codetutor/backend/alembic/versions/001_initial_schema.py

"""Initial schema

Revision ID: 001
Revises:
Create Date: 2025-01-30

"""

from collections.abc import Sequence

import sqlalchemy as sa
from alembic import op
from sqlalchemy.dialects import postgresql

revision: str = "001"
down_revision: str | None = None
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def upgrade() -> None:
    # Create difficulty enum using raw SQL to avoid SQLAlchemy auto-creation issues
    op.execute("CREATE TYPE difficulty_enum AS ENUM ('easy', 'medium', 'hard')")

    # Create questions table
    op.create_table(
        "questions",
        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True),
        sa.Column("title", sa.String(255), nullable=False),
        sa.Column("slug", sa.String(255), unique=True, nullable=False),
        sa.Column(
            "difficulty",
            postgresql.ENUM("easy", "medium", "hard", name="difficulty_enum", create_type=False),
            nullable=False,
        ),
        sa.Column("description", sa.Text, nullable=False),
        sa.Column("constraints", sa.Text, nullable=True),
        sa.Column("examples", postgresql.JSONB, nullable=True),
        sa.Column("leetcode_id", sa.Integer, unique=True, nullable=True),
        sa.Column("leetcode_url", sa.String(512), nullable=True),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            server_default=sa.func.now(),
            nullable=False,
        ),
        sa.Column(
            "updated_at",
            sa.DateTime(timezone=True),
            server_default=sa.func.now(),
            nullable=False,
        ),
    )
    op.create_index("ix_questions_slug", "questions", ["slug"])
    op.create_index("ix_questions_difficulty", "questions", ["difficulty"])

    # Create explanations table
    op.create_table(
        "explanations",
        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True),
        sa.Column(
            "question_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("questions.id", ondelete="CASCADE"),
            unique=True,
            nullable=False,
        ),
        sa.Column("approach", sa.Text, nullable=False),
        sa.Column("intuition", sa.Text, nullable=False),
        sa.Column("common_pitfalls", postgresql.JSONB, nullable=True),
        sa.Column("key_takeaways", postgresql.JSONB, nullable=True),
        sa.Column("time_complexity", sa.String(50), nullable=False),
        sa.Column("space_complexity", sa.String(50), nullable=False),
        sa.Column("complexity_explanation", sa.Text, nullable=True),
    )

    # Create solutions table
    op.create_table(
        "solutions",
        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True),
        sa.Column(
            "question_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("questions.id", ondelete="CASCADE"),
            nullable=False,
        ),
        sa.Column("approach_name", sa.String(100), nullable=False),
        sa.Column("code", sa.Text, nullable=False),
        sa.Column("language", sa.String(20), server_default="python", nullable=False),
        sa.Column("is_optimal", sa.Boolean, server_default="false", nullable=False),
        sa.Column("explanation", sa.Text, nullable=True),
    )
    op.create_index("ix_solutions_question_id", "solutions", ["question_id"])

    # Create categories table
    op.create_table(
        "categories",
        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True),
        sa.Column("name", sa.String(100), unique=True, nullable=False),
        sa.Column("slug", sa.String(100), unique=True, nullable=False),
        sa.Column("description", sa.Text, nullable=True),
    )
    op.create_index("ix_categories_slug", "categories", ["slug"])

    # Create patterns table
    op.create_table(
        "patterns",
        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True),
        sa.Column("name", sa.String(100), unique=True, nullable=False),
        sa.Column("slug", sa.String(100), unique=True, nullable=False),
        sa.Column("description", sa.Text, nullable=True),
        sa.Column("when_to_use", sa.Text, nullable=True),
    )
    op.create_index("ix_patterns_slug", "patterns", ["slug"])

    # Create question_categories junction table
    op.create_table(
        "question_categories",
        sa.Column(
            "question_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("questions.id", ondelete="CASCADE"),
            primary_key=True,
        ),
        sa.Column(
            "category_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("categories.id", ondelete="CASCADE"),
            primary_key=True,
        ),
    )

    # Create question_patterns junction table
    op.create_table(
        "question_patterns",
        sa.Column(
            "question_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("questions.id", ondelete="CASCADE"),
            primary_key=True,
        ),
        sa.Column(
            "pattern_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("patterns.id", ondelete="CASCADE"),
            primary_key=True,
        ),
    )


def downgrade() -> None:
    op.drop_table("question_patterns")
    op.drop_table("question_categories")
    op.drop_table("patterns")
    op.drop_table("categories")
    op.drop_table("solutions")
    op.drop_table("explanations")
    op.drop_table("questions")

    op.execute("DROP TYPE IF EXISTS difficulty_enum")