package sourcerelatedness

import (
	"context"
	"fmt"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
	"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/npcs/shape"
)

const (
	Key               = "extract/dnd/npcs/source_relatedness"
	WarningReasonCode = "npc_not_near_source"
	policy            = "dnd.npcs.validator.source_relatedness.v1"
)

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
	}
	var warnings []contracts.Warning
	for npcIndex, npc := range req.Value.NPCs {
		if npcAppearsInCitedText(req.Source, npc) {
			continue
		}
		warnings = append(warnings, contracts.Warning{
			Scope:      fmt.Sprintf("npcs[%d]", npcIndex),
			ReasonCode: WarningReasonCode,
			Message:    fmt.Sprintf("NPC %s was not found in cited source text", diagnostics.Quote(npc.Name)),
		})
	}
	return contracts.ValidationResult{Approved: true, Warnings: warnings}, nil
}

func npcAppearsInCitedText(doc *source.SourceDocument, npc dnd.NPC) bool {
	cited := citedTextKey(doc, npc.SourceRefs)
	if cited == "" {
		return false
	}
	if strings.Contains(cited, identity.ComparisonKey(npc.Name)) {
		return true
	}
	for _, alias := range npc.Aliases {
		if strings.Contains(cited, identity.ComparisonKey(alias)) {
			return true
		}
	}
	return false
}

func citedTextKey(doc *source.SourceDocument, refs []source.SourceRef) string {
	if doc == nil {
		return ""
	}
	var builder strings.Builder
	for _, ref := range refs {
		if err := source.ValidateRef(doc, ref); err != nil {
			continue
		}
		start, _ := source.UnitIndex(doc, ref.StartUnitID)
		end, _ := source.UnitIndex(doc, ref.EndUnitID)
		for index := start; index <= end; index++ {
			if builder.Len() > 0 {
				builder.WriteByte(' ')
			}
			builder.WriteString(doc.Units[index].Text)
		}
	}
	return identity.ComparisonKey(builder.String())
}

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 }