package tetris

import (
	"context"
	"fmt"
	"strings"
	"time"

	tea "github.com/charmbracelet/bubbletea"

	"code.t-juice.club/torjus/oubliette/internal/shell"
)

type screen int

const (
	screenTitle screen = iota
	screenGame
	screenGameOver
)

type tickMsg time.Time
type lockMsg time.Time

const lockDelay = 500 * time.Millisecond

type model struct {
	sess       *shell.SessionContext
	difficulty string
	screen     screen
	game       *gameState
	quitting   bool
	height     int
	keypresses int
	locking    bool // true when piece has landed and lock delay is active
}

func newModel(sess *shell.SessionContext, difficulty string) *model {
	return &model{
		sess:       sess,
		difficulty: difficulty,
		screen:     screenTitle,
	}
}

func (m *model) Init() tea.Cmd {
	return nil
}

func (m *model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	if m.quitting {
		return m, tea.Quit
	}

	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.height = msg.Height
		return m, nil
	case tea.KeyMsg:
		m.keypresses++
		if msg.Type == tea.KeyCtrlC {
			m.quitting = true
			return m, tea.Batch(
				logAction(m.sess, fmt.Sprintf("QUIT score=%d level=%d lines=%d keys=%d", m.gameScore(), m.gameLevel(), m.gameLines(), m.keypresses), "SESSION ENDED"),
				tea.Quit,
			)
		}
	}

	switch m.screen {
	case screenTitle:
		return m.updateTitle(msg)
	case screenGame:
		return m.updateGame(msg)
	case screenGameOver:
		return m.updateGameOver(msg)
	}

	return m, nil
}

func (m *model) View() string {
	var content string
	switch m.screen {
	case screenTitle:
		content = m.titleView()
	case screenGame:
		content = gameView(m.game)
	case screenGameOver:
		content = m.gameOverView()
	}

	return gameFrame(content, m.height)
}

// --- Title screen ---

func (m *model) titleView() string {
	var b strings.Builder
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("  ████████╗███████╗████████╗██████╗ ██╗███████╗"))
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("  ╚══██╔══╝██╔════╝╚══██╔══╝██╔══██╗██║██╔════╝"))
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("     ██║   █████╗     ██║   ██████╔╝██║███████╗"))
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("     ██║   ██╔══╝     ██║   ██╔══██╗██║╚════██║"))
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("     ██║   ███████╗   ██║   ██║  ██║██║███████║"))
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("     ╚═╝   ╚══════╝   ╚═╝   ╚═╝  ╚═╝╚═╝╚══════╝"))
	b.WriteString("\n\n")
	b.WriteString(baseStyle.Render("  Press any key to start"))
	b.WriteString("\n")
	return b.String()
}

func (m *model) updateTitle(msg tea.Msg) (tea.Model, tea.Cmd) {
	if _, ok := msg.(tea.KeyMsg); ok {
		m.screen = screenGame
		var startLevel int
		if m.difficulty == "hard" {
			startLevel = 5
		}
		m.game = newGame(startLevel)
		return m, tea.Batch(
			tea.ClearScreen,
			m.scheduleTick(),
			logAction(m.sess, "GAME START", fmt.Sprintf("difficulty=%s", m.difficulty)),
		)
	}
	return m, nil
}

// --- Game screen ---

func (m *model) scheduleTick() tea.Cmd {
	ms := tickInterval(m.game.level)
	if m.difficulty == "easy" {
		ms = max(1000-m.game.level*60, 150)
	}
	return tea.Tick(time.Duration(ms)*time.Millisecond, func(t time.Time) tea.Msg {
		return tickMsg(t)
	})
}

func (m *model) scheduleLock() tea.Cmd {
	return tea.Tick(lockDelay, func(t time.Time) tea.Msg {
		return lockMsg(t)
	})
}

// performLock locks the piece, clears lines, and returns commands for logging
// and scheduling the next tick. Returns nil if game over (goToGameOver is
// included in the returned batch).
func (m *model) performLock() tea.Cmd {
	m.locking = false
	cleared := m.game.afterLock()
	if m.game.gameOver {
		return tea.Batch(
			logAction(m.sess, fmt.Sprintf("GAME OVER score=%d level=%d lines=%d keys=%d", m.game.score, m.game.level, m.game.lines, m.keypresses), "GAME OVER"),
			m.goToGameOver(),
		)
	}
	var cmds []tea.Cmd
	cmds = append(cmds, m.scheduleTick())
	if cleared > 0 {
		cmds = append(cmds, logAction(m.sess, fmt.Sprintf("LINES %d score=%d", cleared, m.game.score), fmt.Sprintf("total=%d", m.game.lines)))
		prevLevel := (m.game.lines - cleared) / 10
		if m.game.level > prevLevel {
			cmds = append(cmds, logAction(m.sess, fmt.Sprintf("LEVEL UP %d", m.game.level), fmt.Sprintf("score=%d", m.game.score)))
		}
	}
	return tea.Batch(cmds...)
}

func (m *model) updateGame(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case lockMsg:
		if m.game.gameOver || !m.locking {
			return m, nil
		}
		// Lock delay expired — lock the piece now.
		return m, m.performLock()

	case tickMsg:
		if m.game.gameOver || m.locking {
			return m, nil
		}
		if !m.game.moveDown() {
			// Piece landed — start lock delay instead of locking immediately.
			m.locking = true
			return m, m.scheduleLock()
		}
		return m, m.scheduleTick()

	case tea.KeyMsg:
		if m.game.gameOver {
			return m, nil
		}

		switch msg.String() {
		case "left":
			m.game.moveLeft()
			// If piece can now drop further, cancel lock delay.
			if m.locking && m.game.canPlace(m.game.current, m.game.currentRot, m.game.currentRow+1, m.game.currentCol) {
				m.locking = false
			}
		case "right":
			m.game.moveRight()
			if m.locking && m.game.canPlace(m.game.current, m.game.currentRot, m.game.currentRow+1, m.game.currentCol) {
				m.locking = false
			}
		case "down":
			if m.game.moveDown() {
				m.game.score++ // soft drop bonus
				if m.locking {
					m.locking = false
				}
			}
		case "up", "z":
			m.game.rotate()
			if m.locking && m.game.canPlace(m.game.current, m.game.currentRot, m.game.currentRow+1, m.game.currentCol) {
				m.locking = false
			}
		case " ":
			m.locking = false
			dropped := m.game.hardDrop()
			m.game.score += dropped * 2
			return m, m.performLock()
		case "q":
			m.quitting = true
			return m, tea.Batch(
				logAction(m.sess, fmt.Sprintf("QUIT score=%d level=%d lines=%d keys=%d", m.game.score, m.game.level, m.game.lines, m.keypresses), "PLAYER QUIT"),
				tea.Quit,
			)
		}
		return m, nil
	}

	return m, nil
}

// --- Game over screen ---

func (m *model) goToGameOver() tea.Cmd {
	m.screen = screenGameOver
	return tea.ClearScreen
}

func (m *model) gameOverView() string {
	var b strings.Builder
	b.WriteString("\n")
	b.WriteString(titleStyle.Render("  GAME OVER"))
	b.WriteString("\n\n")
	b.WriteString(baseStyle.Render(fmt.Sprintf("  Score: %s", formatScore(m.game.score))))
	b.WriteString("\n")
	b.WriteString(baseStyle.Render(fmt.Sprintf("  Level: %d", m.game.level)))
	b.WriteString("\n")
	b.WriteString(baseStyle.Render(fmt.Sprintf("  Lines: %d", m.game.lines)))
	b.WriteString("\n\n")
	b.WriteString(dimStyle.Render("  R - Play again"))
	b.WriteString("\n")
	b.WriteString(dimStyle.Render("  Q - Quit"))
	b.WriteString("\n")
	return b.String()
}

func (m *model) updateGameOver(msg tea.Msg) (tea.Model, tea.Cmd) {
	if keyMsg, ok := msg.(tea.KeyMsg); ok {
		switch keyMsg.String() {
		case "r":
			startLevel := 0
			if m.difficulty == "hard" {
				startLevel = 5
			}
			m.game = newGame(startLevel)
			m.screen = screenGame
			m.keypresses = 0
			return m, tea.Batch(
				tea.ClearScreen,
				m.scheduleTick(),
				logAction(m.sess, "RESTART", fmt.Sprintf("difficulty=%s", m.difficulty)),
			)
		case "q":
			m.quitting = true
			return m, tea.Batch(
				logAction(m.sess, fmt.Sprintf("QUIT score=%d level=%d lines=%d keys=%d", m.game.score, m.game.level, m.game.lines, m.keypresses), "PLAYER QUIT"),
				tea.Quit,
			)
		}
	}
	return m, nil
}

// Helper methods for safe access when game may be nil.
func (m *model) gameScore() int {
	if m.game != nil {
		return m.game.score
	}
	return 0
}

func (m *model) gameLevel() int {
	if m.game != nil {
		return m.game.level
	}
	return 0
}

func (m *model) gameLines() int {
	if m.game != nil {
		return m.game.lines
	}
	return 0
}

// logAction returns a tea.Cmd that logs an action to the session store.
func logAction(sess *shell.SessionContext, input, output string) tea.Cmd {
	return func() tea.Msg {
		if sess.Store != nil {
			ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
			defer cancel()
			_ = sess.Store.AppendSessionLog(ctx, sess.SessionID, input, output)
		}
		if sess.OnCommand != nil {
			sess.OnCommand("tetris")
		}
		return nil
	}
}