package postgres

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/gofrs/uuid/v5"
	"github.com/jmoiron/sqlx"

	"github.com/saveinmed/backend-go/internal/domain"
)

// Repository implements the data access layer using sqlx + pgx.
type Repository struct {
	db *sqlx.DB
}

// New creates a Postgres-backed repository and configures pooling.
func New(db *sqlx.DB) *Repository {
	return &Repository{db: db}
}

func (r *Repository) CreateCompany(ctx context.Context, company *domain.Company) error {
	now := time.Now().UTC()
	company.CreatedAt = now
	company.UpdatedAt = now

	query := `INSERT INTO companies (id, role, cnpj, corporate_name, license_number, is_verified, created_at, updated_at)
VALUES (:id, :role, :cnpj, :corporate_name, :license_number, :is_verified, :created_at, :updated_at)`

	_, err := r.db.NamedExecContext(ctx, query, company)
	return err
}

func (r *Repository) ListCompanies(ctx context.Context) ([]domain.Company, error) {
	var companies []domain.Company
	query := `SELECT id, role, cnpj, corporate_name, license_number, is_verified, created_at, updated_at FROM companies ORDER BY created_at DESC`
	if err := r.db.SelectContext(ctx, &companies, query); err != nil {
		return nil, err
	}
	return companies, nil
}

func (r *Repository) GetCompany(ctx context.Context, id uuid.UUID) (*domain.Company, error) {
	var company domain.Company
	query := `SELECT id, role, cnpj, corporate_name, license_number, is_verified, created_at, updated_at FROM companies WHERE id = $1`
	if err := r.db.GetContext(ctx, &company, query, id); err != nil {
		return nil, err
	}
	return &company, nil
}

func (r *Repository) UpdateCompany(ctx context.Context, company *domain.Company) error {
	company.UpdatedAt = time.Now().UTC()

	query := `UPDATE companies
SET role = :role, cnpj = :cnpj, corporate_name = :corporate_name, license_number = :license_number, is_verified = :is_verified, updated_at = :updated_at
WHERE id = :id`

	res, err := r.db.NamedExecContext(ctx, query, company)
	if err != nil {
		return err
	}
	rows, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return errors.New("company not found")
	}
	return nil
}

func (r *Repository) CreateProduct(ctx context.Context, product *domain.Product) error {
	now := time.Now().UTC()
	product.CreatedAt = now
	product.UpdatedAt = now

	query := `INSERT INTO products (id, seller_id, name, description, batch, expires_at, price_cents, stock, created_at, updated_at)
VALUES (:id, :seller_id, :name, :description, :batch, :expires_at, :price_cents, :stock, :created_at, :updated_at)`

	_, err := r.db.NamedExecContext(ctx, query, product)
	return err
}

func (r *Repository) ListProducts(ctx context.Context) ([]domain.Product, error) {
	var products []domain.Product
	query := `SELECT id, seller_id, name, description, batch, expires_at, price_cents, stock, created_at, updated_at FROM products ORDER BY created_at DESC`
	if err := r.db.SelectContext(ctx, &products, query); err != nil {
		return nil, err
	}
	return products, nil
}

func (r *Repository) GetProduct(ctx context.Context, id uuid.UUID) (*domain.Product, error) {
	var product domain.Product
	query := `SELECT id, seller_id, name, description, batch, expires_at, price_cents, stock, created_at, updated_at FROM products WHERE id = $1`
	if err := r.db.GetContext(ctx, &product, query, id); err != nil {
		return nil, err
	}
	return &product, nil
}

func (r *Repository) CreateOrder(ctx context.Context, order *domain.Order) error {
	now := time.Now().UTC()
	order.CreatedAt = now
	order.UpdatedAt = now

	tx, err := r.db.BeginTxx(ctx, nil)
	if err != nil {
		return err
	}

	orderQuery := `INSERT INTO orders (id, buyer_id, seller_id, status, total_cents, created_at, updated_at)
VALUES ($1, $2, $3, $4, $5, $6, $7)`
	if _, err := tx.ExecContext(ctx, orderQuery, order.ID, order.BuyerID, order.SellerID, order.Status, order.TotalCents, order.CreatedAt, order.UpdatedAt); err != nil {
		_ = tx.Rollback()
		return err
	}

	itemQuery := `INSERT INTO order_items (id, order_id, product_id, quantity, unit_cents, batch, expires_at) VALUES ($1, $2, $3, $4, $5, $6, $7)`
	for i := range order.Items {
		item := &order.Items[i]
		item.ID = uuid.Must(uuid.NewV7())
		item.OrderID = order.ID
		if _, err := tx.ExecContext(ctx, itemQuery, item.ID, item.OrderID, item.ProductID, item.Quantity, item.UnitCents, item.Batch, item.ExpiresAt); err != nil {
			_ = tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}

func (r *Repository) GetOrder(ctx context.Context, id uuid.UUID) (*domain.Order, error) {
	var order domain.Order
	orderQuery := `SELECT id, buyer_id, seller_id, status, total_cents, created_at, updated_at FROM orders WHERE id = $1`
	if err := r.db.GetContext(ctx, &order, orderQuery, id); err != nil {
		return nil, err
	}

	var items []domain.OrderItem
	itemQuery := `SELECT id, order_id, product_id, quantity, unit_cents, batch, expires_at FROM order_items WHERE order_id = $1`
	if err := r.db.SelectContext(ctx, &items, itemQuery, id); err != nil {
		return nil, err
	}
	order.Items = items
	return &order, nil
}

func (r *Repository) UpdateOrderStatus(ctx context.Context, id uuid.UUID, status domain.OrderStatus) error {
	query := `UPDATE orders SET status = $1, updated_at = $2 WHERE id = $3`
	res, err := r.db.ExecContext(ctx, query, status, time.Now().UTC(), id)
	if err != nil {
		return err
	}
	rows, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return errors.New("order not found")
	}
	return nil
}

func (r *Repository) AdjustInventory(ctx context.Context, productID uuid.UUID, delta int64, reason string) (*domain.InventoryItem, error) {
	tx, err := r.db.BeginTxx(ctx, nil)
	if err != nil {
		return nil, err
	}

	var product domain.Product
	if err := tx.GetContext(ctx, &product, `SELECT id, seller_id, name, batch, expires_at, price_cents, stock, updated_at FROM products WHERE id = $1 FOR UPDATE`, productID); err != nil {
		_ = tx.Rollback()
		return nil, err
	}

	newStock := product.Stock + delta
	if newStock < 0 {
		_ = tx.Rollback()
		return nil, errors.New("inventory cannot be negative")
	}

	now := time.Now().UTC()
	if _, err := tx.ExecContext(ctx, `UPDATE products SET stock = $1, updated_at = $2 WHERE id = $3`, newStock, now, productID); err != nil {
		_ = tx.Rollback()
		return nil, err
	}

	adj := domain.InventoryAdjustment{
		ID:        uuid.Must(uuid.NewV7()),
		ProductID: productID,
		Delta:     delta,
		Reason:    reason,
		CreatedAt: now,
	}

	if _, err := tx.NamedExecContext(ctx, `INSERT INTO inventory_adjustments (id, product_id, delta, reason, created_at) VALUES (:id, :product_id, :delta, :reason, :created_at)`, &adj); err != nil {
		_ = tx.Rollback()
		return nil, err
	}

	if err := tx.Commit(); err != nil {
		return nil, err
	}

	return &domain.InventoryItem{
		ProductID:  productID,
		SellerID:   product.SellerID,
		Name:       product.Name,
		Batch:      product.Batch,
		ExpiresAt:  product.ExpiresAt,
		Quantity:   newStock,
		PriceCents: product.PriceCents,
		UpdatedAt:  now,
	}, nil
}

func (r *Repository) ListInventory(ctx context.Context, filter domain.InventoryFilter) ([]domain.InventoryItem, error) {
	args := []any{}
	clauses := []string{}
	if filter.ExpiringBefore != nil {
		clauses = append(clauses, fmt.Sprintf("expires_at <= $%d", len(args)+1))
		args = append(args, *filter.ExpiringBefore)
	}

	where := ""
	if len(clauses) > 0 {
		where = " WHERE " + strings.Join(clauses, " AND ")
	}

	query := fmt.Sprintf(`SELECT id AS product_id, seller_id, name, batch, expires_at, stock AS quantity, price_cents, updated_at FROM products%s ORDER BY expires_at ASC`, where)
	var items []domain.InventoryItem
	if err := r.db.SelectContext(ctx, &items, query, args...); err != nil {
		return nil, err
	}
	return items, nil
}

func (r *Repository) CreateUser(ctx context.Context, user *domain.User) error {
	now := time.Now().UTC()
	user.CreatedAt = now
	user.UpdatedAt = now

	query := `INSERT INTO users (id, company_id, role, name, email, password_hash, created_at, updated_at)
VALUES (:id, :company_id, :role, :name, :email, :password_hash, :created_at, :updated_at)`

	_, err := r.db.NamedExecContext(ctx, query, user)
	return err
}

func (r *Repository) ListUsers(ctx context.Context, filter domain.UserFilter) ([]domain.User, int64, error) {
	baseQuery := `FROM users`
	var args []any
	var clauses []string

	if filter.CompanyID != nil {
		clauses = append(clauses, fmt.Sprintf("company_id = $%d", len(args)+1))
		args = append(args, *filter.CompanyID)
	}

	where := ""
	if len(clauses) > 0 {
		where = " WHERE " + strings.Join(clauses, " AND ")
	}

	countQuery := "SELECT count(*) " + baseQuery + where
	var total int64
	if err := r.db.GetContext(ctx, &total, countQuery, args...); err != nil {
		return nil, 0, err
	}

	args = append(args, filter.Limit, filter.Offset)
	listQuery := fmt.Sprintf("SELECT id, company_id, role, name, email, password_hash, created_at, updated_at %s%s ORDER BY created_at DESC LIMIT $%d OFFSET $%d", baseQuery, where, len(args)-1, len(args))

	var users []domain.User
	if err := r.db.SelectContext(ctx, &users, listQuery, args...); err != nil {
		return nil, 0, err
	}

	return users, total, nil
}

func (r *Repository) GetUser(ctx context.Context, id uuid.UUID) (*domain.User, error) {
	var user domain.User
	query := `SELECT id, company_id, role, name, email, password_hash, created_at, updated_at FROM users WHERE id = $1`
	if err := r.db.GetContext(ctx, &user, query, id); err != nil {
		return nil, err
	}
	return &user, nil
}

func (r *Repository) GetUserByEmail(ctx context.Context, email string) (*domain.User, error) {
	var user domain.User
	query := `SELECT id, company_id, role, name, email, password_hash, created_at, updated_at FROM users WHERE email = $1`
	if err := r.db.GetContext(ctx, &user, query, email); err != nil {
		return nil, err
	}
	return &user, nil
}

func (r *Repository) UpdateUser(ctx context.Context, user *domain.User) error {
	user.UpdatedAt = time.Now().UTC()

	query := `UPDATE users
SET company_id = :company_id, role = :role, name = :name, email = :email, password_hash = :password_hash, updated_at = :updated_at
WHERE id = :id`

	res, err := r.db.NamedExecContext(ctx, query, user)
	if err != nil {
		return err
	}
	rows, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return errors.New("user not found")
	}
	return nil
}

func (r *Repository) DeleteUser(ctx context.Context, id uuid.UUID) error {
	res, err := r.db.ExecContext(ctx, "DELETE FROM users WHERE id = $1", id)
	if err != nil {
		return err
	}
	rows, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return errors.New("user not found")
	}
	return nil
}

func (r *Repository) AddCartItem(ctx context.Context, item *domain.CartItem) (*domain.CartItem, error) {
	now := time.Now().UTC()
	item.CreatedAt = now
	item.UpdatedAt = now

	query := `INSERT INTO cart_items (id, buyer_id, product_id, quantity, unit_cents, batch, expires_at, created_at, updated_at)
VALUES (:id, :buyer_id, :product_id, :quantity, :unit_cents, :batch, :expires_at, :created_at, :updated_at)
ON CONFLICT (buyer_id, product_id) DO UPDATE
SET quantity = cart_items.quantity + EXCLUDED.quantity,
    unit_cents = EXCLUDED.unit_cents,
    batch = EXCLUDED.batch,
    expires_at = EXCLUDED.expires_at,
    updated_at = EXCLUDED.updated_at
RETURNING id, buyer_id, product_id, quantity, unit_cents, batch, expires_at, created_at, updated_at`

	var saved domain.CartItem
	rows, err := r.db.NamedQueryContext(ctx, query, item)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	if rows.Next() {
		if err := rows.StructScan(&saved); err != nil {
			return nil, err
		}
		return &saved, nil
	}
	return nil, errors.New("failed to persist cart item")
}

func (r *Repository) ListCartItems(ctx context.Context, buyerID uuid.UUID) ([]domain.CartItem, error) {
	query := `SELECT ci.id, ci.buyer_id, ci.product_id, ci.quantity, ci.unit_cents, ci.batch, ci.expires_at, ci.created_at, ci.updated_at,
       p.name AS product_name
FROM cart_items ci
JOIN products p ON p.id = ci.product_id
WHERE ci.buyer_id = $1
ORDER BY ci.created_at DESC`

	var items []domain.CartItem
	if err := r.db.SelectContext(ctx, &items, query, buyerID); err != nil {
		return nil, err
	}
	return items, nil
}

func (r *Repository) DeleteCartItem(ctx context.Context, id uuid.UUID, buyerID uuid.UUID) error {
	res, err := r.db.ExecContext(ctx, "DELETE FROM cart_items WHERE id = $1 AND buyer_id = $2", id, buyerID)
	if err != nil {
		return err
	}
	rows, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return errors.New("cart item not found")
	}
	return nil
}

// InitSchema applies a minimal schema for development environments.
func (r *Repository) InitSchema(ctx context.Context) error {
	schema := `
CREATE TABLE IF NOT EXISTS companies (
    id UUID PRIMARY KEY,
    role TEXT NOT NULL,
    cnpj TEXT NOT NULL UNIQUE,
    corporate_name TEXT NOT NULL,
    license_number TEXT NOT NULL,
    is_verified BOOLEAN NOT NULL DEFAULT FALSE,
    created_at TIMESTAMPTZ NOT NULL,
    updated_at TIMESTAMPTZ NOT NULL
);

CREATE TABLE IF NOT EXISTS users (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    role TEXT NOT NULL,
    name TEXT NOT NULL,
    email TEXT NOT NULL UNIQUE,
    password_hash TEXT NOT NULL,
    created_at TIMESTAMPTZ NOT NULL,
    updated_at TIMESTAMPTZ NOT NULL
);

CREATE TABLE IF NOT EXISTS products (
    id UUID PRIMARY KEY,
    seller_id UUID NOT NULL REFERENCES companies(id),
    name TEXT NOT NULL,
    description TEXT,
    batch TEXT NOT NULL,
    expires_at DATE NOT NULL,
    price_cents BIGINT NOT NULL,
    stock BIGINT NOT NULL,
    created_at TIMESTAMPTZ NOT NULL,
    updated_at TIMESTAMPTZ NOT NULL
);

CREATE TABLE IF NOT EXISTS inventory_adjustments (
    id UUID PRIMARY KEY,
    product_id UUID NOT NULL REFERENCES products(id),
    delta BIGINT NOT NULL,
    reason TEXT,
    created_at TIMESTAMPTZ NOT NULL
);

CREATE TABLE IF NOT EXISTS orders (
    id UUID PRIMARY KEY,
    buyer_id UUID NOT NULL REFERENCES companies(id),
    seller_id UUID NOT NULL REFERENCES companies(id),
    status TEXT NOT NULL,
    total_cents BIGINT NOT NULL,
    created_at TIMESTAMPTZ NOT NULL,
    updated_at TIMESTAMPTZ NOT NULL
);

CREATE TABLE IF NOT EXISTS order_items (
    id UUID PRIMARY KEY,
    order_id UUID NOT NULL REFERENCES orders(id),
    product_id UUID NOT NULL REFERENCES products(id),
    quantity BIGINT NOT NULL,
    unit_cents BIGINT NOT NULL,
    batch TEXT NOT NULL,
    expires_at DATE NOT NULL
);

CREATE TABLE IF NOT EXISTS cart_items (
    id UUID PRIMARY KEY,
    buyer_id UUID NOT NULL REFERENCES companies(id),
    product_id UUID NOT NULL REFERENCES products(id),
    quantity BIGINT NOT NULL,
    unit_cents BIGINT NOT NULL,
    batch TEXT,
    expires_at DATE,
    created_at TIMESTAMPTZ NOT NULL,
    updated_at TIMESTAMPTZ NOT NULL,
    UNIQUE (buyer_id, product_id)
);
`

	if _, err := r.db.ExecContext(ctx, schema); err != nil {
		return fmt.Errorf("apply schema: %w", err)
	}
	return nil
}