package tickets

import (
	"fmt"
	"strings"

	"velox-bot/internal/db/repos/ticketrepo"

	"github.com/bwmarrin/discordgo"
)

// maxTranscriptMessages bounds how far back a transcript reads: 50 pages of
// 100, far beyond any normal ticket.
const maxTranscriptMessages = 5000

// Transcript renders the whole thread as plain text, oldest first, and
// reports how many messages it holds. Attachments and embeds are listed so
// the log keeps their links and titles.
func Transcript(d Discord, t *ticketrepo.Ticket) ([]byte, int, error) {
	var msgs []*discordgo.Message
	before := ""
	var fetchErr error
	for len(msgs) < maxTranscriptMessages {
		page, err := d.ChannelMessages(id(t.ThreadID), 100, before, "", "")
		if err != nil {
			fetchErr = err
			break
		}
		msgs = append(msgs, page...)
		if len(page) < 100 {
			break
		}
		before = page[len(page)-1].ID
	}

	var b strings.Builder
	fmt.Fprintf(&b, "Ticket #%04d · %s\n", t.Number, t.CategoryName)
	fmt.Fprintf(&b, "Subject: %s\n", t.Subject)
	fmt.Fprintf(&b, "Opened by user %d on %s\n", t.OpenerID, t.CreatedAt.UTC().Format("2006-01-02 15:04 MST"))
	if fetchErr != nil {
		fmt.Fprintf(&b, "Note: only part of the thread could be read (%v)\n", fetchErr)
	}
	b.WriteString(strings.Repeat("-", 60) + "\n\n")

	// Discord returns newest first.
	for i := len(msgs) - 1; i >= 0; i-- {
		writeMessage(&b, msgs[i])
	}
	return []byte(b.String()), len(msgs), fetchErr
}

func writeMessage(b *strings.Builder, m *discordgo.Message) {
	name := "unknown"
	if m.Author != nil {
		name = m.Author.Username
		if m.Author.GlobalName != "" {
			name = m.Author.GlobalName + " (" + m.Author.Username + ")"
		}
		if m.Author.Bot {
			name += " [bot]"
		}
	}
	fmt.Fprintf(b, "[%s] %s\n", m.Timestamp.UTC().Format("2006-01-02 15:04"), name)

	if content := strings.TrimSpace(m.Content); content != "" {
		for _, line := range strings.Split(content, "\n") {
			b.WriteString("    " + line + "\n")
		}
	}
	for _, e := range m.Embeds {
		if e == nil {
			continue
		}
		title := e.Title
		if title == "" {
			title = clip(e.Description, 120)
		}
		if title != "" {
			b.WriteString("    [embed] " + strings.ReplaceAll(title, "\n", " ") + "\n")
		}
	}
	for _, a := range m.Attachments {
		if a != nil {
			b.WriteString("    [file] " + a.Filename + " " + a.URL + "\n")
		}
	}
	b.WriteString("\n")
}