from datetime import date
from decimal import Decimal
from typing import Any

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.core.constants import ActorValue
from app.core.pagination import bounded_limit
from app.core.time import utc_now
from app.modules.audit.constants import (
    AuditAction,
    AuditRiskLevel,
    AuditSource,
    AuditTargetType,
)
from app.modules.audit.schemas import AuditLogCreate
from app.modules.audit.service import AuditService
from app.modules.business.constants import (
    CLOSED_RISK_STATUSES,
    DONE_STATUSES,
    GENERATED_RISK_EVENT_TYPES,
    PROJECT_CLOSED_STATUSES,
    SUPPLIER_RISK_LEVELS,
    BusinessDomain,
    RiskEventType,
    RiskLevel,
    StatusValue,
)
from app.modules.business.models import FundAccount, Project, RiskEvent, Supplier, WorkTask
from app.modules.business.service import serialize_model


class RiskService:
    """Evaluate rule-based business risk signals from internal ledgers."""

    def __init__(self, db: Session):
        self.db = db

    def overdue_tasks(self) -> list[dict[str, Any]]:
        stmt = select(WorkTask).where(
            WorkTask.due_date.is_not(None),
            WorkTask.due_date < date.today(),
            WorkTask.status.notin_(DONE_STATUSES),
        )
        return [serialize_model(item) for item in self.db.execute(stmt).scalars()]

    def delayed_projects(self) -> list[dict[str, Any]]:
        stmt = select(Project).where(
            Project.due_date.is_not(None),
            Project.due_date < date.today(),
            Project.status.notin_(PROJECT_CLOSED_STATUSES),
        )
        return [serialize_model(item) for item in self.db.execute(stmt).scalars()]

    def over_budget_projects(self) -> list[dict[str, Any]]:
        stmt = select(Project).where(
            Project.budget_amount > 0,
            Project.actual_amount > Project.budget_amount,
        )
        return [serialize_model(item) for item in self.db.execute(stmt).scalars()]

    def fund_risks(self) -> list[dict[str, Any]]:
        stmt = select(FundAccount).where(FundAccount.current_balance < FundAccount.safety_line)
        return [serialize_model(item) for item in self.db.execute(stmt).scalars()]

    def supplier_risks(self) -> list[dict[str, Any]]:
        stmt = select(Supplier).where(
            (Supplier.blacklist_status != StatusValue.NORMAL)
            | Supplier.risk_level.in_(SUPPLIER_RISK_LEVELS)
        )
        return [serialize_model(item) for item in self.db.execute(stmt).scalars()]

    def list_events(
        self,
        limit: int = 100,
        status_filter: str | None = None,
    ) -> list[dict[str, Any]]:
        limit_value = bounded_limit(limit)
        stmt = select(RiskEvent).order_by(RiskEvent.id.desc()).limit(limit_value)
        if status_filter:
            stmt = (
                select(RiskEvent)
                .where(RiskEvent.status == status_filter)
                .order_by(RiskEvent.id.desc())
                .limit(limit_value)
            )
        return [serialize_model(item) for item in self.db.execute(stmt).scalars()]

    def summary(self) -> dict[str, Any]:
        overdue_tasks = self.overdue_tasks()
        delayed_projects = self.delayed_projects()
        over_budget_projects = self.over_budget_projects()
        fund_risks = self.fund_risks()
        supplier_risks = self.supplier_risks()
        open_events = self.list_events(status_filter=StatusValue.OPEN)
        external_open_events = [
            item
            for item in open_events
            if item.get("risk_type") not in GENERATED_RISK_EVENT_TYPES
        ]
        risk_score = (
            len(overdue_tasks) * 1
            + len(delayed_projects) * 3
            + len(over_budget_projects) * 4
            + len(fund_risks) * 5
            + len(supplier_risks) * 3
            + len(external_open_events) * 2
        )
        if risk_score >= 15:
            level = RiskLevel.HIGH
        elif risk_score >= 5:
            level = RiskLevel.MEDIUM
        else:
            level = RiskLevel.LOW
        return {
            "risk_level": level,
            "risk_score": Decimal(risk_score),
            "overdue_tasks": overdue_tasks,
            "delayed_projects": delayed_projects,
            "over_budget_projects": over_budget_projects,
            "fund_risks": fund_risks,
            "supplier_risks": supplier_risks,
            "open_events": open_events,
        }

    def generate_events(self, actor: str = ActorValue.API) -> dict[str, Any]:
        """Generate or refresh risk-event ledger entries from current signals."""

        payloads = self._build_event_payloads()
        created = 0
        updated = 0
        skipped = 0
        items: list[dict[str, Any]] = []

        for payload in payloads:
            record = self.db.execute(
                select(RiskEvent).where(RiskEvent.code == payload["code"])
            ).scalar_one_or_none()
            if record is None:
                record = RiskEvent(**payload)
                self.db.add(record)
                self.db.flush()
                created += 1
                action = "created"
            elif record.status in CLOSED_RISK_STATUSES:
                skipped += 1
                items.append({"action": "skipped", "risk_event": serialize_model(record)})
                continue
            else:
                for key, value in payload.items():
                    if key != "code":
                        setattr(record, key, value)
                updated += 1
                action = "updated"
            items.append({"action": action, "risk_event": serialize_model(record)})

        self.db.commit()
        AuditService(self.db).log(
            AuditLogCreate(
                actor=actor,
                source=AuditSource.RISK,
                action=AuditAction.GENERATE_EVENTS,
                target_type=AuditTargetType.RISK_EVENTS,
                risk_level=AuditRiskLevel.MEDIUM,
                response_payload={
                    "created": created,
                    "updated": updated,
                    "skipped": skipped,
                },
            )
        )
        return {"created": created, "updated": updated, "skipped": skipped, "items": items}

    def _build_event_payloads(self) -> list[dict[str, Any]]:
        payloads: list[dict[str, Any]] = []
        payloads.extend(self._overdue_task_payloads())
        payloads.extend(self._delayed_project_payloads())
        payloads.extend(self._over_budget_project_payloads())
        payloads.extend(self._fund_risk_payloads())
        payloads.extend(self._supplier_risk_payloads())
        return payloads

    def _overdue_task_payloads(self) -> list[dict[str, Any]]:
        stmt = select(WorkTask).where(
            WorkTask.due_date.is_not(None),
            WorkTask.due_date < date.today(),
            WorkTask.status.notin_(DONE_STATUSES),
        )
        payloads = []
        for task in self.db.execute(stmt).scalars():
            payloads.append(
                {
                    "code": f"RISK-TASK-OVERDUE-{task.id}",
                    "title": f"任务逾期：{task.title}",
                    "risk_type": RiskEventType.OVERDUE_TASK,
                    "risk_level": RiskLevel.MEDIUM,
                    "status": StatusValue.OPEN,
                    "source_domain": BusinessDomain.TASKS,
                    "source_record_id": str(task.id),
                    "project_code": task.project_code,
                    "owner": task.owner,
                    "due_date": task.due_date,
                    "detected_at": utc_now(),
                    "description": "任务已超过截止日期且未完成。",
                    "mitigation": (
                        "请负责人更新进度、明确阻塞项并给出新的完成时间。"
                    ),
                    "evidence": serialize_model(task),
                }
            )
        return payloads

    def _delayed_project_payloads(self) -> list[dict[str, Any]]:
        stmt = select(Project).where(
            Project.due_date.is_not(None),
            Project.due_date < date.today(),
            Project.status.notin_(PROJECT_CLOSED_STATUSES),
        )
        payloads = []
        for project in self.db.execute(stmt).scalars():
            level = RiskLevel.HIGH if project.progress_percent < 80 else RiskLevel.MEDIUM
            payloads.append(
                {
                    "code": f"RISK-PROJECT-DELAY-{project.id}",
                    "title": f"项目延期：{project.name}",
                    "risk_type": RiskEventType.DELAYED_PROJECT,
                    "risk_level": level,
                    "status": StatusValue.OPEN,
                    "source_domain": BusinessDomain.PROJECTS,
                    "source_record_id": str(project.id),
                    "project_code": project.code,
                    "owner": project.owner,
                    "due_date": project.due_date,
                    "detected_at": utc_now(),
                    "description": "项目已超过计划截止日期且未进入完成状态。",
                    "mitigation": (
                        "请项目负责人提交延期原因、资源需求和纠偏计划。"
                    ),
                    "evidence": serialize_model(project),
                }
            )
        return payloads

    def _over_budget_project_payloads(self) -> list[dict[str, Any]]:
        stmt = select(Project).where(
            Project.budget_amount > 0,
            Project.actual_amount > Project.budget_amount,
        )
        payloads = []
        for project in self.db.execute(stmt).scalars():
            payloads.append(
                {
                    "code": f"RISK-PROJECT-BUDGET-{project.id}",
                    "title": f"项目超预算：{project.name}",
                    "risk_type": RiskEventType.OVER_BUDGET_PROJECT,
                    "risk_level": RiskLevel.HIGH,
                    "status": StatusValue.OPEN,
                    "source_domain": BusinessDomain.PROJECTS,
                    "source_record_id": str(project.id),
                    "project_code": project.code,
                    "owner": project.owner,
                    "due_date": project.due_date,
                    "detected_at": utc_now(),
                    "description": "项目实际成本已超过预算。",
                    "mitigation": (
                        "请复核预算科目、冻结非必要采购并补充审批依据。"
                    ),
                    "evidence": serialize_model(project),
                }
            )
        return payloads

    def _fund_risk_payloads(self) -> list[dict[str, Any]]:
        stmt = select(FundAccount).where(FundAccount.current_balance < FundAccount.safety_line)
        payloads = []
        for account in self.db.execute(stmt).scalars():
            payloads.append(
                {
                    "code": f"RISK-FUND-{account.id}",
                    "title": f"资金低于安全线：{account.name}",
                    "risk_type": RiskEventType.FUND_SAFETY_LINE,
                    "risk_level": RiskLevel.HIGH,
                    "status": StatusValue.OPEN,
                    "source_domain": BusinessDomain.FUND_ACCOUNTS,
                    "source_record_id": str(account.id),
                    "owner": None,
                    "detected_at": utc_now(),
                    "description": "账户当前余额低于设置的安全线。",
                    "mitigation": (
                        "请财务确认收付款计划，"
                        "并优先处理关键项目资金安排。"
                    ),
                    "evidence": serialize_model(account),
                }
            )
        return payloads

    def _supplier_risk_payloads(self) -> list[dict[str, Any]]:
        stmt = select(Supplier).where(
            (Supplier.blacklist_status != StatusValue.NORMAL)
            | Supplier.risk_level.in_(SUPPLIER_RISK_LEVELS)
        )
        payloads = []
        for supplier in self.db.execute(stmt).scalars():
            level = (
                RiskLevel.HIGH
                if supplier.blacklist_status != StatusValue.NORMAL
                else supplier.risk_level
            )
            payloads.append(
                {
                    "code": f"RISK-SUPPLIER-{supplier.id}",
                    "title": f"供应商风险：{supplier.name}",
                    "risk_type": RiskEventType.SUPPLIER_RISK,
                    "risk_level": level,
                    "status": StatusValue.OPEN,
                    "source_domain": BusinessDomain.SUPPLIERS,
                    "source_record_id": str(supplier.id),
                    "owner": supplier.contact,
                    "detected_at": utc_now(),
                    "description": "供应商风险等级或黑名单状态需要关注。",
                    "mitigation": (
                        "请采购负责人复核供应商准入、履约和替代方案。"
                    ),
                    "evidence": serialize_model(supplier),
                }
            )
        return payloads