"""
Document Template and Version models
"""
from sqlalchemy import Column, Integer, String, Text, ForeignKey, Boolean, UniqueConstraint
from sqlalchemy.orm import relationship

from app.models.base import BaseModel


class DocumentTemplate(BaseModel):
    """
    High-level template metadata and current version pointer.
    """
    __tablename__ = "document_templates"

    id = Column(Integer, primary_key=True, autoincrement=True, index=True)
    name = Column(String(200), unique=True, nullable=False, index=True)
    description = Column(Text)
    category = Column(String(100), index=True, default="GENERAL")
    active = Column(Boolean, default=True, nullable=False)

    # Creator username (optional)
    created_by = Column(String(150), ForeignKey("users.username"), nullable=True)

    # Pointer to the currently-approved version
    current_version_id = Column(Integer, ForeignKey("document_template_versions.id", use_alter=True), nullable=True)

    # Relationships
    current_version = relationship(
        "DocumentTemplateVersion",
        foreign_keys=[current_version_id],
        post_update=True,
        primaryjoin="DocumentTemplate.current_version_id==DocumentTemplateVersion.id",
        uselist=False,
    )
    versions = relationship(
        "DocumentTemplateVersion",
        back_populates="template",
        cascade="all, delete-orphan",
        order_by="desc(DocumentTemplateVersion.created_at)",
        foreign_keys="DocumentTemplateVersion.template_id",
    )
    keywords = relationship(
        "TemplateKeyword",
        back_populates="template",
        cascade="all, delete-orphan",
        order_by="asc(TemplateKeyword.keyword)",
        foreign_keys="TemplateKeyword.template_id",
    )


class DocumentTemplateVersion(BaseModel):
    """
    Template binary version metadata and storage location
    """
    __tablename__ = "document_template_versions"

    id = Column(Integer, primary_key=True, autoincrement=True, index=True)
    template_id = Column(Integer, ForeignKey("document_templates.id"), nullable=False, index=True)

    semantic_version = Column(String(50), nullable=False, index=True)  # e.g., 1.0.0
    storage_path = Column(String(512), nullable=False)  # local path or S3 URI
    mime_type = Column(String(100), nullable=False)
    size = Column(Integer, nullable=False, default=0)
    checksum = Column(String(64), nullable=False)  # sha256 hex
    changelog = Column(Text)
    created_by = Column(String(150), ForeignKey("users.username"), nullable=True)
    is_approved = Column(Boolean, default=True, nullable=False)

    # Relationships
    template = relationship(
        "DocumentTemplate",
        back_populates="versions",
        foreign_keys=[template_id],
        primaryjoin="DocumentTemplateVersion.template_id==DocumentTemplate.id",
    )


class TemplateKeyword(BaseModel):
    """
    Keyword/tag assigned to a DocumentTemplate.
    """
    __tablename__ = "template_keywords"

    id = Column(Integer, primary_key=True, autoincrement=True, index=True)
    template_id = Column(Integer, ForeignKey("document_templates.id"), nullable=False, index=True)
    keyword = Column(String(100), nullable=False, index=True)

    __table_args__ = (
        UniqueConstraint("template_id", "keyword", name="uq_template_keyword"),
    )

    template = relationship(
        "DocumentTemplate",
        back_populates="keywords",
        foreign_keys=[template_id],
        primaryjoin="TemplateKeyword.template_id==DocumentTemplate.id",
    )