"""Stochastic quarterly events that create cross-quarter cascading effects."""

from __future__ import annotations

import random
from dataclasses import dataclass
from typing import List, Optional

from hr_env.server.company import Company


@dataclass
class Event:
    """A stochastic event that affects the company."""

    name: str
    description: str
    probability: float
    affected_department: Optional[str] = None  # None = company-wide

    def apply(self, company: Company, rng: random.Random) -> str:
        """Apply the event's effects. Returns description of what happened."""
        raise NotImplementedError


class MarketDownturn(Event):
    def __init__(self):
        super().__init__(
            name="market_downturn",
            description="Economic downturn reduces market demand",
            probability=0.10,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        company.market_modifier *= 0.88  # Revenue -12%
        # Increase flight risk for top performers (they have options)
        for emp in company.all_active_employees:
            if emp.performance_score >= 4.0:
                emp.flight_risk = min(0.95, emp.flight_risk + 0.05)
        return "Market downturn: revenue reduced by 12%. Top performer flight risk increased."


class CompetitorPoaching(Event):
    def __init__(self):
        super().__init__(
            name="competitor_poaching",
            description="Competitor aggressively recruiting from one department",
            probability=0.12,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        dept_name = rng.choice(list(company.departments.keys()))
        self.affected_department = dept_name
        dept = company.departments[dept_name]
        for emp in dept.active_employees:
            emp.flight_risk = min(0.95, emp.flight_risk + 0.25)
            emp.update_engagement(-5)
        return f"Competitor poaching in {dept_name}: flight risk +25% for all department employees."


class ProductLaunch(Event):
    def __init__(self):
        super().__init__(
            name="product_launch",
            description="Major product launch increases workload",
            probability=0.10,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        for dept_name in ["Engineering", "Sales"]:
            dept = company.departments.get(dept_name)
            if dept:
                for emp in dept.active_employees:
                    emp.update_engagement(-8)  # Stress from overwork
                    # But productivity boost
                    emp.performance_score = min(5.0, emp.performance_score + 0.1)
        company.market_modifier *= 1.08  # Revenue boost from launch
        return "Product launch: Engineering/Sales workload +25%, engagement decreased, but revenue +8%."


class ExecDeparture(Event):
    def __init__(self):
        super().__init__(
            name="exec_departure",
            description="Senior executive departs suddenly",
            probability=0.07,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        dept_name = rng.choice(list(company.departments.keys()))
        self.affected_department = dept_name
        dept = company.departments[dept_name]
        # Remove highest-level employee
        seniors = sorted(dept.active_employees, key=lambda e: (-e.level, -e.tenure_months))
        if seniors:
            seniors[0].is_active = False
        # Leadership gap: engagement drops
        for emp in dept.active_employees:
            emp.update_engagement(-12)
        return f"Executive departure in {dept_name}: leadership gap, engagement -12% department-wide."


class MinWageIncrease(Event):
    def __init__(self):
        super().__init__(
            name="min_wage_increase",
            description="Regulatory minimum wage increase",
            probability=0.06,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        floor_increase = 0.06
        affected = 0
        for emp in company.all_active_employees:
            if emp.salary < 50000:
                emp.salary *= (1 + floor_increase)
                affected += 1
        return f"Minimum wage increase: {affected} employees received 6% salary floor adjustment."


class EmployerAward(Event):
    def __init__(self):
        super().__init__(
            name="employer_award",
            description="Company wins employer award, boosting brand",
            probability=0.06,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        # Boost engagement and reduce flight risk
        for emp in company.all_active_employees:
            emp.update_engagement(5)
            emp.flight_risk = max(0.02, emp.flight_risk - 0.05)
        return "Employer award: company brand boost, engagement +5, flight risk reduced."


class BudgetCut(Event):
    def __init__(self):
        super().__init__(
            name="budget_cut",
            description="Corporate budget reduction for HR",
            probability=0.08,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        reduction = company.hr_budget_remaining * 0.20
        company.hr_budget_remaining -= reduction
        return f"Budget cut: HR budget reduced by 20% (${reduction:,.0f} lost)."


class TrainingBreakthrough(Event):
    def __init__(self):
        super().__init__(
            name="training_breakthrough",
            description="Training program yields exceptional results in one department",
            probability=0.05,
        )

    def apply(self, company: Company, rng: random.Random) -> str:
        dept_name = rng.choice(list(company.departments.keys()))
        self.affected_department = dept_name
        dept = company.departments[dept_name]
        for emp in dept.active_employees:
            emp.performance_score = min(5.0, emp.performance_score + 0.3)
            emp.update_engagement(5)
        return f"Training breakthrough in {dept_name}: productivity +8%, performance improved."


ALL_EVENTS: List[Event] = [
    MarketDownturn(),
    CompetitorPoaching(),
    ProductLaunch(),
    ExecDeparture(),
    MinWageIncrease(),
    EmployerAward(),
    BudgetCut(),
    TrainingBreakthrough(),
]


def draw_quarterly_events(rng: random.Random, max_events: int = 2) -> List[Event]:
    """Draw 0-2 random events for a quarter based on probabilities."""
    triggered = []
    for event in ALL_EVENTS:
        if rng.random() < event.probability:
            triggered.append(event)
    # Cap at max_events
    if len(triggered) > max_events:
        triggered = rng.sample(triggered, max_events)
    return triggered


def apply_events(company: Company, rng: random.Random) -> List[str]:
    """Draw and apply quarterly events. Returns list of event descriptions."""
    events = draw_quarterly_events(rng)
    descriptions = []
    for event in events:
        desc = event.apply(company, rng)
        descriptions.append(desc)
    return descriptions