package main

import (
	"time"

	tea "github.com/charmbracelet/bubbletea"
)

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch m.mode {
	case monthView:
		return m.updateMonthView(msg)
	case hourlyView:
		return m.updateHourlyView(msg)
	default:
		return m, nil
	}
}

func (m model) updateMonthView(msg tea.Msg) (tea.Model, tea.Cmd) {
	firstDay := time.Date(m.year, time.Month(m.monthIndex+1), 1, 0, 0, 0, 0, time.UTC)
	m.startOffset = int(firstDay.Weekday())
	m.daysInMonth = time.Date(m.year, time.Month(m.monthIndex+2), 0, 0, 0, 0, 0, time.UTC).Day()

	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "ctrl+c", "q":
			return m, tea.Quit
		case "a": // Previous month
			if m.monthIndex == 0 {
				m.monthIndex = 11
				m.year--
			} else {
				m.monthIndex--
			}

			first := time.Date(m.year, time.Month(m.monthIndex+1), 1, 0, 0, 0, 0, time.UTC)
			offset := int(first.Weekday())

			m.startOffset = offset
			m.daysInMonth = time.Date(m.year, time.Month(m.monthIndex+2), 0, 0, 0, 0, 0, time.UTC).Day()

			m.cursorRow = offset / numCols
			m.cursorCol = offset % numCols

			return m, nil
		case "d": // Next month
			if m.monthIndex == 11 {
				m.monthIndex = 0
				m.year++
			} else {
				m.monthIndex++
			}

			first := time.Date(m.year, time.Month(m.monthIndex+1), 1, 0, 0, 0, 0, time.UTC)
			offset := int(first.Weekday())

			m.startOffset = offset
			m.daysInMonth = time.Date(m.year, time.Month(m.monthIndex+2), 0, 0, 0, 0, 0, time.UTC).Day()

			m.cursorRow = offset / numCols
			m.cursorCol = offset % numCols

			return m, nil
		case "up":
			if m.cursorRow > 0 {
				m.cursorRow--
			}
		case "down":
			if m.cursorRow < numRows-1 {
				m.cursorRow++
			}
		case "left":
			if m.cursorCol > 0 {
				m.cursorCol--
			}
		case "right":
			if m.cursorCol < numCols-1 {
				m.cursorCol++
			}
		case "enter":
			// Calculate selected day based on cursor
			dayIndex := m.cursorRow*numCols + m.cursorCol
			if dayIndex >= m.startOffset && dayIndex < m.startOffset+m.daysInMonth {
				m.selectedDay = dayIndex - m.startOffset + 1
				m.hourCursor = 0
				m.mode = hourlyView
			}
		}

		// Clamp cursor to valid days
		dayIndex := m.cursorRow*numCols + m.cursorCol
		if dayIndex < m.startOffset || dayIndex >= m.startOffset+m.daysInMonth {
			m.cursorRow = m.startOffset / numCols
			m.cursorCol = m.startOffset % numCols
		}
		return m, nil
	default:
		return m, nil
	}
}

func (m model) updateHourlyView(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "esc":
			m.mode = monthView
			return m, nil
		case "ctrl+c", "q":
			return m, tea.Quit
		case "up":
			if m.hourCursor > 0 {
				m.hourCursor--
			}
		case "down":
			if m.hourCursor < 23 {
				m.hourCursor++
			}
		}
	}
	return m, nil
}