"""RecurringElement API — AP0.9e."""

from __future__ import annotations

from datetime import datetime
from typing import Literal, Optional

from capabilities import require_capability
from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel, Field
from services import recurring as recurring_service
from tenant_context import TenantContext

router = APIRouter(prefix="/api/recurring", tags=["recurring"])


class RecurringUpdateRequest(BaseModel):
    title: Optional[str] = Field(default=None, min_length=1, max_length=255)
    description: Optional[str] = None
    status: Optional[Literal["active", "paused", "ended"]] = None
    interval_days: Optional[int] = Field(default=None, gt=0)
    clear_interval_days: bool = False
    next_due_at: Optional[str] = None
    clear_next_due_at: bool = False


class RecurringCompleteRequest(BaseModel):
    measurement_note: Optional[str] = Field(default=None, max_length=2000)


def _parse_datetime(value: Optional[str]) -> Optional[datetime]:
    if value is None:
        return None
    try:
        return datetime.fromisoformat(value.replace("Z", "+00:00"))
    except ValueError as exc:
        raise HTTPException(status_code=400, detail="Ungültiges next_due_at") from exc


@router.get("/{recurring_id}")
def get_recurring_element(
    recurring_id: str,
    ctx: TenantContext = Depends(require_capability("kairo.recurring.read")),
):
    item = recurring_service.get_recurring_element(
        tenant_id=ctx.tenant_id, recurring_id=recurring_id
    )
    if not item:
        raise HTTPException(status_code=404, detail="Recurring-Element nicht gefunden")
    return item


@router.patch("/{recurring_id}")
def update_recurring_element(
    recurring_id: str,
    body: RecurringUpdateRequest,
    ctx: TenantContext = Depends(require_capability("kairo.recurring.manage")),
):
    next_due_at = _parse_datetime(body.next_due_at) if body.next_due_at is not None else None
    try:
        item = recurring_service.update_recurring_element(
            tenant_id=ctx.tenant_id,
            recurring_id=recurring_id,
            user_id=ctx.user_id,
            title=body.title,
            description=body.description,
            status=body.status,
            interval_days=body.interval_days,
            clear_interval_days=body.clear_interval_days,
            next_due_at=next_due_at,
            clear_next_due_at=body.clear_next_due_at,
        )
    except ValueError as exc:
        raise HTTPException(status_code=400, detail=str(exc)) from exc
    if not item:
        raise HTTPException(status_code=404, detail="Recurring-Element nicht gefunden")
    return item


@router.post("/{recurring_id}/complete")
def complete_recurring_practice(
    recurring_id: str,
    body: RecurringCompleteRequest,
    ctx: TenantContext = Depends(require_capability("kairo.recurring.manage")),
):
    from services.cadence_instance import complete_open_instance

    try:
        result = complete_open_instance(
            tenant_id=ctx.tenant_id,
            recurring_element_id=recurring_id,
            user_id=ctx.user_id or None,
            measurement_note=body.measurement_note or "",
        )
    except ValueError as exc:
        detail = str(exc)
        if detail == "Recurring-Element nicht gefunden":
            raise HTTPException(status_code=404, detail=detail) from exc
        raise HTTPException(status_code=400, detail=detail) from exc
    return result


@router.delete("/{recurring_id}", status_code=204)
def delete_recurring_element(
    recurring_id: str,
    ctx: TenantContext = Depends(require_capability("kairo.recurring.manage")),
):
    if not recurring_service.delete_recurring_element(
        tenant_id=ctx.tenant_id, recurring_id=recurring_id, user_id=ctx.user_id
    ):
        raise HTTPException(status_code=404, detail="Recurring-Element nicht gefunden")