package app

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"strconv"
	"strings"

	"sub2api-cn-relay-manager/internal/batch"
	"sub2api-cn-relay-manager/internal/pack"
	"sub2api-cn-relay-manager/internal/probe"
	"sub2api-cn-relay-manager/internal/store/sqlite"
)

type batchImportReuseInspector struct {
	store        *sqlite.DB
	hostRow      sqlite.Host
	currentRunID string
}

func (i batchImportReuseInspector) Inspect(ctx context.Context, input batch.ReuseLookupInput) (batch.ReuseLookupResult, error) {
	if i.store == nil {
		return batch.ReuseLookupResult{}, fmt.Errorf("store is required")
	}
	if i.hostRow.ID <= 0 {
		return batch.ReuseLookupResult{}, fmt.Errorf("host row is required")
	}

	if reuse, ok, err := i.lookupPriorRunItem(ctx, input); err != nil {
		return batch.ReuseLookupResult{}, err
	} else if ok {
		return reuse, nil
	}

	return i.lookupLegacyImportBatch(ctx, input)
}

func (i batchImportReuseInspector) lookupPriorRunItem(ctx context.Context, input batch.ReuseLookupInput) (batch.ReuseLookupResult, bool, error) {
	runs, err := i.store.ImportRuns().List(ctx, 1000)
	if err != nil {
		return batch.ReuseLookupResult{}, false, err
	}

	for _, run := range runs {
		if strings.TrimSpace(run.HostID) != strings.TrimSpace(i.hostRow.HostID) {
			continue
		}
		if strings.TrimSpace(run.RunID) == strings.TrimSpace(i.currentRunID) {
			continue
		}
		items, err := i.store.ImportRunItems().ListByRunID(ctx, run.RunID)
		if err != nil {
			return batch.ReuseLookupResult{}, false, err
		}
		for _, item := range items {
			if strings.TrimSpace(item.ProviderID) != strings.TrimSpace(input.ProviderID) {
				continue
			}
			if !apiKeyFingerprintMatches(item.APIKeyFingerprint, input.APIKeyFingerprint) {
				continue
			}
			return i.reuseFromRunItem(ctx, item)
		}
	}

	return batch.ReuseLookupResult{}, false, nil
}

func (i batchImportReuseInspector) reuseFromRunItem(ctx context.Context, item sqlite.ImportRunItem) (batch.ReuseLookupResult, bool, error) {
	modelMapping, err := i.loadExistingModelMapping(ctx, item.ProviderID)
	if err != nil {
		return batch.ReuseLookupResult{}, false, err
	}

	reusedAccountID := int64(0)
	if item.AccountID != nil {
		reusedAccountID = *item.AccountID
	} else if item.ReusedFromAccountID != nil {
		reusedAccountID = *item.ReusedFromAccountID
	}

	state := strings.TrimSpace(item.MatchedAccountState)
	if state == "" {
		state = string(batch.MatchedAccountStateNone)
	}

	return batch.ReuseLookupResult{
		ProviderMatched:          true,
		ExistingProviderID:       strings.TrimSpace(item.ProviderID),
		ExistingAccessStatus:     normalizeRunItemAccessStatus(item.AccessStatus),
		ExistingCanonicalFamilys: parseStringArrayJSON(item.CanonicalFamiliesJSON),
		MatchedAccountID:         reusedAccountID,
		MatchedAccountState:      batch.MatchedAccountState(state),
		ExistingModelMapping:     modelMapping,
		LegacyBatchID:            item.LegacyBatchID,
	}, true, nil
}

func (i batchImportReuseInspector) lookupLegacyImportBatch(ctx context.Context, input batch.ReuseLookupInput) (batch.ReuseLookupResult, error) {
	providers, err := i.lookupLegacyProviders(ctx, input)
	if err != nil {
		return batch.ReuseLookupResult{}, err
	}

	type candidate struct {
		provider  sqlite.Provider
		batch     sqlite.ImportBatch
		item      sqlite.ImportBatchItem
		resources []sqlite.ManagedResource
	}

	var best *candidate
	for _, providerRow := range providers {
		batches, err := i.store.ImportBatches().ListByProviderIDAndHostID(ctx, providerRow.ID, i.hostRow.ID)
		if err != nil {
			return batch.ReuseLookupResult{}, err
		}
		for _, batchRow := range batches {
			items, err := i.store.ImportBatchItems().GetByBatchID(ctx, batchRow.ID)
			if err != nil {
				return batch.ReuseLookupResult{}, err
			}
			for _, item := range items {
				if !apiKeyFingerprintMatches(item.KeyFingerprint, input.APIKeyFingerprint) {
					continue
				}
				resources, err := i.store.ManagedResources().GetByBatchID(ctx, batchRow.ID)
				if err != nil {
					return batch.ReuseLookupResult{}, err
				}
				best = &candidate{
					provider:  providerRow,
					batch:     batchRow,
					item:      item,
					resources: resources,
				}
				break
			}
			if best != nil && best.batch.ID == batchRow.ID {
				break
			}
		}
		if best != nil {
			break
		}
	}

	if best == nil {
		return batch.ReuseLookupResult{}, nil
	}

	modelMapping, err := providerModelMapping(best.provider)
	if err != nil {
		return batch.ReuseLookupResult{}, err
	}
	canonicalFamilies, err := providerCanonicalFamilies(best.provider)
	if err != nil {
		return batch.ReuseLookupResult{}, err
	}

	accountHostID, err := accountIDFromProbeSummary(best.item.ProbeSummaryJSON)
	if err != nil {
		return batch.ReuseLookupResult{}, err
	}

	return batch.ReuseLookupResult{
		ProviderMatched:          true,
		ExistingProviderID:       strings.TrimSpace(best.provider.ProviderID),
		ExistingAccessStatus:     normalizeLegacyBatchAccessStatus(best.batch.AccessStatus),
		ExistingCanonicalFamilys: canonicalFamilies,
		MatchedAccountID:         resolveManagedAccountNumericID(accountHostID, best.resources),
		MatchedAccountState:      normalizeLegacyMatchedAccountState(best.item.AccountStatus, best.batch.AccessStatus),
		ExistingModelMapping:     modelMapping,
		LegacyBatchID:            int64Ptr(best.batch.ID),
	}, nil
}

func (i batchImportReuseInspector) lookupLegacyProviders(ctx context.Context, input batch.ReuseLookupInput) ([]sqlite.Provider, error) {
	seen := make(map[int64]struct{})
	providers := make([]sqlite.Provider, 0)
	appendUnique := func(rows []sqlite.Provider) {
		for _, row := range rows {
			if _, ok := seen[row.ID]; ok {
				continue
			}
			seen[row.ID] = struct{}{}
			providers = append(providers, row)
		}
	}

	if strings.TrimSpace(input.ProviderID) != "" {
		rows, err := i.store.Providers().ListByProviderID(ctx, input.ProviderID)
		if err != nil {
			return nil, err
		}
		appendUnique(rows)
	}

	if strings.TrimSpace(input.BaseURL) != "" {
		rows, err := i.store.Providers().ListByBaseURL(ctx, strings.TrimSpace(input.BaseURL))
		if err != nil {
			return nil, err
		}
		appendUnique(rows)
	}

	return providers, nil
}

func (i batchImportReuseInspector) loadExistingModelMapping(ctx context.Context, providerID string) (map[string]string, error) {
	providers, err := i.store.Providers().ListByProviderID(ctx, providerID)
	if err != nil {
		return nil, err
	}
	if len(providers) == 0 {
		return nil, nil
	}

	for idx := len(providers) - 1; idx >= 0; idx-- {
		providerRow := providers[idx]
		batchRow, err := i.store.ImportBatches().GetLatestByProviderIDAndHostID(ctx, providerRow.ID, i.hostRow.ID)
		if err != nil {
			if err == sql.ErrNoRows {
				continue
			}
			return nil, err
		}
		if batchRow.ID <= 0 {
			continue
		}
		return providerModelMapping(providerRow)
	}

	return nil, nil
}

func providerModelMapping(providerRow sqlite.Provider) (map[string]string, error) {
	type channelTemplatePayload struct {
		ModelMapping map[string]string `json:"model_mapping"`
	}

	var manifest pack.ProviderManifest
	if strings.TrimSpace(providerRow.ManifestJSON) != "" && strings.TrimSpace(providerRow.ManifestJSON) != "{}" {
		if err := json.Unmarshal([]byte(providerRow.ManifestJSON), &manifest); err != nil {
			return nil, fmt.Errorf("decode provider manifest for %q: %w", providerRow.ProviderID, err)
		}
		if len(manifest.ChannelTemplate.ModelMapping) > 0 {
			return cloneStringMap(manifest.ChannelTemplate.ModelMapping), nil
		}
	}

	if strings.TrimSpace(providerRow.ChannelTemplateJSON) != "" && strings.TrimSpace(providerRow.ChannelTemplateJSON) != "{}" {
		var payload channelTemplatePayload
		if err := json.Unmarshal([]byte(providerRow.ChannelTemplateJSON), &payload); err != nil {
			return nil, fmt.Errorf("decode provider channel template for %q: %w", providerRow.ProviderID, err)
		}
		return cloneStringMap(payload.ModelMapping), nil
	}

	return map[string]string{}, nil
}

func providerCanonicalFamilies(providerRow sqlite.Provider) ([]string, error) {
	models := make([]string, 0)

	var manifest pack.ProviderManifest
	if strings.TrimSpace(providerRow.ManifestJSON) != "" && strings.TrimSpace(providerRow.ManifestJSON) != "{}" {
		if err := json.Unmarshal([]byte(providerRow.ManifestJSON), &manifest); err != nil {
			return nil, fmt.Errorf("decode provider manifest for %q: %w", providerRow.ProviderID, err)
		}
		models = append(models, manifest.DefaultModels...)
		for _, mapped := range manifest.ChannelTemplate.ModelMapping {
			models = append(models, mapped)
		}
	}

	models = append(models, parseStringArrayJSON(providerRow.DefaultModelsJSON)...)

	seen := make(map[string]struct{}, len(models))
	families := make([]string, 0, len(models))
	for _, modelID := range models {
		canonical := probe.CanonicalModelFamily(modelID)
		if canonical == "" {
			continue
		}
		if _, ok := seen[canonical]; ok {
			continue
		}
		seen[canonical] = struct{}{}
		families = append(families, canonical)
	}
	return families, nil
}

func normalizeRunItemAccessStatus(raw string) batch.AccessStatus {
	switch strings.TrimSpace(raw) {
	case string(batch.AccessStatusActive):
		return batch.AccessStatusActive
	case string(batch.AccessStatusDegraded):
		return batch.AccessStatusDegraded
	case string(batch.AccessStatusBroken):
		return batch.AccessStatusBroken
	default:
		return batch.AccessStatusUnknown
	}
}

func normalizeLegacyBatchAccessStatus(raw string) batch.AccessStatus {
	switch strings.TrimSpace(raw) {
	case "subscription_ready", "self_service_ready", "fully_ready":
		return batch.AccessStatusActive
	case "degraded":
		return batch.AccessStatusDegraded
	case "broken":
		return batch.AccessStatusBroken
	default:
		return batch.AccessStatusUnknown
	}
}

func normalizeLegacyMatchedAccountState(accountStatus string, batchAccessStatus string) batch.MatchedAccountState {
	if normalizeLegacyBatchAccessStatus(batchAccessStatus) == batch.AccessStatusBroken {
		return batch.MatchedAccountStateBroken
	}

	switch strings.TrimSpace(accountStatus) {
	case "passed", "warning":
		return batch.MatchedAccountStateActive
	case "disabled":
		return batch.MatchedAccountStateDisabled
	case "deprecated":
		return batch.MatchedAccountStateDeprecated
	case "failed":
		return batch.MatchedAccountStateBroken
	default:
		return batch.MatchedAccountStateNone
	}
}

func accountIDFromProbeSummary(summaryJSON string) (string, error) {
	if strings.TrimSpace(summaryJSON) == "" {
		return "", nil
	}
	var payload map[string]any
	if err := json.Unmarshal([]byte(summaryJSON), &payload); err != nil {
		return "", err
	}
	accountID, _ := payload["account_id"].(string)
	return strings.TrimSpace(accountID), nil
}

func resolveManagedAccountNumericID(accountHostID string, resources []sqlite.ManagedResource) int64 {
	accountHostID = strings.TrimSpace(accountHostID)
	if accountHostID == "" {
		return 0
	}
	if numericID, err := strconv.ParseInt(accountHostID, 10, 64); err == nil && numericID > 0 {
		return numericID
	}
	for _, resource := range resources {
		if strings.TrimSpace(resource.ResourceType) != "account" {
			continue
		}
		if strings.TrimSpace(resource.HostResourceID) == accountHostID {
			return resource.ID
		}
	}
	return 0
}

func apiKeyFingerprintMatches(stored string, lookup string) bool {
	stored = normalizeFingerprint(stored)
	lookup = normalizeFingerprint(lookup)
	if stored == "" || lookup == "" {
		return false
	}
	if stored == lookup {
		return true
	}
	return strings.HasPrefix(stored, lookup) || strings.HasPrefix(lookup, stored)
}

func normalizeFingerprint(raw string) string {
	trimmed := strings.TrimSpace(raw)
	if trimmed == "" {
		return ""
	}
	return strings.TrimPrefix(trimmed, "sha256:")
}

func parseStringArrayJSON(raw string) []string {
	values := []string{}
	if strings.TrimSpace(raw) == "" {
		return values
	}
	if err := json.Unmarshal([]byte(raw), &values); err != nil {
		return []string{}
	}
	return values
}

func cloneStringMap(input map[string]string) map[string]string {
	if len(input) == 0 {
		return map[string]string{}
	}
	cloned := make(map[string]string, len(input))
	for key, value := range input {
		cloned[key] = value
	}
	return cloned
}

func int64Ptr(value int64) *int64 {
	if value <= 0 {
		return nil
	}
	cloned := value
	return &cloned
}