listens"),
		Type:  models.Bool,
	}, {
		Name:    "append",
		Label:   i18n.Tr("Append to file"),
		Type:    models.Bool,
		Default: "true",
	}, {
		Name:  "time-zone",
		Label: i18n.Tr("Specify a time zone for the listen timestamps"),
		Type:  models.String,
	}}
}

func (b *ScrobblerLogBackend) InitConfig(config *config.ServiceConfig) error {
	b.filePath = config.GetString("file-path")
	b.includeSkipped = config.GetBool("include-skipped", false)
	b.append = config.GetBool("append", true)
	timezone := config.GetString("time-zone")
	if timezone != "" {
		location, err := time.LoadLocation(timezone)
		if err != nil {
			return fmt.Errorf("Invalid time-zone %q: %w", timezone, err)
		}
		b.log.FallbackTimezone = location
	}
	b.log = scrobblerlog.ScrobblerLog{
		TZ:     scrobblerlog.TZ_UTC,
		Client: "Rockbox unknown $Revision$",
	}
	return nil
}

func (b *ScrobblerLogBackend) StartImport() error {
	flags := os.O_RDWR | os.O_CREATE
	if !b.append {
		flags |= os.O_TRUNC
	}
	file, err := os.OpenFile(b.filePath, flags, 0666)
	if err != nil {
		return err
	}

	if b.append {
		stat, err := file.Stat()
		if err != nil {
			file.Close()
			return err
		}

		if stat.Size() == 0 {
			// Zero length file, treat as a new file
			b.append = false
		} else {
			// Verify existing file is a scrobbler log
			reader := bufio.NewReader(file)
			if err = b.log.ReadHeader(reader); err != nil {
				file.Close()
				return err
			}
			if _, err = file.Seek(0, 2); err != nil {
				return err
			}
		}
	}

	if !b.append {
		if err = b.log.WriteHeader(file); err != nil {
			file.Close()
			return err
		}
	}

	b.file = file
	return nil
}

func (b *ScrobblerLogBackend) FinishImport() error {
	return b.file.Close()
}

func (b *ScrobblerLogBackend) ExportListens(oldestTimestamp time.Time, results chan models.ListensResult, progress chan models.Progress) {
	defer close(results)
	file, err := os.Open(b.filePath)
	if err != nil {
		progress <- models.Progress{}.Complete()
		results <- models.ListensResult{Error: err}
		return
	}

	defer file.Close()

	err = b.log.Parse(file, b.includeSkipped)
	if err != nil {
		progress <- models.Progress{}.Complete()
		results <- models.ListensResult{Error: err}
		return
	}

	listens := make(models.ListensList, 0, len(b.log.Records))
	client := strings.Split(b.log.Client, " ")[0]
	for _, record := range b.log.Records {
		listens = append(listens, recordToListen(record, client))
	}
	sort.Sort(listens.NewerThan(oldestTimestamp))
	progress <- models.Progress{Elapsed: int64(len(listens))}.Complete()
	results <- models.ListensResult{Items: listens}
}

func (b *ScrobblerLogBackend) ImportListens(export models.ListensResult, importResult models.ImportResult, progress chan models.Progress) (models.ImportResult, error) {
	records := make([]scrobblerlog.Record, len(export.Items))
	for i, listen := range export.Items {
		records[i] = listenToRecord(listen)
	}
	lastTimestamp, err := b.log.Append(b.file, records)
	if err != nil {
		return importResult, err
	}

	importResult.UpdateTimestamp(lastTimestamp)
	importResult.ImportCount += len(export.Items)
	progress <- models.Progress{}.FromImportResult(importResult)

	return importResult, nil
}

func recordToListen(record scrobblerlog.Record, client string) models.Listen {
	return models.Listen{
		ListenedAt: record.Timestamp,
		Track: models.Track{
			ArtistNames:   []string{record.ArtistName},
			ReleaseName:   record.AlbumName,
			TrackName:     record.TrackName,
			TrackNumber:   record.TrackNumber,
			Duration:      record.Duration,
			RecordingMBID: record.MusicBrainzRecordingID,
			AdditionalInfo: models.AdditionalInfo{
				"rockbox_rating": record.Rating,
				"media_player":   client,
			},
		},
	}
}

func listenToRecord(listen models.Listen) scrobblerlog.Record {
	var rating scrobblerlog.Rating
	rockboxRating, ok := listen.AdditionalInfo["rockbox_rating"].(string)
	if !ok || rockboxRating == "" {
		rating = scrobblerlog.RATING_LISTENED
	} else {
		rating = scrobblerlog.Rating(rating)
	}

	return scrobblerlog.Record{
		ArtistName:             listen.ArtistName(),
		AlbumName:              listen.ReleaseName,
		TrackName:              listen.TrackName,
		TrackNumber:            listen.TrackNumber,
		Duration:               listen.Duration,
		Rating:                 rating,
		Timestamp:              listen.ListenedAt,
		MusicBrainzRecordingID: listen.RecordingMBID,
	}
}