package dbx

import (
	"context"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
)

// Querier is the common interface satisfied by pgxpool.Pool, pgx.Tx, and pgx.Conn.
type Querier interface {
	Exec(ctx context.Context, sql string, arguments ...any) (pgconn.CommandTag, error)
	Query(ctx context.Context, sql string, args ...any) (pgx.Rows, error)
	QueryRow(ctx context.Context, sql string, args ...any) pgx.Row
	SendBatch(ctx context.Context, b *pgx.Batch) pgx.BatchResults
	CopyFrom(ctx context.Context, tableName pgx.Identifier, columnNames []string, rowSrc pgx.CopyFromSource) (int64, error)
}

// DB extends Querier with transaction support and lifecycle management.
type DB interface {
	Querier
	Begin(ctx context.Context) (pgx.Tx, error)
	BeginTx(ctx context.Context, txOptions pgx.TxOptions) (pgx.Tx, error)
	Ping(ctx context.Context) error
	Close()
}

// Logger is the interface for pluggable structured logging.
type Logger interface {
	Debug(ctx context.Context, msg string, fields ...any)
	Info(ctx context.Context, msg string, fields ...any)
	Warn(ctx context.Context, msg string, fields ...any)
	Error(ctx context.Context, msg string, fields ...any)
}

// MetricsHook provides optional callbacks for observability.
// All fields are nil-safe — only set the hooks you need.
type MetricsHook struct {
	OnQueryStart      func(ctx context.Context, node string, sql string)
	OnQueryEnd        func(ctx context.Context, node string, sql string, err error, duration time.Duration)
	OnRetry           func(ctx context.Context, node string, attempt int, err error)
	OnNodeDown        func(ctx context.Context, node string, err error)
	OnNodeUp          func(ctx context.Context, node string)
	OnReplicaFallback func(ctx context.Context, fromNode string, toNode string)
}

// nopLogger is a Logger that discards all output.
type nopLogger struct{}

func (nopLogger) Debug(context.Context, string, ...any) {}
func (nopLogger) Info(context.Context, string, ...any)  {}
func (nopLogger) Warn(context.Context, string, ...any)  {}
func (nopLogger) Error(context.Context, string, ...any) {}