"""migrate legacy placeholders and memoir_images to assets

1. 从 chapters.canonical_markdown 移除 {{IMAGE:...}} / {{{{IMAGE:...}}}} 占位符
2. 将已完成 memoir_images（含 storage_key）写入 assets；章节封面绑定 cover_asset_id

Revision ID: 0008_legacy_assets
Revises: 0007_assets
Create Date: 2026-03-19

"""

import uuid
from datetime import datetime, timezone
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa

revision: str = "0008_legacy_assets"
down_revision: Union[str, Sequence[str], None] = "0007_assets"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    from app.features.memoir.asset_resolver import strip_legacy_image_placeholders

    conn = op.get_bind()

    rows_ch = conn.execute(
        sa.text(
            "SELECT id, canonical_markdown FROM chapters WHERE canonical_markdown IS NOT NULL"
        )
    ).fetchall()
    for cid, md in rows_ch:
        if not md or not str(md).strip():
            continue
        cleaned = strip_legacy_image_placeholders(str(md))
        if cleaned != str(md).strip():
            conn.execute(
                sa.text("UPDATE chapters SET canonical_markdown = :md WHERE id = :id"),
                {"md": cleaned, "id": cid},
            )

    rows_mi = conn.execute(
        sa.text(
            """
            SELECT id, chapter_id, section_id, storage_key, url, provider, style, status
            FROM memoir_images
            WHERE status = 'completed'
              AND storage_key IS NOT NULL
              AND TRIM(storage_key) <> ''
            """
        )
    ).fetchall()

    existing = {
        r[0]
        for r in conn.execute(sa.text("SELECT storage_key FROM assets")).fetchall()
        if r[0]
    }

    for row in rows_mi:
        _mid, chapter_id, section_id, storage_key, url, provider, style, _status = row
        sk = (storage_key or "").strip()
        if not sk or sk in existing:
            continue
        aid = str(uuid.uuid4())
        asset_type = "chapter_cover" if section_id is None else "story_image"
        now = datetime.now(timezone.utc)
        conn.execute(
            sa.text(
                """
                INSERT INTO assets (
                    id, asset_type, storage_key, url, provider, style_profile,
                    prompt_final, status, width, height, created_at
                ) VALUES (
                    :id, :atype, :sk, :url, :prov, :style,
                    :prompt, 'completed', NULL, NULL, :created
                )
                """
            ),
            {
                "id": aid,
                "atype": asset_type,
                "sk": sk,
                "url": url,
                "prov": provider,
                "style": style,
                "prompt": None,
                "created": now,
            },
        )
        existing.add(sk)
        if section_id is None and chapter_id:
            conn.execute(
                sa.text(
                    """
                    UPDATE chapters
                    SET cover_asset_id = :aid
                    WHERE id = :cid
                      AND (cover_asset_id IS NULL OR cover_asset_id = '')
                    """
                ),
                {"aid": aid, "cid": chapter_id},
            )


def downgrade() -> None:
    pass