package nostr

import (
	"fmt"
	"strings"

	"github.com/nbd-wtf/go-nostr"
)

// IndexEvent represents a kind 30040 publication index event (NKBIP-01)
type IndexEvent struct {
	Event      *nostr.Event
	Title      string
	DTag       string
	Author     string
	Items      []IndexItem
	AutoUpdate string
	Type       string
	Version    string
	Summary    string
	Image      string
}

// IndexItem represents an item in a publication index (from 'a' tags)
type IndexItem struct {
	Kind      int
	Pubkey    string
	DTag      string
	RelayHint string
	EventID   string // Optional event ID for version tracking
}

// ParseIndexEvent parses an index event according to NKBIP-01
func ParseIndexEvent(event *nostr.Event, expectedKind int) (*IndexEvent, error) {
	if event.Kind != expectedKind {
		return nil, fmt.Errorf("expected kind %d, got %d", expectedKind, event.Kind)
	}

	index := &IndexEvent{
		Event:  event,
		Author: event.PubKey,
	}

	// Extract d tag
	var dTag string
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "d" && len(tag) > 1 {
			dTag = tag[1]
			break
		}
	}
	index.DTag = dTag

	// Extract title
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "title" && len(tag) > 1 {
			index.Title = tag[1]
			break
		}
	}

	// Extract 'a' tags (index items)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "a" && len(tag) > 1 {
			// Format: ["a", "<kind:pubkey:dtag>", "<relay hint>", "<event id>"]
			ref := tag[1]
			parts := strings.Split(ref, ":")
			if len(parts) >= 3 {
				var kind int
				fmt.Sscanf(parts[0], "%d", &kind)
				item := IndexItem{
					Kind:      kind,
					Pubkey:    parts[1],
					DTag:      parts[2],
					RelayHint: "",
					EventID:   "",
				}
				if len(tag) > 2 {
					item.RelayHint = tag[2]
				}
				if len(tag) > 3 {
					item.EventID = tag[3]
				}
				index.Items = append(index.Items, item)
			}
		}
	}

	// Extract auto-update tag
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "auto-update" && len(tag) > 1 {
			index.AutoUpdate = tag[1]
			break
		}
	}

	// Extract type tag
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "type" && len(tag) > 1 {
			index.Type = tag[1]
			break
		}
	}

	// Extract version tag
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "version" && len(tag) > 1 {
			index.Version = tag[1]
			break
		}
	}

	// Extract summary tag
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "summary" && len(tag) > 1 {
			index.Summary = tag[1]
			break
		}
	}

	// Extract image tag
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "image" && len(tag) > 1 {
			index.Image = tag[1]
			break
		}
	}

	return index, nil
}

// WikiEvent represents a kind 30818 wiki event (NIP-54)
type WikiEvent struct {
	Event   *nostr.Event
	DTag    string
	Title   string
	Summary string
	Content string
}

// ParseWikiEvent parses a wiki event according to NIP-54
func ParseWikiEvent(event *nostr.Event, expectedKind int) (*WikiEvent, error) {
	if event.Kind != expectedKind {
		return nil, fmt.Errorf("expected kind %d, got %d", expectedKind, event.Kind)
	}

	wiki := &WikiEvent{
		Event:   event,
		Content: event.Content,
	}

	// Extract d tag (normalized identifier)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "d" && len(tag) > 1 {
			wiki.DTag = tag[1]
			break
		}
	}

	// Extract title tag (optional, falls back to d tag)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "title" && len(tag) > 1 {
			wiki.Title = tag[1]
			break
		}
	}
	if wiki.Title == "" {
		wiki.Title = wiki.DTag
	}

	// Extract summary tag (optional)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "summary" && len(tag) > 1 {
			wiki.Summary = tag[1]
			break
		}
	}

	return wiki, nil
}

// BlogEvent represents a kind 30041 blog event
type BlogEvent struct {
	Event   *nostr.Event
	DTag    string
	Title   string
	Summary string
	Content string
}

// ParseBlogEvent parses a blog event
func ParseBlogEvent(event *nostr.Event, expectedKind int) (*BlogEvent, error) {
	if event.Kind != expectedKind {
		return nil, fmt.Errorf("expected kind %d, got %d", expectedKind, event.Kind)
	}

	blog := &BlogEvent{
		Event:   event,
		Content: event.Content,
	}

	// Extract d tag (normalized identifier)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "d" && len(tag) > 1 {
			blog.DTag = tag[1]
			break
		}
	}

	// Extract title tag (optional, falls back to d tag)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "title" && len(tag) > 1 {
			blog.Title = tag[1]
			break
		}
	}
	if blog.Title == "" {
		blog.Title = blog.DTag
	}

	// Extract summary tag (optional)
	for _, tag := range event.Tags {
		if len(tag) > 0 && tag[0] == "summary" && len(tag) > 1 {
			blog.Summary = tag[1]
			break
		}
	}

	return blog, nil
}

// NormalizeDTag normalizes a d tag according to NIP-54 rules
func NormalizeDTag(dTag string) string {
	// Convert to lowercase
	dTag = strings.ToLower(dTag)

	// Convert whitespace to hyphens
	dTag = strings.ReplaceAll(dTag, " ", "-")
	dTag = strings.ReplaceAll(dTag, "\t", "-")
	dTag = strings.ReplaceAll(dTag, "\n", "-")

	// Remove punctuation and symbols (keep alphanumeric, hyphens, and non-ASCII)
	var result strings.Builder
	for _, r := range dTag {
		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-' || r > 127 {
			result.WriteRune(r)
		}
	}
	dTag = result.String()

	// Collapse multiple consecutive hyphens
	for strings.Contains(dTag, "--") {
		dTag = strings.ReplaceAll(dTag, "--", "-")
	}

	// Remove leading and trailing hyphens
	dTag = strings.Trim(dTag, "-")

	return dTag
}