import logging
from typing import Dict, List, Optional

from fastapi import HTTPException
from hdbcli import dbapi
from pydantic import BaseModel, Field

from core.crud_router import make_crud_router
from core.hana import hana_connection, HANA_SCHEMA

router = make_crud_router(
    "BatchNumberDetails",
    tags=["Lotes"],
    supports_orderby=True,
    supports_create=False,
)

logger = logging.getLogger(__name__)

# ============================================================================
# Stock de un lote por almacén. OBTN es el maestro de lotes: cada DistNumber
# (número de lote) tiene un AbsEntry propio. OBTQ guarda la cantidad actual
# por almacén, pero se enlaza a OBTN por "MdAbsEntry" = OBTN."AbsEntry" (no
# por DistNumber ni ItemCode directamente). Confirmado contra el HANA real
# de tagumedica con el lote 2090456 (AbsEntry 74701).
BATCH_STOCK_QUERY = f"""
    SELECT
        T1."WhsCode" AS "WarehouseCode",
        T2."WhsName" AS "WarehouseName",
        T1."Quantity" AS "Quantity",
        T1."CommitQty" AS "CommitQty",
        T1."CountQty" AS "CountQty",
        T1."ItemCode" AS "ItemCode",
        T3."ItemName" AS "ItemDescription"
    FROM "{HANA_SCHEMA}".OBTN T0
    INNER JOIN "{HANA_SCHEMA}".OBTQ T1 ON T1."MdAbsEntry" = T0."AbsEntry"
    INNER JOIN "{HANA_SCHEMA}".OWHS T2 ON T2."WhsCode" = T1."WhsCode"
    INNER JOIN "{HANA_SCHEMA}".OITM T3 ON T3."ItemCode" = T1."ItemCode"
    WHERE T0."DistNumber" = ? AND T1."Quantity" > 0
    ORDER BY T3."ItemName", T2."WhsName"
"""

# ============================================================================
class WarehouseStock(BaseModel):
    WarehouseCode: str
    WarehouseName: str
    Quantity: float
    CommitQty: float
    CountQty: float
    ItemCode: str
    ItemDescription: Optional[str] = None

# ============================================================================
class BatchStockResponse(BaseModel):
    Batch: str
    Warehouses: List[WarehouseStock]

# ============================================================================
@router.get("/api/batch/stock", response_model=BatchStockResponse)
async def batch_stock(batch: str):
    batch = batch.strip()
    if not batch:
        raise HTTPException(status_code=400, detail="Debe indicar el número de lote")

    try:
        with hana_connection() as conn:
            cursor = conn.cursor()
            cursor.execute(BATCH_STOCK_QUERY, (batch,))
            rows = cursor.fetchall()
            columns = [d[0] for d in cursor.description]
    except dbapi.Error as exc:
        logger.error(f"Error al consultar stock del lote {batch}: {exc}")
        raise HTTPException(status_code=500, detail=f"Error al consultar el stock del lote: {exc}")

    warehouses = [dict(zip(columns, row)) for row in rows]
    if not warehouses:
        raise HTTPException(status_code=404, detail=f"No se encontró stock para el lote '{batch}'")

    return {"Batch": batch, "Warehouses": warehouses}


# ============================================================================
# Para "Confirmar Liberación Lote": un lote inmovilizado (llevado a un
# almacén como 302) puede haber llegado ahí en más de una transferencia y
# desde más de un almacén de origen distinto (confirmado con datos reales:
# ej. el lote 51232313 llegó a 302 con 2 unidades desde el almacén 207 y 1
# desde el 208). Por eso la línea de la Solicitud de Liberación (que sale
# con el total del lote desde 302) puede tener que dividirse en una línea
# por cada almacén de origen encontrado, repartiendo la cantidad entre ellos
# a prorrata de cuánto trajo cada transferencia históricamente.
#
# Se buscan todas las transferencias ejecutadas (OWTR, DocType 67 en OITL)
# que ingresaron el lote al almacén dado; de cada una (mismo DocEntry) se
# toma la línea hermana de salida (cantidad negativa) para saber de qué
# almacén salió. OITL/ITL1 es el log de transacciones de lote/serie de SAP
# (mismo que usa el reporte estándar "Transacciones de Números de Serie y
# Lote"), unidas por "LogEntry"; OBTN da el AbsEntry del lote a partir de
# ItemCode+DistNumber.
INBOUND_TRANSFERS_QUERY = f"""
    SELECT DISTINCT T1."DocEntry", T1."DocDate"
    FROM "{HANA_SCHEMA}".ITL1 T0
    INNER JOIN "{HANA_SCHEMA}".OITL T1 ON T1."LogEntry" = T0."LogEntry"
    INNER JOIN "{HANA_SCHEMA}".OBTN T2 ON T2."AbsEntry" = T0."MdAbsEntry"
    WHERE T2."ItemCode" = ? AND T2."DistNumber" = ?
        AND T1."LocCode" = ? AND T1."StockEff" = 1
        AND T0."Quantity" > 0 AND T1."DocType" = 67
    ORDER BY T1."DocDate", T1."DocEntry"
"""

INBOUND_QUANTITY_QUERY = f"""
    SELECT T0."Quantity"
    FROM "{HANA_SCHEMA}".ITL1 T0
    INNER JOIN "{HANA_SCHEMA}".OITL T1 ON T1."LogEntry" = T0."LogEntry"
    INNER JOIN "{HANA_SCHEMA}".OBTN T2 ON T2."AbsEntry" = T0."MdAbsEntry"
    WHERE T1."DocEntry" = ? AND T2."ItemCode" = ? AND T2."DistNumber" = ?
        AND T1."LocCode" = ? AND T0."Quantity" > 0
    LIMIT 1
"""

TRANSFER_SOURCE_WAREHOUSE_QUERY = f"""
    SELECT T1."LocCode"
    FROM "{HANA_SCHEMA}".ITL1 T0
    INNER JOIN "{HANA_SCHEMA}".OITL T1 ON T1."LogEntry" = T0."LogEntry"
    INNER JOIN "{HANA_SCHEMA}".OBTN T2 ON T2."AbsEntry" = T0."MdAbsEntry"
    WHERE T1."DocEntry" = ? AND T2."ItemCode" = ? AND T2."DistNumber" = ?
        AND T0."Quantity" < 0
    LIMIT 1
"""


class LotSourceWarehouseLine(BaseModel):
    ItemCode: str
    DistNumber: str
    # Almacén donde está inmovilizado hoy el lote (ej. 302): se busca de qué
    # almacén(es) vino, entre las transferencias que lo trajeron A este.
    Warehouse: str
    # Cantidad de la línea a liberar: se reparte entre los almacenes de
    # origen encontrados, a prorrata de cuánto trajo cada uno.
    Quantity: float


class LotSourceWarehouseRequest(BaseModel):
    Lines: List[LotSourceWarehouseLine] = Field(min_length=1)


class LotSourceAllocation(BaseModel):
    WarehouseCode: str
    Quantity: float


class LotSourceWarehouseResult(BaseModel):
    ItemCode: str
    DistNumber: str
    Allocations: List[LotSourceAllocation] = []


def _allocate_by_origin(
    origin_totals: Dict[str, float], release_qty: float
) -> List[LotSourceAllocation]:
    """
    Reparte release_qty entre los almacenes de origin_totals a prorrata de
    su participación histórica, redondeando cada asignación a un entero (los
    artículos se mueven en unidades completas). El último almacén se ajusta
    para que la suma coincida exactamente con release_qty (evita descuadres
    de redondeo, ya que el histórico puede no calzar 1 a 1 con la cantidad
    actual si parte del lote salió de 302 por otra vía mientras tanto).
    """
    total_historical = sum(origin_totals.values())
    if total_historical <= 0:
        return []

    origins = list(origin_totals.items())
    allocations: List[LotSourceAllocation] = []
    allocated_so_far = 0.0
    for index, (warehouse_code, historical_qty) in enumerate(origins):
        is_last = index == len(origins) - 1
        allocated_qty = (
            round(release_qty - allocated_so_far)
            if is_last
            else round(release_qty * (historical_qty / total_historical))
        )
        allocated_qty = max(allocated_qty, 0)
        allocated_so_far += allocated_qty
        if allocated_qty > 0:
            allocations.append(
                LotSourceAllocation(WarehouseCode=warehouse_code, Quantity=allocated_qty)
            )
    return allocations


@router.post(
    "/api/batch/lot-source-warehouse",
    response_model=List[LotSourceWarehouseResult],
)
async def lot_source_warehouse(payload: LotSourceWarehouseRequest):
    results: List[LotSourceWarehouseResult] = []
    try:
        with hana_connection() as conn:
            cursor = conn.cursor()
            for line in payload.Lines:
                cursor.execute(
                    INBOUND_TRANSFERS_QUERY,
                    (line.ItemCode, line.DistNumber, line.Warehouse),
                )
                doc_entries = [row[0] for row in cursor.fetchall()]

                origin_totals: Dict[str, float] = {}
                for doc_entry in doc_entries:
                    cursor.execute(
                        INBOUND_QUANTITY_QUERY,
                        (doc_entry, line.ItemCode, line.DistNumber, line.Warehouse),
                    )
                    inbound_row = cursor.fetchone()
                    if not inbound_row:
                        continue

                    cursor.execute(
                        TRANSFER_SOURCE_WAREHOUSE_QUERY,
                        (doc_entry, line.ItemCode, line.DistNumber),
                    )
                    source_row = cursor.fetchone()
                    if not source_row:
                        continue

                    warehouse_code = source_row[0]
                    origin_totals[warehouse_code] = origin_totals.get(
                        warehouse_code, 0
                    ) + float(inbound_row[0])

                results.append(
                    LotSourceWarehouseResult(
                        ItemCode=line.ItemCode,
                        DistNumber=line.DistNumber,
                        Allocations=_allocate_by_origin(origin_totals, line.Quantity),
                    )
                )
    except dbapi.Error as exc:
        logger.error(f"Error al buscar el almacén de origen de lotes: {exc}")
        raise HTTPException(
            status_code=500,
            detail=f"Error al buscar el almacén de origen de los lotes: {exc}",
        )

    return results