"""add debug_sessions + debug_screenshots, and index log_events.debug_session_id (E16)

Revision ID: 0089_debug_sessions
Revises: 0088_channels_feed_fallback_at
Create Date: 2026-09-19

A debug session is one recording: Start → reproduce → Stop (app/debugsession.py). Every log line
of that user's requests while it runs carries its id in `log_events.debug_session_id` — the column
E22 created and left NULL — and the issue it ends in is built from exactly those rows, so the column
gets its index now. Partial: nearly every row has no session, and an index of NULLs would be most
of the table for nothing.

At most one OPEN session per user, held by a partial unique index rather than by the start handler
alone: two tabs pressing Start at once would otherwise both pass a "none open" check.

Screenshots are rows, not files: bounded (size and count per session, app/debugsession.py), gone
with their session by cascade, and a self-host has no file volume to configure for them.
"""

import sqlalchemy as sa
from alembic import op

revision: str = "0089_debug_sessions"
down_revision: str | None = "0088_channels_feed_fallback_at"
branch_labels: str | None = None
depends_on: str | None = None


def upgrade() -> None:
    op.create_table(
        "debug_sessions",
        sa.Column("id", sa.String(16), primary_key=True),
        sa.Column(
            "user_id",
            sa.Integer,
            sa.ForeignKey("users.id", ondelete="CASCADE"),
            nullable=False,
            index=True,
        ),
        sa.Column("level", sa.String(8), nullable=False),
        sa.Column("started_at", sa.DateTime(timezone=True), nullable=False),
        sa.Column("until", sa.DateTime(timezone=True), nullable=False),
        sa.Column("ended_at", sa.DateTime(timezone=True), nullable=True),
        sa.Column("ended_reason", sa.String(16), nullable=True),
        sa.Column("issue_url", sa.String(512), nullable=True),
    )
    op.create_index(
        "uq_debug_sessions_open_per_user",
        "debug_sessions",
        ["user_id"],
        unique=True,
        postgresql_where=sa.text("ended_at IS NULL"),
    )
    op.create_table(
        "debug_screenshots",
        sa.Column("id", sa.Integer, primary_key=True),
        sa.Column(
            "session_id",
            sa.String(16),
            sa.ForeignKey("debug_sessions.id", ondelete="CASCADE"),
            nullable=False,
            index=True,
        ),
        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
        sa.Column("mime", sa.String(16), nullable=False),
        sa.Column("size", sa.Integer, nullable=False),
        sa.Column("data", sa.LargeBinary, nullable=False),
    )
    op.create_index(
        "ix_log_events_debug_session",
        "log_events",
        ["debug_session_id"],
        postgresql_where=sa.text("debug_session_id IS NOT NULL"),
    )


def downgrade() -> None:
    op.drop_index("ix_log_events_debug_session", table_name="log_events")
    op.drop_table("debug_screenshots")
    op.drop_index("uq_debug_sessions_open_per_user", table_name="debug_sessions")
    op.drop_table("debug_sessions")