@startuml Music Metadata ERD

skinparam linetype ortho
skinparam ranksep 50
skinparam nodesep 30

skinparam entity {
    BackgroundColor White
    BorderColor #333333
}

skinparam package {
    BackgroundColor #FAFAFA
    BorderColor #DDDDDD
}

title Music Metadata Aggregator - Internal Structure

' ══════════════════════════════════════════════════════════════
' CORE MUSIC ENTITIES
' ══════════════════════════════════════════════════════════════

package "Core Entities" #E3F2FD {
    entity "artists" {
        * id : UUID <<PK>>
        --
        name : TEXT
        sort_name : TEXT
        artist_type : TEXT
        country : TEXT
        formed_date : DATE
        disbanded_date : DATE
        description : TEXT
        image_url : TEXT
        --
        source : TEXT
        source_id : TEXT
        created_at : TIMESTAMPTZ
        updated_at : TIMESTAMPTZ
    }

    entity "works" {
        * id : UUID <<PK>>
        --
        title : TEXT
        work_type : TEXT
        language : TEXT
        --
        source : TEXT
        source_id : TEXT
        created_at : TIMESTAMPTZ
        updated_at : TIMESTAMPTZ
    }

    entity "tracks" {
        * id : UUID <<PK>>
        --
        work_id : UUID <<FK>>
        --
        title : TEXT
        duration_ms : INT
        isrc : TEXT
        explicit : BOOLEAN
        --
        source : TEXT
        source_id : TEXT
        created_at : TIMESTAMPTZ
        updated_at : TIMESTAMPTZ
    }

    entity "albums" {
        * id : UUID <<PK>>
        --
        label_id : UUID <<FK>>
        --
        title : TEXT
        album_type : TEXT
        release_date : DATE
        upc : TEXT
        total_tracks : INT
        total_discs : INT
        cover_url : TEXT
        --
        source : TEXT
        source_id : TEXT
        created_at : TIMESTAMPTZ
        updated_at : TIMESTAMPTZ
    }

    entity "labels" {
        * id : UUID <<PK>>
        --
        name : TEXT
        country : TEXT
        founded_date : DATE
        --
        source : TEXT
        source_id : TEXT
        created_at : TIMESTAMPTZ
        updated_at : TIMESTAMPTZ
    }

    entity "genres" {
        * id : UUID <<PK>>
        --
        name : TEXT
        parent_id : UUID <<FK>>
    }
}

' ══════════════════════════════════════════════════════════════
' RELATIONSHIPS
' ══════════════════════════════════════════════════════════════

package "Relationships" #FFF3E0 {
    entity "track_artists" {
        * track_id : UUID <<FK>>
        * artist_id : UUID <<FK>>
        --
        role : TEXT
        position : INT
    }

    entity "album_artists" {
        * album_id : UUID <<FK>>
        * artist_id : UUID <<FK>>
        --
        role : TEXT
        position : INT
    }

    entity "album_tracks" {
        * album_id : UUID <<FK>>
        * track_id : UUID <<FK>>
        --
        disc_number : INT
        track_number : INT
    }

    entity "work_artists" {
        * work_id : UUID <<FK>>
        * artist_id : UUID <<FK>>
        --
        role : TEXT
    }

    entity "artist_genres" {
        * artist_id : UUID <<FK>>
        * genre_id : UUID <<FK>>
    }

    entity "album_genres" {
        * album_id : UUID <<FK>>
        * genre_id : UUID <<FK>>
    }

    entity "similar_artists" {
        * artist_id : UUID <<FK>>
        * similar_artist_id : UUID <<FK>>
        --
        score : REAL
    }
}

' ══════════════════════════════════════════════════════════════
' CONTENT
' ══════════════════════════════════════════════════════════════

package "Content" #E8F5E9 {
    entity "lyrics" {
        * id : UUID <<PK>>
        --
        track_id : UUID <<FK>>
        --
        content : TEXT
        synced_content : JSONB
        language : TEXT
        --
        source : TEXT
        source_id : TEXT
        created_at : TIMESTAMPTZ
    }

    entity "playlists" {
        * id : UUID <<PK>>
        --
        name : TEXT
        description : TEXT
        is_public : BOOLEAN
        cover_url : TEXT
        --
        created_at : TIMESTAMPTZ
        updated_at : TIMESTAMPTZ
    }

    entity "playlist_tracks" {
        * playlist_id : UUID <<FK>>
        * track_id : UUID <<FK>>
        --
        position : INT
        added_at : TIMESTAMPTZ
    }
}

' ══════════════════════════════════════════════════════════════
' EXTERNAL IDS (Cross-platform linking)
' ══════════════════════════════════════════════════════════════

package "External IDs" #FCE4EC {
    entity "artist_external_ids" {
        * artist_id : UUID <<FK>>
        * source : TEXT
        * source_id : TEXT
        --
        url : TEXT
        fetched_at : TIMESTAMPTZ
    }

    entity "album_external_ids" {
        * album_id : UUID <<FK>>
        * source : TEXT
        * source_id : TEXT
        --
        url : TEXT
        fetched_at : TIMESTAMPTZ
    }

    entity "track_external_ids" {
        * track_id : UUID <<FK>>
        * source : TEXT
        * source_id : TEXT
        --
        url : TEXT
        fetched_at : TIMESTAMPTZ
    }
}

' ══════════════════════════════════════════════════════════════
' RELATIONSHIPS DIAGRAM
' ══════════════════════════════════════════════════════════════

' Core relationships
works ||--o{ tracks : "recorded as"
albums ||--o{ album_tracks : "contains"
tracks ||--o{ album_tracks : "appears on"
labels ||--o{ albums : "released by"
genres ||--o{ genres : "parent"

' Artist relationships
artists ||--o{ track_artists : ""
tracks ||--o{ track_artists : ""
artists ||--o{ album_artists : ""
albums ||--o{ album_artists : ""
artists ||--o{ work_artists : ""
works ||--o{ work_artists : ""

' Genre relationships
artists ||--o{ artist_genres : ""
genres ||--o{ artist_genres : ""
albums ||--o{ album_genres : ""
genres ||--o{ album_genres : ""

' Similar artists
artists ||--o{ similar_artists : ""

' Content
tracks ||--o| lyrics : "has"
playlists ||--o{ playlist_tracks : ""
tracks ||--o{ playlist_tracks : ""

' External IDs
artists ||--o{ artist_external_ids : ""
albums ||--o{ album_external_ids : ""
tracks ||--o{ track_external_ids : ""

@enduml