// Package identity validates the stable identity invariants of D&D NPC lists.
package identity

import (
	"context"
	"fmt"

	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
	domainidentity "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/identity"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/npcs/diagnostics"
	npcshape "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/npcs/shape"
)

const (
	Key        = "normalize/dnd/npcs/identity"
	ReasonCode = "invalid_npc_identity"
	policy     = domainidentity.Policy
)

type Options struct{}
type Validator struct{}

var _ contracts.TypedValidator[dnd.NPCList] = (*Validator)(nil)
var _ pipeline.CheckpointFingerprintProvider = (*Validator)(nil)

func New(Options) *Validator      { return &Validator{} }
func (v *Validator) Name() string { return Key }

func (v *Validator) ExecutionClass() contracts.ExecutionClass {
	return contracts.ExecutionClassDeterministic
}

func (v *Validator) CheckpointFingerprints() []pipeline.CheckpointFingerprint {
	return []pipeline.CheckpointFingerprint{{Name: "policy", Value: policy}}
}

func (v *Validator) Validate(_ context.Context, req contracts.TypedValidationRequest[dnd.NPCList]) (contracts.ValidationResult, error) {
	if err := npcshape.Validate(req.Value); err != nil {
		return contracts.ValidationResult{Approved: true}, nil
	}
	identityIssues := domainidentity.ValidateRegistry(req.Value.NPCs)
	if len(identityIssues) == 0 {
		return contracts.ValidationResult{Approved: true}, nil
	}

	issues := make([]string, len(identityIssues))
	for index, issue := range identityIssues {
		location := fmt.Sprintf("npcs[%d]", issue.RecordIndex)
		if issue.AliasIndex >= 0 {
			location += fmt.Sprintf(".aliases[%d]", issue.AliasIndex)
		}
		issues[index] = fmt.Sprintf("%s %s: %s", location, issue.Code, diagnostics.Quote(issue.Value))
	}
	return contracts.ValidationResult{
		Approved:   false,
		ReasonCode: ReasonCode,
		Message:    diagnostics.Aggregate("invalid NPC identity", issues),
	}, nil
}

func Spec() pipeline.ValidatorSpec {
	return pipeline.ValidatorSpec{Key: Key, ExecutionClass: contracts.ExecutionClassDeterministic}
}

func Register(registry *pipeline.ValidatorRegistry) error {
	return pipeline.RegisterTypedValidatorBuilder(registry, dnd.NPCListKind, Spec(), validateOptions, func(request pipeline.BuildRequest) (contracts.TypedValidator[dnd.NPCList], error) {
		options, err := DecodeOptions(request.Options)
		if err != nil {
			return nil, err
		}
		return New(options), nil
	})
}

func DecodeOptions(options map[string]any) (Options, error) {
	if err := pipeline.RejectUnknownOptions(options); err != nil {
		return Options{}, err
	}
	return Options{}, nil
}

func validateOptions(options map[string]any) error { _, err := DecodeOptions(options); return err }