from __future__ import annotations

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

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

from app.models.credit_record import CreditRecord
from app.models.generation_record import GenerationRecord
from app.models.system_config import SystemConfig
from app.services.credits import calc_image_credits, calc_text_credits, calc_video_credits, deduct_credits


CHARGE_TEXT_PROMPT = "text_prompt"
CHARGE_FILE_PARSE = "file_parse"
CHARGE_VISION_INPUT = "vision_input"
CHARGE_MEDIA = "media"

OWNER_GENERATION_RECORD = "generation_record"
OWNER_CHAT_GENERATION_TASK = "chat_generation_task"

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


@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:
        return round(sum(item.amount for item in self.items if item.charge_key == charge_key and item.charged), 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 _safe_int(value: Any, default: int = 0) -> int:
    try:
        if value is None:
            return default
        return int(value)
    except Exception:
        return default


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", "refund"):
        raise ValueError("action 仅支持 charge/refund")
    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_config_float_or_none(db: AsyncSession, key: str) -> float | None:
    result = await db.execute(select(SystemConfig).where(SystemConfig.key == key).limit(1))
    config = result.scalar_one_or_none()
    if not config:
        return None
    try:
        return float(config.value)
    except Exception:
        return None


async def _calc_optional_token_credits(db: AsyncSession, tokens: int, config_key: str) -> float:
    tokens = _safe_int(tokens)
    if tokens <= 0:
        return 0.0
    rate = await _get_config_float_or_none(db, config_key)
    if rate is None:
        return 0.0
    return round(tokens * rate / 1000, 2)


async def _find_existing_by_biz_key(db: AsyncSession, *, user_id: str, biz_key: str) -> CreditRecord | None:
    result = await db.execute(
        select(CreditRecord)
        .where(CreditRecord.user_id == user_id, CreditRecord.biz_key == biz_key)
        .limit(1)
    )
    return result.scalar_one_or_none()


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,
) -> BillingItem:
    """按 biz_key 做幂等扣费。

    charge_key 只保留为业务分类；正式幂等以 biz_key 为准。
    """
    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)

    if biz_key:
        existing_charge = await _find_existing_by_biz_key(db, user_id=user_id, biz_key=biz_key)
        if existing_charge:
            return BillingItem(
                charge_key=charge_key,
                amount=abs(_round2(existing_charge.amount)),
                charged=False,
                skipped_reason="already_charged",
                biz_key=biz_key,
                attempt_no=attempt_no,
            )

    await deduct_credits(
        db,
        user_id=user_id,
        amount=amount,
        description=description,
        related_id=related_id,
        biz_key=biz_key,
    )
    return BillingItem(charge_key=charge_key, amount=amount, charged=True, biz_key=biz_key, attempt_no=attempt_no)


async def charge_chatapi_prompt_usage(
    db: AsyncSession,
    *,
    record: GenerationRecord,
    usage: Mapping[str, Any],
    project_name: str | None = None,
) -> BillingSummary:
    """提示词整理扣费仍按记录维度一次性幂等，不参与生成失败媒体退款。"""
    project_name = project_name or "AI生成任务"
    items: list[BillingItem] = []

    attempt_no = 1
    owner_type = OWNER_GENERATION_RECORD
    owner_id = record.id

    input_tokens = _safe_int(usage.get("input_tokens"))
    output_tokens = _safe_int(usage.get("output_tokens"))
    text_credits = await calc_text_credits(db, input_tokens, output_tokens)
    items.append(
        await deduct_credits_locked_once(
            db,
            user_id=record.user_id,
            amount=text_credits,
            description=f"ChatAPI提示词整理",
            related_id=record.id,
            charge_key=CHARGE_TEXT_PROMPT,
            biz_key=build_credit_biz_key(
                owner_type=owner_type,
                owner_id=owner_id,
                attempt_no=attempt_no,
                charge_kind=CHARGE_TEXT_PROMPT,
                action="charge",
            ),
            attempt_no=attempt_no,
        )
    )

    file_tokens = usage.get("file_parse_tokens") or usage.get("file_tokens") or usage.get("document_tokens") or 0
    file_parse_credits = await _calc_optional_token_credits(db, _safe_int(file_tokens), "file_parse_credits_per_1000_tokens")
    items.append(
        await deduct_credits_locked_once(
            db,
            user_id=record.user_id,
            amount=file_parse_credits,
            description=f"文件解析Token",
            related_id=record.id,
            charge_key=CHARGE_FILE_PARSE,
            biz_key=build_credit_biz_key(
                owner_type=owner_type,
                owner_id=owner_id,
                attempt_no=attempt_no,
                charge_kind=CHARGE_FILE_PARSE,
                action="charge",
            ),
            attempt_no=attempt_no,
        )
    )

    vision_tokens = usage.get("vision_input_tokens") or usage.get("image_input_tokens") or usage.get("image_tokens") or 0
    vision_input_credits = await _calc_optional_token_credits(db, _safe_int(vision_tokens), "vision_input_credits_per_1000_tokens")
    items.append(
        await deduct_credits_locked_once(
            db,
            user_id=record.user_id,
            amount=vision_input_credits,
            description=f"图片理解Token",
            related_id=record.id,
            charge_key=CHARGE_VISION_INPUT,
            biz_key=build_credit_biz_key(
                owner_type=owner_type,
                owner_id=owner_id,
                attempt_no=attempt_no,
                charge_kind=CHARGE_VISION_INPUT,
                action="charge",
            ),
            attempt_no=attempt_no,
        )
    )

    if hasattr(record, "text_credits_cost"):
        record.text_credits_cost = round(text_credits + file_parse_credits + vision_input_credits, 2)
    if hasattr(record, "text_tokens_used"):
        record.text_tokens_used = _safe_int(usage.get("total_tokens"), input_tokens + output_tokens)

    return BillingSummary(record_id=record.id, user_id=record.user_id, items=items)


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,
    project_name: str | None = None,
    description_prefix: str = "AI创作-",
    owner_type: str = OWNER_CHAT_GENERATION_TASK,
    attempt_no: int | None = None,
) -> 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()
    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] = []

    if gen_type == "image":
        size = image_size or "2K"
        amount = await calc_image_credits(db, size, engine_id=engine_id)
        items.append(
            await deduct_credits_locked_once(
                db,
                user_id=user_id,
                amount=amount,
                description=f"{description_prefix}图片生成",
                related_id=record_id,
                charge_key=CHARGE_MEDIA,
                biz_key=biz_key,
                attempt_no=attempt_no,
            )
        )
    elif gen_type == "video":
        amount = await calc_video_credits(db, duration or 5, resolution or "720p", engine_id=engine_id)
        items.append(
            await deduct_credits_locked_once(
                db,
                user_id=user_id,
                amount=amount,
                description=f"{description_prefix}视频生成",
                related_id=record_id,
                charge_key=CHARGE_MEDIA,
                biz_key=biz_key,
                attempt_no=attempt_no,
            )
        )
    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,
) -> BillingSummary:
    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,
        project_name=project_name,
        description_prefix=description_prefix,
        owner_type=OWNER_GENERATION_RECORD,
        attempt_no=attempt_no,
    )