"""T04 模拟案例生成与数据集划分。

依据：docs/v2/14-experience-loop.md §8（配比与隔离）、§4（划分先于经验提炼）；
契约 owner：docs/v2/03-detailed-design.md §9.2 的 DatasetManifest（数据集服务）。

**边界先行**：先用手工 fixture 固化逻辑（0 例、单组、近重复、跨时间边界），
再按 14 §8 的配比批量生成。生成全程用程序组合结构化场景，**不做任何模型调用**
（14 §8 末：不为每条案例进行多轮昂贵模型调用）。

隔离要求（BR-35 / AC-36）：
- 关联组（同客户/同集团/近重复）**整体**落入同一划分，不跨集合
- 时间划分按组的最早发生时间分桶，不按单条案例切
- 保留集及其衍生知识不得进入开发；越界即判定泄漏、该知识作废

不声称真实效果：所有记录标 synthetic/demo，概览文案不得写成准确率。
"""

from __future__ import annotations

import json
import random
from datetime import datetime, timedelta, timezone
from pathlib import Path

from services import assistant_store as store

GENERATOR_VERSION = "simulation_dataset@1.0.0"
TEMPLATE_VERSION = "xingbang-sim-templates@1.0.0"
SPLIT_POLICY_VERSION = "group-time-split@1.0.0"

SPLITS = ("development", "calibration", "holdout")

# 时间划分比例（按组的代表时间分桶，14 §8：划分先于经验提炼）
SPLIT_RATIOS = (("development", 0.6), ("calibration", 0.2), ("holdout", 0.2))

# 结果配比（docs/v2/14-experience-loop.md §8）。总计 3000 是**可调整的演示规模**，
# 不是效果样本量承诺。
#
# 两个刻意的建模决定：
# 1. "补件后通过" 是 approved 的**子类型**，不是独立 outcome——06 §3 要求区分
#    "首次提交通过"与"补件后最终通过"，但事件编码本身仍是 approved（设计 §9.1 的
#    EventOutcome 只有 7 个值，不得自行扩充）。
# 2. conditional（附条件通过）是否计入目标由客户映射决定（OQ-05），故 label=None，
#    绝不默认当 approved（E-26 / BR-21）。
TEMPLATES = (
    {"outcome": "approved", "subtype": "direct", "count": 900, "label": True,
     "desc": "材料齐全，评审会直接通过"},
    {"outcome": "approved", "subtype": "after_supplement", "count": 900, "label": True,
     "desc": "补件后通过；初始材料不足"},
    {"outcome": "rejected", "subtype": "direct", "count": 600, "label": False,
     "desc": "评审会未通过"},
    {"outcome": "conditional", "subtype": "conditional", "count": 100, "label": None,
     "desc": "附条件通过，是否计入目标由映射决定"},
    {"outcome": "not_submitted", "subtype": "not_submitted", "count": 175, "label": None,
     "desc": "未送审，不当作否决"},
    {"outcome": "withdrawn", "subtype": "withdrawn", "count": 175, "label": None,
     "desc": "主动退出，不当作否决"},
    {"outcome": "deferred", "subtype": "deferred", "count": 150, "label": None,
     "desc": "会议待定，口径未确认"},
)

FIELDS_SHAPE = {
    "facility.amount": ("600", "2400"),        # 万元
    "lease.total_value": ("500", "2000"),
    "financial.total_assets": ("3000", "40000"),
    "financial.total_liabilities": ("1000", "30000"),
    "financial.operating_cashflow": ("-800", "6000"),
}


def _text(value) -> str:
    return json.dumps(value, ensure_ascii=False, sort_keys=True, separators=(",", ":"))


def _counts(records: list[dict]) -> list[dict]:
    tally: dict[str, int] = {}
    for record in records:
        tally[record["outcome"]] = tally.get(record["outcome"], 0) + 1
    return [{"outcome": key, "count": tally[key]} for key in sorted(tally)]


def generate(seed: int = 20260929, scale: float = 1.0,
             templates=TEMPLATES) -> list[dict]:
    """按配比生成虚构项目。同 seed + 同 templates → 逐字节一致。

    scale 只按比例缩放各档数量（便于小规模演示与测试），不改变配比结构。
    """
    if seed < 0:
        raise ValueError("seed 必须为非负整数")
    if scale <= 0:
        raise ValueError("scale 必须为正数")

    rng = random.Random(seed)
    records: list[dict] = []
    base_time = datetime(2023, 1, 2, tzinfo=timezone.utc)
    serial = 0

    for template in templates:
        wanted = max(1, int(round(template["count"] * scale)))
        for _ in range(wanted):
            serial += 1
            # 关联组：每 3 条构成一组（同客户多项目 / 近重复），模拟"关联组不得跨集合"。
            # 组号必须由记录序号**唯一**推出，且 near_duplicate_of 只能指向同组记录——
            # 早先版本里分组与近重复用了两套独立公式，导致近重复落到别组（integrity 检查抓到）。
            group_index = (serial - 1) // 3 + 1
            near = f"SIM-{serial - 1:06d}" if serial % 3 == 2 else None
            occurred = base_time + timedelta(days=rng.randint(0, 900), hours=rng.randint(0, 23))
            facts = {
                field: str(round(rng.uniform(float(low), float(high)), 2))
                for field, (low, high) in FIELDS_SHAPE.items()
            }
            records.append({
                "id": f"SIM-{serial:06d}",
                "synthetic": True,
                "data_domain": "demo",
                "customer": f"虚构客户{group_index:05d}",
                "customer_group": f"CG-{group_index:05d}",
                "near_duplicate_of": near,
                "occurred_at": occurred.isoformat(),
                "outcome": template["outcome"],
                "outcome_subtype": template["subtype"],
                # 未送审/待定/附条件一律 null：绝不默认当通过（BR-21 / E-26）
                "label": template["label"],
                "initial_facts": facts,
                "trace": {
                    "generator_version": GENERATOR_VERSION,
                    "template_version": TEMPLATE_VERSION,
                    "seed": seed,
                    "template": f'{template["outcome"]}/{template["subtype"]}',
                },
            })
    return records


def source_hash(records: list[dict]) -> str:
    """对**规范化**后的记录取哈希，用于证明两次生成一致（AC-35）。"""
    normalized = [{k: v for k, v in sorted(record.items())} for record in records]
    normalized.sort(key=lambda item: item["id"])
    return store.digest(normalized)


def split(records: list[dict], policy_version: str = SPLIT_POLICY_VERSION) -> dict:
    """按关联组 + 时间分桶。

    组的代表时间取该组**最早**的 occurred_at，然后按整体时间轴切三段。
    以组为单位分配，因此天然不会把同客户/近重复拆到不同集合。
    """
    if not records:
        raise ValueError("没有可划分的案例")

    groups: dict[str, list[dict]] = {}
    for record in records:
        groups.setdefault(record["customer_group"], []).append(record)

    members = []
    for group_id, items in groups.items():
        representatives = sorted(item["occurred_at"] for item in items)
        # 近重复必须同组：分组键相同即为同组，这里再校验一次
        members.append((group_id, representatives[0], representatives[-1], items))
    members.sort(key=lambda item: (item[1], item[0]))

    total = len(members)
    boundaries, cursor = {}, 0
    for index, (name, ratio) in enumerate(SPLIT_RATIOS):
        # 末段取剩余，避免四舍五入后总和超过组数；并夹到非负，
        # 否则极端小样本下会产生负切片而静默给出错误划分。
        take = total - cursor if index == len(SPLIT_RATIOS) - 1 else int(round(total * ratio))
        take = max(0, take)
        boundaries[name] = members[cursor:cursor + take]
        cursor += take

    assignments: dict[str, str] = {}
    for name, chunk in boundaries.items():
        for group_id, _, _, items in chunk:
            assignments[group_id] = name
            for item in items:
                assignments[item["id"]] = name

    assert_group_integrity(records, assignments)
    return {
        "split_policy_version": policy_version,
        "assignments": assignments,
        "group_of": {item["id"]: item["customer_group"] for item in records},
        "group_counts": {name: len(chunk) for name, chunk in boundaries.items()},
    }


def assert_group_integrity(records: list[dict], assignments: dict[str, str]) -> None:
    """按组成员逐条校验：同组所有案例必须落在同一集合。"""
    by_group: dict[str, set] = {}
    for record in records:
        by_group.setdefault(record["customer_group"], set()).add(assignments[record["id"]])
    broken = {group: names for group, names in by_group.items() if len(names) > 1}
    if broken:
        raise ValueError(f"存在跨集合的关联组：{sorted(broken)[:5]}")
    for record in records:
        duplicate = record.get("near_duplicate_of")
        if duplicate and assignments.get(duplicate) != assignments[record["id"]]:
            raise ValueError(f"近重复案例跨集合：{record['id']} 与 {duplicate}")


def assert_source_allowed(split_result: dict, source_ids, target_split: str) -> None:
    """衍生知识不得使用保留集来源（BR-35 / AC-36）。

    越界即判定泄漏：调用方必须作废该候选，而不是降级使用。
    """
    assignments = split_result["assignments"]
    if target_split == "holdout":
        raise ValueError("保留集自身不参与经验提炼")
    offenders = [source_id for source_id in source_ids
                 if assignments.get(source_id) == "holdout"]
    if offenders:
        raise ValueError(f"来源属于保留集，禁止用于提炼并须作废：{sorted(offenders)[:5]}")


def manifest(records: list[dict], split_result: dict, seed: int | None = None,
             split_id: str = "p0-demo") -> dict:
    """构造 DatasetManifest 契约体（03 §9.2）。"""
    from contracts.prescreen import DatasetManifest

    payload = {
        "id": store.uid("dataset"),
        "version": f"{GENERATOR_VERSION}+{TEMPLATE_VERSION}",
        "data_domain": "demo",
        "seed": seed,
        "generator_version": GENERATOR_VERSION,
        "template_version": TEMPLATE_VERSION,
        "source_hash": source_hash(records),
        "split_id": split_id,
        "split_policy_version": split_result["split_policy_version"],
        "group_assignments_ref": store.digest(split_result["assignments"]),
        "counts": _counts(records),
        "created_at": store.now(),
        "synthetic": True,
    }
    return DatasetManifest(**payload).model_dump(mode="json")


def assert_labelled_outcomes_are_mapped(records: list[dict]) -> None:
    """有 label 的结果只能是明确映射过的（BR-21）。"""
    allowed = {"approved", "approved_after_supplement", "rejected"}
    for record in records:
        if record["label"] is not None and record["outcome"] not in allowed:
            raise ValueError(f"结果 {record['outcome']} 尚未确认口径，不得带标签")


def write(records: list[dict], directory: Path, name: str = "simulation.jsonl") -> Path:
    """落盘到指定目录。**默认不入 Git**：调用方应指向被 gitignore 的数据根。"""
    if "xingbang_data" not in str(directory):
        raise ValueError("模拟数据只写入 xingbang_data 数据根（该路径已被 gitignore）")
    directory.mkdir(parents=True, exist_ok=True)
    target = directory / name
    with target.open("w", encoding="utf-8", newline="\n") as handle:
        for record in records:
            handle.write(_text(record) + "\n")
    return target