from __future__ import annotations

from collections import OrderedDict
from datetime import date, datetime, timedelta, timezone
from typing import Any

from sqlalchemy import or_, select
from sqlalchemy.orm import Session, selectinload

from app.modules.clients.models import Client
from app.modules.consultants.models import ClientConsultantLink, ConsultantProfile, ConsultantServiceRequest
from app.modules.documents.models import EngagementDocument, PermanentClientDocument
from app.modules.services.models import (
    ClientServiceSubscription,
    ClientServiceTaskInstance,
    ServiceCatalogue,
    ServiceTaskComment,
)

CONSULTANT_BOARD_COLUMNS = OrderedDict(
    [
        ("assigned", "Assigned"),
        ("awaiting_documents", "Awaiting Documents"),
        ("in_progress", "In Progress"),
        ("submitted", "Submitted"),
        ("accepted", "Accepted"),
        ("closed", "Closed"),
    ]
)


def _allowed_client_ids(db: Session, *, consultant: ConsultantProfile, require_communications: bool = False) -> list[int]:
    query = select(ClientConsultantLink.client_id).where(
        ClientConsultantLink.tenant_id == consultant.tenant_id,
        ClientConsultantLink.consultant_id == consultant.id,
        ClientConsultantLink.is_active.is_(True),
    )
    if require_communications:
        query = query.where(ClientConsultantLink.can_view_communications.is_(True))
    return [int(x) for x in db.execute(query).scalars().all()]


def _board_key_for_status(status: str | None) -> str:
    value = (status or "pending").strip().lower()
    if value in {"blocked", "awaiting_documents", "document_pending", "clarification_required"}:
        return "awaiting_documents"
    if value in {"in_progress", "under_process", "processing", "started"}:
        return "in_progress"
    if value in {"pending_review", "ready_for_review", "submitted", "completed"}:
        return "submitted"
    if value in {"approved", "accepted"}:
        return "accepted"
    if value in {"closed", "locked", "cancelled", "inactive"}:
        return "closed"
    return "assigned"


def _matches_search(*values: Any, q: str = "") -> bool:
    term = (q or "").strip().lower()
    if not term:
        return True
    return any(term in str(v or "").lower() for v in values)


def get_consultant_work_board(db: Session, *, consultant: ConsultantProfile, q: str = "", status: str = "") -> dict:
    links = db.execute(select(ClientConsultantLink).where(ClientConsultantLink.tenant_id == consultant.tenant_id, ClientConsultantLink.consultant_id == consultant.id, ClientConsultantLink.is_active.is_(True), ClientConsultantLink.can_view_engagements.is_(True), ClientConsultantLink.can_view_task_status.is_(True))).scalars().all()
    links_by_client: dict[int, list[ClientConsultantLink]] = {}
    for link in links:
        links_by_client.setdefault(int(link.client_id), []).append(link)
    columns = {key: {"label": label, "items": []} for key, label in CONSULTANT_BOARD_COLUMNS.items()}
    items=[]
    if links_by_client:
        rows=db.execute(select(ClientServiceTaskInstance, ClientServiceSubscription, Client, ServiceCatalogue).join(ClientServiceSubscription, ClientServiceSubscription.id==ClientServiceTaskInstance.subscription_id).join(Client, Client.id==ClientServiceTaskInstance.client_id).join(ServiceCatalogue, ServiceCatalogue.id==ClientServiceTaskInstance.service_catalogue_id).where(ClientServiceTaskInstance.tenant_id==consultant.tenant_id, ClientServiceTaskInstance.client_id.in_(list(links_by_client)), ClientServiceTaskInstance.is_active.is_(True)).order_by(ClientServiceTaskInstance.internal_target_date.asc(), ClientServiceTaskInstance.id.desc()).limit(500)).all()
        for task, subscription, client, catalogue in rows:
            allowed=next((ln for ln in links_by_client[int(client.id)] if ln.service_catalogue_id in (None, task.service_catalogue_id)),None)
            if not allowed or not _matches_search(client.client_name, getattr(client,"client_code",""), catalogue.service_name, task.task_name, q=q): continue
            key=_board_key_for_status(task.status)
            if status and key!=status: continue
            latest=db.execute(select(ServiceTaskComment).where(ServiceTaskComment.task_instance_id==task.id, ServiceTaskComment.visibility=="consultant", ServiceTaskComment.is_deleted.is_(False)).order_by(ServiceTaskComment.created_at_utc.desc()).limit(1)).scalars().first()
            item={"comment":latest,"task":task,"subscription":subscription,"client":client,"catalogue":catalogue,"board_key":key,"link":allowed,"is_overdue":bool(task.internal_target_date and task.internal_target_date<date.today())}
            columns[key]["items"].append(item); items.append(item)
    service_requests=db.execute(select(ConsultantServiceRequest).options(selectinload(ConsultantServiceRequest.managed_client),selectinload(ConsultantServiceRequest.firm_client),selectinload(ConsultantServiceRequest.service_catalogue)).where(ConsultantServiceRequest.tenant_id==consultant.tenant_id,ConsultantServiceRequest.consultant_id==consultant.id,ConsultantServiceRequest.is_active.is_(True)).order_by(ConsultantServiceRequest.created_at_utc.desc()).limit(50)).scalars().all()
    return {"columns":columns,"column_options":list(CONSULTANT_BOARD_COLUMNS.items()),"total_tasks":len(items),"service_requests":service_requests}


def get_consultant_assignment_detail(db: Session, *, consultant: ConsultantProfile, task_id: int) -> dict | None:
    client_ids = _allowed_client_ids(db, consultant=consultant, require_communications=False)
    if not client_ids:
        return None
    row = db.execute(
        select(ClientServiceTaskInstance, ClientServiceSubscription, Client, ServiceCatalogue)
        .join(ClientServiceSubscription, ClientServiceSubscription.id == ClientServiceTaskInstance.subscription_id)
        .join(Client, Client.id == ClientServiceTaskInstance.client_id)
        .join(ServiceCatalogue, ServiceCatalogue.id == ClientServiceTaskInstance.service_catalogue_id)
        .where(
            ClientServiceTaskInstance.id == task_id,
            ClientServiceTaskInstance.tenant_id == consultant.tenant_id,
            ClientServiceTaskInstance.client_id.in_(client_ids),
            ClientServiceTaskInstance.is_active.is_(True),
        )
    ).first()
    if not row:
        return None
    task, subscription, client, catalogue = row
    link = db.execute(select(ClientConsultantLink).where(ClientConsultantLink.tenant_id == consultant.tenant_id, ClientConsultantLink.client_id == client.id, ClientConsultantLink.consultant_id == consultant.id, ClientConsultantLink.is_active.is_(True), ClientConsultantLink.can_view_engagements.is_(True), or_(ClientConsultantLink.service_catalogue_id.is_(None), ClientConsultantLink.service_catalogue_id == task.service_catalogue_id))).scalars().first()
    if not link:
        return None
    timeline = db.execute(
        select(ServiceTaskComment)
        .options(selectinload(ServiceTaskComment.created_by))
        .where(
            ServiceTaskComment.tenant_id == consultant.tenant_id,
            ServiceTaskComment.task_instance_id == task.id,
            ServiceTaskComment.visibility == "consultant",
            ServiceTaskComment.is_deleted.is_(False),
        )
        .order_by(ServiceTaskComment.created_at_utc.asc(), ServiceTaskComment.id.asc())
    ).scalars().all()
    engagement_documents = db.execute(
        select(EngagementDocument)
        .options(selectinload(EngagementDocument.versions))
        .where(
            EngagementDocument.tenant_id == consultant.tenant_id,
            EngagementDocument.client_id == client.id,
            EngagementDocument.engagement_id == subscription.id,
            EngagementDocument.is_deleted.is_(False),
        )
        .order_by(EngagementDocument.document_type.asc(), EngagementDocument.title.asc())
        .limit(50)
    ).scalars().all()
    if not (link.can_view_final_documents or link.can_upload_documents):
        engagement_documents = []
    permanent_documents = db.execute(
        select(PermanentClientDocument)
        .options(selectinload(PermanentClientDocument.versions))
        .where(
            PermanentClientDocument.tenant_id == consultant.tenant_id,
            PermanentClientDocument.client_id == client.id,
            PermanentClientDocument.is_deleted.is_(False),
        )
        .order_by(PermanentClientDocument.category.asc(), PermanentClientDocument.title.asc())
        .limit(50)
    ).scalars().all()
    if not link.can_view_permanent_documents:
        permanent_documents = []
    return {
        "link": link,
        "task": task,
        "subscription": subscription,
        "client": client,
        "catalogue": catalogue,
        "timeline": timeline,
        "engagement_documents": engagement_documents,
        "permanent_documents": permanent_documents,
    }


def get_consultant_document_centre(db: Session, *, consultant: ConsultantProfile, q: str = "") -> dict:
    links=db.execute(select(ClientConsultantLink).where(ClientConsultantLink.tenant_id==consultant.tenant_id,ClientConsultantLink.consultant_id==consultant.id,ClientConsultantLink.is_active.is_(True))).scalars().all()
    engagement_ids={int(x.client_id) for x in links if x.can_view_final_documents or x.can_upload_documents}
    permanent_ids={int(x.client_id) for x in links if x.can_view_permanent_documents}
    engagement_documents=[]; permanent_documents=[]
    if engagement_ids:
        stmt=select(EngagementDocument).options(selectinload(EngagementDocument.client),selectinload(EngagementDocument.engagement),selectinload(EngagementDocument.versions)).where(EngagementDocument.tenant_id==consultant.tenant_id,EngagementDocument.client_id.in_(engagement_ids),EngagementDocument.is_deleted.is_(False))
        if q.strip():
            term=f"%{q.strip()}%"; stmt=stmt.where(or_(EngagementDocument.title.ilike(term),EngagementDocument.document_type.ilike(term),EngagementDocument.document_code.ilike(term)))
        engagement_documents=db.execute(stmt.order_by(EngagementDocument.created_at_utc.desc()).limit(200)).scalars().all()
    if permanent_ids:
        stmt=select(PermanentClientDocument).options(selectinload(PermanentClientDocument.client),selectinload(PermanentClientDocument.versions)).where(PermanentClientDocument.tenant_id==consultant.tenant_id,PermanentClientDocument.client_id.in_(permanent_ids),PermanentClientDocument.is_deleted.is_(False))
        if q.strip():
            term=f"%{q.strip()}%"; stmt=stmt.where(or_(PermanentClientDocument.title.ilike(term),PermanentClientDocument.category.ilike(term),PermanentClientDocument.document_code.ilike(term)))
        permanent_documents=db.execute(stmt.order_by(PermanentClientDocument.created_at_utc.desc()).limit(200)).scalars().all()
    return {"engagement_documents":engagement_documents,"permanent_documents":permanent_documents,"total":len(engagement_documents)+len(permanent_documents)}


def consultant_can_execute_task(*, consultant: ConsultantProfile, task: ClientServiceTaskInstance) -> bool:
    return bool(task.execution_mode == "consultant" and task.assigned_consultant_id == consultant.id and task.is_active and not task.is_locked)


def update_consultant_assignment(db: Session, *, consultant: ConsultantProfile, task: ClientServiceTaskInstance, action: str, note: str, user_id: int) -> tuple[bool, str | None]:
    if not consultant_can_execute_task(consultant=consultant, task=task):
        return False, "This task is not assigned to your consultant profile."
    action = (action or "").strip().lower()
    note = (note or "").strip()
    current = (task.consultant_assignment_status or "not_applicable").lower()
    now = datetime.now(timezone.utc)
    message = None
    if action == "accept" and current == "offered":
        task.consultant_assignment_status = "accepted"
        task.consultant_accepted_at_utc = now
        task.consultant_declined_at_utc = None
        task.consultant_decline_reason = None
        task.status = "pending"
        message = "Consultant accepted the assignment."
    elif action == "decline" and current == "offered":
        if not note:
            return False, "Decline reason is required."
        task.consultant_assignment_status = "declined"
        task.consultant_declined_at_utc = now
        task.consultant_decline_reason = note
        task.status = "pending"
        message = f"Consultant declined the assignment: {note}"
    elif action == "start" and current in {"accepted", "rework_required"}:
        task.consultant_assignment_status = "in_progress"
        task.consultant_started_at_utc = task.consultant_started_at_utc or now
        task.status = "in_progress"
        if current == "rework_required":
            task.rework_status = "in_progress"
        message = "Consultant started work on the assignment."
    elif action == "submit" and current in {"accepted", "in_progress", "rework_required"}:
        if not note:
            return False, "Submission note is required."
        task.consultant_assignment_status = "submitted"
        task.consultant_submitted_at_utc = now
        task.consultant_submission_note = note
        task.status = "pending_review"
        if task.rework_status in {"requested", "in_progress"}:
            task.rework_status = "resolved"
            task.rework_resolved_at_utc = now
        message = f"Consultant submitted the assignment for firm review: {note}"
    else:
        return False, "This action is not allowed for the current assignment status."
    task.updated_by_user_id = user_id
    db.add(ServiceTaskComment(tenant_id=task.tenant_id, branch_id=task.branch_id, subscription_id=task.subscription_id, task_instance_id=task.id, comment_type="consultant_execution", visibility="consultant", message=message, created_by_user_id=user_id))
    return True, None