package ui

import (
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"

	"github.com/gmgauthier/gralculator/internal/calc"
)

// flashMsg and clearFlashMsg for timed visual feedback (140ms style from gostations).
type flashMsg struct{ which string }
type clearFlashMsg struct{ which string }

// tick returns a command that sends a flash clear after the given duration.
func tick(d time.Duration, which string) tea.Cmd {
	return tea.Tick(d, func(_ time.Time) tea.Msg {
		return clearFlashMsg{which: which}
	})
}

// App is the root Bubble Tea model.
// This is the focused rendering spike for the two-row display + single BASE keypad.
type App struct {
	engine *calc.Engine
	width  int
	height int

	// flash state for key actions and CERR
	flash     string // "base", "cerr", "op", etc.
	cerrFlash bool
}

func NewApp() *App {
	return &App{
		engine: calc.NewEngine(),
	}
}

func (a *App) Init() tea.Cmd { return nil }

func (a *App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		a.width = msg.Width
		a.height = msg.Height

	case flashMsg:
		a.flash = msg.which
		if msg.which == "cerr" {
			a.cerrFlash = true
		}
		return a, tick(140*time.Millisecond, msg.which)

	case clearFlashMsg:
		if msg.which == "cerr" {
			a.cerrFlash = false
		}
		if a.flash == msg.which {
			a.flash = ""
		}
		return a, nil

	case tea.KeyMsg:
		switch msg.String() {
		case "q", "ctrl+c", "esc":
			return a, tea.Quit

		case "tab":
			if err := a.engine.CycleBase(); err == calc.ErrConversionNotPossible {
				a.flash = "cerr"
				a.cerrFlash = true
				return a, tick(600*time.Millisecond, "cerr")
			}
			a.flash = "base"
			return a, tick(140*time.Millisecond, "base")

		case "c", "C":
			a.engine.ClearEntry()
			a.flash = "clear"
			return a, tick(140*time.Millisecond, "clear")

		case "backspace":
			a.engine.Backspace()

		case ".":
			a.engine.EnterDecimalPoint()

		case "+", "-", "*", "/":
			a.engine.SetOperator(msg.String())
			a.flash = "op"
			return a, tick(140*time.Millisecond, "op")

		case "m", "M": // MOD as immediate for convenience in spike
			a.engine.Mod()
			a.flash = "op"
			return a, tick(140*time.Millisecond, "op")

		case "=", "enter":
			a.engine.Equals()
			a.flash = "eq"
			return a, tick(140*time.Millisecond, "eq")

		case "0", "1", "2", "3", "4", "5", "6", "7", "8", "9":
			a.engine.EnterDigit(rune(msg.String()[0]))

		case "ac", "ctrl+l": // All Clear
			a.engine.AllClear()
			a.flash = "clear"
			return a, tick(140*time.Millisecond, "clear")
		}
	}
	return a, nil
}

func (a *App) View() string {
	// Styles (reusing gostations idioms: 63 for accents/flashes, 238 subtle borders, 46 green LCD, 235 bg)
	outer := lipgloss.NewStyle().
		Border(lipgloss.RoundedBorder()).
		BorderForeground(lipgloss.Color("63")).
		Padding(1, 2)

	lcd := lipgloss.NewStyle().
		Background(lipgloss.Color("235")).
		Foreground(lipgloss.Color("46")).
		Border(lipgloss.NormalBorder()).
		BorderForeground(lipgloss.Color("238")).
		Padding(1, 2).
		Align(lipgloss.Right)

	smallRow := lipgloss.NewStyle().
		Foreground(lipgloss.Color("245")).
		Align(lipgloss.Center)

	flashStyle := lipgloss.NewStyle().
		Foreground(lipgloss.Color("15")).
		Background(lipgloss.Color("63")).
		Bold(true).
		Align(lipgloss.Center)

	// Large number area (tall for "big font" weight)
	num := a.engine.FormatForDisplay()
	if a.cerrFlash {
		num = "CERR"
	}
	large := lcd.Height(5).Render(num)

	// Small bottom row — only the current base
	curBase := string(a.engine.CurrentBase())
	if a.flash == "base" {
		curBase = flashStyle.Render(curBase)
	} else {
		curBase = smallRow.Render(curBase)
	}
	small := lcd.Height(1).Render(curBase)

	display := lipgloss.JoinVertical(lipgloss.Center, large, small)

	// Minimal keypad grid (text cells for the spike; real button cells can be expanded)
	btn := func(s string) string {
		st := lipgloss.NewStyle().Width(5).Align(lipgloss.Center).Padding(0, 1)
		if a.flash != "" && s == "BASE" {
			return flashStyle.Width(5).Align(lipgloss.Center).Padding(0, 1).Render(s)
		}
		return st.Render(s)
	}

	row1 := lipgloss.JoinHorizontal(lipgloss.Top, btn("7"), btn("8"), btn("9"), btn("/"), btn("MOD"))
	row2 := lipgloss.JoinHorizontal(lipgloss.Top, btn("4"), btn("5"), btn("6"), btn("*"), btn("C"))
	row3 := lipgloss.JoinHorizontal(lipgloss.Top, btn("1"), btn("2"), btn("3"), btn("-"), btn("AC"))
	row4 := lipgloss.JoinHorizontal(lipgloss.Top, btn("0"), btn("."), btn("+/-"), btn("+"), btn("="))
	rowBase := lipgloss.JoinHorizontal(lipgloss.Top, "          ", btn("BASE"), "          ")

	grid := lipgloss.JoinVertical(lipgloss.Left, row1, row2, row3, row4, rowBase)

	// Hint (minimal, non-wrapping, like gostations final player)
	hint := lipgloss.NewStyle().Faint(true).Render("Tab:BASE  0-9 . = + - * / m:MOD  c:C  ac:AC  q:quit")

	inner := lipgloss.JoinVertical(lipgloss.Left,
		lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("63")).Render("gralculator"),
		"",
		display,
		"",
		grid,
		"",
		hint,
	)

	// Center the whole card (content-sized, not stretched)
	card := outer.Render(inner)
	return lipgloss.Place(a.width, a.height, lipgloss.Center, lipgloss.Center, card)
}

// Run is a convenience for main.go (spike).
func Run() error {
	p := tea.NewProgram(NewApp(), tea.WithAltScreen())
	_, err := p.Run()
	return err
}