package sourcerelatedness

import (
	"context"
	"fmt"
	"strings"
	"unicode"
	"unicode/utf8"

	"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"
	combatshape "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/combatturns/shape"
)

const (
	Key               = "extract/dnd/combat-turns/source_relatedness"
	WarningReasonCode = "combat_turn_not_near_source"
	policy            = "dnd.combat_turns.validator.source_relatedness.v1"
)

type Options struct{}
type Validator struct{}

var _ contracts.TypedValidator[dnd.CombatTurnList] = (*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.CombatTurnList]) (contracts.ValidationResult, error) {
	if combatshape.Validate(req.Value) != nil || !sourceRefsValid(req.Source, req.Value) {
		return contracts.ValidationResult{Approved: true}, nil
	}

	warnings := make([]contracts.Warning, 0)
	for turnIndex, turn := range req.Value.CombatTurns {
		citedText := citedTextKey(req.Source, turn.SourceRefs)
		issues := make([]string, 0)
		if !actorAppearsInCitedText(citedText, turn.Actor) {
			issues = append(issues, fmt.Sprintf("actor %s was not found in cited source text", diagnostics.Quote(turn.Actor)))
		}
		for actionIndex, action := range turn.Actions {
			if !declarationAppearsInCitedText(citedText, action.Declaration) {
				issues = append(issues, fmt.Sprintf("action %d declaration %s was not found in cited source text", actionIndex, diagnostics.Quote(action.Declaration)))
			}
		}
		if len(issues) == 0 {
			continue
		}
		warnings = append(warnings, contracts.Warning{
			Scope:      fmt.Sprintf("combat_turns[%d]", turnIndex),
			ReasonCode: WarningReasonCode,
			Message:    diagnostics.Aggregate("combat turn not near source", issues),
		})
	}
	return contracts.ValidationResult{Approved: true, Warnings: warnings}, nil
}

func sourceRefsValid(doc *source.SourceDocument, value dnd.CombatTurnList) bool {
	for _, turn := range value.CombatTurns {
		for _, ref := range turn.SourceRefs {
			if source.ValidateRef(doc, ref) != nil {
				return false
			}
		}
	}
	return true
}

func citedTextKey(doc *source.SourceDocument, refs []source.SourceRef) string {
	if doc == nil {
		return ""
	}
	included := make([]bool, len(doc.Units))
	for _, ref := range refs {
		start, _ := source.UnitIndex(doc, ref.StartUnitID)
		end, _ := source.UnitIndex(doc, ref.EndUnitID)
		for index := start; index <= end && index < len(included); index++ {
			included[index] = true
		}
	}
	parts := make([]string, 0)
	for index, unit := range doc.Units {
		if included[index] {
			parts = append(parts, unit.Text)
		}
	}
	return identity.ComparisonKey(strings.Join(parts, " "))
}

func actorAppearsInCitedText(citedText string, actor string) bool {
	key := identity.ComparisonKey(actor)
	return key != "" && strings.Contains(citedText, key)
}

func declarationAppearsInCitedText(citedText string, declaration string) bool {
	citedTokens := tokenSet(citedText)
	for _, token := range comparisonTokens(declaration) {
		if utf8.RuneCountInString(token) >= 4 {
			if _, ok := citedTokens[token]; ok {
				return true
			}
		}
	}
	return false
}

func comparisonTokens(value string) []string {
	value = identity.ComparisonKey(value)
	if value == "" {
		return nil
	}
	return strings.FieldsFunc(value, func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsDigit(r) })
}

func tokenSet(value string) map[string]struct{} {
	tokens := comparisonTokens(value)
	set := make(map[string]struct{}, len(tokens))
	for _, token := range tokens {
		set[token] = struct{}{}
	}
	return set
}

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

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