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"
	spellshape "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/spells/shape"
)

const Key = "extract/dnd/spells/source_relatedness"
const WarningReasonCode = "spell_not_near_source"

type Options struct{}
type Validator struct{}
type legacyValidator struct{ codec decoder }
type decoder interface {
	DecodeCandidate([]byte) (dnd.SpellList, error)
}

var _ contracts.TypedValidator[dnd.SpellList] = (*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) Validate(_ context.Context, req contracts.TypedValidationRequest[dnd.SpellList]) (contracts.ValidationResult, error) {
	if err := spellshape.Validate(req.Value); err != nil {
		return contracts.ValidationResult{Approved: true}, nil
	}
	var warnings []contracts.Warning
	for spellIndex, spell := range req.Value.SpellCasts {
		if !spellAppearsInCitedText(req.Source, spell) {
			warnings = append(warnings, contracts.Warning{Scope: fmt.Sprintf("spell_casts[%d]", spellIndex), ReasonCode: WarningReasonCode, Message: fmt.Sprintf("spell %q was not found in cited source text", strings.TrimSpace(spell.Spell))})
		}
	}
	return contracts.ValidationResult{Approved: true, Warnings: warnings}, nil
}
func (v *legacyValidator) Name() string { return Key }
func (v *legacyValidator) ExecutionClass() contracts.ExecutionClass {
	return contracts.ExecutionClassDeterministic
}
func (v *legacyValidator) Validate(ctx context.Context, req contracts.ValidationRequest) (contracts.ValidationResult, error) {
	value, err := v.codec.DecodeCandidate(req.Payload.Content)
	if err != nil {
		return contracts.ValidationResult{Approved: true}, nil
	}
	if err := spellshape.Validate(value); err != nil {
		return contracts.ValidationResult{Approved: true}, nil
	}
	return New(Options{}).Validate(ctx, contracts.TypedValidationRequest[dnd.SpellList]{Source: req.Source, Value: value})
}
func spellAppearsInCitedText(doc *source.SourceDocument, spell dnd.SpellCast) bool {
	name := strings.ToLower(strings.TrimSpace(spell.Spell))
	if name == "" {
		return true
	}
	for _, ref := range spell.SourceRefs {
		if text, ok := citedText(doc, ref); ok && strings.Contains(strings.ToLower(text), name) {
			return true
		}
	}
	return false
}
func citedText(doc *source.SourceDocument, ref source.SourceRef) (string, bool) {
	if doc == nil {
		return "", false
	}
	start, ok := source.UnitIndex(doc, ref.StartUnitID)
	if !ok {
		return "", false
	}
	end, ok := source.UnitIndex(doc, ref.EndUnitID)
	if !ok || start > end {
		return "", false
	}
	var b strings.Builder
	for i := start; i <= end; i++ {
		if b.Len() > 0 {
			b.WriteByte('\n')
		}
		b.WriteString(doc.Units[i].Text)
	}
	return b.String(), true
}
func Spec() pipeline.ValidatorSpec {
	return pipeline.ValidatorSpec{Key: Key, ExecutionClass: contracts.ExecutionClassDeterministic}
}
func Register(registry *pipeline.ValidatorRegistry) error {
	return pipeline.RegisterTypedValidatorBuilder(registry, dnd.SpellListKind, Spec(), validateOptions, func(request pipeline.BuildRequest) (contracts.TypedValidator[dnd.SpellList], error) {
		options, err := DecodeOptions(request.Options)
		if err != nil {
			return nil, err
		}
		return New(options), nil
	})
}
func RegisterLegacy(registry *pipeline.ValidatorRegistry, codec decoder) error {
	if codec == nil {
		return fmt.Errorf("spell source relatedness validator codec must not be nil")
	}
	return registry.RegisterLegacyRawBuilderWithSpec(Spec(), validateOptions, func(request pipeline.BuildRequest) (contracts.LegacyRawValidator, error) {
		if _, err := DecodeOptions(request.Options); err != nil {
			return nil, err
		}
		return &legacyValidator{codec: codec}, 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 }