"""
HITL Approval Models
====================
CISO-101: 授權請求與簽核資料模型

Features:
- 狀態機 (PENDING → APPROVED/REJECTED/EXPIRED)
- 風險等級判定 (LOW/MEDIUM/CRITICAL)
- Multi-Sig 簽核追蹤
- Pydantic 強型別驗證
"""

from datetime import datetime, timezone
from enum import Enum
from typing import Literal
from uuid import UUID, uuid4

from pydantic import BaseModel, Field, field_validator


# =============================================================================
# Enums
# =============================================================================

class ApprovalStatus(str, Enum):
    """
    授權請求狀態機

    PENDING → APPROVED → EXECUTION_SUCCESS
                      → EXECUTION_FAILED
    PENDING → REJECTED
    PENDING → EXPIRED
    """
    PENDING = "pending"                    # 等待簽核
    APPROVED = "approved"                  # 已批准 (滿足簽核數，準備執行)
    REJECTED = "rejected"                  # 已拒絕
    EXPIRED = "expired"                    # 已過期
    EXECUTION_SUCCESS = "execution_success"  # 執行成功
    EXECUTION_FAILED = "execution_failed"    # 執行失敗


class RiskLevel(str, Enum):
    """
    風險等級 - 決定所需簽核人數

    - LOW: 0 人，自動放行
    - MEDIUM: 需 1 人簽核
    - CRITICAL: 需 2 人 Multi-Sig 雙重簽核
    """
    LOW = "low"
    MEDIUM = "medium"
    CRITICAL = "critical"


class DataImpact(str, Enum):
    """資料影響類型"""
    NONE = "none"
    READ_ONLY = "read_only"
    WRITE = "write"
    DESTRUCTIVE = "destructive"


# =============================================================================
# Sub-models
# =============================================================================

class BlastRadius(BaseModel):
    """爆炸半徑 - 影響範圍評估"""
    affected_pods: int = Field(default=0, ge=0)
    estimated_downtime: str = Field(default="0")
    related_services: list[str] = Field(default_factory=list)
    data_impact: DataImpact = Field(default=DataImpact.NONE)


class DryRunCheck(BaseModel):
    """Dry-Run 預演檢查結果"""
    name: str
    passed: bool
    message: str | None = None


class SignatureSource(str, Enum):
    """
    簽核來源通道 (Phase 5.4.5: AuditLog 擴充)

    用於追溯簽核是從哪個通道發起
    """
    WEB = "web"               # Web UI 簽核
    TELEGRAM = "telegram"     # Telegram 簽核
    API = "api"               # API 直接呼叫
    SYSTEM = "system"         # 系統自動 (LOW 風險)


class Signature(BaseModel):
    """
    簽核記錄

    Phase 5.4.5: 新增 Telegram 審計欄位
    - source: 簽核來源通道
    - telegram_user_id: Telegram User ID (永久追溯憑證)
    - telegram_message_id: Telegram 訊息 ID
    """
    id: UUID = Field(default_factory=uuid4)
    signer_id: str = Field(..., description="簽核者 ID")
    signer_name: str = Field(..., description="簽核者名稱")
    signed_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
    comment: str | None = None

    # Phase 5.4.5: Telegram 審計軌跡
    source: SignatureSource = Field(
        default=SignatureSource.WEB,
        description="簽核來源通道 (web/telegram/api/system)",
    )
    telegram_user_id: int | None = Field(
        default=None,
        description="Telegram User ID (永久追溯憑證)",
    )
    telegram_message_id: int | None = Field(
        default=None,
        description="Telegram 訊息 ID",
    )

    class Config:
        json_encoders = {
            datetime: lambda v: v.isoformat(),
            UUID: lambda v: str(v),
        }


# =============================================================================
# Main Models
# =============================================================================

class ApprovalRequestBase(BaseModel):
    """授權請求基礎模型"""
    action: str = Field(..., description="執行動作描述")
    description: str = Field(..., description="詳細說明")
    risk_level: RiskLevel = Field(..., description="風險等級")
    blast_radius: BlastRadius = Field(default_factory=BlastRadius)
    dry_run_checks: list[DryRunCheck] = Field(default_factory=list)
    requested_by: str = Field(..., description="請求發起者")
    expires_at: datetime | None = Field(default=None, description="到期時間")
    metadata: dict | None = Field(default=None, description="額外元資料")


class ApprovalRequestCreate(ApprovalRequestBase):
    """建立授權請求 (API 輸入)"""
    pass


class ApprovalRequest(ApprovalRequestBase):
    """完整授權請求模型"""
    id: UUID = Field(default_factory=uuid4)
    status: ApprovalStatus = Field(default=ApprovalStatus.PENDING)
    required_signatures: int = Field(..., description="所需簽核數")
    signatures: list[Signature] = Field(default_factory=list)
    created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
    updated_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
    resolved_at: datetime | None = Field(default=None, description="解決時間")
    rejection_reason: str | None = Field(default=None)
    # 戰略 B: 告警風暴收斂
    fingerprint: str | None = Field(default=None, description="告警指紋 Hash")
    hit_count: int = Field(default=1, description="聚合觸發次數")
    last_seen_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc), description="最後觸發時間")

    @property
    def current_signatures(self) -> int:
        """目前已收集的簽核數"""
        return len(self.signatures)

    @property
    def is_fully_signed(self) -> bool:
        """是否已滿足所需簽核數"""
        return self.current_signatures >= self.required_signatures

    @property
    def remaining_signatures(self) -> int:
        """還需要的簽核數"""
        return max(0, self.required_signatures - self.current_signatures)

    def has_signer(self, signer_id: str) -> bool:
        """檢查某人是否已簽核"""
        return any(s.signer_id == signer_id for s in self.signatures)

    class Config:
        json_encoders = {
            datetime: lambda v: v.isoformat(),
            UUID: lambda v: str(v),
        }


# =============================================================================
# API Response Models
# =============================================================================

class ApprovalRequestResponse(BaseModel):
    """授權請求 API 回應"""
    id: str
    action: str
    description: str
    status: ApprovalStatus
    risk_level: RiskLevel
    blast_radius: BlastRadius
    dry_run_checks: list[DryRunCheck]
    required_signatures: int
    current_signatures: int
    signatures: list[Signature]
    requested_by: str
    created_at: datetime
    expires_at: datetime | None
    resolved_at: datetime | None
    # 戰略 B: 告警風暴收斂
    fingerprint: str | None = None
    hit_count: int = 1
    last_seen_at: datetime | None = None

    @classmethod
    def from_approval(cls, approval: ApprovalRequest) -> "ApprovalRequestResponse":
        """從 ApprovalRequest 轉換"""
        return cls(
            id=str(approval.id),
            action=approval.action,
            description=approval.description,
            status=approval.status,
            risk_level=approval.risk_level,
            blast_radius=approval.blast_radius,
            dry_run_checks=approval.dry_run_checks,
            required_signatures=approval.required_signatures,
            current_signatures=approval.current_signatures,
            signatures=approval.signatures,
            requested_by=approval.requested_by,
            created_at=approval.created_at,
            expires_at=approval.expires_at,
            resolved_at=approval.resolved_at,
            # 戰略 B
            fingerprint=approval.fingerprint,
            hit_count=approval.hit_count,
            last_seen_at=approval.last_seen_at,
        )


class SignRequest(BaseModel):
    """簽核請求"""
    signer_id: str = Field(..., description="簽核者 ID")
    signer_name: str = Field(..., description="簽核者名稱")
    comment: str | None = Field(default=None, description="簽核備註")


class RejectRequest(BaseModel):
    """退回請求"""
    rejector_id: str = Field(..., description="退回者 ID")
    rejector_name: str = Field(..., description="退回者名稱")
    reason: str = Field(..., description="退回原因")


class SignResponse(BaseModel):
    """簽核回應"""
    success: bool
    message: str
    approval: ApprovalRequestResponse
    execution_triggered: bool = Field(
        default=False,
        description="是否觸發執行 (當簽核數滿足時)"
    )


class PendingApprovalsResponse(BaseModel):
    """待簽核清單回應"""
    count: int
    approvals: list[ApprovalRequestResponse]