package userstore

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"time"

	pgtable "galaxy/user/internal/adapters/postgres/jet/user/table"
	"galaxy/user/internal/domain/account"
	"galaxy/user/internal/domain/common"
	"galaxy/user/internal/ports"

	pg "github.com/go-jet/jet/v2/postgres"
)

// SQL constraint names declared in 00001_init.sql; referenced from error
// translation so we can disambiguate UNIQUE violations on (email) versus
// (user_name).
const (
	accountsEmailUniqueConstraint    = "accounts_email_unique"
	accountsUserNameUniqueConstraint = "accounts_user_name_unique"
)

// accountSelectColumns is the canonical SELECT list for accounts, matching
// scanAccountRow's column order.
var accountSelectColumns = pg.ColumnList{
	pgtable.Accounts.UserID,
	pgtable.Accounts.Email,
	pgtable.Accounts.UserName,
	pgtable.Accounts.DisplayName,
	pgtable.Accounts.PreferredLanguage,
	pgtable.Accounts.TimeZone,
	pgtable.Accounts.DeclaredCountry,
	pgtable.Accounts.CreatedAt,
	pgtable.Accounts.UpdatedAt,
	pgtable.Accounts.DeletedAt,
}

// Create stores one new account record. Email and user-name uniqueness are
// enforced by the schema; conflicts on those columns surface as
// ports.ErrConflict (with ports.ErrUserNameConflict for the dedicated
// user-name index).
func (store *Store) Create(ctx context.Context, input ports.CreateAccountInput) error {
	if err := input.Validate(); err != nil {
		return fmt.Errorf("create account in postgres: %w", err)
	}

	operationCtx, cancel, err := store.operationContext(ctx, "create account in postgres")
	if err != nil {
		return err
	}
	defer cancel()

	if err := insertAccount(operationCtx, store.db, input.Account); err != nil {
		return err
	}
	return nil
}

// insertAccount runs one INSERT against accounts using the supplied Queryer
// (a *sql.DB or a *sql.Tx). It centralises the column list and error
// translation used by Create and EnsureByEmail.
func insertAccount(ctx context.Context, q queryer, record account.UserAccount) error {
	stmt := pgtable.Accounts.INSERT(
		pgtable.Accounts.UserID,
		pgtable.Accounts.Email,
		pgtable.Accounts.UserName,
		pgtable.Accounts.DisplayName,
		pgtable.Accounts.PreferredLanguage,
		pgtable.Accounts.TimeZone,
		pgtable.Accounts.DeclaredCountry,
		pgtable.Accounts.CreatedAt,
		pgtable.Accounts.UpdatedAt,
		pgtable.Accounts.DeletedAt,
	).VALUES(
		record.UserID.String(),
		record.Email.String(),
		record.UserName.String(),
		record.DisplayName.String(),
		record.PreferredLanguage.String(),
		record.TimeZone.String(),
		nullableCountry(record.DeclaredCountry),
		record.CreatedAt.UTC(),
		record.UpdatedAt.UTC(),
		nullableTime(record.DeletedAt),
	)

	query, args := stmt.Sql()
	_, err := q.ExecContext(ctx, query, args...)
	if err == nil {
		return nil
	}
	if mapped := classifyUniqueViolation(err, accountsUserNameUniqueConstraint, ports.ErrUserNameConflict); mapped != nil {
		return fmt.Errorf("create account %q in postgres: %w", record.UserID, mapped)
	}
	if isUniqueViolation(err) {
		return fmt.Errorf("create account %q in postgres: %w", record.UserID, ports.ErrConflict)
	}
	return fmt.Errorf("create account %q in postgres: %w", record.UserID, err)
}

// queryer is the subset of *sql.DB / *sql.Tx used by helpers that need to
// run inside an existing transaction or against the bare pool.
type queryer interface {
	QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row
	QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error)
	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
}

// GetByUserID returns the stored account identified by userID.
func (store *Store) GetByUserID(ctx context.Context, userID common.UserID) (account.UserAccount, error) {
	if err := userID.Validate(); err != nil {
		return account.UserAccount{}, fmt.Errorf("get account by user id from postgres: %w", err)
	}

	operationCtx, cancel, err := store.operationContext(ctx, "get account by user id from postgres")
	if err != nil {
		return account.UserAccount{}, err
	}
	defer cancel()

	record, err := scanAccountByUserID(operationCtx, store.db, userID)
	switch {
	case errors.Is(err, ports.ErrNotFound):
		return account.UserAccount{}, fmt.Errorf("get account by user id %q from postgres: %w", userID, ports.ErrNotFound)
	case err != nil:
		return account.UserAccount{}, fmt.Errorf("get account by user id %q from postgres: %w", userID, err)
	}
	return record, nil
}

// GetByEmail returns the stored account identified by the normalized e-mail
// address.
func (store *Store) GetByEmail(ctx context.Context, email common.Email) (account.UserAccount, error) {
	if err := email.Validate(); err != nil {
		return account.UserAccount{}, fmt.Errorf("get account by email from postgres: %w", err)
	}

	operationCtx, cancel, err := store.operationContext(ctx, "get account by email from postgres")
	if err != nil {
		return account.UserAccount{}, err
	}
	defer cancel()

	record, err := scanAccountByEmail(operationCtx, store.db, email)
	switch {
	case errors.Is(err, ports.ErrNotFound):
		return account.UserAccount{}, fmt.Errorf("get account by email %q from postgres: %w", email, ports.ErrNotFound)
	case err != nil:
		return account.UserAccount{}, fmt.Errorf("get account by email %q from postgres: %w", email, err)
	}
	return record, nil
}

// GetByUserName returns the stored account identified by the exact stored
// user name.
func (store *Store) GetByUserName(ctx context.Context, userName common.UserName) (account.UserAccount, error) {
	if err := userName.Validate(); err != nil {
		return account.UserAccount{}, fmt.Errorf("get account by user name from postgres: %w", err)
	}

	operationCtx, cancel, err := store.operationContext(ctx, "get account by user name from postgres")
	if err != nil {
		return account.UserAccount{}, err
	}
	defer cancel()

	record, err := scanAccountByUserName(operationCtx, store.db, userName)
	switch {
	case errors.Is(err, ports.ErrNotFound):
		return account.UserAccount{}, fmt.Errorf("get account by user name %q from postgres: %w", userName, ports.ErrNotFound)
	case err != nil:
		return account.UserAccount{}, fmt.Errorf("get account by user name %q from postgres: %w", userName, err)
	}
	return record, nil
}

// ExistsByUserID reports whether userID currently identifies a stored account
// that is not soft-deleted. Soft-deleted accounts are treated as non-existing
// for external callers per Stage 22.
func (store *Store) ExistsByUserID(ctx context.Context, userID common.UserID) (bool, error) {
	if err := userID.Validate(); err != nil {
		return false, fmt.Errorf("exists by user id from postgres: %w", err)
	}

	operationCtx, cancel, err := store.operationContext(ctx, "exists by user id from postgres")
	if err != nil {
		return false, err
	}
	defer cancel()

	stmt := pg.SELECT(pgtable.Accounts.DeletedAt).
		FROM(pgtable.Accounts).
		WHERE(pgtable.Accounts.UserID.EQ(pg.String(userID.String())))

	query, args := stmt.Sql()
	var deletedAt *time.Time
	err = store.db.QueryRowContext(operationCtx, query, args...).Scan(&deletedAt)
	switch {
	case errors.Is(err, sql.ErrNoRows):
		return false, nil
	case err != nil:
		return false, fmt.Errorf("exists by user id %q from postgres: %w", userID, err)
	}
	return deletedAt == nil, nil
}

// Update replaces the stored account state for record.UserID. Email and
// user_name are immutable; mutation attempts return ports.ErrConflict.
// declared_country, display_name, preferred_language, time_zone, updated_at,
// and deleted_at are the columns affected.
func (store *Store) Update(ctx context.Context, record account.UserAccount) error {
	if err := record.Validate(); err != nil {
		return fmt.Errorf("update account in postgres: %w", err)
	}

	return store.withTx(ctx, "update account in postgres", func(ctx context.Context, tx *sql.Tx) error {
		current, err := scanAccountForUpdate(ctx, tx, record.UserID)
		if err != nil {
			if errors.Is(err, ports.ErrNotFound) {
				return fmt.Errorf("update account %q in postgres: %w", record.UserID, ports.ErrNotFound)
			}
			return fmt.Errorf("update account %q in postgres: %w", record.UserID, err)
		}
		if current.Email != record.Email || current.UserName != record.UserName {
			return fmt.Errorf("update account %q in postgres: %w", record.UserID, ports.ErrConflict)
		}

		stmt := pgtable.Accounts.UPDATE(
			pgtable.Accounts.DisplayName,
			pgtable.Accounts.PreferredLanguage,
			pgtable.Accounts.TimeZone,
			pgtable.Accounts.DeclaredCountry,
			pgtable.Accounts.UpdatedAt,
			pgtable.Accounts.DeletedAt,
		).SET(
			record.DisplayName.String(),
			record.PreferredLanguage.String(),
			record.TimeZone.String(),
			nullableCountry(record.DeclaredCountry),
			record.UpdatedAt.UTC(),
			nullableTime(record.DeletedAt),
		).WHERE(pgtable.Accounts.UserID.EQ(pg.String(record.UserID.String())))

		query, args := stmt.Sql()
		if _, err := tx.ExecContext(ctx, query, args...); err != nil {
			return fmt.Errorf("update account %q in postgres: %w", record.UserID, err)
		}
		return nil
	})
}

// scanAccountByUserID is a thin wrapper around scanAccountWhere for the
// (user_id) column so atomic flows can reuse the same scanner with FOR
// UPDATE locking semantics.
func scanAccountByUserID(ctx context.Context, q queryer, userID common.UserID) (account.UserAccount, error) {
	return scanAccountWhere(ctx, q, pgtable.Accounts.UserID.EQ(pg.String(userID.String())), false)
}

func scanAccountByEmail(ctx context.Context, q queryer, email common.Email) (account.UserAccount, error) {
	return scanAccountWhere(ctx, q, pgtable.Accounts.Email.EQ(pg.String(email.String())), false)
}

func scanAccountByUserName(ctx context.Context, q queryer, userName common.UserName) (account.UserAccount, error) {
	return scanAccountWhere(ctx, q, pgtable.Accounts.UserName.EQ(pg.String(userName.String())), false)
}

func scanAccountForUpdate(ctx context.Context, q queryer, userID common.UserID) (account.UserAccount, error) {
	return scanAccountWhere(ctx, q, pgtable.Accounts.UserID.EQ(pg.String(userID.String())), true)
}

func scanAccountForUpdateByEmail(ctx context.Context, q queryer, email common.Email) (account.UserAccount, error) {
	return scanAccountWhere(ctx, q, pgtable.Accounts.Email.EQ(pg.String(email.String())), true)
}

func scanAccountWhere(ctx context.Context, q queryer, condition pg.BoolExpression, forUpdate bool) (account.UserAccount, error) {
	stmt := pg.SELECT(accountSelectColumns).
		FROM(pgtable.Accounts).
		WHERE(condition)
	if forUpdate {
		stmt = stmt.FOR(pg.UPDATE())
	}
	query, args := stmt.Sql()
	row := q.QueryRowContext(ctx, query, args...)
	return scanAccountRow(row)
}

func scanAccountRow(row *sql.Row) (account.UserAccount, error) {
	var (
		record          account.UserAccount
		userID          string
		email           string
		userName        string
		displayName     string
		preferredLang   string
		timeZone        string
		declaredCountry *string
		createdAt       time.Time
		updatedAt       time.Time
		deletedAt       *time.Time
	)

	if err := row.Scan(
		&userID, &email, &userName, &displayName,
		&preferredLang, &timeZone, &declaredCountry,
		&createdAt, &updatedAt, &deletedAt,
	); err != nil {
		return account.UserAccount{}, mapNotFound(err)
	}

	record.UserID = common.UserID(userID)
	record.Email = common.Email(email)
	record.UserName = common.UserName(userName)
	record.DisplayName = common.DisplayName(displayName)
	record.PreferredLanguage = common.LanguageTag(preferredLang)
	record.TimeZone = common.TimeZoneName(timeZone)
	if declaredCountry != nil {
		record.DeclaredCountry = common.CountryCode(*declaredCountry)
	}
	record.CreatedAt = createdAt.UTC()
	record.UpdatedAt = updatedAt.UTC()
	record.DeletedAt = timeFromNullable(deletedAt)
	return record, nil
}

// AccountStore adapts Store to the UserAccountStore port. The wrapper is
// returned by Store.Accounts() so callers that need only the narrow port
// interface remain unaware of the broader Store surface.
type AccountStore struct {
	store *Store
}

// Accounts returns one adapter that exposes the user-account store port over
// Store.
func (store *Store) Accounts() *AccountStore {
	if store == nil {
		return nil
	}
	return &AccountStore{store: store}
}

// Create stores one new account record.
func (adapter *AccountStore) Create(ctx context.Context, input ports.CreateAccountInput) error {
	return adapter.store.Create(ctx, input)
}

// GetByUserID returns the stored account identified by userID.
func (adapter *AccountStore) GetByUserID(ctx context.Context, userID common.UserID) (account.UserAccount, error) {
	return adapter.store.GetByUserID(ctx, userID)
}

// GetByEmail returns the stored account identified by email.
func (adapter *AccountStore) GetByEmail(ctx context.Context, email common.Email) (account.UserAccount, error) {
	return adapter.store.GetByEmail(ctx, email)
}

// GetByUserName returns the stored account identified by userName.
func (adapter *AccountStore) GetByUserName(ctx context.Context, userName common.UserName) (account.UserAccount, error) {
	return adapter.store.GetByUserName(ctx, userName)
}

// ExistsByUserID reports whether userID currently identifies a stored
// account.
func (adapter *AccountStore) ExistsByUserID(ctx context.Context, userID common.UserID) (bool, error) {
	return adapter.store.ExistsByUserID(ctx, userID)
}

// Update replaces the stored account state for record.UserID.
func (adapter *AccountStore) Update(ctx context.Context, record account.UserAccount) error {
	return adapter.store.Update(ctx, record)
}

var _ ports.UserAccountStore = (*AccountStore)(nil)