package discord

import (
	"bytes"
	"io"
	"strings"

	"plumber/internal/events"
)

const (
	embedTitleLimit       = 256
	embedDescriptionLimit = 4096
	threadNameLimit       = 100
	embedColor            = 0xe96a26
)

// Attachment is a local file Discord should upload with the message.
type Attachment struct {
	Name        string
	ContentType string
	Kind        string
	Reader      io.Reader
}

// Message is a Discord-ready snapshot of a site post event.
type Message struct {
	Title       string
	URL         string
	Description string
	City        string
	Author      string
	ImageURLs   []string
	VideoURLs   []string
	Files       []Attachment
	ThreadName  string
}

func formatMessage(ev events.PostEvent) Message {
	return formatCreated(events.PostCreated{PostEvent: ev})
}

func formatCreated(e events.PostCreated) Message {
	title := strings.TrimSpace(e.Title)
	if title == "" {
		title = "Reply"
	}
	author := strings.TrimSpace(e.AuthorName)
	if author == "" {
		author = "Someone"
	}
	msg := Message{
		Title:       truncateRunes(title, embedTitleLimit),
		URL:         strings.TrimSpace(e.Permalink),
		Description: truncateRunes(strings.TrimSpace(e.Body), embedDescriptionLimit),
		City:        strings.TrimSpace(e.City),
		Author:      author,
		ThreadName:  threadName(author, e.Title),
		Files:       filesFromMedia(e.Media),
	}
	for _, img := range e.Images {
		url := strings.TrimSpace(img.URL)
		if url == "" {
			continue
		}
		if img.Kind == "video" {
			msg.VideoURLs = append(msg.VideoURLs, url)
			continue
		}
		msg.ImageURLs = append(msg.ImageURLs, url)
	}
	return msg
}

func filesFromMedia(media []events.Media) []Attachment {
	if len(media) == 0 {
		return nil
	}
	files := make([]Attachment, 0, len(media))
	for _, m := range media {
		var r io.Reader
		switch {
		case len(m.Bytes) > 0:
			r = bytes.NewReader(m.Bytes)
		case m.Body != nil:
			r = m.Body
		default:
			continue
		}
		name := strings.TrimSpace(m.Name)
		if name == "" {
			name = "upload"
		}
		files = append(files, Attachment{
			Name:        name,
			ContentType: m.ContentType,
			Kind:        m.Kind,
			Reader:      r,
		})
	}
	return files
}

func threadName(author, title string) string {
	author = strings.TrimSpace(author)
	if author == "" {
		author = "Someone"
	}
	title = strings.TrimSpace(title)
	if title == "" {
		title = "Question"
	}
	return truncateRunes(author+" asks: "+title, threadNameLimit)
}

func truncateRunes(s string, max int) string {
	if max <= 0 {
		return ""
	}
	runes := []rune(s)
	if len(runes) <= max {
		return s
	}
	return string(runes[:max])
}

func isRoot(ev events.PostEvent) bool {
	return strings.TrimSpace(ev.ParentID) == ""
}

func messageContent(msg Message) string {
	var parts []string
	if body := strings.TrimSpace(msg.Description); body != "" {
		parts = append(parts, body)
	}
	var meta []string
	if msg.City != "" {
		meta = append(meta, msg.City)
	}
	if msg.Author != "" {
		meta = append(meta, msg.Author)
	}
	if len(meta) > 0 {
		parts = append(parts, strings.Join(meta, " · "))
	}
	if u := publicURL(msg.URL); u != "" {
		parts = append(parts, u)
	}
	if len(msg.Files) == 0 {
		for _, mediaURL := range msg.ImageURLs {
			if u := publicURL(mediaURL); u != "" {
				parts = append(parts, u)
			}
		}
		for _, mediaURL := range msg.VideoURLs {
			if u := publicURL(mediaURL); u != "" {
				parts = append(parts, u)
			}
		}
	}
	return truncateRunes(strings.Join(parts, "\n"), 2000)
}

func publicURL(raw string) string {
	raw = strings.TrimSpace(raw)
	if !strings.HasPrefix(raw, "https://") {
		return ""
	}
	if strings.Contains(raw, "localhost") || strings.Contains(raw, "127.0.0.1") {
		return ""
	}
	return raw
}