// Package operationlog implements the PostgreSQL-backed adapter for
// `ports.OperationLogStore`.
//
// The package owns the on-disk shape of the `operation_log` table
// defined in
// `galaxy/gamemaster/internal/adapters/postgres/migrations/00001_init.sql`
// and translates the schema-agnostic `ports.OperationLogStore`
// interface declared in `internal/ports/operationlog.go` into
// concrete go-jet/v2 statements driven by the pgx driver.
//
// Append uses `INSERT ... RETURNING id` to surface the bigserial id
// back to callers; ListByGame is index-driven by
// `operation_log_game_started_idx`.
package operationlog

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/operation"
	"galaxy/gamemaster/internal/ports"

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

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

// Store persists Game Master operation-log entries in PostgreSQL.
type Store struct {
	db               *sql.DB
	operationTimeout time.Duration
}

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

// operationLogSelectColumns matches scanRow's column order.
var operationLogSelectColumns = pg.ColumnList{
	pgtable.OperationLog.ID,
	pgtable.OperationLog.GameID,
	pgtable.OperationLog.OpKind,
	pgtable.OperationLog.OpSource,
	pgtable.OperationLog.SourceRef,
	pgtable.OperationLog.Outcome,
	pgtable.OperationLog.ErrorCode,
	pgtable.OperationLog.ErrorMessage,
	pgtable.OperationLog.StartedAt,
	pgtable.OperationLog.FinishedAt,
}

// Append inserts entry into the operation log and returns the
// generated bigserial id. entry is validated through
// operation.OperationEntry.Validate before the SQL is issued.
func (store *Store) Append(ctx context.Context, entry operation.OperationEntry) (int64, error) {
	if store == nil || store.db == nil {
		return 0, errors.New("append operation log entry: nil store")
	}
	if err := entry.Validate(); err != nil {
		return 0, fmt.Errorf("append operation log entry: %w", err)
	}

	operationCtx, cancel, err := sqlx.WithTimeout(ctx, "append operation log entry", store.operationTimeout)
	if err != nil {
		return 0, err
	}
	defer cancel()

	stmt := pgtable.OperationLog.INSERT(
		pgtable.OperationLog.GameID,
		pgtable.OperationLog.OpKind,
		pgtable.OperationLog.OpSource,
		pgtable.OperationLog.SourceRef,
		pgtable.OperationLog.Outcome,
		pgtable.OperationLog.ErrorCode,
		pgtable.OperationLog.ErrorMessage,
		pgtable.OperationLog.StartedAt,
		pgtable.OperationLog.FinishedAt,
	).VALUES(
		entry.GameID,
		string(entry.OpKind),
		string(entry.OpSource),
		entry.SourceRef,
		string(entry.Outcome),
		entry.ErrorCode,
		entry.ErrorMessage,
		entry.StartedAt.UTC(),
		sqlx.NullableTimePtr(entry.FinishedAt),
	).RETURNING(pgtable.OperationLog.ID)

	query, args := stmt.Sql()
	row := store.db.QueryRowContext(operationCtx, query, args...)
	var id int64
	if err := row.Scan(&id); err != nil {
		return 0, fmt.Errorf("append operation log entry: %w", err)
	}
	return id, nil
}

// ListByGame returns the most recent entries for gameID, ordered by
// started_at descending and id descending (a tie-breaker that keeps
// the order stable when two rows share a started_at). The result is
// capped by limit; non-positive limit is rejected.
func (store *Store) ListByGame(ctx context.Context, gameID string, limit int) ([]operation.OperationEntry, error) {
	if store == nil || store.db == nil {
		return nil, errors.New("list operation log entries by game: nil store")
	}
	if strings.TrimSpace(gameID) == "" {
		return nil, fmt.Errorf("list operation log entries by game: game id must not be empty")
	}
	if limit <= 0 {
		return nil, fmt.Errorf("list operation log entries by game: limit must be positive, got %d", limit)
	}

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

	stmt := pg.SELECT(operationLogSelectColumns).
		FROM(pgtable.OperationLog).
		WHERE(pgtable.OperationLog.GameID.EQ(pg.String(gameID))).
		ORDER_BY(pgtable.OperationLog.StartedAt.DESC(), pgtable.OperationLog.ID.DESC()).
		LIMIT(int64(limit))

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

	entries := make([]operation.OperationEntry, 0)
	for rows.Next() {
		got, err := scanRow(rows)
		if err != nil {
			return nil, fmt.Errorf("list operation log entries by game: scan: %w", err)
		}
		entries = append(entries, got)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("list operation log entries by game: %w", err)
	}
	if len(entries) == 0 {
		return nil, nil
	}
	return entries, 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 operation_log row from rs.
func scanRow(rs rowScanner) (operation.OperationEntry, error) {
	var (
		id           int64
		gameID       string
		opKind       string
		opSource     string
		sourceRef    string
		outcome      string
		errorCode    string
		errorMessage string
		startedAt    time.Time
		finishedAt   sql.NullTime
	)
	if err := rs.Scan(
		&id,
		&gameID,
		&opKind,
		&opSource,
		&sourceRef,
		&outcome,
		&errorCode,
		&errorMessage,
		&startedAt,
		&finishedAt,
	); err != nil {
		return operation.OperationEntry{}, err
	}
	return operation.OperationEntry{
		ID:           id,
		GameID:       gameID,
		OpKind:       operation.OpKind(opKind),
		OpSource:     operation.OpSource(opSource),
		SourceRef:    sourceRef,
		Outcome:      operation.Outcome(outcome),
		ErrorCode:    errorCode,
		ErrorMessage: errorMessage,
		StartedAt:    startedAt.UTC(),
		FinishedAt:   sqlx.TimePtrFromNullable(finishedAt),
	}, nil
}

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