import re

from sqlalchemy import text

from app.core.config import settings
from app.db.mysql import SessionLocal

IDENTIFIER_RE = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*$")
DATE_RE = re.compile(r"^\d{8}$")


def _normalize_date(date_value: str | None) -> str | None:
    if not date_value:
        return None
    normalized = date_value.replace("-", "").strip()
    if not normalized:
        return None
    if not DATE_RE.match(normalized):
        raise ValueError("date must be yyyymmdd or yyyy-mm-dd")
    return normalized


MAX_EXPORT_ROWS = 50_000


def _build_demand_pool_filters(
    strategies: list[str] | None = None,
    start_dt: str | None = None,
    end_dt: str | None = None,
    demand_name: str | None = None,
    min_weight: float | None = None,
    max_weight: float | None = None,
    sort_by: str | None = None,
    sort_order: str | None = None,
) -> tuple[str, str, dict[str, object]]:
    where_parts: list[str] = []
    params: dict[str, object] = {}

    cleaned_strategies = [value.strip() for value in (strategies or []) if value.strip()]
    if cleaned_strategies:
        placeholders: list[str] = []
        for index, strategy_value in enumerate(cleaned_strategies):
            key = f"strategy_{index}"
            placeholders.append(f":{key}")
            params[key] = strategy_value
        where_parts.append(f"strategy IN ({','.join(placeholders)})")
    normalized_start_dt = _normalize_date(start_dt)
    normalized_end_dt = _normalize_date(end_dt)

    if normalized_start_dt:
        where_parts.append("dt >= :start_dt")
        params["start_dt"] = normalized_start_dt
    if normalized_end_dt:
        where_parts.append("dt <= :end_dt")
        params["end_dt"] = normalized_end_dt
    demand_name_needle = (demand_name or "").strip()
    if demand_name_needle:
        where_parts.append("LOCATE(:demand_name_filter, demand_name) > 0")
        params["demand_name_filter"] = demand_name_needle
    if min_weight is not None:
        where_parts.append("weight >= :min_weight")
        params["min_weight"] = min_weight
    if max_weight is not None:
        where_parts.append("weight <= :max_weight")
        params["max_weight"] = max_weight

    where_sql = f"WHERE {' AND '.join(where_parts)}" if where_parts else ""
    sort_column_map = {
        "id": "id",
        "strategy": "strategy",
        "demand_name": "demand_name",
        "weight": "weight",
        "type": "`type`",
        "video_count": "video_count",
        "dt": "dt",
    }
    order_column = sort_column_map.get(sort_by or "", "weight")
    order_direction = "ASC" if (sort_order or "").lower() == "asc" else "DESC"
    order_sql = f"ORDER BY {order_column} {order_direction}"
    return where_sql, order_sql, params


def query_demand_pool_records(
    strategies: list[str] | None = None,
    start_dt: str | None = None,
    end_dt: str | None = None,
    demand_name: str | None = None,
    min_weight: float | None = None,
    max_weight: float | None = None,
    sort_by: str | None = None,
    sort_order: str | None = None,
    page: int = 1,
    page_size: int = 20,
) -> dict[str, object]:
    table_name = settings.demand_pool_target_table
    if not IDENTIFIER_RE.match(table_name):
        raise ValueError("invalid table name in settings")

    where_sql, order_sql, params = _build_demand_pool_filters(
        strategies=strategies,
        start_dt=start_dt,
        end_dt=end_dt,
        demand_name=demand_name,
        min_weight=min_weight,
        max_weight=max_weight,
        sort_by=sort_by,
        sort_order=sort_order,
    )
    offset = (page - 1) * page_size
    page_params: dict[str, object] = {
        **params,
        "page_size": page_size,
        "offset": offset,
    }
    count_sql = text(
        f"""
        SELECT COUNT(1) AS total
        FROM {table_name}
        {where_sql}
        """
    )
    query_sql = text(
        f"""
        SELECT
            id,
            strategy,
            demand_id,
            demand_name,
            weight,
            `type`,
            video_count,
            video_list,
            ext_info,
            dt,
            create_time,
            update_time
        FROM {table_name}
        {where_sql}
        {order_sql}
        LIMIT :page_size OFFSET :offset
        """
    )

    with SessionLocal() as session:
        total = int(session.execute(count_sql, params).scalar() or 0)
        rows = session.execute(query_sql, page_params).mappings().all()

    return {
        "total": total,
        "page": page,
        "page_size": page_size,
        "items": [dict(row) for row in rows],
    }


def export_demand_pool_records(
    strategies: list[str] | None = None,
    start_dt: str | None = None,
    end_dt: str | None = None,
    demand_name: str | None = None,
    min_weight: float | None = None,
    max_weight: float | None = None,
    sort_by: str | None = None,
    sort_order: str | None = None,
    max_rows: int = MAX_EXPORT_ROWS,
) -> list[dict[str, object]]:
    table_name = settings.demand_pool_target_table
    if not IDENTIFIER_RE.match(table_name):
        raise ValueError("invalid table name in settings")

    where_sql, order_sql, params = _build_demand_pool_filters(
        strategies=strategies,
        start_dt=start_dt,
        end_dt=end_dt,
        demand_name=demand_name,
        min_weight=min_weight,
        max_weight=max_weight,
        sort_by=sort_by,
        sort_order=sort_order,
    )
    export_params: dict[str, object] = {**params, "max_rows": max_rows}
    query_sql = text(
        f"""
        SELECT
            id,
            strategy,
            demand_name,
            weight,
            `type`,
            video_count,
            dt
        FROM {table_name}
        {where_sql}
        {order_sql}
        LIMIT :max_rows
        """
    )

    with SessionLocal() as session:
        rows = session.execute(query_sql, export_params).mappings().all()

    return [dict(row) for row in rows]


def query_strategy_options(
    start_dt: str | None = None,
    end_dt: str | None = None,
    min_weight: float | None = None,
    max_weight: float | None = None,
) -> dict[str, object]:
    table_name = settings.demand_pool_target_table
    if not IDENTIFIER_RE.match(table_name):
        raise ValueError("invalid table name in settings")

    base_where_parts = ["strategy IS NOT NULL", "strategy != ''"]
    params: dict[str, object] = {}

    normalized_start_dt = _normalize_date(start_dt)
    normalized_end_dt = _normalize_date(end_dt)

    if normalized_start_dt:
        base_where_parts.append("dt >= :start_dt")
        params["start_dt"] = normalized_start_dt
    if normalized_end_dt:
        base_where_parts.append("dt <= :end_dt")
        params["end_dt"] = normalized_end_dt

    filtered_where_parts = list(base_where_parts)
    if min_weight is not None:
        filtered_where_parts.append("weight >= :min_weight")
        params["min_weight"] = min_weight
    if max_weight is not None:
        filtered_where_parts.append("weight <= :max_weight")
        params["max_weight"] = max_weight

    base_where_sql = f"WHERE {' AND '.join(base_where_parts)}"
    filtered_where_sql = f"WHERE {' AND '.join(filtered_where_parts)}"
    query_sql = text(
        f"""
        SELECT
            base.strategy,
            COALESCE(filtered.record_count, 0) AS record_count
        FROM (
            SELECT DISTINCT strategy
            FROM {table_name}
            {base_where_sql}
        ) AS base
        LEFT JOIN (
            SELECT
                strategy,
                COUNT(1) AS record_count
            FROM {table_name}
            {filtered_where_sql}
            GROUP BY strategy
        ) AS filtered
            ON base.strategy = filtered.strategy
        ORDER BY record_count DESC, base.strategy ASC
        """
    )

    with SessionLocal() as session:
        rows = session.execute(query_sql, params).mappings().all()

    return {"items": [dict(row) for row in rows]}