/*
	Timelinize
	Copyright (c) 2013 Matthew Holt

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

	This program 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 Affero General Public License for more details.

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

// Package media implements a data source for general media files (photos, videos, and audio)
// that may have come from a camera roll, photo library, etc.
package media

import (
	"context"
	"fmt"
	"io"
	"io/fs"
	"path"
	"strings"
	"sync"

	"github.com/timelinize/timelinize/datasources/generic"
	"github.com/timelinize/timelinize/timeline"
	"go.uber.org/zap"
)

func init() {
	err := timeline.RegisterDataSource(timeline.DataSource{
		Name:            "media",
		Title:           "Media",
		Icon:            "media.png",
		NewOptions:      func() any { return new(Options) },
		NewFileImporter: func() timeline.FileImporter { return new(FileImporter) },
	})
	if err != nil {
		timeline.Log.Fatal("registering data source", zap.Error(err))
	}
}

// Options configures the data source.
type Options struct {
	// We will attempt to extract timestamps for each media item in this order:
	// embedded (EXIF/XMP), filepath (if enabled), and as a last resort, file
	// modification time (if enabled). If more than one timestamp is available, a
	// date range can be specified to help choose one. If specified, a timestamp
	// within this range will be preferred over one not in the range. If both
	// timestamps are either in or out of the range, then the range will be
	// ignored in the choice of timestamp.
	//
	// Items with chosen timestamps that are outside this range will still be
	// processed. To avoid importing items that don't have any timestamp in a
	// certain range, use the Timeframe in ListingOptions instead.
	DateRange timeline.Timeframe `json:"date_range,omitempty"`

	// If true, a timestamp found in the file path may be used.
	UseFilePathTime bool `json:"use_filepath_time,omitempty"`

	// If true, fall back to file modification time if no other timestamp is found.
	// This can be accurate in some cases, like exports/downloads from Google Photos
	// of media files like "creations" (gifs, etc), or Apple .MOV files that don't
	// have a timestamp embedded within them.
	UseFileModTime bool `json:"use_file_mod_time,omitempty"`

	// If true, a collection will be created for each folder with items in it.
	FolderIsAlbum bool `json:"folder_is_album,omitempty"`

	// The ID of the owner entity. REQUIRED if entity is to be related in DB.
	OwnerEntityID uint64 `json:"owner_entity_id"`
}

// FileImporter can import the data from a file.
type FileImporter struct{}

// Recognize returns whether the file or folder is recognized.
func (FileImporter) Recognize(_ context.Context, dirEntry timeline.DirEntry, _ timeline.RecognizeParams) (timeline.Recognition, error) {
	// this threshold is a little lower because it's not uncommon to have a photo library where
	// each media file has a sidecar file for metadata, like .xmp.
	// TODO: Should there be a way to tell the import planner to not count a non-recognized file against this threshold? kind of a "we can use this, just not by itself"?
	rec := timeline.Recognition{DirThreshold: .45}

	// we can import directories, but let the import planner figure that out; only recognize files
	if dirEntry.IsDir() {
		return rec, nil
	}

	// for regular files, file type must be recognized (relying on extension is hopefully good enough for now)
	if _, ok := ItemClassByExtension(dirEntry.Name()); ok {
		rec.Confidence = 1
	}

	return rec, nil
}

// FileImport imports data from the file or folder.
func (imp *FileImporter) FileImport(ctx context.Context, dirEntry timeline.DirEntry, params timeline.ImportParams) error {
	dsOpt := params.DataSourceOptions.(*Options)

	owner := timeline.Entity{ID: dsOpt.OwnerEntityID}

	collections := make(map[string]*timeline.Item)
	var collectionsMu sync.Mutex

	// processing files in parallel can greatly speed up imports,
	// but use a throttle to avoid unbounded goroutines
	const maxGoroutines = 100
	throttle := make(chan struct{}, maxGoroutines)
	var wg sync.WaitGroup

	// prevent subtle bug: we spawn goroutines which send graphs down the pipeline;
	// if we return before they finish sending a value, they'll get deadlocked
	// since the workers are stopped once we return, meaning their send will never
	// get received; thus, we need to wait for the goroutines to finish before we
	// return
	defer wg.Wait()

	err := fs.WalkDir(dirEntry.FS, dirEntry.Filename, func(fpath string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if err := ctx.Err(); err != nil {
			return err
		}
		if strings.HasPrefix(d.Name(), ".") {
			// skip hidden files & folders
			if d.IsDir() {
				return fs.SkipDir
			}
			return nil
		}
		if d.IsDir() {
			return nil // traverse into subdirectories
		}

		// // get the extension and directory; but this is nuanced if it's a single file, which comes up as "." in the walk
		// fname, itemPath := fpath, fpath
		// if fpath == "." {
		// 	if _, ok := fsys.(archives.FileFS); ok {
		// 		fname = filename
		// 		itemPath = filepath.Base(filename)
		// 	}
		// }

		// TODO: a lot of this logic is duplicated by the iCloud importer, except:
		// the concurrency model is a little different; we don't discover items by
		// traversing a folder (they are listed in a CSV file); we don't assign
		// timestamps from folder paths or modtime; collection membership is different;
		// etc. Come to think of it, we might need to move a lot of this logic into
		// the Google Photos importer as well.

		class, supported := ItemClassByExtension(d.Name())
		if !supported {
			// skip unsupported files by filename extension (naive, but hopefully OK)
			params.Log.Debug("skipping unrecognized file",
				zap.String("filename", fpath),
				zap.String("dir_entry_name", d.Name()))
			return nil
		}

		// if this is a sidecar video for a photograph (a motion picture or live photo),
		// skip it, since we'll come back to this when we get to the photograph file itself
		if IsSidecarVideo(dirEntry.FS, fpath) {
			return nil
		}

		throttle <- struct{}{}
		wg.Add(1)

		go func() {
			defer func() {
				<-throttle
				wg.Done()
			}()

			if ctx.Err() != nil {
				return
			}

			item := &timeline.Item{
				Classification:       class,
				Owner:                owner,
				IntermediateLocation: fpath,
				Content: timeline.ItemData{
					Filename: d.Name(),
					Data: func(_ context.Context) (io.ReadCloser, error) {
						return dirEntry.FS.Open(fpath)
					},
				},
			}

			// get as much metadata as possible
			pic, err := ExtractAllMetadata(params.Log, dirEntry.FS, fpath, item, timeline.MetaMergeAppend)
			if err != nil {
				params.Log.Warn("extracting metadata",
					zap.String("file", fpath),
					zap.Error(err))
			}

			// try to extract time from filepath (media files are often organized by date)
			if dsOpt.UseFilePathTime {
				fpathTimestamp, err := generic.TimestampFromFilePath(fpath)
				if err == nil {
					// use the filepath timestamp if the embedded timestamp is missing OR
					// the embedded timestamp is not within the specified range but the
					// filepath timestamp IS within range
					if item.Timestamp.IsZero() ||
						(!dsOpt.DateRange.Contains(item.Timestamp) && dsOpt.DateRange.Contains(fpathTimestamp)) {
						item.Timestamp = fpathTimestamp
					}
				}
			}

			// as a last resort, use file modification time as a timestamp; I've seen this
			// be accurate for downloads from Google Photos where the timestamp is otherwise
			// missing: common with iPhone videos, gifs/animations, and other "creations"
			if dsOpt.UseFileModTime {
				info, err := d.Info()
				if err == nil {
					// use the modtime if the timestamp is still missing OR if
					// the preferred timestamp is not within the specified range
					// and this one is
					modTime := info.ModTime()
					if item.Timestamp.IsZero() ||
						(!dsOpt.DateRange.Contains(item.Timestamp) && dsOpt.DateRange.Contains(modTime)) {
						item.Timestamp = modTime
					}
				}
			}

			// Media items are often manually organized and data that was originally
			// not digital (like scanned photos) might not have an exact date or time;
			// thus we can set a timeframe for these items, so instead of an item
			// being on a certain day at precisely midnight 00:00, we can mark it as
			// during that day, without certainty as to what time.
			item.SetTimeframe()

			ig := &timeline.Graph{Item: item}

			// if picture is attached, create related item for that
			if pic != nil && len(pic.Data) > 0 {
				embeddedPicName := "embedded" // you have a better idea?
				if pic.Ext != "" {
					embeddedPicName += "." + pic.Ext
				}

				picItem := &timeline.Item{
					Classification:       timeline.ClassMedia,
					Owner:                owner,
					IntermediateLocation: path.Join(dirEntry.Filename, embeddedPicName), // this works, I guess? Not sure if it should be same as parent file as that might be confusing?
					Content: timeline.ItemData{
						Filename:  embeddedPicName,
						MediaType: pic.MIMEType,
						Data:      timeline.ByteData(pic.Data),
					},
					Metadata: timeline.Metadata{
						"Description": pic.Description,
						"Type":        pic.Type,
					},
				}

				// TODO: UI needs to support this
				ig.ToItem(RelCoverArt, picItem)
			}

			ConnectMotionPhoto(params.Log, dirEntry.FS, fpath, ig)

			// now assemble collection info

			collectionsMu.Lock()
			defer collectionsMu.Unlock()

			// if item is part of an album according to metadata, add it to the collection
			if albumStr, ok := item.Metadata["Album"].(string); ok && albumStr != "" {
				collName := albumStr
				if albumYear, ok := item.Metadata["Year"].(int); ok && albumYear > 0 {
					collName += fmt.Sprintf(" (%d)", albumYear)
				}
				coll, ok := collections[collName]
				if !ok {
					coll = &timeline.Item{
						Classification: timeline.ClassCollection,
						Content: timeline.ItemData{
							Data: timeline.StringData(collName),
						},
					}
				}

				// we can only be certain of the position of the track in the album if a track number
				// is available AND this is disc 1 (that is most common, so by default, we assume there
				// is just 1 disc, if unspecified)
				var position any
				if trackNum, ok := item.Metadata["Track"].(int); ok && trackNum > 0 {
					if disc, ok := item.Metadata["Disc"].(int); !ok || (disc == 0 || disc == 1) {
						position = trackNum
					}
				}

				ig.ToItemWithValue(timeline.RelInCollection, coll, position)

				collections[collName] = coll
			}

			// if enabled, add item to collection based on parent folder name
			if dsOpt.FolderIsAlbum {
				dir := path.Dir(dirEntry.Filename)
				coll, ok := collections[dir]
				if !ok {
					coll = &timeline.Item{
						Classification: timeline.ClassCollection,
						Content: timeline.ItemData{
							Data: timeline.StringData(path.Base(dir)),
						},
						Owner: owner,
					}
				}
				ig.ToItem(timeline.RelInCollection, coll)
				collections[dir] = coll
			}

			params.Pipeline <- ig
		}()

		return nil
	})
	if err != nil {
		return err
	}

	// TODO: process the collections too (we still need to upgrade this logic after the schema rewrite)

	return nil
}

// ItemClassByExtension uses the file extension to return a best-guess item classification.
// It returns false if no matching classification could be found for the file extension.
func ItemClassByExtension(filename string) (timeline.Classification, bool) {
	ext := strings.ToLower(path.Ext(filename))
	if _, ok := imageExts[ext]; ok {
		return timeline.ClassMedia, true
	}
	if _, ok := videoExts[ext]; ok {
		return timeline.ClassMedia, true
	}
	if _, ok := audioExts[ext]; ok {
		return timeline.ClassMedia, true
	}
	return timeline.Classification{}, false
}

// Extensions used for file recognition.
var (
	imageExts = map[string]struct{}{
		".arw":  {}, // x-sony-arw (Sony Alpha)
		".bmp":  {},
		".cr2":  {}, // x-canon-cr2 or x-dcraw
		".crw":  {}, // x-canon-crw
		".dcr":  {}, // x-kodak-dcr
		".dng":  {}, // x-adobe-dng
		".erf":  {}, // x-epson-erf
		".gif":  {},
		".heic": {},
		".heif": {},
		".hif":  {}, // fujifilm's heif extension
		".jpeg": {},
		".jpe":  {},
		".jpg":  {},
		".k25":  {}, // x-kodak-x25
		".kdc":  {}, // x-kodak-kdc
		".nef":  {}, // x-nikon-nef
		".orf":  {}, // x-olympus-orf
		".pbm":  {},
		".pef":  {}, // x-pentax-pef
		".pgm":  {},
		".png":  {},
		".pnm":  {},
		".ppm":  {},
		".raf":  {}, // x-fuji-raf
		".raw":  {}, // x-panasonic-raw - most likely an image, but could be anything
		".sr2":  {}, // x-sony-sr2
		".srf":  {}, // x-sony-srf
		".svg":  {},
		".tiff": {},
		".webp": {},
	}

	videoExts = map[string]struct{}{
		".3g2":  {},
		".3gp":  {},
		".3gpp": {},
		".asf":  {},
		".avi":  {},
		".divx": {},
		".flv":  {},
		".m2t":  {},
		".m2ts": {},
		".m4v":  {},
		".mkv":  {},
		".mov":  {},
		".mp":   {}, // One generation of Google Photos / Pixel phones motion pictures... sigh
		".mp4":  {},
		".mpeg": {},
		".mpg":  {},
		".mts":  {},
		".vob":  {},
		".wmv":  {},
	}

	audioExts = map[string]struct{}{
		".aa":   {},
		".aac":  {},
		".aax":  {},
		".aiff": {},
		".alac": {},
		".au":   {},
		".flac": {},
		".m4a":  {},
		".m4b":  {},
		".m4p":  {},
		".mogg": {},
		".mp3":  {},
		".oga":  {},
		".ogg":  {},
		".opus": {},
		".wav":  {},
		".wma":  {},
	}
)

var (
	// RelMotionPhoto describes a motion photo (live photo/picture, moving picture, etc.) relation.
	// "<to> is a motion photo (aka 'live photo' or video) of <from>"
	RelMotionPhoto = timeline.Relation{Label: "motion", Directed: true, Subordinating: true}

	// RelCoverArt describes a relation for cover art.
	// "<to> is the album art for <from>"
	RelCoverArt = timeline.Relation{Label: "cover_art", Directed: true}
)