package views

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

	"github.com/charmbracelet/lipgloss"

	"task/internal/ticket"
)

// TimeEntriesStyles holds styles for the time-entry list.
type TimeEntriesStyles struct {
	Title    lipgloss.Style
	Row      lipgloss.Style
	Selected lipgloss.Style
	Meta     lipgloss.Style
	Total    lipgloss.Style
	Hint     lipgloss.Style
	Empty    lipgloss.Style
}

// TimeEntriesView lists time entries for one ticket.
type TimeEntriesView struct {
	TicketTitle string
	Entries     []ticket.TimeEntry
	Total       time.Duration
	Cursor      int
	Offset      int
	Width       int
	Height      int
	Styles      TimeEntriesStyles
}

// NewTimeEntriesView builds a sorted (newest first) entry list.
func NewTimeEntriesView(title string, entries []ticket.TimeEntry, width, height int, styles TimeEntriesStyles) TimeEntriesView {
	cp := append([]ticket.TimeEntry(nil), entries...)
	sort.Slice(cp, func(i, j int) bool {
		return cp[i].Start.After(cp[j].Start)
	})
	var total time.Duration
	for _, e := range cp {
		total += e.Duration
	}
	v := TimeEntriesView{
		TicketTitle: title,
		Entries:     cp,
		Total:       total,
		Width:       width,
		Height:      height,
		Styles:      styles,
	}
	v.ensureVisible()
	return v
}

// SetSize updates viewport size.
func (v *TimeEntriesView) SetSize(width, height int) {
	v.Width = width
	v.Height = height
	v.ensureVisible()
}

// Selected returns the highlighted entry.
func (v TimeEntriesView) Selected() (ticket.TimeEntry, bool) {
	if len(v.Entries) == 0 || v.Cursor < 0 || v.Cursor >= len(v.Entries) {
		return ticket.TimeEntry{}, false
	}
	return v.Entries[v.Cursor], true
}

// Len returns the number of entries.
func (v TimeEntriesView) Len() int { return len(v.Entries) }

// MoveDown moves selection down.
func (v *TimeEntriesView) MoveDown() {
	if v.Cursor < len(v.Entries)-1 {
		v.Cursor++
		v.ensureVisible()
	}
}

// MoveUp moves selection up.
func (v *TimeEntriesView) MoveUp() {
	if v.Cursor > 0 {
		v.Cursor--
		v.ensureVisible()
	}
}

// View renders the list.
func (v TimeEntriesView) View() string {
	title := strings.TrimSpace(v.TicketTitle)
	if title == "" {
		title = "ticket"
	}
	head := v.Styles.Title.Render(fmt.Sprintf("Time entries · %s", truncateOneLine(title, max(8, v.Width-20))))
	hint := v.Styles.Hint.Render("j/k navigate · e edit · x delete · esc back")

	innerW := max(20, v.Width-2)
	var lines []string
	lines = append(lines, head, "")

	visibleH := v.Height - 4
	if visibleH < 1 {
		visibleH = 1
	}

	if len(v.Entries) == 0 {
		lines = append(lines, v.Styles.Empty.Render("No time entries for this ticket"))
	} else {
		end := v.Offset + visibleH
		if end > len(v.Entries) {
			end = len(v.Entries)
		}
		for i := v.Offset; i < end; i++ {
			line := formatEntryLine(v.Entries[i], innerW)
			if i == v.Cursor {
				line = v.Styles.Selected.Render(line)
			} else {
				line = v.Styles.Row.Render(line)
			}
			lines = append(lines, line)
		}
	}

	for len(lines) < visibleH+2 {
		lines = append(lines, "")
	}

	totalLabel := "Total"
	totalDur := ticket.FormatDurationHuman(v.Total)
	totalLine := totalLabel + dotsPad(totalLabel, totalDur, innerW) + totalDur
	lines = append(lines, v.Styles.Total.Render(totalLine), hint)

	body := strings.Join(lines, "\n")
	return lipgloss.NewStyle().Width(v.Width).Height(v.Height).Render(body)
}

func formatEntryLine(e ticket.TimeEntry, width int) string {
	when := e.Start.Local().Format("2006-01-02 15:04")
	if e.Start.IsZero() {
		when = "—"
	}
	dur := ticket.FormatDurationHuman(e.Duration)
	src := e.Source
	if src == "" {
		src = "?"
	}
	left := when + "  ·  " + dur + "  ·  " + src
	return truncateOneLine(left, width)
}

func (v *TimeEntriesView) ensureVisible() {
	if len(v.Entries) == 0 {
		v.Offset = 0
		v.Cursor = 0
		return
	}
	if v.Cursor < 0 {
		v.Cursor = 0
	}
	if v.Cursor >= len(v.Entries) {
		v.Cursor = len(v.Entries) - 1
	}
	visibleH := v.Height - 4
	if visibleH < 1 {
		visibleH = 1
	}
	if v.Cursor < v.Offset {
		v.Offset = v.Cursor
	}
	if v.Cursor >= v.Offset+visibleH {
		v.Offset = v.Cursor - visibleH + 1
	}
	if v.Offset < 0 {
		v.Offset = 0
	}
}