from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from sqlalchemy.orm import selectinload

from app.dependencies import get_db, get_current_user
from app.models.schedule import ScheduleTemplate, ScheduleBlock
from app.models.user import User
from app.schemas.schedule import (
    ScheduleTemplateCreate,
    ScheduleTemplateOut,
    ScheduleTemplateUpdate,
    ScheduleBlockCreate,
    ScheduleBlockOut,
)

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


@router.get("", response_model=list[ScheduleTemplateOut])
async def list_templates(
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(ScheduleTemplate)
        .where(ScheduleTemplate.user_id == current_user.id)
        .options(selectinload(ScheduleTemplate.blocks))
        .order_by(ScheduleTemplate.name)
    )
    return result.scalars().all()


@router.post("", response_model=ScheduleTemplateOut, status_code=status.HTTP_201_CREATED)
async def create_template(
    body: ScheduleTemplateCreate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    template = ScheduleTemplate(
        user_id=current_user.id,
        name=body.name,
        child_id=body.child_id,
        is_default=body.is_default,
    )
    db.add(template)
    await db.flush()  # get template.id before adding blocks

    for block_data in body.blocks:
        block = ScheduleBlock(template_id=template.id, **block_data.model_dump())
        db.add(block)

    await db.commit()
    await db.refresh(template)

    # Re-fetch with blocks loaded
    result = await db.execute(
        select(ScheduleTemplate)
        .where(ScheduleTemplate.id == template.id)
        .options(selectinload(ScheduleTemplate.blocks))
    )
    return result.scalar_one()


@router.get("/{template_id}", response_model=ScheduleTemplateOut)
async def get_template(
    template_id: int,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(ScheduleTemplate)
        .where(ScheduleTemplate.id == template_id, ScheduleTemplate.user_id == current_user.id)
        .options(selectinload(ScheduleTemplate.blocks))
    )
    template = result.scalar_one_or_none()
    if not template:
        raise HTTPException(status_code=404, detail="Template not found")
    return template


@router.patch("/{template_id}", response_model=ScheduleTemplateOut)
async def update_template(
    template_id: int,
    body: ScheduleTemplateUpdate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(ScheduleTemplate)
        .where(ScheduleTemplate.id == template_id, ScheduleTemplate.user_id == current_user.id)
        .options(selectinload(ScheduleTemplate.blocks))
    )
    template = result.scalar_one_or_none()
    if not template:
        raise HTTPException(status_code=404, detail="Template not found")

    for field, value in body.model_dump(exclude_none=True).items():
        setattr(template, field, value)
    await db.commit()
    await db.refresh(template)
    return template


@router.delete("/{template_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_template(
    template_id: int,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(ScheduleTemplate)
        .where(ScheduleTemplate.id == template_id, ScheduleTemplate.user_id == current_user.id)
    )
    template = result.scalar_one_or_none()
    if not template:
        raise HTTPException(status_code=404, detail="Template not found")
    await db.delete(template)
    await db.commit()


# --- Schedule Block sub-routes ---

@router.post("/{template_id}/blocks", response_model=ScheduleBlockOut, status_code=status.HTTP_201_CREATED)
async def add_block(
    template_id: int,
    body: ScheduleBlockCreate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(ScheduleTemplate)
        .where(ScheduleTemplate.id == template_id, ScheduleTemplate.user_id == current_user.id)
    )
    if not result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Template not found")

    block = ScheduleBlock(template_id=template_id, **body.model_dump())
    db.add(block)
    await db.commit()
    await db.refresh(block)
    return block


@router.delete("/{template_id}/blocks/{block_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_block(
    template_id: int,
    block_id: int,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(ScheduleBlock)
        .join(ScheduleTemplate)
        .where(
            ScheduleBlock.id == block_id,
            ScheduleBlock.template_id == template_id,
            ScheduleTemplate.user_id == current_user.id,
        )
    )
    block = result.scalar_one_or_none()
    if not block:
        raise HTTPException(status_code=404, detail="Block not found")
    await db.delete(block)
    await db.commit()