package validators

import (
	"fmt"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
)

const (
	ReasonApproved = "approved"
)

func Approved(candidateIndex int) contracts.ValidationDecision {
	return contracts.ValidationDecision{
		CandidateIndex: candidateIndex,
		Approved:       true,
		ReasonCode:     ReasonApproved,
		Message:        ReasonApproved,
	}
}

func Rejected(candidateIndex int, reasonCode string, message string) contracts.ValidationDecision {
	return contracts.ValidationDecision{
		CandidateIndex: candidateIndex,
		Approved:       false,
		ReasonCode:     strings.TrimSpace(reasonCode),
		Message:        strings.TrimSpace(message),
	}
}

func EnforceDecisionCardinality(candidates []artifacts.Candidate, decisions []contracts.ValidationDecision) error {
	if len(candidates) != len(decisions) {
		return fmt.Errorf("validator returned %d decisions for %d candidates", len(decisions), len(candidates))
	}

	expected := make(map[int]struct{}, len(candidates))
	for _, candidate := range candidates {
		if _, ok := expected[candidate.Index]; ok {
			return fmt.Errorf("candidate index %d is duplicated", candidate.Index)
		}
		expected[candidate.Index] = struct{}{}
	}

	seen := make(map[int]struct{}, len(decisions))
	for _, decision := range decisions {
		if _, ok := expected[decision.CandidateIndex]; !ok {
			return fmt.Errorf("validator returned decision for unknown candidate index %d", decision.CandidateIndex)
		}
		if _, ok := seen[decision.CandidateIndex]; ok {
			return fmt.Errorf("validator returned duplicate decision for candidate index %d", decision.CandidateIndex)
		}
		seen[decision.CandidateIndex] = struct{}{}
	}

	for candidateIndex := range expected {
		if _, ok := seen[candidateIndex]; !ok {
			return fmt.Errorf("validator did not return decision for candidate index %d", candidateIndex)
		}
	}

	return nil
}