monstersirenfetch/composite.go
Yonah bb1164d081
song: enrich metadata from API
This should be the last of the API interactions we need.

Signed-off-by: Yonah <contrib@gensokyo.uk>
2025-09-18 04:10:38 +09:00

108 lines
2.9 KiB
Go

package monstersirenfetch
import (
"maps"
"os"
"slices"
"strconv"
"strings"
)
// AlbumConflictError is returned by [Flatten] if two or more albums share the same CID.
type AlbumConflictError struct {
Index int
Previous Album
Current Album
}
func (e *AlbumConflictError) Error() string {
return "album CID conflict on index " + strconv.Itoa(e.Index) + ": " +
"previous album " + e.Previous.Name + ", " +
"current album " + e.Current.Name
}
// SongConflictError is returned by [Flatten] if two or more songs belonging to the same [Album] share the same CID.
type SongConflictError struct {
Index int
Previous *Song
Current Song
}
func (e *SongConflictError) Error() string {
return "song CID conflict on index " + strconv.Itoa(e.Index) + ": " +
"previous song " + e.Previous.Name + ", " +
"current song " + e.Current.Name
}
// CompositeAlbum represents an [Album] with a collection of its associated [Song].
type CompositeAlbum struct {
// Songs is a map of [Song.CID] to [Song].
Songs SongsMap `json:"songs"`
*Album
}
type (
// CompositeAlbumsMap is a map of [Album.CID] to [CompositeAlbum].
CompositeAlbumsMap map[StringInt]CompositeAlbum
// SongsMap is a map of [Song.CID] to the address of [Song].
SongsMap map[StringInt]*Song
)
func (m CompositeAlbumsMap) String() string {
if len(m) == 0 {
return "<empty>"
}
compAlbums := slices.Collect(maps.Values(m))
slices.SortFunc(compAlbums, func(a, b CompositeAlbum) int { return int(a.CID - b.CID) })
s := make([]string, len(compAlbums))
var buf strings.Builder
for i, ca := range compAlbums {
buf.WriteString(
"Album: " + ca.Name + " (" + ca.CID.String() + ")\n" +
"Cover: " + ca.CoverURL + "\n" +
"Artist(s): " + strings.Join(ca.Artists, ", ") + "\n" +
"Songs:\n")
albumSongs := slices.Collect(maps.Values(ca.Songs))
slices.SortFunc(albumSongs, func(a, b *Song) int { return int(a.CID - b.CID) })
for _, cs := range albumSongs {
buf.WriteString(
" " + strings.Join(cs.Artists, ", ") + " ─ " + cs.Name + "\n")
}
s[i] = buf.String()
buf.Reset()
}
return strings.Join(s, "\n")
}
// Flatten flattens [AlbumsData] and [SongsData] into a [CompositeAlbumsMap].
// All values in [CompositeAlbum.Songs] and the [CompositeAlbum.Album] field are guaranteed to be non-nil.
func Flatten(albumData AlbumsData, songsData SongsData) (CompositeAlbumsMap, error) {
m := make(CompositeAlbumsMap, len(albumData))
for i, a := range albumData {
if c, ok := m[a.CID]; ok {
return nil, &AlbumConflictError{Index: i, Previous: *c.Album, Current: a}
}
m[a.CID] = CompositeAlbum{Songs: make(map[StringInt]*Song), Album: &a}
}
for i, s := range songsData.List {
var c *Song
if a, ok := m[s.AlbumCID]; !ok {
return nil, os.ErrNotExist
} else if c, ok = a.Songs[s.CID]; ok {
return nil, &SongConflictError{Index: i, Previous: c, Current: s}
} else {
a.Songs[s.CID] = &s
}
}
return m, nil
}