package domain

import (
	"errors"
	"fmt"
	"strings"
)

const maxOutputRepairAttempts = 3

// ValidateOutputContract validates source-neutral output-contract invariants.
func ValidateOutputContract(contract OutputContract) error {
	switch contract.Format {
	case FormatText, FormatMarkdown, FormatJSON:
	default:
		return fmt.Errorf("invalid output format: %q", contract.Format)
	}

	switch contract.ValidationMode {
	case ValidationNone, ValidationBasic, ValidationJSON, ValidationJSONSchema:
	default:
		return fmt.Errorf("invalid validation mode: %q", contract.ValidationMode)
	}

	if contract.ValidationMode == ValidationJSONSchema && strings.TrimSpace(contract.SchemaPath) == "" {
		return errors.New("schema_path is required when validation_mode is json_schema")
	}
	if contract.RepairAttempts < 0 {
		return errors.New("repair_attempts must be greater than or equal to 0")
	}
	if contract.RepairAttempts > maxOutputRepairAttempts {
		return fmt.Errorf("repair_attempts must be less than or equal to %d", maxOutputRepairAttempts)
	}
	if contract.ValidationMode == ValidationNone && contract.RepairAttempts > 0 {
		return errors.New("repair_attempts requires basic, json, or json_schema validation")
	}
	return nil
}