package generator

import (
	"fmt"
	"strings"
)

// GenerateMapper generates the mapper snippet (without imports)
func GenerateMapper(ctx *Context) (string, error) {
	var b strings.Builder

	// Mapper registration (snippet only, no imports)
	b.WriteString("    mapper_registry.map_imperatively(\n")
	b.WriteString(fmt.Sprintf("        class_=%s,\n", ctx.EntityName))
	b.WriteString(fmt.Sprintf("        local_table=%s,\n", ctx.TableConstant))
	b.WriteString("        properties={\n")

	// Generate relationships for all foreign keys
	fkRelationships := make(map[string][]string) // entity -> []column_names

	for _, fk := range ctx.TableInfo.ForeignKeys {
		relationName := GetRelationshipName(fk.ColumnName)
		entityName := GetRelationshipEntityName(fk.ForeignTableName)

		// Group by entity name to handle multiple FKs to same table
		fkRelationships[entityName] = append(fkRelationships[entityName], fk.ColumnName)

		if len(fkRelationships[entityName]) == 1 {
			// First FK to this table
			b.WriteString(fmt.Sprintf("            \"%s\": relationship(\n", relationName))
			b.WriteString(fmt.Sprintf("                %s, lazy=relationship_loading_strategy.value\n", entityName))
		} else {
			// Multiple FKs to same table, need to specify foreign_keys
			b.WriteString(fmt.Sprintf("            \"%s\": relationship(\n", relationName))
			b.WriteString(fmt.Sprintf("                %s,\n", entityName))
			b.WriteString("                lazy=relationship_loading_strategy.value,\n")
			b.WriteString(fmt.Sprintf("                foreign_keys=%s.columns.%s,\n",
				ctx.TableConstant, fk.ColumnName))
		}

		b.WriteString("            ),\n")
	}

	b.WriteString("        },\n")
	b.WriteString("    )\n")

	return b.String(), nil
}