package views

import (
	"fmt"
	"strings"
	"time"

	"github.com/charmbracelet/lipgloss"

	"task/internal/ticket"
)

// ReportStyles holds styles for the report dialog.
type ReportStyles struct {
	Title    lipgloss.Style
	Group    lipgloss.Style
	Duration lipgloss.Style
	Total    lipgloss.Style
	Hint     lipgloss.Style
	Selected lipgloss.Style
}

// ReportView renders aggregated time entries.
type ReportView struct {
	Rows    []ticket.GroupRow
	Total   time.Duration
	GroupBy ticket.GroupBy
	Offset  int
	Cursor  int
	Width   int
	Height  int
	Styles  ReportStyles
}

// NewReportView builds a report view from aggregated rows.
func NewReportView(rows []ticket.GroupRow, total time.Duration, groupBy ticket.GroupBy, width, height int, styles ReportStyles) ReportView {
	return ReportView{
		Rows:    rows,
		Total:   total,
		GroupBy: groupBy,
		Width:   width,
		Height:  height,
		Styles:  styles,
	}
}

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

// MoveDown moves selection down.
func (r *ReportView) MoveDown() {
	if r.Cursor < len(r.Rows)-1 {
		r.Cursor++
		r.ensureVisible()
	}
}

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

// View renders the report.
func (r ReportView) View() string {
	title := r.Styles.Title.Render(fmt.Sprintf("Time report · by %s", r.GroupBy.Label()))
	hint := r.Styles.Hint.Render("g group · j/k scroll · esc back")

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

	visibleH := r.Height - 4 // title, blank, total, hint
	if visibleH < 1 {
		visibleH = 1
	}

	if len(r.Rows) == 0 {
		lines = append(lines, r.Styles.Hint.Render("No time entries yet"))
	} else {
		end := r.Offset + visibleH
		if end > len(r.Rows) {
			end = len(r.Rows)
		}
		for i := r.Offset; i < end; i++ {
			row := r.Rows[i]
			label := truncateOneLine(row.Label, max(8, innerW-14))
			dur := ticket.FormatDurationHuman(row.Duration)
			dots := dotsPad(label, dur, innerW)
			line := label + dots + dur
			if i == r.Cursor {
				line = r.Styles.Selected.Render(line)
			} else {
				line = r.Styles.Group.Render(label) + dots + r.Styles.Duration.Render(dur)
			}
			lines = append(lines, line)
		}
	}

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

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

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

func dotsPad(left, right string, width int) string {
	used := lipgloss.Width(left) + lipgloss.Width(right)
	n := width - used
	if n < 2 {
		return " "
	}
	return " " + strings.Repeat("·", n-2) + " "
}

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