from __future__ import annotations

from enum import Enum
from typing import Literal, Optional

from pydantic import BaseModel, ConfigDict, Field, model_validator


def to_camel(value: str) -> str:
    parts = value.split("_")
    return parts[0] + "".join(part.capitalize() for part in parts[1:])


class APIModel(BaseModel):
    model_config = ConfigDict(
        alias_generator=to_camel,
        populate_by_name=True,
        extra="forbid",
        str_strip_whitespace=True,
    )


class PlanningMode(str, Enum):
    QUICK = "quick"
    CUSTOM = "custom"


class Duration(str, Enum):
    HALF_DAY = "half_day"
    FULL_DAY = "full_day"


class Pace(str, Enum):
    RELAXED = "relaxed"
    MODERATE = "moderate"
    COMPACT = "compact"


class Transport(str, Enum):
    WALKING = "walking"
    DRIVING = "driving"
    PUBLIC_TRANSPORT = "public_transport"


class BudgetLevel(str, Enum):
    ECONOMY = "economy"
    STANDARD = "standard"
    QUALITY = "quality"


Theme = Literal["亲子", "情侣", "朋友", "银发", "研学"]
Interest = Literal["自然风光", "文化场馆", "生态科普", "美食", "摄影"]


class TravelPreferences(APIModel):
    destination: Literal["深圳市光明区"] = "深圳市光明区"
    themes: list[Theme] = Field(default_factory=list, max_length=5)
    duration: Duration
    pace: Pace
    interests: list[Interest] = Field(default_factory=list, max_length=5)
    adults: int = Field(default=2, ge=0, le=20)
    children: int = Field(default=0, ge=0, le=20)
    child_ages: list[int] = Field(default_factory=list, max_length=20)
    transport: Transport = Transport.PUBLIC_TRANSPORT
    budget_level: BudgetLevel = BudgetLevel.STANDARD
    extra_requirements: str = Field(default="", max_length=500)

    @model_validator(mode="after")
    def validate_group(self) -> "TravelPreferences":
        if self.adults + self.children < 1:
            raise ValueError("出行总人数至少为 1")
        if self.child_ages and len(self.child_ages) != self.children:
            raise ValueError("儿童年龄数量必须与儿童人数一致")
        if any(age < 0 or age > 17 for age in self.child_ages):
            raise ValueError("儿童年龄须在 0 至 17 岁之间")
        if len(set(self.themes)) != len(self.themes):
            raise ValueError("出行主题不能重复")
        if len(set(self.interests)) != len(self.interests):
            raise ValueError("兴趣偏好不能重复")
        return self


class PoiCandidate(APIModel):
    """Coordinate-free, presentation-free POI data that may reach the model."""

    id: str = Field(min_length=1, max_length=100, pattern=r"^[A-Za-z0-9][A-Za-z0-9_-]*$")
    name: str = Field(min_length=1, max_length=100)
    category_code: str = Field(min_length=1, max_length=64)
    tag_codes: list[str] = Field(default_factory=list, max_length=20)
    summary: str = Field(default="", max_length=300)
    recommendation_index: int = Field(ge=1, le=5)

    @model_validator(mode="after")
    def validate_tags(self) -> "PoiCandidate":
        if len(set(self.tag_codes)) != len(self.tag_codes):
            raise ValueError("POI 标签不能重复")
        return self


class PlanRecommendationRequest(APIModel):
    mode: PlanningMode
    preferences: TravelPreferences
    duration_minutes: int = Field(ge=120, le=600, multiple_of=30)
    selected_poi_ids: list[str] = Field(default_factory=list, max_length=8)
    candidates: list[PoiCandidate] = Field(min_length=1, max_length=100)

    @model_validator(mode="after")
    def validate_planning_scope(self) -> "PlanRecommendationRequest":
        candidate_ids = [candidate.id for candidate in self.candidates]
        if len(set(candidate_ids)) != len(candidate_ids):
            raise ValueError("候选 POI ID 不能重复")
        if len(set(self.selected_poi_ids)) != len(self.selected_poi_ids):
            raise ValueError("自选 POI ID 不能重复")

        if self.mode == PlanningMode.QUICK:
            if self.selected_poi_ids:
                raise ValueError("快速规划不能预选 POI")
        elif not 2 <= len(self.selected_poi_ids) <= 8:
            raise ValueError("自选规划必须选择 2 至 8 个 POI")

        unknown = set(self.selected_poi_ids) - set(candidate_ids)
        if unknown:
            raise ValueError(f"自选规划包含候选白名单外的 POI：{sorted(unknown)}")
        return self


class ModelRecommendation(APIModel):
    poi_id: str = Field(min_length=1, max_length=100)
    reason: str = Field(min_length=1, max_length=300)
    order: Optional[int] = Field(default=None, ge=1, le=8)


class ModelRecommendationSet(APIModel):
    recommendations: list[ModelRecommendation] = Field(min_length=1, max_length=8)


class RecommendationItem(APIModel):
    poi_id: str
    reason: str
    order: int = Field(ge=1, le=8)


class RecommendationResponse(APIModel):
    request_id: str
    mode: PlanningMode
    assistant_message: str
    recommendations: list[RecommendationItem] = Field(min_length=1, max_length=8)
    generation_mode: Literal["mock", "real"]


class HealthResponse(APIModel):
    status: Literal["ok", "degraded"]
    mode: Literal["mock", "real"]
    configured: bool
    ready: bool