package main

import (
	"fmt"
	"os"
	"os/exec"
	"os/signal"
	"strconv"
	"strings"
	"time"

	"github.com/charmbracelet/bubbles/progress"
	"github.com/charmbracelet/bubbles/textinput"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
	"github.com/urfave/cli/v2"
)

type screen int

var version = "dev"

const (
	inputScreen screen = iota
	timerScreen
)

type model struct {
	focusIndex    int
	inputs        []textinput.Model
	progressBar   progress.Model
	state         string
	intervalNum   int
	timer         *time.Timer
	remaining     time.Duration
	totalTime     time.Duration
	currentScreen screen
	intervals     int
	breakTime     time.Duration
	focusTime     time.Duration
	onFocusStart  []string
	onFocusEnd    []string
	onIntervalEnd []string
	isFocus       bool
	fullscreen    bool
	width         int
	height        int
	err           error
}

func initialModel(fullscreen bool, colorLeft string, colorRight string) model {
	numInputs := 3
	inputs := make([]textinput.Model, numInputs)

	// Set up text input models for interval length, break length, and total intervals
	for i := range inputs {
		inputs[i] = textinput.New()
		inputs[i].CharLimit = 10 // Increase char limit to allow duration strings

		if i == 0 {
			inputs[i].Focus() // Start focus on first input
		}
	}

	validateDuration := func(text string) error {
		_, err := parseDuration(text)
		return err
	}

	validateInt := func(text string) error {
		if _, err := strconv.Atoi(text); err != nil {
			return fmt.Errorf("invalid int input: %w", err)
		}

		return nil
	}

	inputs[0].Placeholder = "Interval length (minutes or duration)"
	inputs[0].Validate = validateDuration
	inputs[1].Placeholder = "Break length (minutes or duration)"
	inputs[1].Validate = validateDuration
	inputs[2].Placeholder = "Number of intervals"
	inputs[2].Validate = validateInt

	if colorLeft == "" || colorRight == "" {
		panic("Color values must be provided")
	}

	return model{
		inputs:        inputs,
		progressBar:   progress.New(progress.WithScaledGradient(colorLeft, colorRight)),
		state:         "stopped",
		intervalNum:   1,
		remaining:     0,
		totalTime:     0,
		currentScreen: inputScreen, // Start on input screen
		isFocus:       true,
		fullscreen:    fullscreen,
	}
}

func (m model) Init() tea.Cmd {
	// Handle Ctrl+C for graceful exit
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)

	go func() {
		<-c
		fmt.Println("\nExiting...")
		os.Exit(0)
	}()

	return tea.Batch(tea.WindowSize(), textinput.Blink)
}

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "ctrl+c", "esc":
			// Gracefully exit
			return m, tea.Quit

		case "q":
			// Quit the program if on the timer screen
			if m.currentScreen == timerScreen {
				return m, tea.Quit
			}

		case "tab", "ctrl+n", "j", "down":
			// Move to the next input field
			m.focusIndex = (m.focusIndex + 1) % len(m.inputs)
			m.updateFocus()

			return m, nil

		case "shift+tab", "ctrl+p", "k", "up":
			// Move to the previous input field
			m.focusIndex = (m.focusIndex - 1 + len(m.inputs)) % len(m.inputs)
			m.updateFocus()

			return m, nil

		case "enter":
			if m.currentScreen == inputScreen {
				// Handle inputs and move to the timer screen
				if m.focusIndex == len(m.inputs)-1 {
					focusTime, err := parseDuration(m.inputs[0].Value())
					if err != nil {
						m.err = fmt.Errorf("error parsing focus time duration: %w", err)
						return m, nil
					}

					breakTime, err := parseDuration(m.inputs[1].Value())
					if err != nil {
						m.err = fmt.Errorf("error parsing break time duration: %w", err)
						return m, nil
					}

					m.intervals, err = strconv.Atoi(m.inputs[2].Value())
					if err != nil {
						m.err = fmt.Errorf("error parsing interval: %w", err)
						return m, nil
					}

					m.focusTime = focusTime
					m.breakTime = breakTime
					m.remaining = focusTime
					m.totalTime = focusTime
					m.state = "Focus"
					m.timer = time.NewTimer(time.Second)
					m.currentScreen = timerScreen

					// Run onFocusStart commands
					m.runCommands(m.onFocusStart)

					return m, tick()
				} else {
					// Move to next input field
					m.focusIndex++
					m.updateFocus()
				}
			}
		}

	case timeMsg:
		// Handle timer update for each second
		// TODO: Use absolute times to tick down remaining time rather than incrementing seconds
		m.remaining -= time.Second
		if m.remaining < 0 {
			if m.isFocus {
				// Focus period ends, switch to break
				m.isFocus = false
				m.remaining = m.remaining + m.breakTime
				m.totalTime = m.breakTime
				m.state = "Break"

				// Run onFocusEnd commands
				m.runCommands(m.onFocusEnd)
			} else {
				// Break ends, switch back to focus or next interval
				m.isFocus = true
				m.intervalNum++
				m.runCommands(m.onIntervalEnd)

				if m.intervalNum > m.intervals {
					// All intervals completed
					return m, tea.Quit
				}

				m.remaining = m.remaining + m.focusTime
				m.totalTime = m.focusTime
				m.state = "Focus"

				// Run onFocusStart commands
				m.runCommands(m.onFocusStart)
			}

			return m, tick()
		}

		return m, tick()

	case tea.WindowSizeMsg:
		m.width = msg.Width
		m.height = msg.Height
	}

	// Update text inputs
	cmds := make([]tea.Cmd, len(m.inputs))
	for i := range m.inputs {
		m.inputs[i], cmds[i] = m.inputs[i].Update(msg)
	}

	return m, tea.Batch(cmds...)
}

// Tick every second
type timeMsg time.Time

func tick() tea.Cmd {
	return tea.Tick(time.Second, func(t time.Time) tea.Msg {
		return timeMsg(t)
	})
}

// View rendering for input and timer screens
func (m model) View() string {
	var s strings.Builder

	switch m.currentScreen {
	case inputScreen:
		s.WriteString(m.inputScreenView())
	case timerScreen:
		s.WriteString(m.timerScreenView())
	}

	if m.err != nil {
		s.WriteString(fmt.Sprintf("\n\nError: %v", m.err))
	}

	return s.String()
}

// View for input screen
func (m model) inputScreenView() string {
	var builder strings.Builder

	builder.WriteString("Enter your Pomodoro settings:\n\n")

	for i := range m.inputs {
		builder.WriteString(m.inputs[i].View())

		if m.inputs[i].Value() != "" && m.inputs[i].Err != nil {
			builder.WriteString(fmt.Sprintf("Error: %v", m.inputs[i].Err))
		}

		builder.WriteString("\n")
	}

	builder.WriteString("\nUse TAB to navigate, ENTER to start.")

	return builder.String()
}

// View for timer screen with optional fullscreen centering
func (m model) timerScreenView() string {
	if m.fullscreen {
		progressBarPadding := 5
		m.progressBar.Width = m.width - progressBarPadding
	}

	progressView := m.progressBar.ViewAs(float64(m.totalTime-m.remaining) / float64(m.totalTime))
	status := lipgloss.NewStyle().Bold(true).Render(fmt.Sprintf("State: %s", m.state))
	intervalInfo := fmt.Sprintf("Interval: %d / %d", m.intervalNum, m.intervals)
	timeLeft := fmt.Sprintf("Time left: %s", m.remaining.String())

	timerView := fmt.Sprintf("%s\n%s\n%s\n\n%s", status, intervalInfo, timeLeft, progressView)

	if m.fullscreen {
		return lipgloss.NewStyle().Width(m.width).Height(m.height).Align(lipgloss.Center, lipgloss.Center).Render(timerView)
	}

	return timerView
}

// Helper to update input focus
func (m *model) updateFocus() {
	for i := range m.inputs {
		if i == m.focusIndex {
			m.inputs[i].Focus()
		} else {
			m.inputs[i].Blur()
		}
	}
}

// Helper to run shell commands
func (m *model) runCommands(commands []string) {
	for _, cmdStr := range commands {
		cmd := exec.Command("sh", "-c", cmdStr)
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr

		if err := cmd.Run(); err != nil {
			fmt.Printf("Error running command: %v\n", err)
		}
	}
}

// Helper to parse duration or treat an integer as minutes
func parseDuration(input string) (time.Duration, error) {
	if minutes, err := strconv.Atoi(input); err == nil {
		return time.Duration(minutes) * time.Minute, nil
	}

	d, err := time.ParseDuration(input)
	if err != nil {
		return d, fmt.Errorf("error parsing duration: %w", err)
	}

	return d, nil
}

func main() {
	// Set up CLI app
	app := &cli.App{
		Name:  "Gomodoro",
		Usage: "A Pomodoro timer with customizable shell commands",
		Flags: []cli.Flag{
			&cli.StringSliceFlag{
				Name:  "on-focus-start",
				Usage: "Command(s) to run when focus starts",
			},
			&cli.StringSliceFlag{
				Name:  "on-focus-end",
				Usage: "Command(s) to run when focus ends",
			},
			&cli.StringSliceFlag{
				Name:  "on-interval-end",
				Usage: "Command(s) to run when any interval ends",
			},
			&cli.BoolFlag{
				Name:  "fullscreen",
				Usage: "Enable fullscreen mode",
			},
			&cli.DurationFlag{
				Name:        "focus",
				Usage:       "Focus time duration",
				DefaultText: "prompt for input",
			},
			&cli.DurationFlag{
				Name:        "break",
				Usage:       "Break time duration",
				DefaultText: "prompt for input",
			},
			&cli.IntFlag{
				Name:        "intervals",
				Usage:       "Number of intervals",
				DefaultText: "prompt for input",
			},
			&cli.StringFlag{
				Name:  "color-left",
				Usage: "Left color for progress bar",
				Value: "#ffdd57",
			},
			&cli.StringFlag{
				Name:  "color-right",
				Usage: "Right color for progress bar",
				Value: "#57ddff",
			},
			&cli.BoolFlag{
				Name:  "version",
				Usage: "Show version",
			},
		},
		Action: func(c *cli.Context) error {
			if c.Bool("version") {
				fmt.Println(version)
				return nil
			}

			fmt.Printf("color-left: %s\n", c.String("color-left"))
			fmt.Printf("color-right: %s\n", c.String("color-right"))

			m := initialModel(c.Bool("fullscreen"), c.String("color-left"), c.String("color-right"))

			// Collect command flags
			m.onFocusStart = c.StringSlice("on-focus-start")
			m.onFocusEnd = c.StringSlice("on-focus-end")
			m.onIntervalEnd = c.StringSlice("on-interval-end")

			// Set focus, break, and interval values if provided
			if c.Duration("focus").String() != "0s" {
				m.inputs[0].SetValue(c.String("focus"))
			}
			if c.Duration("break").String() != "0s" {
				m.inputs[1].SetValue(c.String("break"))
			}
			if c.Int("intervals") != 0 {
				m.inputs[2].SetValue(c.String("intervals"))
			}

			// Start tea program

			options := []tea.ProgramOption{}
			if m.fullscreen {
				options = append(options, tea.WithAltScreen())
			}
			p := tea.NewProgram(m, options...)
			if _, err := p.Run(); err != nil {
				return fmt.Errorf("error running program: %w", err)
			}

			return nil
		},
	}

	err := app.Run(os.Args)
	if err != nil {
		fmt.Println("Error:", err)
	}
}