// Package playermappingstore implements the PostgreSQL-backed adapter
// for `ports.PlayerMappingStore`.
//
// The package owns the on-disk shape of the `player_mappings` table
// defined in
// `galaxy/gamemaster/internal/adapters/postgres/migrations/00001_init.sql`
// and translates the schema-agnostic `ports.PlayerMappingStore`
// interface declared in `internal/ports/playermappingstore.go` into
// concrete go-jet/v2 statements driven by the pgx driver.
//
// BulkInsert ships every row in a single multi-row INSERT so the
// operation is atomic — any unique-constraint violation rolls back the
// whole batch and is mapped to playermapping.ErrConflict.
package playermappingstore

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

	"galaxy/gamemaster/internal/adapters/postgres/internal/sqlx"
	pgtable "galaxy/gamemaster/internal/adapters/postgres/jet/gamemaster/table"
	"galaxy/gamemaster/internal/domain/playermapping"
	"galaxy/gamemaster/internal/ports"

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

// Config configures one PostgreSQL-backed player-mapping store.
type Config struct {
	DB               *sql.DB
	OperationTimeout time.Duration
}

// Store persists Game Master player mappings in PostgreSQL.
type Store struct {
	db               *sql.DB
	operationTimeout time.Duration
}

// New constructs one PostgreSQL-backed player-mapping store from cfg.
func New(cfg Config) (*Store, error) {
	if cfg.DB == nil {
		return nil, errors.New("new postgres player mapping store: db must not be nil")
	}
	if cfg.OperationTimeout <= 0 {
		return nil, errors.New("new postgres player mapping store: operation timeout must be positive")
	}
	return &Store{
		db:               cfg.DB,
		operationTimeout: cfg.OperationTimeout,
	}, nil
}

// playerMappingSelectColumns matches scanRow's column order.
var playerMappingSelectColumns = pg.ColumnList{
	pgtable.PlayerMappings.GameID,
	pgtable.PlayerMappings.UserID,
	pgtable.PlayerMappings.RaceName,
	pgtable.PlayerMappings.EnginePlayerUUID,
	pgtable.PlayerMappings.CreatedAt,
}

// BulkInsert installs every mapping in records using a single
// multi-row INSERT. Either every row is persisted or none of them is.
// Any PostgreSQL unique-violation
// (`(game_id, user_id)` PK or `(game_id, race_name)` UNIQUE) is mapped
// to playermapping.ErrConflict.
func (store *Store) BulkInsert(ctx context.Context, records []playermapping.PlayerMapping) error {
	if store == nil || store.db == nil {
		return errors.New("bulk insert player mappings: nil store")
	}
	if len(records) == 0 {
		return nil
	}
	for index, record := range records {
		if err := record.Validate(); err != nil {
			return fmt.Errorf("bulk insert player mappings: record %d: %w", index, err)
		}
	}

	operationCtx, cancel, err := sqlx.WithTimeout(ctx, "bulk insert player mappings", store.operationTimeout)
	if err != nil {
		return err
	}
	defer cancel()

	stmt := pgtable.PlayerMappings.INSERT(
		pgtable.PlayerMappings.GameID,
		pgtable.PlayerMappings.UserID,
		pgtable.PlayerMappings.RaceName,
		pgtable.PlayerMappings.EnginePlayerUUID,
		pgtable.PlayerMappings.CreatedAt,
	)
	for _, record := range records {
		stmt = stmt.VALUES(
			record.GameID,
			record.UserID,
			record.RaceName,
			record.EnginePlayerUUID,
			record.CreatedAt.UTC(),
		)
	}

	query, args := stmt.Sql()
	if _, err := store.db.ExecContext(operationCtx, query, args...); err != nil {
		if sqlx.IsUniqueViolation(err) {
			return fmt.Errorf("bulk insert player mappings: %w", playermapping.ErrConflict)
		}
		return fmt.Errorf("bulk insert player mappings: %w", err)
	}
	return nil
}

// Get returns the mapping identified by (gameID, userID).
func (store *Store) Get(ctx context.Context, gameID, userID string) (playermapping.PlayerMapping, error) {
	if store == nil || store.db == nil {
		return playermapping.PlayerMapping{}, errors.New("get player mapping: nil store")
	}
	if strings.TrimSpace(gameID) == "" {
		return playermapping.PlayerMapping{}, fmt.Errorf("get player mapping: game id must not be empty")
	}
	if strings.TrimSpace(userID) == "" {
		return playermapping.PlayerMapping{}, fmt.Errorf("get player mapping: user id must not be empty")
	}

	operationCtx, cancel, err := sqlx.WithTimeout(ctx, "get player mapping", store.operationTimeout)
	if err != nil {
		return playermapping.PlayerMapping{}, err
	}
	defer cancel()

	stmt := pg.SELECT(playerMappingSelectColumns).
		FROM(pgtable.PlayerMappings).
		WHERE(pg.AND(
			pgtable.PlayerMappings.GameID.EQ(pg.String(gameID)),
			pgtable.PlayerMappings.UserID.EQ(pg.String(userID)),
		))

	query, args := stmt.Sql()
	row := store.db.QueryRowContext(operationCtx, query, args...)
	got, err := scanRow(row)
	if sqlx.IsNoRows(err) {
		return playermapping.PlayerMapping{}, playermapping.ErrNotFound
	}
	if err != nil {
		return playermapping.PlayerMapping{}, fmt.Errorf("get player mapping: %w", err)
	}
	return got, nil
}

// GetByRace returns the mapping identified by (gameID, raceName).
func (store *Store) GetByRace(ctx context.Context, gameID, raceName string) (playermapping.PlayerMapping, error) {
	if store == nil || store.db == nil {
		return playermapping.PlayerMapping{}, errors.New("get player mapping by race: nil store")
	}
	if strings.TrimSpace(gameID) == "" {
		return playermapping.PlayerMapping{}, fmt.Errorf("get player mapping by race: game id must not be empty")
	}
	if strings.TrimSpace(raceName) == "" {
		return playermapping.PlayerMapping{}, fmt.Errorf("get player mapping by race: race name must not be empty")
	}

	operationCtx, cancel, err := sqlx.WithTimeout(ctx, "get player mapping by race", store.operationTimeout)
	if err != nil {
		return playermapping.PlayerMapping{}, err
	}
	defer cancel()

	stmt := pg.SELECT(playerMappingSelectColumns).
		FROM(pgtable.PlayerMappings).
		WHERE(pg.AND(
			pgtable.PlayerMappings.GameID.EQ(pg.String(gameID)),
			pgtable.PlayerMappings.RaceName.EQ(pg.String(raceName)),
		))

	query, args := stmt.Sql()
	row := store.db.QueryRowContext(operationCtx, query, args...)
	got, err := scanRow(row)
	if sqlx.IsNoRows(err) {
		return playermapping.PlayerMapping{}, playermapping.ErrNotFound
	}
	if err != nil {
		return playermapping.PlayerMapping{}, fmt.Errorf("get player mapping by race: %w", err)
	}
	return got, nil
}

// ListByGame returns every mapping owned by gameID, ordered by user_id
// ascending.
func (store *Store) ListByGame(ctx context.Context, gameID string) ([]playermapping.PlayerMapping, error) {
	if store == nil || store.db == nil {
		return nil, errors.New("list player mappings by game: nil store")
	}
	if strings.TrimSpace(gameID) == "" {
		return nil, fmt.Errorf("list player mappings by game: game id must not be empty")
	}

	operationCtx, cancel, err := sqlx.WithTimeout(ctx, "list player mappings by game", store.operationTimeout)
	if err != nil {
		return nil, err
	}
	defer cancel()

	stmt := pg.SELECT(playerMappingSelectColumns).
		FROM(pgtable.PlayerMappings).
		WHERE(pgtable.PlayerMappings.GameID.EQ(pg.String(gameID))).
		ORDER_BY(pgtable.PlayerMappings.UserID.ASC())

	query, args := stmt.Sql()
	rows, err := store.db.QueryContext(operationCtx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("list player mappings by game: %w", err)
	}
	defer rows.Close()

	mappings := make([]playermapping.PlayerMapping, 0)
	for rows.Next() {
		got, err := scanRow(rows)
		if err != nil {
			return nil, fmt.Errorf("list player mappings by game: scan: %w", err)
		}
		mappings = append(mappings, got)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("list player mappings by game: %w", err)
	}
	if len(mappings) == 0 {
		return nil, nil
	}
	return mappings, nil
}

// DeleteByGame removes every mapping owned by gameID. The call is
// idempotent: it returns nil even when no rows were deleted.
func (store *Store) DeleteByGame(ctx context.Context, gameID string) error {
	if store == nil || store.db == nil {
		return errors.New("delete player mappings by game: nil store")
	}
	if strings.TrimSpace(gameID) == "" {
		return fmt.Errorf("delete player mappings by game: game id must not be empty")
	}

	operationCtx, cancel, err := sqlx.WithTimeout(ctx, "delete player mappings by game", store.operationTimeout)
	if err != nil {
		return err
	}
	defer cancel()

	stmt := pgtable.PlayerMappings.DELETE().
		WHERE(pgtable.PlayerMappings.GameID.EQ(pg.String(gameID)))

	query, args := stmt.Sql()
	if _, err := store.db.ExecContext(operationCtx, query, args...); err != nil {
		return fmt.Errorf("delete player mappings by game: %w", err)
	}
	return nil
}

// rowScanner abstracts *sql.Row and *sql.Rows so scanRow can be shared
// across single-row and iterated reads.
type rowScanner interface {
	Scan(dest ...any) error
}

// scanRow scans one player_mappings row from rs.
func scanRow(rs rowScanner) (playermapping.PlayerMapping, error) {
	var (
		gameID           string
		userID           string
		raceName         string
		enginePlayerUUID string
		createdAt        time.Time
	)
	if err := rs.Scan(&gameID, &userID, &raceName, &enginePlayerUUID, &createdAt); err != nil {
		return playermapping.PlayerMapping{}, err
	}
	return playermapping.PlayerMapping{
		GameID:           gameID,
		UserID:           userID,
		RaceName:         raceName,
		EnginePlayerUUID: enginePlayerUUID,
		CreatedAt:        createdAt.UTC(),
	}, nil
}

// Ensure Store satisfies the ports.PlayerMappingStore interface at
// compile time.
var _ ports.PlayerMappingStore = (*Store)(nil)