"""实验系统：从 strategy_staging 增量写入 ODPS dwd_multi_demand_pool_di_tmp。"""

from __future__ import annotations

import json
import re
from collections import defaultdict
from dataclasses import dataclass

from app.core.config import settings
from app.odps.client import get_odps_client
from app.strategies.batch_date import today_yyyymmdd
from app.strategies.config_store import StrategyConfigRecord, fetch_all_configs
from app.strategies.registry import StrategyRegistry
from app.strategies.staging_store import BATCH_SIZE, StagingRow, fetch_staging_rows_for_batch

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


def _safe_identifier(name: str) -> str:
    if not IDENTIFIER_RE.match(name):
        raise ValueError(f"invalid sql identifier: {name}")
    return name


@dataclass(frozen=True)
class ExperimentStrategyContext:
    strategy_id: str
    strategy_name: str
    priority: int
    daily_limit: int
    current_count: int
    staging_rows: list[StagingRow]


@dataclass(frozen=True)
class ExistingPartitionState:
    demand_ids: set[str]
    strategy_counts: dict[str, int]
    claimed_names: dict[str, set[int | str]]


def _normalize_partition_dt(partition_dt: str | None) -> str:
    value = (partition_dt or today_yyyymmdd()).strip()
    if not PARTITION_DT_RE.match(value):
        raise ValueError("partition_dt must be yyyymmdd")
    return value


def _parse_video_list_for_odps(raw: str | None) -> list[str] | None:
    if raw is None:
        return None
    text_value = raw.strip()
    if not text_value:
        return None
    try:
        parsed = json.loads(text_value)
    except json.JSONDecodeError:
        return [text_value]
    if isinstance(parsed, list):
        return [str(item) for item in parsed]
    return [text_value]


def _qualified_target_table_name() -> str:
    target_table = _safe_identifier(settings.experiment_demand_pool_target_table)
    project = settings.odps_project.strip()
    if not project:
        return target_table
    return f"{project}.{target_table}"


def _build_strategy_priority_by_name(
    configs: list[StrategyConfigRecord],
) -> dict[str, int]:
    """含 active / paused 全量配置，避免策略中途暂停后 Hive 占位 priority 丢失。"""
    return {config.name: config.priority for config in configs}


def _resolve_hive_row_priority(
    strategy_name: str,
    priority_by_name: dict[str, int],
) -> int | str:
    if not strategy_name or strategy_name not in priority_by_name:
        return _UNKNOWN_STRATEGY_PRIORITY
    return priority_by_name[strategy_name]


def _select_writable_configs(
    configs: list[StrategyConfigRecord],
) -> list[StrategyConfigRecord]:
    """与策略生成一致：仅 registered + active 的策略参与实验写入。"""
    registered_ids = set(StrategyRegistry.registered_strategy_ids())
    return [
        config
        for config in configs
        if config.active and config.strategy_id in registered_ids
    ]


def _get_odps_target_table():
    odps_client = get_odps_client()
    target_table = _safe_identifier(settings.experiment_demand_pool_target_table)
    if not odps_client.exist_table(target_table):
        raise ValueError(f"ODPS 表不存在: {_qualified_target_table_name()}")
    return odps_client.get_table(target_table)


def _fetch_existing_partition_state(
    partition_dt: str,
    *,
    strategy_priority_by_name: dict[str, int],
) -> ExistingPartitionState:
    table = _get_odps_target_table()
    partition_spec = f"dt={partition_dt}"
    if not table.exist_partition(partition_spec):
        return ExistingPartitionState(
            demand_ids=set(),
            strategy_counts={},
            claimed_names={},
        )

    demand_ids: set[str] = set()
    strategy_counts: dict[str, int] = defaultdict(int)
    claimed_names: dict[str, set[int | str]] = {}

    with table.open_reader(partition=partition_spec) as reader:
        for record in reader:
            demand_id = str(record["demand_id"] or "").strip()
            demand_name = str(record["demand_name"] or "").strip()
            strategy_name = str(record["strategy"] or "").strip()
            if demand_id:
                demand_ids.add(demand_id)
            if strategy_name:
                strategy_counts[strategy_name] += 1
            if not demand_name:
                continue
            priority = _resolve_hive_row_priority(strategy_name, strategy_priority_by_name)
            if demand_name not in claimed_names:
                claimed_names[demand_name] = {priority}
            else:
                claimed_names[demand_name].add(priority)

    return ExistingPartitionState(
        demand_ids=demand_ids,
        strategy_counts=dict(strategy_counts),
        claimed_names=claimed_names,
    )


def _build_strategy_contexts(
    *,
    configs: list[StrategyConfigRecord],
    staging_rows: list[StagingRow],
    strategy_counts: dict[str, int],
) -> list[ExperimentStrategyContext]:
    rows_by_strategy_id: dict[str, list[StagingRow]] = defaultdict(list)
    for row in staging_rows:
        rows_by_strategy_id[row.strategy_config_id].append(row)

    contexts: list[ExperimentStrategyContext] = []
    for config in configs:
        if not config.active:
            continue
        contexts.append(
            ExperimentStrategyContext(
                strategy_id=config.strategy_id,
                strategy_name=config.name,
                priority=config.priority,
                daily_limit=config.daily_write_limit,
                current_count=strategy_counts.get(config.name, 0),
                staging_rows=rows_by_strategy_id.get(config.strategy_id, []),
            )
        )
    return contexts


def select_rows_to_write(
    *,
    strategies: list[ExperimentStrategyContext],
    existing_demand_ids: set[str],
    claimed_names: dict[str, set[int | str]],
) -> tuple[list[StagingRow], dict[str, int]]:
    """跨策略选取待写入行。

    - demand_id 已存在：跳过
    - demand_name 已被其他 priority 写入：跳过（先写入者优先，高 priority 不可覆盖）
    - 同 priority：demand_name 不去重
    """
    selected: list[StagingRow] = []
    selected_counts: dict[str, int] = defaultdict(int)

    ordered = sorted(strategies, key=lambda item: (item.priority, item.strategy_id))
    for ctx in ordered:
        remaining: int | None
        if ctx.daily_limit > 0:
            remaining = ctx.daily_limit - ctx.current_count - selected_counts[ctx.strategy_name]
            if remaining <= 0:
                continue
        else:
            remaining = None

        candidates = sorted(
            ctx.staging_rows,
            key=lambda row: (-(row.weight or 0.0), row.demand_id),
        )
        for row in candidates:
            if remaining is not None and remaining <= 0:
                break
            if row.demand_id in existing_demand_ids:
                continue

            claimed_priorities = claimed_names.get(row.demand_name)
            if claimed_priorities is not None and ctx.priority not in claimed_priorities:
                continue

            if row.demand_name not in claimed_names:
                claimed_names[row.demand_name] = {ctx.priority}
            else:
                claimed_names[row.demand_name].add(ctx.priority)

            selected.append(row)
            existing_demand_ids.add(row.demand_id)
            selected_counts[ctx.strategy_name] += 1
            if remaining is not None:
                remaining -= 1

    return selected, dict(selected_counts)


def _staging_row_to_odps_record(row: StagingRow) -> tuple[object, ...]:
    """字段顺序与 dwd_multi_demand_pool_di_tmp 非分区列一致。"""
    weight = float(row.weight) if row.weight is not None else None
    video_count = int(row.video_count) if row.video_count is not None else None
    extend = row.extend.strip() if row.extend else None
    return (
        row.strategy,
        row.demand_id,
        row.demand_name,
        weight,
        row.demand_type,
        video_count,
        _parse_video_list_for_odps(row.video_list),
        extend,
    )


def _write_rows_to_odps(*, partition_dt: str, rows: list[StagingRow]) -> int:
    if not rows:
        return 0

    table = _get_odps_target_table()
    partition_spec = f"dt={partition_dt}"
    records = [_staging_row_to_odps_record(row) for row in rows]

    # PyODPS Tunnel 追加写入，等价于 INSERT INTO ... PARTITION(dt=...) 追加行
    with table.open_writer(partition=partition_spec, create_partition=True) as writer:
        for start in range(0, len(records), BATCH_SIZE):
            writer.write(records[start : start + BATCH_SIZE])

    return len(records)


def run_experiment_hourly_write(partition_dt: str | None = None) -> dict[str, object]:
    """每小时执行：检查各策略当日写入量，不足则从 staging 继续补充。"""
    StrategyRegistry.load_all_configs()
    batch_date = _normalize_partition_dt(partition_dt)

    configs = fetch_all_configs()
    priority_by_name = _build_strategy_priority_by_name(configs)
    writable_configs = _select_writable_configs(configs)

    existing_state = _fetch_existing_partition_state(
        batch_date,
        strategy_priority_by_name=priority_by_name,
    )
    staging_rows = fetch_staging_rows_for_batch(
        batch_date=batch_date,
        strategy_config_ids=[config.strategy_id for config in writable_configs],
    )
    contexts = _build_strategy_contexts(
        configs=writable_configs,
        staging_rows=staging_rows,
        strategy_counts=existing_state.strategy_counts,
    )

    claimed_names = {
        name: set(priorities) for name, priorities in existing_state.claimed_names.items()
    }
    pending_ids = set(existing_state.demand_ids)
    selected_rows, selected_counts = select_rows_to_write(
        strategies=contexts,
        existing_demand_ids=pending_ids,
        claimed_names=claimed_names,
    )
    written = _write_rows_to_odps(partition_dt=batch_date, rows=selected_rows)
    if written:
        print(
            "[experiment-write] appended "
            f"{written} rows to {_qualified_target_table_name()} "
            f"partition dt={batch_date}"
        )

    strategy_summary = []
    for ctx in sorted(contexts, key=lambda item: (item.priority, item.strategy_id)):
        strategy_summary.append(
            {
                "strategy_id": ctx.strategy_id,
                "strategy_name": ctx.strategy_name,
                "priority": ctx.priority,
                "daily_limit": ctx.daily_limit,
                "existing_count": ctx.current_count,
                "selected_count": selected_counts.get(ctx.strategy_name, 0),
                "staging_total": len(ctx.staging_rows),
            }
        )

    return {
        "partition_dt": batch_date,
        "target_table": _qualified_target_table_name(),
        "write_mode": "tunnel_append",
        "staging_total": len(staging_rows),
        "selected_count": len(selected_rows),
        "written_count": written,
        "existing_count": len(existing_state.demand_ids),
        "writable_strategy_count": len(writable_configs),
        "strategies": strategy_summary,
    }