package views

import (
	"fmt"
	"strings"

	"github.com/charmbracelet/lipgloss"

	"task/internal/ticket"
)

// CollapsedCardHeight is the fixed row height for non-expanded cards
// (single content line; left accent border adds no vertical space).
const CollapsedCardHeight = 1

// TicketListStyles holds styles for card rendering.
type TicketListStyles struct {
	Card         lipgloss.Style
	CardSelected lipgloss.Style
	StatusOPEN   lipgloss.Style
	StatusWIP    lipgloss.Style
	StatusDONE   lipgloss.Style
	Headline     lipgloss.Style
}

// TicketList is a custom viewport list of ticket cards.
type TicketList struct {
	Items  []ticket.Ticket
	Cursor int
	Offset int
	Width  int
	Height int
	Styles TicketListStyles
}

// SetSize updates the viewport dimensions.
func (l *TicketList) SetSize(width, height int) {
	l.Width = width
	l.Height = height
	l.ensureVisible()
}

// SetItems replaces the ticket list, clamping the cursor.
func (l *TicketList) SetItems(items []ticket.Ticket) {
	l.Items = items
	if l.Cursor >= len(l.Items) {
		l.Cursor = max(0, len(l.Items)-1)
	}
	l.Offset = 0
	l.ensureVisible()
}

// Selected returns the currently selected ticket and whether one exists.
func (l *TicketList) Selected() (ticket.Ticket, bool) {
	if len(l.Items) == 0 || l.Cursor < 0 || l.Cursor >= len(l.Items) {
		return ticket.Ticket{}, false
	}
	return l.Items[l.Cursor], true
}

// CursorIndex returns the current cursor.
func (l *TicketList) CursorIndex() int { return l.Cursor }

// Len returns the number of tickets.
func (l *TicketList) Len() int { return len(l.Items) }

// MoveDown moves the cursor down.
func (l *TicketList) MoveDown() {
	if l.Cursor < len(l.Items)-1 {
		l.Cursor++
		l.ensureVisible()
	}
}

// MoveUp moves the cursor up.
func (l *TicketList) MoveUp() {
	if l.Cursor > 0 {
		l.Cursor--
		l.ensureVisible()
	}
}

// Select sets the cursor to idx if in range.
func (l *TicketList) Select(idx int) {
	if idx < 0 || idx >= len(l.Items) {
		return
	}
	l.Cursor = idx
	l.ensureVisible()
}

// View renders only the visible ticket cards.
func (l *TicketList) View() string {
	if l.Height < 1 {
		return ""
	}
	if len(l.Items) == 0 {
		empty := lipgloss.NewStyle().Faint(true).Render("No tickets — press n to create one")
		return lipgloss.NewStyle().Width(l.Width).Height(l.Height).Render(empty)
	}

	var visible []string
	used := 0
	for i := l.Offset; i < len(l.Items); i++ {
		card := l.renderCard(l.Items[i], i == l.Cursor)
		h := lipgloss.Height(card)
		if used > 0 && used+h > l.Height {
			break
		}
		visible = append(visible, card)
		used += h
	}

	body := lipgloss.JoinVertical(lipgloss.Left, visible...)
	return lipgloss.NewStyle().Width(l.Width).Height(l.Height).MaxHeight(l.Height).Render(body)
}

func (l *TicketList) renderCard(t ticket.Ticket, selected bool) string {
	innerWidth := max(10, l.Width-4)

	badge := l.statusBadge(t.Status)
	headline := truncateOneLine(plainHeadline(t.Title), max(8, innerWidth-lipgloss.Width(badge)-2))
	headerLine := badge + " " + l.Styles.Headline.Render(headline)

	var content string
	if selected {
		// Expanded: headline + glamour-rendered description (fixed dark style).
		desc := strings.TrimSpace(t.Description)
		if desc != "" {
			content = headerLine + "\n" + RenderMarkdown(desc, innerWidth)
		} else {
			content = headerLine
		}
	} else {
		content = headerLine
	}

	style := l.Styles.Card
	if selected {
		style = l.Styles.CardSelected
	}
	return style.Width(max(4, l.Width-2)).Render(content)
}

func (l *TicketList) statusBadge(s ticket.Status) string {
	label := fmt.Sprintf(" %s ", s.Label())
	switch s {
	case ticket.StatusInProgress:
		return l.Styles.StatusWIP.Render(label)
	case ticket.StatusDone:
		return l.Styles.StatusDONE.Render(label)
	default:
		return l.Styles.StatusOPEN.Render(label)
	}
}

func (l *TicketList) ensureVisible() {
	if len(l.Items) == 0 {
		l.Offset = 0
		return
	}
	if l.Cursor < l.Offset {
		l.Offset = l.Cursor
		return
	}

	for {
		used := 0
		fits := false
		for i := l.Offset; i < len(l.Items); i++ {
			h := l.estimateHeight(i)
			if used > 0 && used+h > l.Height {
				break
			}
			used += h
			if i == l.Cursor {
				fits = true
				break
			}
		}
		if fits || l.Offset >= l.Cursor {
			break
		}
		l.Offset++
	}
}

// estimateHeight avoids full glamour for collapsed cards.
func (l *TicketList) estimateHeight(index int) int {
	if index < 0 || index >= len(l.Items) {
		return CollapsedCardHeight
	}
	if index == l.Cursor && strings.TrimSpace(l.Items[index].Description) != "" {
		return lipgloss.Height(l.renderCard(l.Items[index], true))
	}
	return CollapsedCardHeight
}

// FilterTickets returns tickets matching query in title or description.
func FilterTickets(tickets []ticket.Ticket, query string) []ticket.Ticket {
	q := strings.ToLower(strings.TrimSpace(query))
	if q == "" {
		return tickets
	}
	var out []ticket.Ticket
	for _, t := range tickets {
		if strings.Contains(strings.ToLower(t.Title), q) ||
			strings.Contains(strings.ToLower(t.Description), q) {
			out = append(out, t)
		}
	}
	return out
}

func plainHeadline(title string) string {
	title = strings.TrimSpace(title)
	title = strings.TrimLeft(title, "#")
	return strings.TrimSpace(title)
}

func truncateOneLine(s string, maxWidth int) string {
	if maxWidth <= 0 {
		return ""
	}
	if lipgloss.Width(s) <= maxWidth {
		return s
	}
	runes := []rune(s)
	for len(runes) > 0 {
		runes = runes[:len(runes)-1]
		if lipgloss.Width(string(runes)) <= maxWidth-1 {
			return string(runes) + "…"
		}
	}
	return ""
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}