// Package identity validates the stable identity invariants of D&D NPC registries.
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/shared/diagnostics"
	npcshape "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/npcregistry/shape"
)

const (
	Key              = "normalize/dnd/npc-registry/identity"
	ReasonCode       = "invalid_npc_identity"
	policy           = domainidentity.Policy
	correctionPolicy = "dnd.npc_registry.validator.identity.v2"
)

type Options struct{}
type Validator struct{}

var _ contracts.TypedValidator[dnd.NPCRegistry] = (*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}, {Name: "correction_policy", Value: correctionPolicy}}
}

func (v *Validator) Validate(_ context.Context, req contracts.TypedValidationRequest[dnd.NPCRegistry]) (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))
	var corrections diagnostics.Corrections
	for index, issue := range identityIssues {
		location := fmt.Sprintf("npcs[%d]", issue.RecordIndex)
		issues[index] = fmt.Sprintf("%s %s: %s", location, issue.Code, diagnostics.Quote(issue.Value))
		if issue.RecordIndex < 0 || issue.RecordIndex >= len(req.Value.NPCs) {
			continue
		}
		npc := req.Value.NPCs[issue.RecordIndex]
		corrections.Add(string(issue.Code), npcIdentityCorrection(issue.Code), fmt.Sprintf("Affected NPC %s %s.", diagnostics.Quote(npc.Name), diagnostics.SourceRange(npc.SourceRefs)))
	}
	return contracts.ValidationResult{
		Approved:           false,
		ReasonCode:         ReasonCode,
		Message:            diagnostics.Aggregate("invalid NPC identity", issues),
		CorrectionGuidance: corrections.Guidance("Correct the duplicate-group proposals and return the complete replacement proposal response"),
	}, nil
}

func npcIdentityCorrection(code domainidentity.IssueCode) string {
	switch code {
	case domainidentity.IssueEmptyCanonicalName:
		return "Select a canonical proposal member with a nonblank, transcript-supported proper NPC name."
	case domainidentity.IssueDuplicateCanonical:
		return "Put duplicate mentions of the same NPC in one proposal group and select one transcript-supported canonical member."
	case domainidentity.IssueInvalidID, domainidentity.IssueIDMismatch:
		return "Revise the proposal so its canonical NPC member has a valid transcript-supported name; Notarius derives durable identity without model input."
	case domainidentity.IssueDuplicateID:
		return "Do not use proposals that collapse distinct NPCs into one canonical identity; group only records that describe the same NPC."
	default:
		return "Revise the duplicate-group proposal so every canonical NPC is transcript-supported and distinct."
	}
}

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

func Register(registry *pipeline.ValidatorRegistry) error {
	return pipeline.RegisterTypedValidatorBuilder(registry, dnd.NPCRegistryKind, Spec(), validateOptions, func(request pipeline.BuildRequest) (contracts.TypedValidator[dnd.NPCRegistry], 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 }