"""
一键执行 chapter_sections 迁移：先执行 SQL 建表/加列，再回填数据并删列。

依赖：.env 中 DATABASE_URL，以及 python-dotenv。
用法（在 api 目录下）:
    python -m scripts.run_chapter_sections_migration
"""
import json
import os
import sys
import uuid
from pathlib import Path

# 配置由 app.core.config 加载；DB 使用 psycopg 同步驱动
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
os.chdir(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from sqlalchemy import create_engine, text
from sqlalchemy.engine import Engine
from app.core.config import settings
from app.core.db import ensure_psycopg_url
from app.core.logging import get_logger, setup_logging

setup_logging()
logger = get_logger(__name__)


def get_engine() -> Engine:
    url = (settings.migration_database_url or "").strip() or settings.database_url
    return create_engine(ensure_psycopg_url(url), pool_pre_ping=True)


def run_sql_migration(engine: Engine):
    sql_path = Path(__file__).parent.parent / "migrations" / "add_chapter_sections.sql"
    sql = sql_path.read_text(encoding="utf-8")
    # 按 DO $$ ... $$; 与普通 ; 拆分，避免把 PL/pgSQL 块拆碎
    stmts = []
    rest = sql
    while rest:
        rest = rest.lstrip()
        if rest.startswith("--"):
            rest = rest[rest.find("\n") + 1:] if "\n" in rest else ""
            continue
        if rest.upper().startswith("DO "):
            # 找到 $$; 或 $$ ;
            i = rest.find("$$")
            if i == -1:
                break
            j = rest.find("$$", i + 2)
            if j == -1:
                break
            stmts.append(rest[: j + 2].strip() + ";")
            rest = rest[j + 2:].lstrip().lstrip(";").lstrip()
            continue
        idx = rest.find(";")
        if idx == -1:
            break
        part = rest[: idx].strip()
        rest = rest[idx + 1:]
        if part and not part.startswith("--"):
            stmts.append(part + ";")
    with engine.begin() as conn:
        for i, s in enumerate(stmts):
            try:
                conn.execute(text(s))
                logger.info("  SQL %s OK", i + 1)
            except Exception as e:
                if "already exists" in str(e).lower():
                    logger.info("  SQL %s (已存在)", i + 1)
                    continue
                raise
    logger.info("1/2 SQL 迁移完成")


def run_data_migration(engine: Engine):
    from app.features.memoir.memoir_images.parser import split_narrative_to_sections

    with engine.connect() as conn:
        r = conn.execute(text("""
            SELECT column_name FROM information_schema.columns
            WHERE table_schema = 'public' AND table_name = 'chapters' AND column_name = 'content'
        """))
        if r.fetchone() is None:
            logger.info("chapters.content 已不存在，跳过数据迁移")
            return

        rows = conn.execute(text("""
            SELECT id, content, images FROM chapters WHERE content IS NOT NULL AND trim(content) != ''
        """)).fetchall()

        for row in rows:
            ch_id, content, images_raw = row[0], row[1], row[2]
            if isinstance(images_raw, str):
                try:
                    images = json.loads(images_raw)
                except Exception:
                    images = []
            else:
                images = images_raw if isinstance(images_raw, list) else []

            sections = split_narrative_to_sections(content or "")
            if not sections:
                section_id = str(uuid.uuid4()).replace("-", "")[:32]
                conn.execute(text("""
                    INSERT INTO chapter_sections (id, chapter_id, order_index, content, image, updated_at)
                    VALUES (:id, :ch_id, 0, :content, NULL, NOW())
                """), {"id": section_id, "ch_id": ch_id, "content": (content or "").strip()})
                conn.commit()
                logger.info("章节 %s: 1 条 section（无图）", ch_id)
                continue

            first_cover = None
            img_index = 0
            for order_idx, seg in enumerate(sections):
                section_id = str(uuid.uuid4()).replace("-", "")[:32]
                seg_content = seg.get("content") or ""
                ph = seg.get("placeholder_info")
                image_json = None
                if ph is not None and img_index < len(images):
                    image_json = json.dumps(images[img_index]) if isinstance(images[img_index], dict) else None
                    if first_cover is None and image_json:
                        first_cover = image_json
                    img_index += 1

                conn.execute(text("""
                    INSERT INTO chapter_sections (id, chapter_id, order_index, content, image, updated_at)
                    VALUES (:id, :ch_id, :ord, :content, CAST(:img AS jsonb), NOW())
                """), {
                    "id": section_id,
                    "ch_id": ch_id,
                    "ord": order_idx,
                    "content": seg_content,
                    "img": image_json,
                })
            if first_cover:
                conn.execute(
                    text("UPDATE chapters SET cover_image = CAST(:img AS jsonb) WHERE id = :id"),
                    {"img": first_cover, "id": ch_id},
                )
            conn.commit()
            logger.info("章节 %s: %d 条 sections", ch_id, len(sections))

        conn.execute(text("ALTER TABLE chapters DROP COLUMN IF EXISTS content"))
        conn.execute(text("ALTER TABLE chapters DROP COLUMN IF EXISTS images"))
        conn.commit()
        logger.info("已删除 chapters.content 与 chapters.images")
    logger.info("2/2 数据迁移完成")


if __name__ == "__main__":
    logger.info("开始 chapter_sections 迁移…")
    engine = get_engine()
    run_sql_migration(engine)
    run_data_migration(engine)
    logger.info("迁移全部完成")