"""
Trust Engine - 信任引擎與漸進自治
Phase 3.2: Progressive Autonomy

核心理念:
當某種特定操作被人類連續批准多次後，
系統自動將該操作的風險等級降級，最終達成 Zero-Touch (免授權自動執行)

信任累積規則:
- 每次 Approve: +1 分
- 每次 Reject: 歸零 (信任瞬間瓦解)

風險降級閾值:
- score >= 5:  medium → low (變成自動執行)
- score >= 10: high → medium (雙簽變單簽)
- critical: 永遠不准降級 (Drop Table 等毀滅性操作)
"""

import logging
from dataclasses import dataclass, field
from datetime import datetime
from typing import Literal, Protocol, runtime_checkable

# Phase 16 R2 (2026-03-25): RiskLevel 統一改從 models/approval.py 導入
# 原因: 消除重複定義，統一風險等級來源
# 執行者: Claude Code
# 回滾: 取消註解下方 RiskLevel class 區塊，移除此 import
from src.models.approval import RiskLevel

logger = logging.getLogger(__name__)


# ==================== Types ====================

# --- 以下為舊定義，已封存 (Phase 16 R2) ---
# class RiskLevel(str, Enum):
#     """風險等級"""
#     LOW = "low"
#     MEDIUM = "medium"
#     HIGH = "high"
#     CRITICAL = "critical"
# --- 封存結束 ---


@dataclass
class TrustRecord:
    """信任記錄"""
    action_pattern: str
    score: int = 0
    total_approvals: int = 0
    total_rejections: int = 0
    last_approval_by: str | None = None
    last_approval_at: datetime | None = None
    last_rejection_by: str | None = None
    last_rejection_at: datetime | None = None
    created_at: datetime = field(default_factory=datetime.utcnow)

    @property
    def approval_rate(self) -> float:
        """批准率"""
        total = self.total_approvals + self.total_rejections
        if total == 0:
            return 0.0
        return self.total_approvals / total


@dataclass
class RiskAdjustment:
    """風險調整結果"""
    original_risk: RiskLevel
    adjusted_risk: RiskLevel
    trust_score: int
    reason: str
    is_downgraded: bool

    def to_dict(self) -> dict:
        return {
            "originalRisk": self.original_risk.value,
            "adjustedRisk": self.adjusted_risk.value,
            "trustScore": self.trust_score,
            "reason": self.reason,
            "isDowngraded": self.is_downgraded,
        }


# ==================== Configuration ====================


@dataclass
class TrustThresholds:
    """信任閾值配置"""
    # 降級閾值
    medium_to_low: int = 5      # medium → low (自動執行)
    high_to_medium: int = 10    # high → medium (雙簽→單簽)

    # Reject 懲罰
    rejection_penalty: int = -5  # Reject 時直接扣分 (或歸零)
    reset_on_reject: bool = True # True = 歸零, False = 扣分

    # 信任衰減 (可選，防止過時信任)
    decay_enabled: bool = False
    decay_days: int = 30        # 幾天沒操作後開始衰減
    decay_rate: float = 0.1     # 每天衰減比例


# 預設閾值
DEFAULT_THRESHOLDS = TrustThresholds()


# ==================== Protocol Interface (Phase 17 P1) ====================


@runtime_checkable
class ITrustScoreManager(Protocol):
    """
    TrustScoreManager 介面定義

    用途:
    - 依賴注入 (DI) 時的型別約束
    - 測試時 Mock 的型別檢查
    - 符合 leWOOOgo 積木化規範

    Tier 3 紅區服務: 修改需首席架構師簽核

    @see feedback_lewooogo_modular_enforcement.md
    @see docs/RED_ZONES.md
    """

    def record_approval(
        self,
        action_pattern: str,
        user_role: str,
        user_id: str | None = None,
    ) -> TrustRecord:
        """記錄人類批准"""
        ...

    def record_rejection(
        self,
        action_pattern: str,
        user_role: str,
        user_id: str | None = None,
        reason: str | None = None,
    ) -> TrustRecord:
        """記錄人類拒絕"""
        ...

    def evaluate_adjusted_risk(
        self,
        action_pattern: str,
        original_risk: str | RiskLevel,
    ) -> RiskAdjustment:
        """評估調整後的風險等級"""
        ...

    def get_trust_record(self, action_pattern: str) -> TrustRecord | None:
        """取得信任記錄"""
        ...


# ==================== Trust Engine ====================


class TrustScoreManager:
    """
    信任分數管理器

    追蹤每個 action_pattern 的信任分數，
    根據人類批准/拒絕歷史動態調整風險等級
    """

    def __init__(self, thresholds: TrustThresholds | None = None):
        self.thresholds = thresholds or DEFAULT_THRESHOLDS
        # In-memory storage (Phase 4+ 換成 Redis/PostgreSQL)
        self._records: dict[str, TrustRecord] = {}

    def _get_or_create_record(self, action_pattern: str) -> TrustRecord:
        """取得或建立信任記錄"""
        if action_pattern not in self._records:
            self._records[action_pattern] = TrustRecord(action_pattern=action_pattern)
        return self._records[action_pattern]

    def record_approval(
        self,
        action_pattern: str,
        user_role: str,
        user_id: str | None = None,
    ) -> TrustRecord:
        """
        記錄人類批准

        每次 Approve，該 pattern 的信任分數 +1
        連續批准累積信任，最終達成 Zero-Touch

        Args:
            action_pattern: 操作模式 (例如: "delete_pod:nginx-*")
            user_role: 批准者角色
            user_id: 批准者 ID (可選)

        Returns:
            更新後的 TrustRecord
        """
        record = self._get_or_create_record(action_pattern)

        # 累積信任
        record.score += 1
        record.total_approvals += 1
        record.last_approval_by = user_id or user_role
        record.last_approval_at = datetime.utcnow()

        logger.info(
            f"[TrustEngine] Approval recorded: {action_pattern} "
            f"(score: {record.score}, by: {user_role})"
        )

        return record

    def record_rejection(
        self,
        action_pattern: str,
        user_role: str,
        user_id: str | None = None,
        reason: str | None = None,
    ) -> TrustRecord:
        """
        記錄人類拒絕

        ⚠️ 信任瞬間瓦解: Reject 會讓分數歸零或大幅扣分
        這確保系統不會因為歷史批准而忽視人類當下的判斷

        Args:
            action_pattern: 操作模式
            user_role: 拒絕者角色
            user_id: 拒絕者 ID (可選)
            reason: 拒絕原因 (可選)

        Returns:
            更新後的 TrustRecord
        """
        record = self._get_or_create_record(action_pattern)

        # 信任瓦解
        old_score = record.score
        if self.thresholds.reset_on_reject:
            record.score = 0  # 歸零
        else:
            record.score = max(0, record.score + self.thresholds.rejection_penalty)

        record.total_rejections += 1
        record.last_rejection_by = user_id or user_role
        record.last_rejection_at = datetime.utcnow()

        logger.warning(
            f"[TrustEngine] Rejection recorded: {action_pattern} "
            f"(score: {old_score} → {record.score}, by: {user_role}, reason: {reason})"
        )

        return record

    def evaluate_adjusted_risk(
        self,
        action_pattern: str,
        original_risk: str | RiskLevel,
    ) -> RiskAdjustment:
        """
        評估調整後的風險等級

        根據信任分數決定是否降級風險

        降級規則:
        - score >= 5:  medium → low (自動執行)
        - score >= 10: high → medium (雙簽→單簽)
        - critical: 永遠不准降級

        Args:
            action_pattern: 操作模式
            original_risk: 原始風險等級

        Returns:
            RiskAdjustment 包含調整後風險與原因
        """
        # 標準化 risk level
        if isinstance(original_risk, str):
            original_risk = RiskLevel(original_risk.lower())

        record = self._get_or_create_record(action_pattern)
        score = record.score

        # ╔════════════════════════════════════════════════════╗
        # ║  CRITICAL 永遠不准降級 - 企業鐵律                   ║
        # ║  Drop Table, Delete Namespace 等毀滅性操作         ║
        # ║  無論多少次批准，都必須人類雙簽                     ║
        # ╚════════════════════════════════════════════════════╝
        if original_risk == RiskLevel.CRITICAL:
            return RiskAdjustment(
                original_risk=original_risk,
                adjusted_risk=RiskLevel.CRITICAL,
                trust_score=score,
                reason="CRITICAL operations never auto-downgrade (enterprise policy)",
                is_downgraded=False,
            )

        adjusted_risk = original_risk
        reason = "No adjustment"
        is_downgraded = False

        # HIGH → MEDIUM (score >= 10)
        if original_risk == RiskLevel.HIGH and score >= self.thresholds.high_to_medium:
            adjusted_risk = RiskLevel.MEDIUM
            reason = f"Trust score {score} >= {self.thresholds.high_to_medium}: HIGH → MEDIUM (2-sig → 1-sig)"
            is_downgraded = True

        # MEDIUM → LOW (score >= 5)
        elif original_risk == RiskLevel.MEDIUM and score >= self.thresholds.medium_to_low:
            adjusted_risk = RiskLevel.LOW
            reason = f"Trust score {score} >= {self.thresholds.medium_to_low}: MEDIUM → LOW (auto-execute)"
            is_downgraded = True

        # HIGH 但未達降級閾值
        elif original_risk == RiskLevel.HIGH and score < self.thresholds.high_to_medium:
            reason = f"Trust score {score} < {self.thresholds.high_to_medium}: HIGH maintained"

        # MEDIUM 但未達降級閾值
        elif original_risk == RiskLevel.MEDIUM and score < self.thresholds.medium_to_low:
            reason = f"Trust score {score} < {self.thresholds.medium_to_low}: MEDIUM maintained"

        # LOW 已是最低
        elif original_risk == RiskLevel.LOW:
            reason = "Already at lowest risk level"

        if is_downgraded:
            logger.info(
                f"[TrustEngine] Risk downgraded: {action_pattern} "
                f"({original_risk.value} → {adjusted_risk.value}, score: {score})"
            )

        return RiskAdjustment(
            original_risk=original_risk,
            adjusted_risk=adjusted_risk,
            trust_score=score,
            reason=reason,
            is_downgraded=is_downgraded,
        )

    def get_trust_record(self, action_pattern: str) -> TrustRecord | None:
        """取得信任記錄"""
        return self._records.get(action_pattern)

    def get_all_records(self) -> list[TrustRecord]:
        """取得所有信任記錄"""
        return list(self._records.values())

    def reset_trust(self, action_pattern: str) -> None:
        """重置特定 pattern 的信任分數"""
        if action_pattern in self._records:
            self._records[action_pattern].score = 0
            logger.info(f"[TrustEngine] Trust reset: {action_pattern}")

    def reset_all(self) -> None:
        """重置所有信任分數 (緊急用)"""
        for record in self._records.values():
            record.score = 0
        logger.warning("[TrustEngine] All trust scores reset!")


# ==================== Pattern Matching Utilities ====================


def normalize_action_pattern(
    operation: str,
    parameters: dict,
    granularity: Literal["exact", "resource", "operation"] = "resource",
) -> str:
    """
    正規化操作為 pattern

    granularity 控制信任累積粒度:
    - exact: "delete_pod:nginx-frontend-7d4b8c9f5-xk2m3" (精確到實例)
    - resource: "delete_pod:nginx-frontend-*" (資源類型)
    - operation: "delete_pod:*" (操作類型)

    Args:
        operation: 操作名稱
        parameters: 操作參數
        granularity: 粒度

    Returns:
        正規化後的 pattern
    """
    if granularity == "operation":
        return f"{operation}:*"

    # 嘗試從參數提取資源名稱
    resource_name = (
        parameters.get("pod_name") or
        parameters.get("deployment") or
        parameters.get("table_name") or
        parameters.get("resource") or
        parameters.get("name") or
        "*"
    )

    if granularity == "exact":
        return f"{operation}:{resource_name}"

    # resource: 提取資源前綴
    # nginx-frontend-7d4b8c9f5-xk2m3 → nginx-frontend-*
    if isinstance(resource_name, str) and resource_name != "*":
        parts = resource_name.rsplit("-", 2)
        if len(parts) >= 3:
            resource_name = f"{parts[0]}-*"

    return f"{operation}:{resource_name}"


# 全域實例
trust_engine = TrustScoreManager()


def get_trust_manager() -> TrustScoreManager:
    """取得 TrustScoreManager singleton (ADR-030 Phase 4)"""
    return trust_engine