package domain

import (
	"errors"
	"slices"
	"strings"

	"git.cin.su/m/Assistant/contracts/work"
)

var ErrInvalidDevelopmentGate = errors.New("invalid governed self-development gate")
var ErrInsufficientExtensionEvidence = errors.New("insufficient repeated extension evidence")
var ErrInvalidExtensionProposal = errors.New("invalid extension proposal")

// BuildExtensionProposal deterministically turns a repeated evidence signal
// into a proposal. It retains every distinct evidence reference for lineage,
// while deduplicating signal keys so repeated reports do not create duplicate
// proposals. It never creates a task, mutates an implementation or grants
// authority.
func BuildExtensionProposal(evidence []work.ExtensionEvidence, request work.ExtensionProposalRequest) (work.ExtensionProposal, error) {
	owners := cleanStrings(request.AffectedOwners)
	contracts := cleanStrings(request.AffectedContracts)
	evaluation := cleanStrings(request.EvaluationPlan)
	alternatives := cleanStrings(request.Alternatives)
	assumptions := cleanStrings(request.Assumptions)
	if request.ID == "" || request.CreatedAt.IsZero() || strings.TrimSpace(request.DesiredOutcome) == "" || strings.TrimSpace(request.SmallestChangeLayer) == "" || strings.TrimSpace(request.RiskTier) == "" || strings.TrimSpace(request.RollbackPlan) == "" || len(owners) == 0 || len(contracts) == 0 || len(evaluation) == 0 || len(alternatives) == 0 || len(assumptions) == 0 {
		return work.ExtensionProposal{}, ErrInvalidExtensionProposal
	}
	refs := make([]string, 0, len(evidence))
	refSeen := make(map[string]struct{}, len(evidence))
	counts := make(map[string]int, len(evidence))
	keys := make([]string, 0, len(evidence))
	keySeen := make(map[string]struct{}, len(evidence))
	for _, item := range evidence {
		ref := strings.TrimSpace(item.Ref)
		key := strings.TrimSpace(item.SignalKey)
		if ref == "" || key == "" {
			return work.ExtensionProposal{}, ErrInvalidExtensionProposal
		}
		if _, ok := refSeen[ref]; !ok {
			refs = append(refs, ref)
			refSeen[ref] = struct{}{}
		}
		counts[key]++
		if _, ok := keySeen[key]; !ok {
			keys = append(keys, key)
			keySeen[key] = struct{}{}
		}
	}
	if len(refs) < 2 {
		return work.ExtensionProposal{}, ErrInsufficientExtensionEvidence
	}
	repeated := false
	for _, count := range counts {
		if count >= 2 {
			repeated = true
			break
		}
	}
	if !repeated {
		return work.ExtensionProposal{}, ErrInsufficientExtensionEvidence
	}
	return work.ExtensionProposal{
		ID: request.ID, Stage: work.ExtensionProposalProposed, EvidenceRefs: refs, DeduplicatedSignalKeys: keys,
		DesiredOutcome: strings.TrimSpace(request.DesiredOutcome), SmallestChangeLayer: strings.TrimSpace(request.SmallestChangeLayer),
		AffectedOwners: owners, AffectedContracts: contracts,
		RiskTier: strings.TrimSpace(request.RiskTier), EvaluationPlan: evaluation, Alternatives: alternatives,
		RollbackPlan: strings.TrimSpace(request.RollbackPlan), Assumptions: assumptions, CreatedAtUnixMillis: request.CreatedAt.UnixMilli(),
	}, nil
}

func cleanStrings(values []string) []string {
	result := make([]string, 0, len(values))
	seen := make(map[string]struct{}, len(values))
	for _, value := range values {
		value = strings.TrimSpace(value)
		if value == "" {
			continue
		}
		if _, ok := seen[value]; ok {
			continue
		}
		seen[value] = struct{}{}
		result = append(result, value)
	}
	return result
}

func AdvanceDevelopmentGate(current work.DevelopmentGate, next work.DevelopmentStage) (work.DevelopmentGate, error) {
	if err := ValidateDevelopmentGate(current); err != nil {
		return work.DevelopmentGate{}, err
	}
	if !validDevelopmentTransition(current.Stage, next) {
		return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
	}
	current.Stage = next
	switch next {
	case work.DevelopmentProposalCreated:
		if current.ProposalRef == "" {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	case work.DevelopmentTaskAdmitted:
		if current.TaskPacketRef == "" {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	case work.DevelopmentIsolated:
		if current.WorktreeRef == "" {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	case work.DevelopmentVerified:
		if current.VerificationEvidence == "" || len(current.VerifierRunRefs) == 0 || len(current.ProducerRunRefs) == 0 || sameRuns(current.ProducerRunRefs, current.VerifierRunRefs) {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	case work.DevelopmentCanary:
		if current.CanaryEvidence == "" {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	case work.DevelopmentPromoted:
		if current.PromotionRef == "" {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	case work.DevelopmentRolledBack:
		if current.RollbackRef == "" {
			return work.DevelopmentGate{}, ErrInvalidDevelopmentGate
		}
	}
	return current, nil
}

func ValidateDevelopmentGate(value work.DevelopmentGate) error {
	if value.ID == "" || len(value.EvidenceRefs) == 0 || !validDevelopmentStage(value.Stage) || duplicateStrings(value.EvidenceRefs) {
		return ErrInvalidDevelopmentGate
	}
	return nil
}

func validDevelopmentTransition(current, next work.DevelopmentStage) bool {
	if current == work.DevelopmentCanary && next == work.DevelopmentRolledBack {
		return true
	}
	if current == work.DevelopmentPromoted || current == work.DevelopmentRolledBack {
		return false
	}
	order := []work.DevelopmentStage{work.DevelopmentEvidenceCollected, work.DevelopmentProposalCreated, work.DevelopmentTaskAdmitted, work.DevelopmentIsolated, work.DevelopmentVerified, work.DevelopmentCanary, work.DevelopmentPromoted}
	index := func(value work.DevelopmentStage) int { return slices.Index(order, value) }
	return index(next) == index(current)+1
}

func validDevelopmentStage(value work.DevelopmentStage) bool {
	return slices.Contains([]work.DevelopmentStage{work.DevelopmentEvidenceCollected, work.DevelopmentProposalCreated, work.DevelopmentTaskAdmitted, work.DevelopmentIsolated, work.DevelopmentVerified, work.DevelopmentCanary, work.DevelopmentPromoted, work.DevelopmentRolledBack}, value)
}

func duplicateStrings(values []string) bool {
	seen := map[string]bool{}
	for _, value := range values {
		if value == "" || seen[value] {
			return true
		}
		seen[value] = true
	}
	return false
}

func sameRuns(left, right []work.AgentRunID) bool {
	if len(left) != len(right) {
		return false
	}
	for _, value := range left {
		if !slices.Contains(right, value) {
			return false
		}
	}
	return true
}