// Package gormkit contains reusable GORM integration helpers.
package gormkit

import (
	"context"
	"database/sql/driver"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/logger"
	"gorm.io/gorm/schema"
)

// JSON is a portable JSON value for GORM models. It selects a native JSON
// column where the driver supports one and a textual fallback elsewhere.
type JSON []byte

func (JSON) GormDataType() string { return "json" }
func (JSON) GormDBDataType(db *gorm.DB, _ *schema.Field) string {
	switch db.Dialector.Name() {
	case "mysql", "sqlite":
		return "JSON"
	case "postgres":
		return "JSONB"
	case "sqlserver":
		return "NVARCHAR(MAX)"
	case "oracle":
		return "CLOB"
	default:
		return "TEXT"
	}
}
func (j JSON) Value() (driver.Value, error) {
	if len(j) == 0 {
		return nil, nil
	}
	return string(j), nil
}
func (j *JSON) Scan(value any) error {
	switch raw := value.(type) {
	case nil:
		*j = nil
	case []byte:
		*j = append((*j)[:0], raw...)
	case string:
		*j = append((*j)[:0], raw...)
	default:
		return fmt.Errorf("cannot scan JSON from %T", value)
	}
	return nil
}

// Logger forwards GORM diagnostics through an application slog logger.
type Logger struct {
	logger        *slog.Logger
	slowThreshold time.Duration
	level         logger.LogLevel
}

func NewLogger(log *slog.Logger, level logger.LogLevel) *Logger {
	if log == nil {
		log = slog.New(slog.NewTextHandler(io.Discard, nil))
	}
	return &Logger{logger: log, slowThreshold: 200 * time.Millisecond, level: level}
}

func (g *Logger) LogMode(level logger.LogLevel) logger.Interface {
	next := *g
	next.level = level
	return &next
}

func (g *Logger) Info(ctx context.Context, message string, args ...any) {
	g.logger.InfoContext(ctx, fmt.Sprintf(message, args...), "mod", "sql", "gorm_logger", true)
}

func (g *Logger) Warn(ctx context.Context, message string, args ...any) {
	g.logger.WarnContext(ctx, fmt.Sprintf(message, args...), "mod", "sql", "gorm_logger", true)
}

func (g *Logger) Error(ctx context.Context, message string, args ...any) {
	g.logger.ErrorContext(ctx, fmt.Sprintf(message, args...), "mod", "sql", "gorm_logger", true)
}

func (g *Logger) Trace(ctx context.Context, begin time.Time, query func() (string, int64), queryErr error) {
	if g.level <= logger.Silent {
		return
	}
	elapsed := time.Since(begin)
	sql, rows := query()
	fields := []any{"mod", "sql", "gorm_logger", true, "sql", sql, "rows", rows, "elapsed_ms", elapsed.Milliseconds()}
	switch {
	case queryErr != nil && g.level >= logger.Error && !errors.Is(queryErr, logger.ErrRecordNotFound):
		fields = append(fields, "error", queryErr)
		g.logger.ErrorContext(ctx, "SQL 执行错误", fields...)
	case elapsed > g.slowThreshold && g.level >= logger.Warn:
		g.logger.WarnContext(ctx, "SQL 慢查询", fields...)
	case g.level >= logger.Info:
		g.logger.InfoContext(ctx, "SQL", fields...)
	}
}