from __future__ import annotations

import re
from dataclasses import asdict, dataclass
from typing import Any

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.enums.credit_record import CreditRecordChargeKind, CreditRecordOwnerType, CreditRecordSourceModule
from app.models.credit_record import CreditRecord
from app.models.generation_record import GenerationRecord
from app.services.generation.media_reference_service import calculate_media_reference_usage
from app.services.credit_record_meta_service import (
    CreditRecordMeta,
    build_generation_media_meta,
)
from app.services.credits import calc_image_credits, calc_video_credits, deduct_credits_result


CHARGE_MEDIA = CreditRecordChargeKind.MEDIA.value

OWNER_GENERATION_RECORD = CreditRecordOwnerType.GENERATION_RECORD.value
OWNER_CHAT_GENERATION_TASK = CreditRecordOwnerType.CHAT_GENERATION_TASK.value

_BIZ_KEY_PATTERN = re.compile(
    r"^(?P<owner_type>[^:]+):(?P<owner_id>[^:]+):attempt:(?P<attempt_no>\d+):(?P<charge_kind>[^:]+):(?P<action>charge|llm_charge|refund|pre_deduct|hold|hold_release)$"
)


@dataclass
class BillingItem:
    charge_key: str
    amount: float
    charged: bool
    skipped_reason: str | None = None
    biz_key: str | None = None
    attempt_no: int | None = None


@dataclass
class BillingSummary:
    record_id: str
    user_id: str
    items: list[BillingItem]

    @property
    def total_charged(self) -> float:
        return round(sum(item.amount for item in self.items if item.charged), 2)

    def get_amount(self, charge_key: str) -> float:
        """返回该业务动作的已记录金额；幂等重放命中旧流水时也返回真实金额。"""
        return round(sum(item.amount for item in self.items if item.charge_key == charge_key), 2)

    def to_dict(self) -> dict[str, Any]:
        data = asdict(self)
        data["total_charged"] = self.total_charged
        return data


def _round2(value: float | int | None) -> float:
    return round(float(value or 0), 2)


def build_credit_biz_key(
    *,
    owner_type: str,
    owner_id: str,
    attempt_no: int,
    charge_kind: str,
    action: str,
) -> str:
    """生成正式积分流水幂等键。

    示例：generation_record:xxx:attempt:2:media:charge
    """
    owner_type = owner_type.strip()
    owner_id = owner_id.strip()
    charge_kind = charge_kind.strip()
    action = action.strip()
    if action not in ("charge", "llm_charge", "refund", "pre_deduct", "hold", "hold_release"):
        raise ValueError("action 仅支持 charge/llm_charge/refund/pre_deduct/hold/hold_release")
    if attempt_no <= 0:
        raise ValueError("attempt_no 必须大于 0")
    return f"{owner_type}:{owner_id}:attempt:{attempt_no}:{charge_kind}:{action}"


def parse_credit_biz_key(biz_key: str | None) -> dict[str, Any] | None:
    if not biz_key:
        return None
    match = _BIZ_KEY_PATTERN.match(biz_key)
    if not match:
        return None
    data = match.groupdict()
    data["attempt_no"] = int(data["attempt_no"])
    return data


async def get_next_credit_attempt_no(
    db: AsyncSession,
    *,
    owner_type: str,
    owner_id: str,
    charge_kind: str = CHARGE_MEDIA,
) -> int:
    """根据已有正式 biz_key 计算下一轮扣费 attempt_no。

    不依赖任务表 retry_count，防止 worker 崩溃/重复消息造成状态字段不可信。
    """
    prefix = f"{owner_type}:{owner_id}:attempt:%:{charge_kind}:charge"
    result = await db.execute(
        select(CreditRecord.biz_key)
        .where(CreditRecord.related_id == owner_id)
        .where(CreditRecord.type == "consume")
        .where(CreditRecord.biz_key.like(prefix))
    )
    max_attempt = 0
    for (biz_key,) in result.all():
        parsed = parse_credit_biz_key(biz_key)
        if parsed and parsed.get("owner_type") == owner_type and parsed.get("owner_id") == owner_id:
            max_attempt = max(max_attempt, int(parsed.get("attempt_no") or 0))
    return max_attempt + 1


async def deduct_credits_locked_once(
    db: AsyncSession,
    *,
    user_id: str,
    amount: float,
    description: str,
    related_id: str,
    charge_key: str,
    biz_key: str | None = None,
    attempt_no: int | None = None,
    record_meta: CreditRecordMeta | dict | None = None,
    allow_negative: bool = False,
) -> BillingItem:
    """按 biz_key 做幂等扣费。

    幂等判断、用户行锁、余额更新和流水写入由 deduct_credits_result 在同一短事务内完成，
    避免先查一次 biz_key、加锁后再查一次的重复 SQL 和竞态窗口。
    """
    amount = _round2(amount)
    if amount <= 0:
        return BillingItem(
            charge_key=charge_key,
            amount=0.0,
            charged=False,
            skipped_reason="amount_lte_zero",
            biz_key=biz_key,
            attempt_no=attempt_no,
        )

    mutation = await deduct_credits_result(
        db,
        user_id=user_id,
        amount=amount,
        description=description,
        related_id=related_id,
        biz_key=biz_key,
        record_meta=record_meta,
        allow_negative=allow_negative,
    )
    return BillingItem(
        charge_key=charge_key,
        amount=mutation.amount if not mutation.created else amount,
        charged=mutation.created,
        skipped_reason=None if mutation.created else "already_charged",
        biz_key=biz_key,
        attempt_no=attempt_no,
    )


async def charge_generation_media_by_params(
    db: AsyncSession,
    *,
    user_id: str,
    record_id: str,
    gen_type: str,
    image_size: str | None = None,
    duration: int | None = None,
    resolution: str | None = None,
    engine_id: str | None = None,
    input_video_duration: float | None = None,
    input_image_count: int | None = None,
    project_name: str | None = None,
    description_prefix: str = "AI创作-",
    owner_type: str = OWNER_CHAT_GENERATION_TASK,
    attempt_no: int | None = None,
    source_module: str | None = None,
    source_project_id: str | None = None,
    source_step_id: str | None = None,
    source_step_code: str | None = None,
    billing_scene: str | None = None,
    quantity: int = 1,
) -> BillingSummary:
    """图片/视频媒体生成扣费。

    正式幂等由 owner_type + record_id + attempt_no + media + charge 组成。
    每次用户主动重试必须传入新的 attempt_no。
    """
    project_name = project_name or "AI生成任务"
    gen_type = (gen_type or "").lower().strip()
    quantity = max(1, int(quantity or 1))
    attempt_no = attempt_no or await get_next_credit_attempt_no(
        db,
        owner_type=owner_type,
        owner_id=record_id,
        charge_kind=CHARGE_MEDIA,
    )
    biz_key = build_credit_biz_key(
        owner_type=owner_type,
        owner_id=record_id,
        attempt_no=attempt_no,
        charge_kind=CHARGE_MEDIA,
        action="charge",
    )
    items: list[BillingItem] = []
    record_meta = await build_generation_media_meta(
        db,
        owner_type=owner_type,
        owner_id=record_id,
        attempt_no=attempt_no,
        gen_type=gen_type,
        engine_id=engine_id,
        source_module=source_module,
        source_project_id=source_project_id,
        source_step_id=source_step_id,
        source_step_code=source_step_code,
        billing_scene=billing_scene,
    )

    if gen_type == "image":
        size = image_size or "2K"
        unit_amount = await calc_image_credits(
            db, size, engine_id=engine_id, input_image_count=input_image_count
        )
        amount = round(unit_amount * quantity, 2)
        items.append(
            await deduct_credits_locked_once(
                db,
                user_id=user_id,
                amount=amount,
                description=f"{description_prefix}图片生成" + (f"×{quantity}" if quantity > 1 else ""),
                related_id=record_id,
                charge_key=CHARGE_MEDIA,
                biz_key=biz_key,
                attempt_no=attempt_no,
                record_meta=record_meta,
            )
        )
    elif gen_type == "video":
        unit_amount = await calc_video_credits(
            db, duration or 5, resolution or "720p",
            engine_id=engine_id,
            input_video_duration=input_video_duration,
            input_image_count=input_image_count,
        )
        amount = round(unit_amount * quantity, 2)
        items.append(
            await deduct_credits_locked_once(
                db,
                user_id=user_id,
                amount=amount,
                description=f"{description_prefix}视频生成" + (f"×{quantity}" if quantity > 1 else ""),
                related_id=record_id,
                charge_key=CHARGE_MEDIA,
                biz_key=biz_key,
                attempt_no=attempt_no,
                record_meta=record_meta,
            )
        )
    else:
        raise ValueError(f"不支持的生成类型: {gen_type}")

    return BillingSummary(record_id=record_id, user_id=user_id, items=items)


async def charge_generation_media_for_record(
    db: AsyncSession,
    *,
    record: GenerationRecord,
    project_name: str | None = None,
    description_prefix: str = "AI创作-",
    attempt_no: int | None = None,
    engine_id: str | None = None,
) -> BillingSummary:
    reference_usage = calculate_media_reference_usage(
        record.media_references,
        include=bool(record.include_media_references),
    )
    return await charge_generation_media_by_params(
        db,
        user_id=record.user_id,
        record_id=record.id,
        gen_type=record.gen_type,
        image_size=record.image_size,
        duration=record.duration,
        resolution=record.resolution,
        engine_id=engine_id or getattr(record, "engine_id", None),
        input_video_duration=reference_usage.input_video_duration or None,
        input_image_count=reference_usage.image_count or None,
        project_name=project_name,
        description_prefix=description_prefix,
        owner_type=OWNER_GENERATION_RECORD,
        attempt_no=attempt_no,
        source_module=CreditRecordSourceModule.GENERATION_RECORD.value,
    )