package domain

import (
	"errors"
	"strings"

	"git.cin.su/m/Assistant/contracts/epistemics"
	"git.cin.su/m/Assistant/platform/ids"
)

var ErrInvalidExperience = errors.New("invalid experience")
var ErrInvalidExpectation = errors.New("invalid expectation")
var ErrInvalidReflectionCandidate = errors.New("invalid reflection candidate")

func NewSystemExpectation(value epistemics.SystemExpectation) (epistemics.SystemExpectation, error) {
	if value.ID == "" {
		id, err := ids.New()
		if err != nil {
			return epistemics.SystemExpectation{}, err
		}
		value.ID = epistemics.SystemExpectationID(id)
	}
	if value.OriginalIntentID == "" || value.SourceUtteranceID == "" || value.ExpectedOutcome == "" ||
		strings.TrimSpace(value.ExpectedEffect) == "" || value.ConfidenceMillis < 0 || value.ConfidenceMillis > 1000 ||
		value.RecordedAtUnixMillis < 1 {
		return epistemics.SystemExpectation{}, ErrInvalidExpectation
	}
	if value.EvidenceBasis == nil {
		value.EvidenceBasis = []epistemics.EvidenceRef{}
	}
	return value, nil
}

func NewExperienceRecord(value epistemics.ExperienceRecord) (epistemics.ExperienceRecord, error) {
	if value.ID == "" {
		id, err := ids.New()
		if err != nil {
			return epistemics.ExperienceRecord{}, err
		}
		value.ID = epistemics.ExperienceRecordID(id)
	}
	if value.SourceKind == "" || value.OriginalIntentID == "" || value.SourceUtteranceID == "" ||
		value.HelpMethod == "" || value.ExpectedOutcome == "" || value.ActualOutcome == "" ||
		value.ConfidenceMillis < 0 || value.ConfidenceMillis > 1000 || value.RecordedAtUnixMillis < 1 {
		return epistemics.ExperienceRecord{}, ErrInvalidExperience
	}
	if value.ContextRefs == nil {
		value.ContextRefs = []epistemics.ContextRef{}
	}
	if value.VerificationEvidence == nil {
		value.VerificationEvidence = []epistemics.EvidenceRef{}
	}
	return value, nil
}

func ReflectionForExperience(value epistemics.ExperienceRecord) (epistemics.ReflectionCandidate, bool, error) {
	normalized, err := NewExperienceRecord(value)
	if err != nil {
		return epistemics.ReflectionCandidate{}, false, err
	}
	value = normalized
	trigger, ok := reflectionTrigger(value)
	if !ok {
		return epistemics.ReflectionCandidate{}, false, nil
	}
	id, err := ids.New()
	if err != nil {
		return epistemics.ReflectionCandidate{}, false, err
	}
	candidate := epistemics.ReflectionCandidate{
		ID:                   epistemics.ReflectionCandidateID(id),
		Trigger:              trigger,
		State:                epistemics.ReflectionCandidateOpen,
		SourceExperienceID:   value.ID,
		OriginalIntentID:     value.OriginalIntentID,
		SourceUtteranceID:    value.SourceUtteranceID,
		Summary:              reflectionSummary(trigger, value),
		EvidenceRefs:         reflectionEvidence(value),
		RequiresCognition:    reflectionNeedsCognition(trigger),
		RecordedAtUnixMillis: value.RecordedAtUnixMillis,
		Revision:             1,
	}
	if err := ValidateReflectionCandidate(candidate); err != nil {
		return epistemics.ReflectionCandidate{}, false, err
	}
	return candidate, true, nil
}

func reflectionNeedsCognition(trigger epistemics.ReflectionTriggerKind) bool {
	switch trigger {
	case epistemics.ReflectionUserCorrection, epistemics.ReflectionUnexpectedOutcome, epistemics.ReflectionFailure, epistemics.ReflectionLowConfidence, epistemics.ReflectionContradiction, epistemics.ReflectionRepeatedDegradation:
		return true
	default:
		return false
	}
}

func ValidateReflectionCandidate(value epistemics.ReflectionCandidate) error {
	if value.ID == "" || value.Trigger == "" || value.State == "" || value.SourceExperienceID == "" ||
		value.OriginalIntentID == "" || value.SourceUtteranceID == "" || strings.TrimSpace(value.Summary) == "" ||
		value.RecordedAtUnixMillis < 1 || value.Revision < 1 {
		return ErrInvalidReflectionCandidate
	}
	if value.EvidenceRefs == nil {
		value.EvidenceRefs = []epistemics.EvidenceRef{}
	}
	return nil
}

func FastPathDeclineExperience(intent epistemics.OriginalIntentRef, utterance epistemics.SourceUtteranceRef, skill epistemics.SkillRef, reason string, millis int64) (epistemics.ExperienceRecord, error) {
	outcome := epistemics.OutcomeNotApplicable
	switch reason {
	case string(epistemics.OutcomeLowConfidence):
		outcome = epistemics.OutcomeLowConfidence
	case string(epistemics.OutcomeOutOfDistribution):
		outcome = epistemics.OutcomeOutOfDistribution
	case string(epistemics.OutcomeConflict):
		outcome = epistemics.OutcomeConflict
	case string(epistemics.OutcomeStale):
		outcome = epistemics.OutcomeStale
	}
	return NewExperienceRecord(epistemics.ExperienceRecord{
		SourceKind:           epistemics.ExperienceSourceInteraction,
		OriginalIntentID:     intent,
		SourceUtteranceID:    utterance,
		HelpMethod:           epistemics.HelpMethodDeterministicFastPath,
		SkillRef:             skill,
		ExpectedOutcome:      epistemics.OutcomeSuccess,
		ActualOutcome:        outcome,
		OutcomeDetail:        "fast path declined and returned to broader reasoning: " + reason,
		ConfidenceMillis:     1000,
		RecordedAtUnixMillis: millis,
		VerificationEvidence: []epistemics.EvidenceRef{"fast-path-decline"},
	})
}

func reflectionTrigger(value epistemics.ExperienceRecord) (epistemics.ReflectionTriggerKind, bool) {
	switch value.ActualOutcome {
	case epistemics.OutcomeUserCorrected:
		return epistemics.ReflectionUserCorrection, true
	case epistemics.OutcomeUnexpected:
		return epistemics.ReflectionUnexpectedOutcome, true
	case epistemics.OutcomeFailed:
		return epistemics.ReflectionFailure, true
	case epistemics.OutcomeLowConfidence:
		return epistemics.ReflectionLowConfidence, true
	case epistemics.OutcomeOutOfDistribution, epistemics.OutcomeConflict, epistemics.OutcomeStale:
		return epistemics.ReflectionSampledAudit, true
	default:
		return "", false
	}
}

func reflectionSummary(trigger epistemics.ReflectionTriggerKind, value epistemics.ExperienceRecord) string {
	if value.OutcomeDetail != "" {
		return string(trigger) + ": " + value.OutcomeDetail
	}
	return string(trigger) + " for experience " + string(value.ID)
}

func reflectionEvidence(value epistemics.ExperienceRecord) []epistemics.EvidenceRef {
	refs := append([]epistemics.EvidenceRef{}, value.VerificationEvidence...)
	if value.HumanResponseRef != "" {
		refs = append(refs, epistemics.EvidenceRef("continuity:human-response:"+value.HumanResponseRef))
	}
	if value.CorrectionUtteranceID != "" {
		refs = append(refs, epistemics.EvidenceRef("interaction:correction:"+value.CorrectionUtteranceID))
	}
	if value.CapabilityUsageObservationRef != "" {
		refs = append(refs, epistemics.EvidenceRef("capability:usage:"+value.CapabilityUsageObservationRef))
	}
	if value.CapabilityGapRef != "" {
		refs = append(refs, epistemics.EvidenceRef("capability:gap:"+value.CapabilityGapRef))
	}
	return refs
}