"""迁移 019: 修复已有 schema 和数据问题。

修复内容：
1. 转换 slides_config_json 中的对象格式 {"slides": [...]} 为数组格式 [...]
2. 为 poster_records 表添加生成方式追踪字段
3. 为常用查询添加索引
"""
import json
import logging
from sqlalchemy import text, inspect

logger = logging.getLogger(__name__)


def migrate():
    """执行迁移。"""
    from insurance.db.compat import db
    dialect = db.engine.dialect.name

    _fix_slides_config_json(db)
    _add_poster_record_fields(db, dialect)
    _add_indexes(db, dialect)
    db.session.commit()


def _column_exists(db, table_name: str, column_name: str) -> bool:
    """检查列是否存在。"""
    dialect = db.engine.dialect.name
    if dialect == "postgresql":
        result = db.session.execute(text(
            "SELECT COUNT(*) FROM information_schema.columns "
            "WHERE table_name = :table AND column_name = :column"
        ), {"table": table_name, "column": column_name})
        return result.scalar() > 0
    else:
        try:
            result = db.session.execute(text(f"PRAGMA table_info({table_name})"))
            return any(row[1] == column_name for row in result.fetchall())
        except Exception:
            return False


def _fix_slides_config_json(db):
    """将对象格式 {"slides": [...]} 转换为数组格式 [...]。

    历史数据中 migrate_017 写入的是 {"slides": [...]}，
    但渲染器和前端均期望数组格式。
    """
    templates = db.session.execute(text(
        "SELECT id, slides_config_json FROM insurance_ppt_templates "
        "WHERE slides_config_json IS NOT NULL"
    )).fetchall()

    fixed_count = 0
    for tpl_id, config_json in templates:
        if not config_json or not config_json.strip():
            continue
        try:
            config = json.loads(config_json)
        except (json.JSONDecodeError, TypeError):
            logger.warning(f"模板 {tpl_id} 的 slides_config_json 无法解析，跳过")
            continue

        # 如果是对象格式 {"slides": [...]}，转换为数组
        if isinstance(config, dict) and "slides" in config:
            slides_array = config["slides"]
            if isinstance(slides_array, list):
                db.session.execute(text(
                    "UPDATE insurance_ppt_templates SET slides_config_json = :config WHERE id = :id"
                ), {"config": json.dumps(slides_array, ensure_ascii=False), "id": tpl_id})
                fixed_count += 1
                logger.info(f"模板 {tpl_id}: 对象格式已转换为数组格式")
            else:
                logger.warning(f"模板 {tpl_id}: slides 值不是数组，跳过")
        elif isinstance(config, list):
            pass  # 已经是数组格式，无需处理
        else:
            logger.warning(f"模板 {tpl_id}: 未知格式 {type(config).__name__}，跳过")

    if fixed_count > 0:
        logger.info(f"已修复 {fixed_count} 个模板的 slides_config_json 格式")


def _add_poster_record_fields(db, dialect):
    """为 poster_records 表添加生成方式追踪和任务状态字段。"""
    new_columns = [
        ("generation_mode", "VARCHAR(20)", "生成方式: ai/fallback"),
        ("image_provider", "VARCHAR(50)", "图片供应商"),
        ("image_model", "VARCHAR(100)", "图片模型名称"),
        ("task_status", "VARCHAR(20)", "任务状态: pending/queued/generating/done/failed"),
        ("task_progress", "INTEGER", "任务进度 0-100"),
        ("task_error", "TEXT", "任务错误信息"),
        ("started_at", "TIMESTAMP", "任务开始时间"),
        ("finished_at", "TIMESTAMP", "任务完成时间"),
    ]

    for col_name, col_type, comment in new_columns:
        if _column_exists(db, "poster_records", col_name):
            logger.debug(f"poster_records.{col_name} 已存在，跳过")
            continue

        try:
            db.session.execute(text(
                f"ALTER TABLE poster_records ADD COLUMN {col_name} {col_type}"
            ))
            db.session.commit()
            logger.info(f"已添加 poster_records.{col_name} ({comment})")
        except Exception as e:
            db.session.rollback()
            logger.warning(f"添加 poster_records.{col_name} 失败（已回滚，不影响其他字段）: {e}")


def _add_indexes(db, dialect):
    """为常用查询添加索引。"""
    indexes = [
        ("idx_poster_records_user_id", "poster_records", ["user_id"]),
        ("idx_poster_records_created_at", "poster_records", ["created_at"]),
        ("idx_poster_case_uploads_user_id", "poster_case_uploads", ["user_id"]),
        ("idx_ppt_history_user_id", "insurance_ppt_history", ["user_id"]),
        ("idx_ppt_history_created_at", "insurance_ppt_history", ["created_at"]),
        ("idx_system_settings_key", "system_settings", ["key"]),
    ]

    for idx_name, table_name, columns in indexes:
        try:
            # 检查表是否存在
            if dialect == "postgresql":
                result = db.session.execute(text(
                    "SELECT COUNT(*) FROM information_schema.tables WHERE table_name = :table"
                ), {"table": table_name})
                if result.scalar() == 0:
                    continue
            else:
                try:
                    db.session.execute(text(f"SELECT 1 FROM {table_name} LIMIT 0"))
                except Exception:
                    continue

            # 检查索引是否已存在
            if dialect == "postgresql":
                result = db.session.execute(text(
                    "SELECT COUNT(*) FROM pg_indexes WHERE indexname = :idx"
                ), {"idx": idx_name})
                if result.scalar() > 0:
                    continue
            else:
                try:
                    result = db.session.execute(text(
                        "SELECT COUNT(*) FROM sqlite_master WHERE type='index' AND name = :idx"
                    ), {"idx": idx_name})
                    if result.scalar() > 0:
                        continue
                except Exception:
                    continue

            cols = ", ".join(columns)
            db.session.execute(text(f"CREATE INDEX {idx_name} ON {table_name} ({cols})"))
            logger.info(f"已创建索引 {idx_name}")
        except Exception as e:
            logger.warning(f"创建索引 {idx_name} 失败: {e}")
            db.session.rollback()