import uuid
from datetime import date

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

from app.core.deps import get_current_user, get_db_session, require_study_member
from app.crud import audit as audit_crud
from app.crud import issue as issue_crud
from app.crud import member as member_crud
from app.crud import study as study_crud
from app.schemas.issue import IssueCreate, IssueRead, IssueUpdate

router = APIRouter()

ALLOWED_EDIT_ROLES = {"PM", "PV"}


async def _ensure_study_exists(db: AsyncSession, study_id: uuid.UUID):
    study = await study_crud.get(db, study_id)
    if not study:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Study not found")
    return study


async def _get_member_role(db: AsyncSession, study_id: uuid.UUID, user_id: uuid.UUID) -> str | None:
    member = await member_crud.get_member(db, study_id, user_id)
    return member.role_in_study if member else None


def _is_overdue(issue: IssueRead) -> bool:
    return bool(issue.due_date and date.today() > issue.due_date and issue.status != "CLOSED")


@router.post(
    "/",
    response_model=IssueRead,
    status_code=status.HTTP_201_CREATED,
    dependencies=[Depends(require_study_member())],
)
async def create_issue(
    study_id: uuid.UUID,
    issue_in: IssueCreate,
    db: AsyncSession = Depends(get_db_session),
    current_user=Depends(get_current_user),
) -> IssueRead:
    await _ensure_study_exists(db, study_id)
    member_role = await _get_member_role(db, study_id, current_user.id)
    if current_user.role != "ADMIN" and member_role not in ALLOWED_EDIT_ROLES:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Insufficient permissions")
    try:
        issue = await issue_crud.create_issue(db, study_id, issue_in, created_by=current_user.id)
    except ValueError as exc:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)) from exc
    await audit_crud.log_action(
        db,
        study_id=study_id,
        entity_type="issue",
        entity_id=issue.id,
        action="CREATE_ISSUE",
        detail=f"Issue {issue.id} created",
        operator_id=current_user.id,
        operator_role=current_user.role,
    )
    data = IssueRead.model_validate(issue)
    data.is_overdue = _is_overdue(data)
    return data


@router.get(
    "/",
    response_model=list[IssueRead],
    dependencies=[Depends(require_study_member())],
)
async def list_issues(
    study_id: uuid.UUID,
    status_filter: str | None = None,
    level: str | None = None,
    category: str | None = None,
    overdue: bool | None = None,
    db: AsyncSession = Depends(get_db_session),
) -> list[IssueRead]:
    await _ensure_study_exists(db, study_id)
    issues = await issue_crud.list_issues(db, study_id, status=status_filter, level=level, category=category, overdue=overdue)
    result: list[IssueRead] = []
    for item in issues:
        obj = IssueRead.model_validate(item)
        obj.is_overdue = _is_overdue(obj)
        result.append(obj)
    return result


@router.get(
    "/{issue_id}",
    response_model=IssueRead,
    dependencies=[Depends(require_study_member())],
)
async def get_issue(
    study_id: uuid.UUID,
    issue_id: uuid.UUID,
    db: AsyncSession = Depends(get_db_session),
) -> IssueRead:
    await _ensure_study_exists(db, study_id)
    issue = await issue_crud.get_issue(db, issue_id)
    if not issue or issue.study_id != study_id:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Issue not found")
    data = IssueRead.model_validate(issue)
    data.is_overdue = _is_overdue(data)
    return data


@router.patch(
    "/{issue_id}",
    response_model=IssueRead,
    dependencies=[Depends(require_study_member())],
)
async def update_issue(
    study_id: uuid.UUID,
    issue_id: uuid.UUID,
    issue_in: IssueUpdate,
    db: AsyncSession = Depends(get_db_session),
    current_user=Depends(get_current_user),
) -> IssueRead:
    await _ensure_study_exists(db, study_id)
    issue = await issue_crud.get_issue(db, issue_id)
    if not issue or issue.study_id != study_id:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Issue not found")

    member_role = await _get_member_role(db, study_id, current_user.id)
    if current_user.role != "ADMIN" and member_role not in ALLOWED_EDIT_ROLES:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Insufficient permissions")

    old_status = issue.status
    old_level = issue.level
    updated = await issue_crud.update_issue(db, issue, issue_in)

    detail = None
    action = "UPDATE_ISSUE"
    if issue_in.status and issue_in.status != old_status:
        detail = f"Issue {issue_id} status {old_status} -> {issue_in.status}"
        action = "ISSUE_STATUS_CHANGE"
    elif issue_in.level and issue_in.level != old_level:
        detail = f"Issue {issue_id} level {old_level} -> {issue_in.level}"
    await audit_crud.log_action(
        db,
        study_id=study_id,
        entity_type="issue",
        entity_id=issue_id,
        action=action,
        detail=detail or "Issue updated",
        operator_id=current_user.id,
        operator_role=current_user.role,
    )
    data = IssueRead.model_validate(updated)
    data.is_overdue = _is_overdue(data)
    return data