from __future__ import annotations

from urllib.parse import urlencode

from fastapi import APIRouter, Form, Request
from fastapi.responses import RedirectResponse
from sqlalchemy import select

from app.core.db.common import CommonSessionLocal
from app.core.security.csrf import get_or_create_csrf_token, validate_csrf
from app.core.templating import templates
from app.modules.accounting.chart_models import AccountingChartLedger
from app.modules.accounting.chart_service import ROLE_LABELS
from app.modules.accounting.ui import _find_visible_client, _require_partner, _visible_clients
from app.modules.accounting.voucher_engine_service import (
    BUSINESS_NATURES,
    VOUCHER_TYPES,
    approve_draft,
    chart_ledgers,
    create_draft,
    get_draft,
    list_drafts,
    queue_post,
    queue_preflight,
    review_draft,
    sync_drafts,
    visible_workstations,
    void_draft,
)
from app.modules.core.rbac.deps import get_user_permissions, get_user_roles

router = APIRouter(prefix="/tools/accounting/voucher-engine", tags=["accounting-native-voucher-engine-ui"])


def _go(client_id=0, message="", error="", **extra):
    params = {}
    if client_id:
        params["client_id"] = client_id
    if message:
        params["message"] = message[:350]
    if error:
        params["error"] = error[:350]
    for key, value in extra.items():
        if value not in ("", None):
            params[key] = value
    return RedirectResponse(
        "/tools/accounting/voucher-engine" + ("?" + urlencode(params) if params else ""),
        status_code=303,
    )


def _company_options(db, tenant_id, client_id):
    rows = list(
        db.execute(
            select(AccountingChartLedger.tally_guid, AccountingChartLedger.company_name)
            .where(
                AccountingChartLedger.tenant_id == int(tenant_id),
                AccountingChartLedger.client_id == int(client_id),
            )
            .distinct()
            .order_by(AccountingChartLedger.company_name)
        ).all()
    )
    return [{"guid": guid, "name": name or guid} for guid, name in rows if guid]


def _company_name(options, tally_guid):
    return next((row["name"] for row in options if row["guid"] == tally_guid), "")


@router.get("")
def page(
    request: Request,
    client_id: int | None = None,
    tally_guid: str = "",
    status: str = "",
    page: int = 1,
    per_page: int = 20,
    message: str = "",
    error: str = "",
):
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.view")
        if denied:
            return denied

        clients, scope = _visible_clients(db, request, user)
        selected = next((c for c in clients if client_id and int(c.id) == int(client_id)), None)

        company_options = []
        ledgers = []
        drafts = []
        total = 0
        pages = 1
        workstations = []

        if selected:
            company_options = _company_options(db, scope.tenant_id, selected.id)
            if not tally_guid and len(company_options) == 1:
                tally_guid = company_options[0]["guid"]
            if tally_guid and tally_guid not in {row["guid"] for row in company_options}:
                tally_guid = ""

            if tally_guid:
                ledgers = chart_ledgers(
                    db,
                    tenant_id=scope.tenant_id,
                    client_id=selected.id,
                    tally_guid=tally_guid,
                )

            drafts, total, page, pages = list_drafts(
                db,
                tenant_id=scope.tenant_id,
                client_id=selected.id,
                status=status,
                page=page,
                per_page=per_page,
            )
            sync_drafts(db, drafts)
            drafts, total, page, pages = list_drafts(
                db,
                tenant_id=scope.tenant_id,
                client_id=selected.id,
                status=status,
                page=page,
                per_page=per_page,
            )
            workstations = visible_workstations(
                db,
                tenant_id=scope.tenant_id,
                branch_id=scope.branch_id,
            )

        return templates.TemplateResponse(
            "modules/accounting/templates/accounting/voucher_engine.html",
            {
                "request": request,
                "current_user": user,
                "current_user_roles": get_user_roles(db, user.id),
                "current_user_permissions": get_user_permissions(db, user.id),
                "csrf_token": get_or_create_csrf_token(request),
                "title": "Accounting Voucher Engine",
                "clients": clients,
                "selected_client": selected,
                "selected_tally_guid": tally_guid,
                "company_options": company_options,
                "ledgers": ledgers,
                "role_labels": ROLE_LABELS,
                "voucher_types": VOUCHER_TYPES,
                "business_natures": BUSINESS_NATURES,
                "drafts": drafts,
                "total": total,
                "page": page,
                "pages": pages,
                "per_page": per_page,
                "status_filter": status,
                "workstations": workstations,
                "message": message,
                "error": error,
            },
        )
    finally:
        db.close()


@router.post("/draft")
def create(
    request: Request,
    client_id: int = Form(...),
    tally_guid: str = Form(...),
    voucher_type: str = Form(...),
    business_nature: str = Form(...),
    voucher_date: str = Form(...),
    reference: str = Form(""),
    narration: str = Form(""),
    source_type: str = Form("manual"),
    ledger_name: list[str] = Form(...),
    dr_cr: list[str] = Form(...),
    amount: list[float] = Form(...),
    line_note: list[str] = Form([]),
    csrf_token: str = Form(...),
):
    validate_csrf(request, csrf_token)
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.manage")
        if denied:
            return denied
        client, _clients, scope = _find_visible_client(db, request, user, client_id)
        if not client:
            return _go(error="Client is not visible.")

        options = _company_options(db, scope.tenant_id, client.id)
        company_name = _company_name(options, tally_guid)
        if not company_name:
            raise ValueError("Chart of Accounts for the selected Tally company is not available.")

        draft = create_draft(
            db,
            tenant_id=scope.tenant_id,
            client_id=client.id,
            tally_guid=tally_guid,
            company_name=company_name,
            voucher_type=voucher_type,
            business_nature=business_nature,
            voucher_date=voucher_date,
            reference=reference,
            narration=narration,
            source_type=source_type,
            ledger_names=ledger_name,
            dr_cr_values=dr_cr,
            amounts=amount,
            notes=line_note,
            user_id=user.id,
        )
        return _go(client.id, tally_guid=tally_guid, message=f"{draft.voucher_type} voucher draft #{draft.id} created.")
    except Exception as exc:
        db.rollback()
        return _go(client_id, tally_guid=tally_guid, error=str(exc))
    finally:
        db.close()


def _draft_for_action(db, request, user, client_id, draft_id):
    client, _clients, scope = _find_visible_client(db, request, user, client_id)
    if not client:
        raise ValueError("Client is not visible.")
    draft = get_draft(
        db,
        tenant_id=scope.tenant_id,
        client_id=client.id,
        draft_id=draft_id,
    )
    if not draft:
        raise ValueError("Voucher draft was not found.")
    return client, scope, draft


@router.post("/draft/{draft_id}/review")
def review(
    request: Request,
    draft_id: int,
    client_id: int = Form(...),
    note: str = Form(""),
    csrf_token: str = Form(...),
):
    validate_csrf(request, csrf_token)
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.manage")
        if denied:
            return denied
        client, scope, draft = _draft_for_action(db, request, user, client_id, draft_id)
        review_draft(db, draft=draft, note=note, user_id=user.id)
        return _go(client.id, message=f"Voucher draft #{draft.id} reviewed.")
    except Exception as exc:
        db.rollback()
        return _go(client_id, error=str(exc))
    finally:
        db.close()


@router.post("/draft/{draft_id}/approve")
def approve(
    request: Request,
    draft_id: int,
    client_id: int = Form(...),
    csrf_token: str = Form(...),
):
    validate_csrf(request, csrf_token)
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.manage")
        if denied:
            return denied
        client, scope, draft = _draft_for_action(db, request, user, client_id, draft_id)
        approve_draft(db, draft=draft, user_id=user.id)
        return _go(client.id, message=f"Voucher draft #{draft.id} approved for Tally preflight.")
    except Exception as exc:
        db.rollback()
        return _go(client_id, error=str(exc))
    finally:
        db.close()


@router.post("/draft/{draft_id}/preflight")
def preflight(
    request: Request,
    draft_id: int,
    client_id: int = Form(...),
    workstation_id: int = Form(...),
    csrf_token: str = Form(...),
):
    validate_csrf(request, csrf_token)
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.manage")
        if denied:
            return denied
        client, scope, draft = _draft_for_action(db, request, user, client_id, draft_id)
        queue_preflight(db, draft=draft, workstation_id=workstation_id, user_id=user.id)
        return _go(client.id, message=f"Voucher draft #{draft.id} Tally preflight queued.")
    except Exception as exc:
        db.rollback()
        return _go(client_id, error=str(exc))
    finally:
        db.close()


@router.post("/draft/{draft_id}/post")
def post(
    request: Request,
    draft_id: int,
    client_id: int = Form(...),
    csrf_token: str = Form(...),
):
    validate_csrf(request, csrf_token)
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.manage")
        if denied:
            return denied
        client, scope, draft = _draft_for_action(db, request, user, client_id, draft_id)
        queue_post(db, draft=draft, user_id=user.id)
        return _go(client.id, message=f"Voucher draft #{draft.id} controlled Tally posting queued.")
    except Exception as exc:
        db.rollback()
        return _go(client_id, error=str(exc))
    finally:
        db.close()


@router.post("/draft/{draft_id}/void")
def void(
    request: Request,
    draft_id: int,
    client_id: int = Form(...),
    csrf_token: str = Form(...),
):
    validate_csrf(request, csrf_token)
    db = CommonSessionLocal()
    try:
        user, denied = _require_partner(request, db, "accounting.learning.manage")
        if denied:
            return denied
        client, scope, draft = _draft_for_action(db, request, user, client_id, draft_id)
        void_draft(db, draft=draft)
        return _go(client.id, message=f"Voucher draft #{draft.id} voided.")
    except Exception as exc:
        db.rollback()
        return _go(client_id, error=str(exc))
    finally:
        db.close()