import uuid
from datetime import datetime, timezone
from sqlalchemy import (
    Boolean, DateTime, ForeignKey, Integer, String, Text
)
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.core.database import Base


def new_uuid() -> str:
    return str(uuid.uuid4())

def now_utc() -> datetime:
    return datetime.now(timezone.utc)


# ── User ──────────────────────────────────────────────────────────────────────

class User(Base):
    __tablename__ = "users"

    id:            Mapped[str]      = mapped_column(String(36), primary_key=True, default=new_uuid)
    username:      Mapped[str]      = mapped_column(String(64), unique=True, nullable=False)
    email:         Mapped[str]      = mapped_column(String(255), unique=True, nullable=False)
    password_hash: Mapped[str]      = mapped_column(String(255), nullable=False)
    created_at:    Mapped[datetime] = mapped_column(DateTime, default=now_utc)

    projects:      Mapped[list["Project"]]       = relationship("Project", back_populates="owner")
    memberships:   Mapped[list["ProjectMember"]] = relationship("ProjectMember", back_populates="user")
    songs:         Mapped[list["Song"]]          = relationship("Song", back_populates="owner")
    alternatives:  Mapped[list["DanceAlternative"]]       = relationship("DanceAlternative", foreign_keys="DanceAlternative.created_by", back_populates="creator")
    alt_ratings:   Mapped[list["DanceAlternativeRating"]] = relationship("DanceAlternativeRating", foreign_keys="DanceAlternativeRating.user_id", back_populates="user")


# ── Project ───────────────────────────────────────────────────────────────────

class Project(Base):
    __tablename__ = "projects"

    id:          Mapped[str]      = mapped_column(String(36), primary_key=True, default=new_uuid)
    owner_id:    Mapped[str]      = mapped_column(String(36), ForeignKey("users.id"), nullable=False)
    name:        Mapped[str]      = mapped_column(String(128), nullable=False)
    description: Mapped[str]      = mapped_column(Text, default="")
    is_public:   Mapped[bool]     = mapped_column(Boolean, default=False)
    updated_at:  Mapped[datetime] = mapped_column(DateTime, default=now_utc, onupdate=now_utc)

    owner:        Mapped["User"]               = relationship("User", back_populates="projects")
    members:      Mapped[list["ProjectMember"]] = relationship("ProjectMember", back_populates="project", cascade="all, delete-orphan")
    project_songs: Mapped[list["ProjectSong"]] = relationship("ProjectSong", back_populates="project", order_by="ProjectSong.position", cascade="all, delete-orphan")


class ProjectMember(Base):
    __tablename__ = "project_members"

    id:          Mapped[str]      = mapped_column(String(36), primary_key=True, default=new_uuid)
    project_id:  Mapped[str]      = mapped_column(String(36), ForeignKey("projects.id"), nullable=False)
    user_id:     Mapped[str]      = mapped_column(String(36), ForeignKey("users.id"), nullable=False)
    role:        Mapped[str]      = mapped_column(String(16), default="viewer")   # owner | editor | viewer
    status:      Mapped[str]      = mapped_column(String(16), default="pending")  # pending | accepted
    invited_at:  Mapped[datetime] = mapped_column(DateTime, default=now_utc)

    project: Mapped["Project"] = relationship("Project", back_populates="members")
    user:    Mapped["User"]    = relationship("User", back_populates="memberships")


# ── Song ──────────────────────────────────────────────────────────────────────

class Song(Base):
    __tablename__ = "songs"

    id:           Mapped[str]      = mapped_column(String(36), primary_key=True, default=new_uuid)
    owner_id:     Mapped[str]      = mapped_column(String(36), ForeignKey("users.id"), nullable=False)
    title:        Mapped[str]      = mapped_column(String(255), nullable=False)
    artist:       Mapped[str]      = mapped_column(String(255), default="")
    local_path:   Mapped[str]      = mapped_column(String(512), default="")  # kun relevant på PC
    bpm:          Mapped[int]      = mapped_column(Integer, default=0)
    duration_sec: Mapped[int]      = mapped_column(Integer, default=0)
    synced_at:    Mapped[datetime] = mapped_column(DateTime, default=now_utc)

    owner:         Mapped["User"]           = relationship("User", back_populates="songs")
    dances:        Mapped[list["SongDance"]] = relationship("SongDance", back_populates="song", order_by="SongDance.dance_order", cascade="all, delete-orphan")
    project_songs: Mapped[list["ProjectSong"]] = relationship("ProjectSong", back_populates="song")


class ProjectSong(Base):
    __tablename__ = "project_songs"

    id:         Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
    project_id: Mapped[str] = mapped_column(String(36), ForeignKey("projects.id"), nullable=False)
    song_id:    Mapped[str] = mapped_column(String(36), ForeignKey("songs.id"), nullable=False)
    position:   Mapped[int] = mapped_column(Integer, nullable=False)
    status:     Mapped[str] = mapped_column(String(16), default="pending")  # pending | playing | played | skipped

    project: Mapped["Project"] = relationship("Project", back_populates="project_songs")
    song:    Mapped["Song"]    = relationship("Song", back_populates="project_songs")


# ── Dance ─────────────────────────────────────────────────────────────────────

class SongDance(Base):
    __tablename__ = "song_dances"

    id:          Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
    song_id:     Mapped[str] = mapped_column(String(36), ForeignKey("songs.id"), nullable=False)
    dance_name:  Mapped[str] = mapped_column(String(128), nullable=False)
    dance_order: Mapped[int] = mapped_column(Integer, default=1)

    song:         Mapped["Song"]                    = relationship("Song", back_populates="dances")
    alternatives: Mapped[list["DanceAlternative"]]  = relationship("DanceAlternative", foreign_keys="DanceAlternative.song_dance_id", back_populates="song_dance", cascade="all, delete-orphan")


class DanceAlternative(Base):
    __tablename__ = "dance_alternatives"

    id:                Mapped[str]   = mapped_column(String(36), primary_key=True, default=new_uuid)
    song_dance_id:     Mapped[str]   = mapped_column(String(36), ForeignKey("song_dances.id"), nullable=False)
    alt_song_dance_id: Mapped[str]   = mapped_column(String(36), ForeignKey("song_dances.id"), nullable=False)
    created_by:        Mapped[str]   = mapped_column(String(36), ForeignKey("users.id"), nullable=False)
    note:              Mapped[str]   = mapped_column(Text, default="")
    bayesian_score:    Mapped[float] = mapped_column(default=0.0)  # genberegnes ved hver rating

    song_dance:     Mapped["SongDance"]                  = relationship("SongDance", foreign_keys=[song_dance_id], back_populates="alternatives")
    alt_song_dance: Mapped["SongDance"]                  = relationship("SongDance", foreign_keys=[alt_song_dance_id])
    creator:        Mapped["User"]                       = relationship("User", foreign_keys=[created_by])
    ratings:        Mapped[list["DanceAlternativeRating"]] = relationship("DanceAlternativeRating", back_populates="alternative", cascade="all, delete-orphan")


class DanceAlternativeRating(Base):
    __tablename__ = "dance_alternative_ratings"

    id:             Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
    alternative_id: Mapped[str] = mapped_column(String(36), ForeignKey("dance_alternatives.id"), nullable=False)
    user_id:        Mapped[str] = mapped_column(String(36), ForeignKey("users.id"), nullable=False)
    score:          Mapped[int] = mapped_column(Integer, nullable=False)  # 1-5

    alternative: Mapped["DanceAlternative"] = relationship("DanceAlternative", back_populates="ratings")
    user:        Mapped["User"]             = relationship("User", foreign_keys=[user_id])