"""Chapter evidence snapshots + normalized links (Phase C)

Revision ID: 0010_ce_snapshots (short id: alembic_version.version_num is VARCHAR(32))
Revises: 0009_ce_bundle_mem_trace
"""

from typing import Sequence, Union

import sqlalchemy as sa
from sqlalchemy.dialects import postgresql

from alembic import op

revision: str = "0010_ce_snapshots"
down_revision: Union[str, None] = "0009_ce_bundle_mem_trace"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def _has_table(name: str) -> bool:
    bind = op.get_bind()
    return sa.inspect(bind).has_table(name)


def _has_column(table: str, column: str) -> bool:
    bind = op.get_bind()
    return any(c["name"] == column for c in sa.inspect(bind).get_columns(table))


def upgrade() -> None:
    if not _has_table("chapter_evidence_snapshots"):
        op.create_table(
            "chapter_evidence_snapshots",
            sa.Column("id", sa.String(), nullable=False),
            sa.Column("chapter_id", sa.String(), nullable=False),
            sa.Column("user_id", sa.String(), nullable=False),
            sa.Column("version_no", sa.Integer(), nullable=False),
            sa.Column("schema_version", sa.Integer(), nullable=False, server_default="1"),
            sa.Column("segment_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("conversation_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("story_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("memory_chunk_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("memory_fact_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("timeline_event_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("summary_ids", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column("notes", postgresql.JSON(astext_type=sa.Text()), nullable=True),
            sa.Column(
                "captured_at",
                sa.DateTime(timezone=True),
                nullable=False,
                server_default=sa.text("now()"),
            ),
            sa.ForeignKeyConstraint(
                ["chapter_id"],
                ["chapters.id"],
                name="chapter_evidence_snapshots_chapter_id_fkey",
                ondelete="CASCADE",
            ),
            sa.ForeignKeyConstraint(
                ["user_id"],
                ["users.id"],
                name="chapter_evidence_snapshots_user_id_fkey",
            ),
            sa.PrimaryKeyConstraint("id", name="chapter_evidence_snapshots_pkey"),
            sa.UniqueConstraint(
                "chapter_id",
                "version_no",
                name="uq_chapter_evidence_snapshots_chapter_version",
            ),
        )
        op.create_index(
            "ix_chapter_evidence_snapshots_chapter_id",
            "chapter_evidence_snapshots",
            ["chapter_id"],
        )
        op.create_index(
            "ix_chapter_evidence_snapshots_user_id",
            "chapter_evidence_snapshots",
            ["user_id"],
        )

    if not _has_table("chapter_evidence_links"):
        op.create_table(
            "chapter_evidence_links",
            sa.Column("id", sa.String(), nullable=False),
            sa.Column("chapter_id", sa.String(), nullable=False),
            sa.Column("evidence_type", sa.String(), nullable=False),
            sa.Column("evidence_id", sa.String(), nullable=False),
            sa.Column("role", sa.String(), nullable=True),
            sa.Column("weight", sa.Float(), nullable=True),
            sa.Column(
                "created_at",
                sa.DateTime(timezone=True),
                server_default=sa.text("now()"),
                nullable=False,
            ),
            sa.ForeignKeyConstraint(
                ["chapter_id"],
                ["chapters.id"],
                name="chapter_evidence_links_chapter_id_fkey",
                ondelete="CASCADE",
            ),
            sa.PrimaryKeyConstraint("id", name="chapter_evidence_links_pkey"),
        )
        op.create_index(
            "ix_chapter_evidence_links_chapter_id",
            "chapter_evidence_links",
            ["chapter_id"],
        )

    if not _has_column("chapters", "current_evidence_snapshot_id"):
        op.add_column(
            "chapters",
            sa.Column("current_evidence_snapshot_id", sa.String(), nullable=True),
        )
        op.create_foreign_key(
            "fk_chapters_current_evidence_snapshot_id",
            "chapters",
            "chapter_evidence_snapshots",
            ["current_evidence_snapshot_id"],
            ["id"],
            ondelete="SET NULL",
        )


def downgrade() -> None:
    if _has_column("chapters", "current_evidence_snapshot_id"):
        op.drop_constraint(
            "fk_chapters_current_evidence_snapshot_id",
            "chapters",
            type_="foreignkey",
        )
        op.drop_column("chapters", "current_evidence_snapshot_id")
    if _has_table("chapter_evidence_links"):
        op.drop_index("ix_chapter_evidence_links_chapter_id", table_name="chapter_evidence_links")
        op.drop_table("chapter_evidence_links")
    if _has_table("chapter_evidence_snapshots"):
        op.drop_index("ix_chapter_evidence_snapshots_user_id", table_name="chapter_evidence_snapshots")
        op.drop_index("ix_chapter_evidence_snapshots_chapter_id", table_name="chapter_evidence_snapshots")
        op.drop_table("chapter_evidence_snapshots")