package reports

import (
	"fmt"
	"sort"
	"strconv"
	"strings"
	"time"

	"evobgp/internal/store"
)

// RevisionDiagnosticLog is plain-text diagnostic output for a revision.
type RevisionDiagnosticLog struct {
	Body     []byte
	Filename string
}

// BuildRevisionDiagnosticLog aggregates revision prefixes by source and community.
func BuildRevisionDiagnosticLog(st store.Backend, tenantID string, rev *store.Revision) (*RevisionDiagnosticLog, error) {
	moduleType := ""
	moduleName := ""
	if strings.TrimSpace(rev.ModuleID) != "" {
		if mod, modErr := st.GetModule(tenantID, rev.ModuleID); modErr == nil && mod != nil {
			moduleType = strings.TrimSpace(mod.Type)
			moduleName = strings.TrimSpace(mod.Name)
		}
	}

	communityLabels := map[string]string{}
	if communities, listErr := st.ListCommunities(tenantID); listErr == nil {
		for _, c := range communities {
			if c == nil {
				continue
			}
			label := strings.TrimSpace(c.Title)
			if label == "" {
				label = strings.TrimSpace(c.Community)
			}
			if label == "" {
				label = c.ID
			}
			communityLabels[c.ID] = label
		}
	}

	type rawRow struct {
		Prefix         string
		Source         string
		Kind           string
		SourceName     string
		SourceDetail   string
		CommunityID    string
		CommunityLabel string
	}
	type summary struct {
		Kind           string
		Source         string
		SourceDetail   string
		CommunityID    string
		CommunityLabel string
		Count          int
		Sample         []string
	}

	cdnSourceURLByID := map[string]string{}
	if moduleType == "CDN_CIDRS" && strings.TrimSpace(rev.ModuleID) != "" {
		if sources, srcErr := st.ListCDNSources(tenantID, rev.ModuleID); srcErr == nil {
			for _, src := range sources {
				if src == nil {
					continue
				}
				id := strings.TrimSpace(src.ID)
				url := strings.TrimSpace(src.URL)
				if id != "" && url != "" {
					cdnSourceURLByID[id] = url
				}
			}
		}
	}

	rows := make([]rawRow, 0, rev.MaterializedPrefixCount)
	byGroup := map[string]*summary{}
	cursor := ""
	for {
		page, next, more := st.ListRevisionPrefixes(tenantID, rev.ID, cursor, 2000)
		for _, p := range page {
			kind, sourceName := classifyRevisionSource(p.Source)
			sourceDetail := sourceName
			if kind == "cdn" {
				if url, ok := cdnSourceURLByID[sourceName]; ok && strings.TrimSpace(url) != "" {
					sourceDetail = url
				}
			}
			communityID := "none"
			if p.CommunityID != nil && strings.TrimSpace(*p.CommunityID) != "" {
				communityID = strings.TrimSpace(*p.CommunityID)
			}
			communityLabel := "без community"
			if communityID != "none" {
				if lbl, ok := communityLabels[communityID]; ok && strings.TrimSpace(lbl) != "" {
					communityLabel = lbl
				} else {
					communityLabel = communityID
				}
			}
			rows = append(rows, rawRow{
				Prefix:         p.Prefix,
				Source:         p.Source,
				Kind:           kind,
				SourceName:     sourceName,
				SourceDetail:   sourceDetail,
				CommunityID:    communityID,
				CommunityLabel: communityLabel,
			})
			groupKey := kind + "|" + sourceName + "|" + communityID
			g, ok := byGroup[groupKey]
			if !ok {
				g = &summary{
					Kind:           kind,
					Source:         sourceName,
					SourceDetail:   sourceDetail,
					CommunityID:    communityID,
					CommunityLabel: communityLabel,
					Sample:         make([]string, 0, 5),
				}
				byGroup[groupKey] = g
			}
			g.Count++
			if len(g.Sample) < 5 {
				g.Sample = append(g.Sample, p.Prefix)
			}
		}
		if !more || strings.TrimSpace(next) == "" {
			break
		}
		cursor = next
	}

	summaryKeys := make([]string, 0, len(byGroup))
	for k := range byGroup {
		summaryKeys = append(summaryKeys, k)
	}
	sort.Strings(summaryKeys)

	sort.Slice(rows, func(i, j int) bool {
		if rows[i].Kind != rows[j].Kind {
			return rows[i].Kind < rows[j].Kind
		}
		if rows[i].SourceName != rows[j].SourceName {
			return rows[i].SourceName < rows[j].SourceName
		}
		if rows[i].CommunityID != rows[j].CommunityID {
			return rows[i].CommunityID < rows[j].CommunityID
		}
		return rows[i].Prefix < rows[j].Prefix
	})

	var b strings.Builder
	b.WriteString("EvoBGP revision diagnostic log\n")
	b.WriteString("generated_at=" + time.Now().UTC().Format(time.RFC3339Nano) + "\n")
	b.WriteString("tenant_id=" + tenantID + "\n")
	b.WriteString("revision_id=" + rev.ID + "\n")
	b.WriteString("revision_created_at=" + rev.CreatedAt.UTC().Format(time.RFC3339Nano) + "\n")
	b.WriteString("content_hash=" + rev.ContentHash + "\n")
	b.WriteString("materialized_prefix_count=" + strconv.Itoa(rev.MaterializedPrefixCount) + "\n")
	if rev.ModuleID != "" {
		b.WriteString("module_id=" + rev.ModuleID + "\n")
	} else {
		b.WriteString("module_id=\n")
	}
	b.WriteString("module_type=" + moduleType + "\n")
	b.WriteString("module_name=" + moduleName + "\n")
	b.WriteString("fetched_rows=" + strconv.Itoa(len(rows)) + "\n\n")

	b.WriteString("## Aggregation by source and community\n")
	for _, k := range summaryKeys {
		g := byGroup[k]
		b.WriteString("- kind=" + g.Kind +
			" source=" + g.Source +
			" source_detail=" + g.SourceDetail +
			" community_id=" + g.CommunityID +
			" community_label=" + g.CommunityLabel +
			" count=" + strconv.Itoa(g.Count))
		if len(g.Sample) > 0 {
			b.WriteString(" sample=" + strings.Join(g.Sample, ","))
		}
		b.WriteByte('\n')
	}

	b.WriteString("\n## Raw rows\n")
	b.WriteString("prefix\tkind\tsource\tsource_detail\tcommunity_id\tcommunity_label\n")
	for _, row := range rows {
		b.WriteString(row.Prefix)
		b.WriteByte('\t')
		b.WriteString(row.Kind)
		b.WriteByte('\t')
		b.WriteString(row.Source)
		b.WriteByte('\t')
		b.WriteString(strings.ReplaceAll(row.SourceDetail, "\t", " "))
		b.WriteByte('\t')
		b.WriteString(row.CommunityID)
		b.WriteByte('\t')
		b.WriteString(strings.ReplaceAll(row.CommunityLabel, "\t", " "))
		b.WriteByte('\n')
	}

	filename := fmt.Sprintf("revision-%s-diagnostic.log", shortRevisionID(rev.ID))
	return &RevisionDiagnosticLog{Body: []byte(b.String()), Filename: filename}, nil
}

func classifyRevisionSource(src string) (kind, sourceName string) {
	switch {
	case strings.HasPrefix(src, "as:"):
		return "asn", strings.TrimPrefix(src, "as:")
	case strings.HasPrefix(src, "domain:"):
		return "domain", strings.TrimPrefix(src, "domain:")
	case strings.HasPrefix(src, "cdn:"):
		return "cdn", strings.TrimPrefix(src, "cdn:")
	case src == "ip_range":
		return "ip_range", "manual_ranges"
	default:
		if strings.TrimSpace(src) == "" {
			return "unknown", "unknown"
		}
		return "source", strings.TrimSpace(src)
	}
}

func shortRevisionID(id string) string {
	s := strings.TrimSpace(id)
	if len(s) <= 8 {
		return s
	}
	return s[:8]
}