"""Composition root + FastAPI dependencies.

This is the only place that wires concrete adapters into the domain packages.
Everything below it takes its collaborators as constructor arguments, which is
what keeps ``packages/domain`` and ``packages/llm`` unit-testable without IO.
"""

from __future__ import annotations

from collections.abc import AsyncIterator
from decimal import Decimal
from typing import Annotated

from fastapi import Depends, Request
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from sqlalchemy.ext.asyncio import AsyncSession

from packages.agent.context import PROFILE_SUMMARY_MAX_CHARS
from packages.agent.service import AgentService
from packages.analytics.service import AnalyticsService
from packages.billing.service import BillingService
from packages.identity.service import IdentityService
from packages.llm.budget import DailyBudgetGuard, RedisCostCounter
from packages.llm.circuit import CircuitBreakerRegistry
from packages.llm.cost import (
    CompositeAICallRecorder,
    ModelRate,
    PeakAwareRateTable,
    RateTable,
)
from packages.llm.gateway import LLMGateway
from packages.llm.prompts import PromptRegistry
from packages.llm.providers.base import LLMProvider
from packages.llm.providers.deepseek import DeepSeekProvider
from packages.llm.providers.zhipu import ZhipuGLMProvider
from packages.llm.recording import PrometheusAICallRecorder, SqlAlchemyAICallRecorder
from packages.llm.routing import SceneRouter, build_scene_configs
from packages.report.profile import latest_profile_summary
from packages.shared.config import Settings, get_settings
from packages.shared.context import bind_context
from packages.shared.db import get_session_factory
from packages.shared.errors import AppError, ErrorCode
from packages.shared.redis_client import get_redis
from packages.shared.security import decode_access_token
from packages.storage.service import StorageService
from packages.task.service import TaskService

bearer_scheme = HTTPBearer(auto_error=False)


def build_llm_gateway(settings: Settings) -> LLMGateway:
    """Assemble the gateway from configuration (架构文档 §8.1)."""
    providers: dict[str, LLMProvider] = {
        "deepseek": DeepSeekProvider(
            api_key=settings.deepseek_api_key,
            base_url=settings.deepseek_base_url,
            default_model=settings.deepseek_model,
        ),
        "zhipu": ZhipuGLMProvider(
            api_key=settings.zhipu_api_key,
            base_url=settings.zhipu_base_url,
            default_model=settings.zhipu_model,
        ),
    }

    router = SceneRouter(
        build_scene_configs(
            primary_provider=settings.llm_primary_provider,
            backup_provider=settings.llm_backup_provider,
            structured_max_retries=settings.llm_structured_max_retries,
            overrides=settings.llm_scene_overrides,
        )
    )

    default_rate = ModelRate.from_mapping(settings.llm_default_cost_rate)
    rates = PeakAwareRateTable(
        RateTable(
            {
                model: ModelRate.from_mapping(rate)
                for model, rate in settings.llm_cost_rates.items()
            },
            default=default_rate,
        ),
        RateTable(
            {
                model: ModelRate.from_mapping(rate)
                for model, rate in settings.llm_cost_rates_peak.items()
            },
            default=default_rate,
        )
        if settings.llm_cost_rates_peak
        else None,
        enabled=settings.llm_peak_pricing_enabled,
    )

    recorder = CompositeAICallRecorder(
        SqlAlchemyAICallRecorder(get_session_factory()),
        PrometheusAICallRecorder(),
    )

    budget = DailyBudgetGuard(
        RedisCostCounter(get_redis()),
        daily_budget_cents=Decimal(settings.llm_daily_budget_cents),
        enabled=settings.llm_daily_budget_enabled,
        tz_offset_hours=settings.llm_budget_timezone_offset_hours,
        tiers=list(settings.llm_budget_tiers),
    )

    return LLMGateway(
        providers=providers,
        router=router,
        prompts=PromptRegistry(
            settings.prompts_dir, cache_prefix_mode=settings.llm_cache_prefix_mode
        ),
        rates=rates,
        recorder=recorder,
        budget=budget,
        breakers=CircuitBreakerRegistry(
            failure_threshold=settings.llm_circuit_failure_threshold,
            cooldown_seconds=settings.llm_circuit_cooldown_seconds,
        ),
    )


# --- request-scoped dependencies -------------------------------------------


def settings_dep() -> Settings:
    return get_settings()


async def session_dep() -> AsyncIterator[AsyncSession]:
    factory = get_session_factory()
    async with factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


def gateway_dep(request: Request) -> LLMGateway:
    # app.state 是无类型的属性袋，取出来必须显式收窄
    gateway: LLMGateway | None = getattr(request.app.state, "llm_gateway", None)
    if gateway is None:  # pragma: no cover - startup guarantees this
        raise AppError(ErrorCode.CONFIG_ERROR, message="LLM 网关未初始化")
    return gateway


SettingsDep = Annotated[Settings, Depends(settings_dep)]
SessionDep = Annotated[AsyncSession, Depends(session_dep)]
GatewayDep = Annotated[LLMGateway, Depends(gateway_dep)]


async def current_user_id(
    credentials: Annotated[HTTPAuthorizationCredentials | None, Depends(bearer_scheme)],
    settings: SettingsDep,
) -> int:
    """架构文档 §9.1: ``Authorization: Bearer <access_token>``."""
    if credentials is None or not credentials.credentials:
        raise AppError(ErrorCode.UNAUTHENTICATED)
    claims = decode_access_token(
        credentials.credentials,
        secret=settings.jwt_secret,
        algorithm=settings.jwt_algorithm,
        issuer=settings.jwt_issuer,
    )
    bind_context(user_id=claims.user_id)
    return claims.user_id


CurrentUserId = Annotated[int, Depends(current_user_id)]


def identity_service_dep(session: SessionDep) -> IdentityService:
    return IdentityService(session)


def billing_service_dep(session: SessionDep, settings: SettingsDep) -> BillingService:
    return BillingService(session, tz_offset_hours=settings.llm_budget_timezone_offset_hours)


def task_service_dep(session: SessionDep) -> TaskService:
    return TaskService(session)


def analytics_service_dep(session: SessionDep) -> AnalyticsService:
    return AnalyticsService(session)


def storage_service_dep(settings: SettingsDep) -> StorageService:
    return StorageService(settings)


def budget_guard_dep(settings: SettingsDep) -> DailyBudgetGuard:
    """全局日预算的场景闸（架构 §13.3）：hd_export 等可降级场景在请求入口先过它。

    每次请求新建实例是刻意的：Guard 本身无状态（水位读 Redis），
    与 build_llm_gateway 里给网关用的那只互不影响。
    """
    return DailyBudgetGuard(
        RedisCostCounter(get_redis()),
        daily_budget_cents=Decimal(settings.llm_daily_budget_cents),
        enabled=settings.llm_daily_budget_enabled,
        tz_offset_hours=settings.llm_budget_timezone_offset_hours,
        tiers=list(settings.llm_budget_tiers),
    )


def agent_service_dep(
    session: SessionDep,
    gateway: GatewayDep,
    billing: Annotated[BillingService, Depends(billing_service_dep)],
    settings: SettingsDep,
) -> AgentService:
    # agent 与 report 在 import-linter 分层里同层、不允许直接互调，画像摘要
    # 以闭包在 apps 层接线；report 域内部仍只有 report.repo 触 rp_report。
    async def profile_provider(user_id: int) -> str | None:
        return await latest_profile_summary(
            session, user_id=user_id, max_chars=PROFILE_SUMMARY_MAX_CHARS
        )

    return AgentService(
        session,
        gateway=gateway,
        billing=billing,
        profile_provider=profile_provider,
        history_turns=settings.agent_history_turns,
    )


IdentityServiceDep = Annotated[IdentityService, Depends(identity_service_dep)]
BillingServiceDep = Annotated[BillingService, Depends(billing_service_dep)]
TaskServiceDep = Annotated[TaskService, Depends(task_service_dep)]
AnalyticsServiceDep = Annotated[AnalyticsService, Depends(analytics_service_dep)]
StorageServiceDep = Annotated[StorageService, Depends(storage_service_dep)]
BudgetGuardDep = Annotated[DailyBudgetGuard, Depends(budget_guard_dep)]
AgentServiceDep = Annotated[AgentService, Depends(agent_service_dep)]