from datetime import datetime
import pytz
from app.extensions import db, beijing_time
from app.models.borrow import BorrowApproval
from app.models.system import SysUser


class BorrowApprovalService:
    """借库审批服务"""

    @staticmethod
    def generate_request_no():
        """
        生成审批单号: APR-BOR-yyyyMMdd-HHmm-当日流水(4位)
        """
        beijing_tz = pytz.timezone('Asia/Shanghai')
        now = datetime.now(beijing_tz)

        date_str = now.strftime('%Y%m%d')
        time_str = now.strftime('%H%M')

        prefix = f"APR-BOR-{date_str}-"

        latest = db.session.query(BorrowApproval.request_no).filter(
            BorrowApproval.request_no.like(f"{prefix}%")
        ).order_by(BorrowApproval.id.desc()).first()

        if latest:
            last_seq = int(latest[0].split('-')[-1])
            sequence = last_seq + 1
        else:
            sequence = 1

        return f"APR-BOR-{date_str}-{time_str}-{sequence:04d}"

    @staticmethod
    def _items_require_approval(items):
        """
        明细中任一物料命中“出库/借库需审批”→ 需要审批。
        申请明细只存 name/spec_model，故按 (name, spec_model) 反查启用物料判定。
        """
        from app.models.base import MaterialBase
        seen = set()
        for item in items:
            name = str(item.get('name') or '').strip()
            spec = str(item.get('spec_model') or '').strip()
            if not name:
                continue
            key = (name, spec)
            if key in seen:
                continue
            seen.add(key)
            hit = MaterialBase.query.filter(
                MaterialBase.name == name,
                MaterialBase.spec_model == spec,
                MaterialBase.is_enabled == True,
                MaterialBase.is_approval_required == True
            ).first()
            if hit:
                return True
        return False

    @staticmethod
    def submit_approval(applicant_id, items, allowed_approvers, remark=None, approver_id=None,
                         borrower_name=None, force_approval=False):
        """
        提交借库申请（仅存储意向，不扣库存）

        Args:
            applicant_id: 申请人ID
            items: 借库物品明细列表，每个物品应包含:
                - name: 物料名称 (必填)
                - spec_model: 规格型号 (必填)
                - quantity: 计划借库数量 (必填)
                - warehouse_location: 库位 (可选)
                - remark: 物品备注 (可选)
            allowed_approvers: 允许审批的人员/角色列表
            approver_id: 指定审批人ID（可选）
            remark: 申请说明
            borrower_name: 借库人姓名（必填）

        Returns:
            BorrowApproval 实例

        Raises:
            ValueError: 当 items 为空或缺少必填字段时抛出
        """
        if not items:
            raise ValueError("借库物品列表不能为空")

        # ★ 借库申请必填：申请原因；预计归还日期(除非勾选长期借用/不限归还)
        if not str(remark or '').strip():
            raise ValueError("借库申请原因不能为空")
        _has_indefinite = any(bool(item.get('is_indefinite')) for item in items)
        _has_date = any(str(item.get('expected_return_time') or '').strip() for item in items)
        if not _has_indefinite and not _has_date:
            raise ValueError("请填写预计归还日期，或勾选长期借用(不限归还)")

        required_fields = ['name', 'spec_model', 'quantity']
        for idx, item in enumerate(items):
            missing_fields = [f for f in required_fields if f not in item or str(item.get(f) or '').strip() == '']
            if missing_fields:
                raise ValueError(
                    f"第 {idx + 1} 条物品缺少必填字段: {', '.join(missing_fields)}。"
                    f"必须包含: name, spec_model, quantity"
                )
            try:
                qty = float(item.get('quantity', 0))
                if qty <= 0:
                    raise ValueError(f"第 {idx + 1} 条物品的借库数量必须大于0")
            except (TypeError, ValueError) as e:
                raise ValueError(f"第 {idx + 1} 条物品的 quantity 格式无效: {str(e)}")

        # ★ 需审批判定：库管代建(force_approval)或明细含需审批物料 → 走审批；否则默认自动通过
        from app.services.approval_control import resolve_approval_control
        need_approval, flagged_materials = resolve_approval_control(items)
        if force_approval:
            need_approval = True
        if need_approval and not approver_id:
            if force_approval:
                raise ValueError("库管代建借库申请必须选择审批人后再提交")
            _names = "；".join(f"{m['name']}（{m['spec_model'] or '-'}）" for m in flagged_materials)
            raise ValueError(f"以下物料需审批出库/借库：{_names}。请选择审批人后再提交")

        if approver_id:
            allowed_approvers = [{"type": "user", "value": int(approver_id)}]
        elif not need_approval:
            allowed_approvers = []  # 免审批单不绑定审批人

        request_no = BorrowApprovalService.generate_request_no()

        if need_approval:
            approval = BorrowApproval(
                request_no=request_no,
                applicant_id=applicant_id,
                remark=remark,
                borrower_name=borrower_name,
                status=0,  # 待审批
            )
        else:
            # 默认不审批：创建即已通过(status=1)，直接进入“待库管执行”
            # ★ approved_at 必须与 created_at(beijing_time) 同为 naive 本地时间：
            #   approved_at 列是 timestamp without time zone，传 aware 时间会被驱动转成 UTC 存库，导致早 8 小时
            approval = BorrowApproval(
                request_no=request_no,
                applicant_id=applicant_id,
                remark=remark,
                borrower_name=borrower_name,
                status=1,
                actual_approver_id=applicant_id,
                approved_at=beijing_time(),
            )

        # ==================================================================
        # ★ Phase 1：库存预占
        # 借出同样会占用库存（借出期间该批货不可再被他人领用），
        # 因此与出库一致：提交即锁定具体批次并扣减 available_quantity。
        # 借出归还时再归还，见 process_return()。
        # ==================================================================
        from app.services.inventory_reservation import reserve_for_items
        from app.utils.decorators import get_current_company_filter

        reserved_items, _shortages = reserve_for_items(
            items, company_limit=get_current_company_filter(), strict=True,
        )

        approval.set_items(reserved_items)
        if allowed_approvers:
            approval.set_allowed_approvers(allowed_approvers)
        else:
            approval.allowed_approvers = '[]'

        db.session.add(approval)
        db.session.commit()

        # 仅需审批单通知审批人；免审批单静默进入“待库管执行”
        if need_approval:
            BorrowApprovalService._notify_new_request(approval, applicant_id, approver_id=approver_id)

        return approval

    @staticmethod
    def _get_emails_by_identifiers(applicant_id=None, role_codes=None):
        """
        根据用户ID或角色列表查询邮箱地址

        Args:
            applicant_id: 用户ID (按 SysUser.id 查找)
            role_codes:    角色代码列表，如 ['SUPERVISOR', 'SUPER_ADMIN']

        Returns:
            去重后的邮箱地址列表
        """
        emails = []

        if applicant_id:
            user = SysUser.query.get(int(applicant_id))
            if user and user.email:
                emails.append(user.email)

        if role_codes:
            for code in role_codes:
                users = SysUser.query.filter_by(role=code).all()
                for u in users:
                    if u.email:
                        emails.append(u.email)

        return list(set(emails))

    @staticmethod
    def _notify_new_request(approval, applicant_id, approver_id=None):
        """发送新借库申请通知邮件给审批人和申请人（静默处理，不阻断主流程）"""
        try:
            from flask import current_app
            from app.utils.email_service import send_borrow_new_request_notify
            from app.models.system import SysUser

            applicant_name = ''
            applicant_emails = []

            # 1. 收集申请人信息
            if applicant_id:
                user = SysUser.query.get(int(applicant_id))
                if user and user.email:
                    applicant_emails.append(user.email)
                    applicant_name = str(user.username).split('/')[0] if '/' in (user.username or '') else (user.username or str(applicant_id))

            # 2. 收集审批人信息
            approver_emails = []
            if approver_id:
                user = SysUser.query.get(int(approver_id))
                if user and user.email:
                    approver_emails.append(user.email)
            else:
                # 兜底：按角色查询
                approvers = approval.get_allowed_approvers()
                role_codes = []
                for a in approvers:
                    if a.get('type') == 'role':
                        role_codes.append(a.get('value', ''))
                approver_emails = BorrowApprovalService._get_emails_by_identifiers(role_codes=role_codes)

            # 去重
            all_emails = list(set(applicant_emails + approver_emails))
            if not all_emails:
                current_app.logger.info(f"[Email] 借库审批单 {approval.request_no} 无收件人邮箱，跳过通知")
                return

            # 3. 获取物料明细
            items = approval.get_items()

            # 4. 分别发送邮件
            if applicant_emails:
                try:
                    send_borrow_new_request_notify(
                        to_emails=applicant_emails,
                        request_no=approval.request_no,
                        applicant_name=applicant_name,
                        remark=f"您的借库申请已提交，等待审批。{approval.remark or ''}",
                        items=items,
                        is_applicant_notify=True
                    )
                except Exception as e:
                    current_app.logger.error(f"[Email] 通知申请人失败: {e}")

            if approver_emails:
                try:
                    send_borrow_new_request_notify(
                        to_emails=approver_emails,
                        request_no=approval.request_no,
                        applicant_name=applicant_name,
                        remark=approval.remark or '',
                        items=items,
                        is_applicant_notify=False
                    )
                except Exception as e:
                    current_app.logger.error(f"[Email] 通知审批人失败: {e}")

        except Exception as e:
            try:
                from flask import current_app
                current_app.logger.error(f"[Email] 发送新借库申请通知邮件失败: {e}")
            except RuntimeError:
                import traceback
                traceback.print_exc()

    @staticmethod
    def _notify_approval_result(approval, approver_id, action):
        """发送借库审批结果通知邮件（静默处理，不阻断主流程）"""
        import logging
        logger = logging.getLogger(__name__)

        try:
            from app.utils.email_service import send_borrow_approval_result_notify, send_borrow_dispatch_notify
            from app.models.system import SysUser as SU

            # 1. 提取申请人信息
            applicant_name = ''
            applicant_emails = []
            if approval.applicant_id:
                user = SU.query.get(approval.applicant_id)
                if user:
                    applicant_name = str(user.username).split('/')[0] if '/' in (user.username or '') else (user.username or '')
                    if user.email:
                        applicant_emails.append(user.email)

            # 2. 提取物料明细
            items = approval.get_items() if approval else []

            # 3. 分支逻辑
            if action == 'approve':
                # 3.1 通知申请人（审批已通过，明确告知结果）
                if applicant_emails:
                    try:
                        send_borrow_approval_result_notify(
                            to_emails=applicant_emails,
                            request_no=approval.request_no,
                            is_passed=True,
                            reject_reason='',
                            applicant_name=applicant_name
                        )
                    except Exception as e:
                        logger.error(f"[Email] 通知申请人（通过）失败: {e}")
                else:
                    logger.warning("[Email] 申请人无邮箱，无法发送审批通过通知")

                # 3.2 通知库管（请备货）
                warehouse_role_codes = ['WAREHOUSE_MGR', 'OUTBOUND']
                warehouse_emails = BorrowApprovalService._get_emails_by_identifiers(role_codes=warehouse_role_codes)

                if warehouse_emails:
                    try:
                        send_borrow_dispatch_notify(
                            to_emails=warehouse_emails,
                            request_no=approval.request_no,
                            applicant_name=applicant_name,
                            items=items
                        )
                    except Exception as e:
                        logger.error(f"[Email] 通知库管失败: {e}")
                else:
                    logger.warning("[Email] 无库管角色邮箱，无法发送备货通知")

            elif action == 'reject':
                # 3.3 通知申请人（已驳回）
                if applicant_emails:
                    try:
                        send_borrow_approval_result_notify(
                            to_emails=applicant_emails,
                            request_no=approval.request_no,
                            is_passed=False,
                            reject_reason=approval.reject_reason or '未说明原因',
                            applicant_name=applicant_name
                        )
                    except Exception as e:
                        logger.error(f"[Email] 通知申请人驳回失败: {e}")
                else:
                    logger.warning("[Email] 申请人无邮箱，无法发送驳回通知")

        except Exception as e:
            import traceback
            traceback.print_exc()
            logger.error(f"[Email] 外层发送异常: {e}")

    @staticmethod
    def can_approve(approval, user_id, user_role):
        """
        检查用户是否有权限审批
        """
        approvers = approval.get_allowed_approvers()

        if user_role and user_role.upper() == 'SUPER_ADMIN':
            return True

        # 拥有 op_borrow_approval:operation 权限的用户可以审批任意借库单
        # (前端按钮以此权限控制显示，后端也必须对齐)
        from app.models.system import SysRolePermission
        has_op = SysRolePermission.query.filter(
            SysRolePermission.role_code == user_role,
            SysRolePermission.target_code.in_(['op_borrow_approval:operation', 'op_borrow_approval:*'])
        ).first() is not None
        if has_op:
            return True

        for approver in approvers:
            approver_type = approver.get('type', '')
            approver_value = approver.get('value', '')

            if approver_type == 'user' and str(approver_value) == str(user_id):
                return True

            if approver_type == 'role' and approver_value == user_role:
                return True

        return False

    @staticmethod
    def approve(request_id, user_id, user_role, action='approve', reject_reason=None):
        """
        执行审批操作

        Returns:
            (success: bool, message: str, approval: BorrowApproval or None)
        """
        # ★ 统一取 naive 北京时间，与 created_at(beijing_time) 同口径
        current_time = beijing_time()

        approval = BorrowApproval.query.get(request_id)
        if not approval:
            return False, "审批单不存在", None

        if approval.status != 0:
            return False, f"审批单状态已更新，无法重复审批 (当前状态: {approval.status})", None

        if not BorrowApprovalService.can_approve(approval, user_id, user_role):
            return False, "您没有审批此单的权限", None

        try:
            if action == 'approve':
                approval.status = 1  # 已通过
                approval.actual_approver_id = user_id
                approval.approved_at = current_time
                # 通过后预占继续保留，直到实际借出执行时才释放并扣减
            elif action == 'reject':
                # ★ Phase 2：驳回即释放预占，避免货被永不执行的单占住
                from app.services.inventory_reservation import release_reserved
                release_reserved(approval.get_items())
                approval.status = 2  # 已驳回
                approval.reject_reason = reject_reason
            else:
                return False, "无效的审批操作", None

            db.session.commit()

            # ★ 审批后，发送邮件通知（静默处理，不阻断主流程）
            BorrowApprovalService._notify_approval_result(approval, user_id, action)

            return True, "审批成功", approval

        except Exception as e:
            db.session.rollback()
            return False, f"审批失败: {str(e)}", None

    @staticmethod
    def get_request_list(page=1, per_page=10, applicant_id=None, status=None):
        """
        获取审批单列表
        """
        from app.models.system import SysUser
        from app.utils.decorators import get_current_company_filter
        from sqlalchemy import desc

        query = BorrowApproval.query

        if applicant_id:
            query = query.filter(BorrowApproval.applicant_id == applicant_id)

        if status is not None:
            query = query.filter(BorrowApproval.status == status)

        # 【行级数据隔离】通过申请人关联用户表过滤公司
        company_limit = get_current_company_filter()
        if company_limit is not None:
            query = query.join(SysUser, BorrowApproval.applicant_id == SysUser.id) \
                         .filter(SysUser.department == company_limit)

        query = query.order_by(desc(BorrowApproval.created_at))

        pagination = query.paginate(page=page, per_page=per_page, error_out=False)

        return {
            'items': [item.to_dict() for item in pagination.items],
            'total': pagination.total,
            'pages': pagination.pages,
            'current_page': page
        }

    @staticmethod
    def get_request_by_id(request_id):
        """根据ID获取审批单"""
        return BorrowApproval.query.get(request_id)

    @staticmethod
    def mark_completed(request_id):
        """
        撤回 / 作废已通过的借库审批单（status 1-已通过 → 4-已完结）。

        注意：真正「扫码借出执行完成」走 trans_service.execute_dispatch，
        会将 status 置为 3(已完成)；本方法只处理「已通过但尚未执行」的撤回。

        ★ 修复：原先只改状态、不释放预占 —— 申请阶段 reserve_for_items()
        扣掉的 available_quantity 会永久泄漏，货被一张作废单锁死。
        现调用 release_reserved() 按 items_json 原样归还。

        执行守卫：执行成功后 status 会被置为 3，故「仅 status==1 可撤回」
        本身就是执行守卫，已执行或已撤回的单都无法再次操作。
        """
        approval = BorrowApproval.query.get(request_id)
        if not approval:
            return False, "审批单不存在", None

        if approval.status != 1:
            status_map = {0: '待审批', 1: '已通过', 2: '已驳回', 3: '已完成', 4: '已撤回'}
            return False, (
                f"只有已通过(待执行)的审批单才能撤回 "
                f"(当前状态: {status_map.get(approval.status, approval.status)})"
            ), None

        return BorrowApprovalService._release_and_close(approval)

    # ------------------------------------------------------------------
    # ★ 申请人撤回自己的借库申请单（严格职责分离）
    #
    # 与 mark_completed（管理路径）的区别：
    #   · mark_completed    —— 需 op_borrow_approval 权限，仅 status==1
    #   · withdraw_request  —— 仅校验「单据归属」，status 0 或 1 均可
    #
    # 两条路径共用底层 _release_and_close，释放逻辑只有一份实现。
    # ------------------------------------------------------------------
    WITHDRAWABLE_STATUS = (0, 1)

    @staticmethod
    def withdraw_request(request_id, user_id):
        """
        申请人撤回自己的借库申请单。

        权限：仅单据本人；库管/主管/超管（is_privileged_viewer）可代撤。
        返回 (success, message, approval)
        """
        from app.utils.decorators import is_privileged_viewer

        approval = BorrowApproval.query.get(request_id)
        if not approval:
            return False, "申请单不存在", None

        # ★ 归属校验：非本人且非特权 → 拒绝（不漏出任何单据信息）
        if not is_privileged_viewer() and int(approval.applicant_id) != int(user_id):
            return False, "无权撤回他人的申请单", None

        if approval.status not in BorrowApprovalService.WITHDRAWABLE_STATUS:
            status_map = {0: '待审批', 1: '已通过(待执行)', 2: '已驳回', 3: '已完成', 4: '已撤回'}
            return False, (
                f"当前状态不可撤回：{status_map.get(approval.status, approval.status)}"
            ), None

        return BorrowApprovalService._release_and_close(approval)

    @staticmethod
    def _release_and_close(approval):
        """
        撤回的共用底层：释放预占 + 置为已撤回。

        两条入口（管理路径 mark_completed / 申请人路径 withdraw_request）
        各自完成权限与状态校验后调用本函数，确保释放逻辑不会因修改
        其中一处而漏掉另一处。
        """
        try:
            # ★ 释放全部预占，把 available_quantity 还回池子
            from app.services.inventory_reservation import release_reserved
            restored = release_reserved(approval.get_items())

            # ★ 清理该单据的扫码草稿（含其他用户的）。
            #   撤回后单据状态变为 4，不再出现在扫码页的下拉里（那里只拉 status=1），
            #   草稿从此成为永远读不到的死数据。
            from app.models.scan_draft import ScanDraft
            ScanDraft.query.filter_by(
                biz_type='borrow', request_id=approval.id
            ).delete(synchronize_session=False)

            approval.status = 4  # 已撤回/已完结
            db.session.commit()
            return True, f"申请单已撤回，释放 {restored} 项预占库存", approval
        except Exception as e:
            db.session.rollback()
            return False, f"撤回归还失败: {str(e)}", None