"""SQLAlchemy ORM models for the Chrysopedia knowledge base.

Seven entities matching chrysopedia-spec.md §6.1:
  Creator, SourceVideo, TranscriptSegment, KeyMoment,
  TechniquePage, RelatedTechniqueLink, Tag
"""

from __future__ import annotations

import enum
import uuid
from datetime import datetime, timezone

from sqlalchemy import (
    Enum,
    Float,
    ForeignKey,
    Integer,
    String,
    Text,
    UniqueConstraint,
    func,
)
from sqlalchemy.dialects.postgresql import ARRAY, JSONB, UUID
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.orm import relationship as sa_relationship

from database import Base


# ── Enums ────────────────────────────────────────────────────────────────────

class ContentType(str, enum.Enum):
    """Source video content type."""
    tutorial = "tutorial"
    livestream = "livestream"
    breakdown = "breakdown"
    short_form = "short_form"


class ProcessingStatus(str, enum.Enum):
    """Pipeline processing status for a source video."""
    pending = "pending"
    transcribed = "transcribed"
    extracted = "extracted"
    reviewed = "reviewed"
    published = "published"


class KeyMomentContentType(str, enum.Enum):
    """Content classification for a key moment."""
    technique = "technique"
    settings = "settings"
    reasoning = "reasoning"
    workflow = "workflow"


class ReviewStatus(str, enum.Enum):
    """Human review status for key moments."""
    pending = "pending"
    approved = "approved"
    edited = "edited"
    rejected = "rejected"


class SourceQuality(str, enum.Enum):
    """Derived source quality for technique pages."""
    structured = "structured"
    mixed = "mixed"
    unstructured = "unstructured"


class PageReviewStatus(str, enum.Enum):
    """Review lifecycle for technique pages."""
    draft = "draft"
    reviewed = "reviewed"
    published = "published"


class RelationshipType(str, enum.Enum):
    """Types of links between technique pages."""
    same_technique_other_creator = "same_technique_other_creator"
    same_creator_adjacent = "same_creator_adjacent"
    general_cross_reference = "general_cross_reference"


# ── Helpers ──────────────────────────────────────────────────────────────────

def _uuid_pk() -> Mapped[uuid.UUID]:
    return mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        server_default=func.gen_random_uuid(),
    )


def _now() -> datetime:
    """Return current UTC time as a naive datetime (no tzinfo).

    PostgreSQL TIMESTAMP WITHOUT TIME ZONE columns require naive datetimes.
    asyncpg rejects timezone-aware datetimes for such columns.
    """
    return datetime.now(timezone.utc).replace(tzinfo=None)


# ── Models ───────────────────────────────────────────────────────────────────

class Creator(Base):
    __tablename__ = "creators"

    id: Mapped[uuid.UUID] = _uuid_pk()
    name: Mapped[str] = mapped_column(String(255), nullable=False)
    slug: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
    genres: Mapped[list[str] | None] = mapped_column(ARRAY(String), nullable=True)
    folder_name: Mapped[str] = mapped_column(String(255), nullable=False)
    view_count: Mapped[int] = mapped_column(Integer, default=0, server_default="0")
    created_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now(), onupdate=_now
    )

    # relationships
    videos: Mapped[list[SourceVideo]] = sa_relationship(back_populates="creator")
    technique_pages: Mapped[list[TechniquePage]] = sa_relationship(back_populates="creator")


class SourceVideo(Base):
    __tablename__ = "source_videos"

    id: Mapped[uuid.UUID] = _uuid_pk()
    creator_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("creators.id", ondelete="CASCADE"), nullable=False
    )
    filename: Mapped[str] = mapped_column(String(500), nullable=False)
    file_path: Mapped[str] = mapped_column(String(1000), nullable=False)
    duration_seconds: Mapped[int] = mapped_column(Integer, nullable=True)
    content_type: Mapped[ContentType] = mapped_column(
        Enum(ContentType, name="content_type", create_constraint=True),
        nullable=False,
    )
    transcript_path: Mapped[str | None] = mapped_column(String(1000), nullable=True)
    processing_status: Mapped[ProcessingStatus] = mapped_column(
        Enum(ProcessingStatus, name="processing_status", create_constraint=True),
        default=ProcessingStatus.pending,
        server_default="pending",
    )
    created_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now(), onupdate=_now
    )

    # relationships
    creator: Mapped[Creator] = sa_relationship(back_populates="videos")
    segments: Mapped[list[TranscriptSegment]] = sa_relationship(back_populates="source_video")
    key_moments: Mapped[list[KeyMoment]] = sa_relationship(back_populates="source_video")


class TranscriptSegment(Base):
    __tablename__ = "transcript_segments"

    id: Mapped[uuid.UUID] = _uuid_pk()
    source_video_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("source_videos.id", ondelete="CASCADE"), nullable=False
    )
    start_time: Mapped[float] = mapped_column(Float, nullable=False)
    end_time: Mapped[float] = mapped_column(Float, nullable=False)
    text: Mapped[str] = mapped_column(Text, nullable=False)
    segment_index: Mapped[int] = mapped_column(Integer, nullable=False)
    topic_label: Mapped[str | None] = mapped_column(String(255), nullable=True)

    # relationships
    source_video: Mapped[SourceVideo] = sa_relationship(back_populates="segments")


class KeyMoment(Base):
    __tablename__ = "key_moments"

    id: Mapped[uuid.UUID] = _uuid_pk()
    source_video_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("source_videos.id", ondelete="CASCADE"), nullable=False
    )
    technique_page_id: Mapped[uuid.UUID | None] = mapped_column(
        ForeignKey("technique_pages.id", ondelete="SET NULL"), nullable=True
    )
    title: Mapped[str] = mapped_column(String(500), nullable=False)
    summary: Mapped[str] = mapped_column(Text, nullable=False)
    start_time: Mapped[float] = mapped_column(Float, nullable=False)
    end_time: Mapped[float] = mapped_column(Float, nullable=False)
    content_type: Mapped[KeyMomentContentType] = mapped_column(
        Enum(KeyMomentContentType, name="key_moment_content_type", create_constraint=True),
        nullable=False,
    )
    plugins: Mapped[list[str] | None] = mapped_column(ARRAY(String), nullable=True)
    review_status: Mapped[ReviewStatus] = mapped_column(
        Enum(ReviewStatus, name="review_status", create_constraint=True),
        default=ReviewStatus.pending,
        server_default="pending",
    )
    raw_transcript: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now(), onupdate=_now
    )

    # relationships
    source_video: Mapped[SourceVideo] = sa_relationship(back_populates="key_moments")
    technique_page: Mapped[TechniquePage | None] = sa_relationship(
        back_populates="key_moments", foreign_keys=[technique_page_id]
    )


class TechniquePage(Base):
    __tablename__ = "technique_pages"

    id: Mapped[uuid.UUID] = _uuid_pk()
    creator_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("creators.id", ondelete="CASCADE"), nullable=False
    )
    title: Mapped[str] = mapped_column(String(500), nullable=False)
    slug: Mapped[str] = mapped_column(String(500), unique=True, nullable=False)
    topic_category: Mapped[str] = mapped_column(String(255), nullable=False)
    topic_tags: Mapped[list[str] | None] = mapped_column(ARRAY(String), nullable=True)
    summary: Mapped[str | None] = mapped_column(Text, nullable=True)
    body_sections: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    signal_chains: Mapped[list | None] = mapped_column(JSONB, nullable=True)
    plugins: Mapped[list[str] | None] = mapped_column(ARRAY(String), nullable=True)
    source_quality: Mapped[SourceQuality | None] = mapped_column(
        Enum(SourceQuality, name="source_quality", create_constraint=True),
        nullable=True,
    )
    view_count: Mapped[int] = mapped_column(Integer, default=0, server_default="0")
    review_status: Mapped[PageReviewStatus] = mapped_column(
        Enum(PageReviewStatus, name="page_review_status", create_constraint=True),
        default=PageReviewStatus.draft,
        server_default="draft",
    )
    created_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now(), onupdate=_now
    )

    # relationships
    creator: Mapped[Creator] = sa_relationship(back_populates="technique_pages")
    key_moments: Mapped[list[KeyMoment]] = sa_relationship(
        back_populates="technique_page", foreign_keys=[KeyMoment.technique_page_id]
    )
    versions: Mapped[list[TechniquePageVersion]] = sa_relationship(
        back_populates="technique_page", order_by="TechniquePageVersion.version_number"
    )
    outgoing_links: Mapped[list[RelatedTechniqueLink]] = sa_relationship(
        foreign_keys="RelatedTechniqueLink.source_page_id", back_populates="source_page"
    )
    incoming_links: Mapped[list[RelatedTechniqueLink]] = sa_relationship(
        foreign_keys="RelatedTechniqueLink.target_page_id", back_populates="target_page"
    )


class RelatedTechniqueLink(Base):
    __tablename__ = "related_technique_links"
    __table_args__ = (
        UniqueConstraint("source_page_id", "target_page_id", "relationship", name="uq_technique_link"),
    )

    id: Mapped[uuid.UUID] = _uuid_pk()
    source_page_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("technique_pages.id", ondelete="CASCADE"), nullable=False
    )
    target_page_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("technique_pages.id", ondelete="CASCADE"), nullable=False
    )
    relationship: Mapped[RelationshipType] = mapped_column(
        Enum(RelationshipType, name="relationship_type", create_constraint=True),
        nullable=False,
    )

    # relationships
    source_page: Mapped[TechniquePage] = sa_relationship(
        foreign_keys=[source_page_id], back_populates="outgoing_links"
    )
    target_page: Mapped[TechniquePage] = sa_relationship(
        foreign_keys=[target_page_id], back_populates="incoming_links"
    )


class TechniquePageVersion(Base):
    """Snapshot of a TechniquePage before a pipeline re-synthesis overwrites it."""
    __tablename__ = "technique_page_versions"

    id: Mapped[uuid.UUID] = _uuid_pk()
    technique_page_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("technique_pages.id", ondelete="CASCADE"), nullable=False
    )
    version_number: Mapped[int] = mapped_column(Integer, nullable=False)
    content_snapshot: Mapped[dict] = mapped_column(JSONB, nullable=False)
    pipeline_metadata: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        default=_now, server_default=func.now()
    )

    # relationships
    technique_page: Mapped[TechniquePage] = sa_relationship(
        back_populates="versions"
    )


class Tag(Base):
    __tablename__ = "tags"

    id: Mapped[uuid.UUID] = _uuid_pk()
    name: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
    category: Mapped[str] = mapped_column(String(255), nullable=False)
    aliases: Mapped[list[str] | None] = mapped_column(ARRAY(String), nullable=True)