package repository

import (
	"database/sql"
	"fmt"

	"github.com/shopspring/decimal"
	"github.com/wmms/wmms/internal/model"
	"github.com/wmms/wmms/pkg/database"
)

type StockRepo struct{}

func NewStockRepo() *StockRepo {
	return &StockRepo{}
}

func (r *StockRepo) GetAllStock(search string, limit, offset int) ([]model.Stock, int64, error) {
	countQuery := `SELECT COUNT(*) FROM materials m WHERE 1=1`
	var countArgs []interface{}

	if search != "" {
		countQuery += ` AND (m.material_code LIKE ? OR m.name LIKE ?)`
		searchPattern := "%" + search + "%"
		countArgs = append(countArgs, searchPattern, searchPattern)
	}

	var total int64
	err := database.DB.QueryRow(countQuery, countArgs...).Scan(&total)
	if err != nil {
		return nil, 0, err
	}

	query := `SELECT m.id, m.material_code, m.name, m.spec, m.unit,
		COALESCE(SUM(ib.on_hand), 0), COALESCE(MAX(swr.minimum_available), 0),
		IFNULL(pc.code, ''), IFNULL(c.code, '')
		FROM materials m
		LEFT JOIN inventory_balances ib ON ib.material_id = m.id
		LEFT JOIN stock_warning_rules swr ON swr.organization_id = ib.organization_id
			AND swr.warehouse_id = ib.warehouse_id AND swr.material_id = m.id AND swr.enabled = TRUE
		LEFT JOIN material_categories c ON c.id = m.category_id
		LEFT JOIN material_categories pc ON pc.id = c.parent_id
		WHERE 1=1`
	var args []interface{}

	if search != "" {
		query += ` AND (m.material_code LIKE ? OR m.name LIKE ?)`
		searchPattern := "%" + search + "%"
		args = append(args, searchPattern, searchPattern)
	}

	query += ` GROUP BY m.id, m.material_code, m.name, m.spec, m.unit, pc.code, c.code ORDER BY m.id LIMIT ? OFFSET ?`
	args = append(args, limit, offset)

	rows, err := database.DB.Query(query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var stocks []model.Stock
	for rows.Next() {
		var s model.Stock
		err := rows.Scan(&s.MaterialID, &s.MaterialCode, &s.Name, &s.Spec, &s.Unit, &s.TotalOnHand, &s.WarningStock, &s.MajorCategory, &s.MinorCategory)
		if err != nil {
			return nil, 0, err
		}
		stocks = append(stocks, s)
	}
	return stocks, total, nil
}

func (r *StockRepo) GetByMaterialID(materialID int64) (*model.Stock, error) {
	s := &model.Stock{}
	query := `SELECT m.id, m.material_code, m.name, m.spec, m.unit,
		COALESCE(SUM(ib.on_hand), 0), COALESCE(MAX(swr.minimum_available), 0),
		IFNULL(pc.code, ''), IFNULL(c.code, '')
		FROM materials m
		LEFT JOIN inventory_balances ib ON ib.material_id = m.id
		LEFT JOIN stock_warning_rules swr ON swr.organization_id = ib.organization_id
			AND swr.warehouse_id = ib.warehouse_id AND swr.material_id = m.id AND swr.enabled = TRUE
		LEFT JOIN material_categories c ON c.id = m.category_id
		LEFT JOIN material_categories pc ON pc.id = c.parent_id
		WHERE m.id = ?
		GROUP BY m.id, m.material_code, m.name, m.spec, m.unit, pc.code, c.code`
	err := database.DB.QueryRow(query, materialID).Scan(&s.MaterialID, &s.MaterialCode, &s.Name, &s.Spec, &s.Unit, &s.TotalOnHand, &s.WarningStock, &s.MajorCategory, &s.MinorCategory)
	if err != nil {
		return nil, err
	}
	return s, nil
}

func (r *StockRepo) GetWarningStock(limit, offset int) ([]model.Stock, int64, error) {
	countQuery := `SELECT COUNT(*) FROM (
		SELECT m.id
		FROM materials m
		LEFT JOIN inventory_balances ib ON ib.material_id = m.id
		LEFT JOIN stock_warning_rules swr ON swr.organization_id = ib.organization_id
			AND swr.warehouse_id = ib.warehouse_id AND swr.material_id = m.id AND swr.enabled = TRUE
		GROUP BY m.id
		HAVING COALESCE(SUM(ib.on_hand), 0) < COALESCE(MAX(swr.minimum_available), 0)
	) warning_materials`
	var total int64
	err := database.DB.QueryRow(countQuery).Scan(&total)
	if err != nil {
		return nil, 0, err
	}

	query := `SELECT m.id, m.material_code, m.name, m.spec, m.unit,
		COALESCE(SUM(ib.on_hand), 0), COALESCE(MAX(swr.minimum_available), 0),
		IFNULL(pc.code, ''), IFNULL(c.code, '')
		FROM materials m
		LEFT JOIN inventory_balances ib ON ib.material_id = m.id
		LEFT JOIN stock_warning_rules swr ON swr.organization_id = ib.organization_id
			AND swr.warehouse_id = ib.warehouse_id AND swr.material_id = m.id AND swr.enabled = TRUE
		LEFT JOIN material_categories c ON c.id = m.category_id
		LEFT JOIN material_categories pc ON pc.id = c.parent_id
		GROUP BY m.id, m.material_code, m.name, m.spec, m.unit, pc.code, c.code
		HAVING COALESCE(SUM(ib.on_hand), 0) < COALESCE(MAX(swr.minimum_available), 0)
		ORDER BY m.id LIMIT ? OFFSET ?`
	rows, err := database.DB.Query(query, limit, offset)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var stocks []model.Stock
	for rows.Next() {
		var s model.Stock
		err := rows.Scan(&s.MaterialID, &s.MaterialCode, &s.Name, &s.Spec, &s.Unit, &s.TotalOnHand, &s.WarningStock, &s.MajorCategory, &s.MinorCategory)
		if err != nil {
			return nil, 0, err
		}
		stocks = append(stocks, s)
	}
	return stocks, total, nil
}

func (r *StockRepo) CreateLog(log *model.StockLog) error {
	query := `INSERT INTO stock_logs (material_id, type, quantity, related_order_type, related_order_id) VALUES (?, ?, ?, ?, ?)`
	result, err := database.DB.Exec(query, log.MaterialID, log.Type, log.Quantity, log.RelatedOrderType, log.RelatedOrderID)
	if err != nil {
		return err
	}
	id, err := result.LastInsertId()
	if err != nil {
		return err
	}
	log.ID = id
	return nil
}

func (r *StockRepo) GetLogsByMaterialID(materialID int64, limit, offset int) ([]model.StockLog, int64, error) {
	countQuery := `SELECT COUNT(*) FROM stock_logs WHERE material_id = ?`
	var total int64
	err := database.DB.QueryRow(countQuery, materialID).Scan(&total)
	if err != nil {
		return nil, 0, err
	}

	query := `SELECT id, material_id, type, quantity, related_order_type, related_order_id, created_at FROM stock_logs WHERE material_id = ? ORDER BY id LIMIT ? OFFSET ?`
	rows, err := database.DB.Query(query, materialID, limit, offset)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var logs []model.StockLog
	for rows.Next() {
		var log model.StockLog
		err := rows.Scan(&log.ID, &log.MaterialID, &log.Type, &log.Quantity, &log.RelatedOrderType, &log.RelatedOrderID, &log.CreatedAt)
		if err != nil {
			return nil, 0, err
		}
		logs = append(logs, log)
	}
	return logs, total, nil
}

func (r *StockRepo) GetAllLogs(limit, offset int) ([]model.StockLog, int64, error) {
	countQuery := `SELECT COUNT(*) FROM stock_logs`
	var total int64
	err := database.DB.QueryRow(countQuery).Scan(&total)
	if err != nil {
		return nil, 0, err
	}

	// Compute running_balance as cumulative sum of (in=+quantity, out=-quantity) ordered by id ASC,
	// then reverse to show newest first while preserving correct cumulative balance for each row
	query := `
		SELECT id, material_id, type, quantity, related_order_type, related_order_id, created_at
		FROM (
			SELECT *,
				(SELECT COALESCE(SUM(CASE WHEN type='in' THEN quantity ELSE -quantity END), 0)
				 FROM stock_logs s2 WHERE s2.id <= stock_logs.id) as running_balance
			FROM stock_logs
		) as t
		ORDER BY id DESC
		LIMIT ? OFFSET ?`
	rows, err := database.DB.Query(query, limit, offset)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var logs []model.StockLog
	for rows.Next() {
		var log model.StockLog
		err := rows.Scan(&log.ID, &log.MaterialID, &log.Type, &log.Quantity, &log.RelatedOrderType, &log.RelatedOrderID, &log.CreatedAt)
		if err != nil {
			return nil, 0, err
		}
		logs = append(logs, log)
	}
	return logs, total, nil
}

// GetAllLogsWithBalance returns logs ordered newest-first with correct running balance.
// Balance = stock level BEFORE this log's change was applied.
// Strategy: Walk rows from oldest to newest within the page, accumulating balance.
// The starting balance for the oldest row is: total on-hand - sum(all deltas for this material newer than the page).
func (r *StockRepo) GetAllLogsWithBalance(limit, offset int) ([]model.StockLog, int64, error) {
	var total int64
	if err := database.DB.QueryRow(`SELECT COUNT(*) FROM stock_logs`).Scan(&total); err != nil {
		return nil, 0, err
	}

	// Fetch page rows ordered newest-first (id DESC).
	rows, err := database.DB.Query(`
		SELECT id, material_id, type, quantity, related_order_type, related_order_id, created_at
		FROM stock_logs ORDER BY id DESC LIMIT ? OFFSET ?`, limit, offset)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	type rowData struct {
		log   model.StockLog
		delta int
	}
	var pageRows []rowData
	materialIDs := make(map[int64]bool)
	for rows.Next() {
		var r rowData
		if err := rows.Scan(&r.log.ID, &r.log.MaterialID, &r.log.Type, &r.log.Quantity,
			&r.log.RelatedOrderType, &r.log.RelatedOrderID, &r.log.CreatedAt); err != nil {
			return nil, 0, err
		}
		if r.log.Type == "in" {
			r.delta = r.log.Quantity
		} else {
			r.delta = -r.log.Quantity
		}
		pageRows = append(pageRows, r)
		materialIDs[r.log.MaterialID] = true
	}

	if len(pageRows) == 0 {
		return []model.StockLog{}, total, nil
	}

	// Get initialBalance: total on-hand of this material minus all deltas for this material.
	// This gives the balance BEFORE the oldest log in this page was applied.
	initialBalances := make(map[int64]decimal.Decimal)
	for mid := range materialIDs {
		var delta int
		database.DB.QueryRow(`
			SELECT COALESCE(SUM(CASE WHEN type='in' THEN quantity ELSE -quantity END), 0)
			FROM stock_logs WHERE material_id = ?`, mid).Scan(&delta)
		var totalOnHand decimal.Decimal
		if err := database.DB.QueryRow(`SELECT COALESCE(SUM(on_hand), 0) FROM inventory_balances WHERE material_id = ?`, mid).Scan(&totalOnHand); err != nil {
			return nil, 0, err
		}
		initialBalances[mid] = totalOnHand.Sub(decimal.NewFromInt(int64(delta)))
	}

	// Process from OLDEST to NEWEST within the page (reverse order of our DESC result).
	// balance_for_oldest = total_on_hand - newer_than_page_delta
	// balance_after_row = balance_before_row + delta
	for i := len(pageRows) - 1; i >= 0; i-- {
		r := &pageRows[i]
		bal := initialBalances[r.log.MaterialID]
		if r.log.Type == "in" {
			bal = bal.Add(decimal.NewFromInt(int64(r.log.Quantity)))
		} else {
			bal = bal.Sub(decimal.NewFromInt(int64(r.log.Quantity)))
		}
		r.log.RunningBalance = bal
		initialBalances[r.log.MaterialID] = bal
	}

	var logs []model.StockLog
	for _, r := range pageRows {
		logs = append(logs, r.log)
	}
	return logs, total, nil
}

// GetStock returns the current on-hand balance for a material across inventory dimensions.
func (r *StockRepo) GetStock(materialID int64) (decimal.Decimal, error) {
	var stock decimal.Decimal
	err := database.DB.QueryRow(`SELECT COALESCE(SUM(on_hand), 0) FROM inventory_balances WHERE material_id = ?`, materialID).Scan(&stock)
	return stock, err
}

// GetStockForUpdateTx locks the legacy default location balance used by current inbound/outbound flows.
func (r *StockRepo) GetStockForUpdateTx(tx *sql.Tx, materialID int64) (decimal.Decimal, error) {
	query := `SELECT ib.on_hand
		FROM inventory_balances ib
		JOIN organizations o ON o.id = ib.organization_id AND o.code = 'DEFAULT'
		JOIN warehouses w ON w.id = ib.warehouse_id AND w.code = 'DEFAULT'
		JOIN warehouse_locations l ON l.id = ib.location_id AND l.code = 'MAIN'
		WHERE ib.material_id = ? FOR UPDATE`
	var stock decimal.Decimal
	err := tx.QueryRow(query, materialID).Scan(&stock)
	if err == sql.ErrNoRows {
		return decimal.Zero, nil
	}
	return stock, err
}

// UpdateStockTx writes the legacy inbound/outbound change to the independent default inventory balance.
func (r *StockRepo) UpdateStockTx(tx *sql.Tx, materialID int64, delta decimal.Decimal) error {
	query := `INSERT INTO inventory_balances (organization_id, warehouse_id, location_id, material_id, on_hand)
		SELECT o.id, w.id, l.id, ?, ?
		FROM organizations o
		JOIN warehouses w ON w.organization_id = o.id AND w.code = 'DEFAULT'
		JOIN warehouse_locations l ON l.warehouse_id = w.id AND l.code = 'MAIN'
		WHERE o.code = 'DEFAULT'
		ON DUPLICATE KEY UPDATE on_hand = on_hand + VALUES(on_hand), version = version + 1`
	result, err := tx.Exec(query, materialID, delta)
	if err != nil {
		return err
	}
	affected, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if affected == 0 {
		return fmt.Errorf("default organization, warehouse, or location is missing")
	}
	return nil
}

// UpdateWarningStock stores the default warehouse threshold in the inventory domain.
func (r *StockRepo) UpdateWarningStock(materialID int64, minimumAvailable decimal.Decimal) error {
	query := `INSERT INTO stock_warning_rules (organization_id, warehouse_id, material_id, minimum_available, enabled)
		SELECT o.id, w.id, ?, ?, TRUE
		FROM organizations o
		JOIN warehouses w ON w.organization_id = o.id AND w.code = 'DEFAULT'
		WHERE o.code = 'DEFAULT'
		ON DUPLICATE KEY UPDATE minimum_available = VALUES(minimum_available), enabled = TRUE`
	result, err := database.DB.Exec(query, materialID, minimumAvailable)
	if err != nil {
		return err
	}
	affected, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if affected == 0 {
		return fmt.Errorf("default organization or warehouse is missing")
	}
	return nil
}

func (r *StockRepo) DeleteLogs(orderType string, orderID int64) error {
	query := `DELETE FROM stock_logs WHERE related_order_type = ? AND related_order_id = ?`
	_, err := database.DB.Exec(query, orderType, orderID)
	return err
}

// CreateLogTx creates a stock log within a transaction
func (r *StockRepo) CreateLogTx(tx *sql.Tx, log *model.StockLog) error {
	query := `INSERT INTO stock_logs (material_id, type, quantity, related_order_type, related_order_id) VALUES (?, ?, ?, ?, ?)`
	result, err := tx.Exec(query, log.MaterialID, log.Type, log.Quantity, log.RelatedOrderType, log.RelatedOrderID)
	if err != nil {
		return err
	}
	id, err := result.LastInsertId()
	if err != nil {
		return err
	}
	log.ID = id
	return nil
}

// DeleteLogsTx deletes stock logs within a transaction
func (r *StockRepo) DeleteLogsTx(tx *sql.Tx, orderType string, orderID int64) error {
	query := `DELETE FROM stock_logs WHERE related_order_type = ? AND related_order_id = ?`
	_, err := tx.Exec(query, orderType, orderID)
	return err
}

func (r *StockRepo) GetInventoryBalanceDetails(materialID int64) ([]model.InventoryBalanceDetail, error) {
	query := `
		SELECT ib.id, ib.organization_id, o.name, ib.warehouse_id, w.name,
		       ib.location_id, l.name, ib.material_id, ib.on_hand, ib.reserved,
		       ib.locked, ib.in_transit, ib.updated_at
		FROM inventory_balances ib
		JOIN organizations o ON o.id = ib.organization_id
		JOIN warehouses w ON w.id = ib.warehouse_id
		JOIN warehouse_locations l ON l.id = ib.location_id
		WHERE ib.material_id = ?
		ORDER BY ib.id`
	rows, err := database.DB.Query(query, materialID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var details []model.InventoryBalanceDetail
	for rows.Next() {
		var d model.InventoryBalanceDetail
		if err := rows.Scan(&d.ID, &d.OrganizationID, &d.Organization, &d.WarehouseID, &d.Warehouse,
			&d.LocationID, &d.Location, &d.MaterialID, &d.OnHand, &d.Reserved,
			&d.Locked, &d.InTransit, &d.UpdatedAt); err != nil {
			return nil, err
		}
		details = append(details, d)
	}
	return details, rows.Err()
}